SUB-COMMITTEE ON STABILITY AND LOAD LINES AND ON FISHING VESSELS

Document Sample
SUB-COMMITTEE ON STABILITY AND LOAD LINES AND ON FISHING VESSELS Powered By Docstoc
					SUB-COMMITTEE ON STABILITY AND                                                         SLF 54/**/**
LOAD LINES AND ON FISHING VESSELS
                                                                                                2011
SAFETY
                                                                                Original : ENGLISH
54th session
Agenda item **


         DEVELOPMENT OF GUIDELINES FOR VERIFICATION OF DAMAGE
      STABILITY REQUIREMENTS FOR OIL, CHEMICAL AND GAS TANKERS AND
                             BULK CARRIERS


      Development of guidelines for the verification of damage stability on oil, chemical and
                                           gas tankers


                            Report of the SLF Correspondence Group




    1        The correspondence group established by the SLF Sub-Committee, at its fifty-third
    session, established the correspondence group on Guidelines for Verification of Damage
    Stability Requirements for Tankers (SLF 53/19, paragraph 8.5) under agenda item 53/8 has
    considered the terms of reference drawn up by the drafting group during the intercessional
    period, under the co-ordinationed by of the United Kingdom.


    2     The correspondence group comprised participants from the following Member
    Governments :


               BRAZIL                                         PORTUGAL
               CHINA                                          SPAIN
               COOK ISLANDS                                   SWEDEN
               FINLAND                                        UNITED KINGDOM
               GERMANY                                        UNITED STATES OF AMERICA
               JAPAN


    Contributions were also received from the following inter-governmental organisation :


               EMSA


    and from the following non-governmental organisations :


               IACS                                           IPTA
               ICS                                            OCIMF
        INTERTANKO                                      SIGTTO


Terms of Reference


   3       The terms of reference for the correspondence group are set out in the report of
   the drafting group (SLF 53/WP.7), instructed the group to :document SLF 53/19,
   paragraph 8.5.


          .1 identify existing IMO instruments and relevant references relating to the issue
          of verification of damage stability requirements, taking into account the outcome
          of the SDS Working Group at SLF 53;


          .2 identify any ambiguities in the existing requirements and consider the need for
          clarifications and/or make recommendations for amendments to mandatory
          instruments;


          .3 develop draft Guidelines for the verification of damage stability requirements
          for tankers, addressing design and operational issues, using documents SLF
          53/INF.9 and SLF 53/8 as base documents;


          .4 consider whether demonstration of verification to third parties should be
          addressed in the draft Guidelines and, if so, include appropriate text;


          .5 consider, when developing the above draft Guidelines, in particular the
          following points:


                  .1 scope of the draft Guidelines;


                  .2 clarification of what is meant by loaded in accordance with an
                  approved condition, whether any deviations are allowed and, if so, to
                  what extent;


                  .3 methods of verification of compliance, such as stability software,
                  stability booklet, shore assistance, KGf/GMf curves and conditions for
                  use of these methods; and


                  .4 clarification of the terms and conditions for use of stability software
                  and documentation which demonstrates that the software is appropriate
                  for its purpose;


          .6 advise on any other relevant issues raised in the course of the group's
          discussion; and
            .7 submit a report to SLF 54.


Identify existing IMO instruments and relevant references relating to the issue of
verification of damage stability requirements, taking into account the outcome of the
SDS Working Group at SLF 53


4        The correspondence group has given consideration to this instruction and has
identified the list of IMO instruments and other relevant references attached at Annex A, as
these apply to damage stability of oil, chemical and gas tankers.


Identify any ambiguities in the existing requirements and consider the need for
clarifications and/or make recommendations for amendments to mandatory instruments


5        The correspondence group has given consideration to this instruction and proposes
the amendments to mandatory instruments attached at Annex B, to improve clarity and to
standardise the application of damage stability requirements between oil, chemical and gas
tankers.


Develop draft Guidelines for the verification of damage stability requirements for
tankers, addressing design and operational issues, using documents SLF 53/INF.9 and
SLF 53/8 as base documents


6       The correspondence group has given consideration to this instruction and has further
developed draft operational and technical guidelines relating to damage stability verification
for tankers, based upon the specified documents. The draft Gguidelines are separated into two
three sections parts and are attached at Annex C.


Consider whether demonstration of verification to third parties should be addressed in
the draft Guidelines and, if so, include appropriate text


7        The correspondence group has concluded that it is desirable for guidance to be given
in relation to acceptable means of demonstrating damage stability verification and compliance
to third parties, including Port State Control Inspectors.


8       Guidance for reference by tankers crew and third parties, including Port State Control
Inspectors, has been included within Section B of Part 31 of the draft Operational Guidelines
attached at Annex C.


Consider in particular the scope of the draft Guidelines


9        The draft Guidelines have been developed to address the immediate need for
guidance on existing oil, chemical and gas tankers to which the latest revisions of the Intact
Stability Code, SOLAS and IACS URL5 do not apply, and in particular, the specific
requirement to be able to verify damage stability compliance prior to departure.
10     Guidance on the correct loading and operation of existing tankers within the
mandatory instruments which apply to them is unclear, and is also seen to be inconsistent
between the different types of vessel under consideration.


11     The report of the correspondence group includes proposals for amendment of existing
instruments to reduce these present ambiguities, at Annex B.


12       The technical guidance proposed in Part 1 of the draft Guidelines is only expected to
apply to new vessels, should they be adopted. However, the correspondence group
recommends due regard is paid to the guidance in Part 1 in any approval of new stability
calculations or stability programs undertaken for existing vessels, in order to avoid a
separation of standards between the two.


1113 In particular, new calculations should not repeat errors or omissions made in previous
approvals where these errors or omissions were contrary to the provisions of the relevant
instruments or the guidance proposed in this document.


12It is further considered thatConversely, the operational guidanadvice contained in Part 21      Formatted: Bullets and Numbering
of the draft uidelinesGuidelines applies equally to both new and existing vessels, as the
technical standards applied by the relevant instruments are the same for both and it is only
being soughtthe intention of the correspondence group to harmonise the guidance on
application between them.


13Conversely, the technical guidance in Part 2 of the draft uidelines is only expected to apply   Formatted: Bullets and Numbering
only to new vessels, should they be adopted. However, it is recommended that due regard is
paid to the guidance in Part 2 in any approval of new stability programs retro-fitted on
existing vessels, in order to avoid a separation of standards between the two.


14     In particular, new approvals should not repeat errors or omissions made in previous
approvals where these errors or omissions were contrary to the provisions of the relevant
instruments.


Consider in particular clarification of what is meant by loaded “in accordance with” an
approved condition, whether any deviations are allowed and, if so, to what extent


15       The correspondence group has given consideration to this issue and has noted the
content of the note included in sections 57 and 75 respectively of the model forms of
International Certificate of Fitness for the carriage of chemicals and liquefied gases and
chemicals in bulk.


16      It is the opinion of the correspondence group that, unless otherwise provided for (for
example by the use of approved critical KG/GM curves or loading within defined limitations
authorised in an attachment to a Certificate of Fitness), a vessel must load only in accordance
with approved cargo loading conditions from the approved intact stability information, each
of which have been verified as compliant with both intact and damage stability provisions of
the applicable international instruments during the certification process.


17       Members of the correspondence group expressed a range of opinion whether or not
any variation in loading from the approved cargo loading conditions is permitted. In this
respect the following observations weare made :


            a. If no variation is permissible permitted from an approved cargo loading
               condition the approval process becomes redundant as it shall not be possible
               to maintain compliance with any approved cargo loading condition beyond
               the immediate point of departure or arrival considered, due to the variation
               caused by consumption of fuel, water and provisions, and the possibility
               consequences of ballasting during the voyage.
            b. If it is necessary to maintain full intact and damage stability compliance
               throughout a voyage, it shall be necessary to approve additional loading
               conditions which consider consumption of fuel and stores, and possible
               counter-ballasting, during voyages of all possible durations, and this is not
               common practice.
            c. Existing guidance requires pessimistic consideration of free surface when
               preparing cargo loading conditions for approval, to allow for the possibility
               of free surfaces occurring during the consumption of consumables or transfer
               of ballast, and these loading conditions may not necessarily occur in practice.
               If no variation is permissible from such an approved cargo loading condition,
               these approved cargo loading conditions would be invalidated as a basis for
               loading.
            d. Existing guidance on drafting of stability information for approval provides
               for the preparation of standardised loading conditions with consumables
               arranged in “100% departure”, “50% departure” and “10% arrival”
               distributions cargo loading conditions for approval, but there is no certainty
               that a vessel will depart or arrive at port in the 100% condition or arrive in
               port in the 10% conditionwith these assumed distributions.


18       It is the conclusion of the correspondence group that the standardised cargo loading
conditions included in the approved stability information are accorded special status as
“approved loading conditions” and that the vessel should strive to load as closely as possible
to the departure condition and to arrive as close as possible to the arrival condition., with the
provision that . Further stability checks may not be required when transiting between these
approved loading conditions is permissible without further stability checks being made unless
there is a substantial change anticipated in the distribution of ballast or other loading during
the voyage, in which case suitable intermediate conditions should be derived and included in
the approved stability information.


19      In striving to load as closely as possible to an approved loading condition so as to be
considered to be loaded “in accordance with” that condition, the correspondence groupit is
further considereded that some variation in the loading of cargo and ballast tanks shall beis
permissible to account for minor variations in cargo filling level and and seawater SG from
those considered in the approved loading condition under consideration.
20      In this respect the correspondence groupit is concluded that in order to be loaded “in
accordance with” an approved loading condition the permissible variation in [the content of
any individual cargo or ballast tank should be no more than [1% or ] or [2%] or 3% or 5%] by
weight] from that assumed in the approved loading condition being replicated, and [the
condition KGfKG should not exceed that of the approved loading condition by more than
2cm or the condition GMfGM fall below that of the approved loading condition by more than
2cm].


21      Provided the approved loading condition which is being loaded is approved for both
100% departure and 10% arrival capacity of consumables and stores, the correspondence
group it is further concluded by the correspondence group that the approval of this condition
covers departure from or arrival at port with any level of consumables between 100% and
10% without the requirement to make a. F further verification of the stability may not be
required, provided that the cargo and ballast capacity does not change during the voyage or
that such changes are covered by suitable intermediate approved loading conditions.


Consider in particular methods of verification of compliance, such as stability software,
stability booklet, shore assistance, KGfKG/GMfGM curves and conditions for use of
these methods


22       The correspondence group considered the various available methods of verification of
compliance with damage stability requirements. During this consideration it was noted that
eExisting international instruments provide for the approved stability information to be the
definitive guidance to the master for determining adequacy of stability and that. Pprovided
that a vessel is loaded in accordance with” an approved loading condition from the approved
stability information, (as described in paragraphs [15 to 21] above) no further verification of
stability is required.]


23Approval of a range of loading conditions with variation of cargo SG or cargo distribution      Formatted: Bullets and Numbering
within approved stability information does not confer the ability to load all other possible
combinations of cargo SG and/or distribution of cargo without the need for further
verification of stability, particularly when significant variations in ballasting and condition
draught and trim are also taken into account.


2423 In support of this conclusion tThe correspondence group considered that guidance on
verification of compliance should clarify s that it is not acceptable to carrycarriage of a
loading distribution for of a particular SG cargo which was rejected for inclusionis not
considered directly[, or within an approved range of loading conditions,] in the approved
stability information during initial approval process, as it was found toprovided on board may
be non-compliant with damage stability requirements, even if another distribution of the same
SG cargo was subsequentlyis approved and included in the approved stability information.


2524 To promote flexibility of operation, and to permit conditions of loading other than
approved loading conditions from the approved stability information to be employed,
additional means for stability verification of such loading conditions is required. Such means
may include The correspondence group considered the use of critical GMfGM/KGfKG data,
where these are approved during the initial approval of stability information and supporting
damage stability calculations, as a means to promote flexibility of operation and to permit
conditions of loading other than approved loading conditions from the approved stability
information to be employed.. [The correspondence group concluded that loading conditions
verified as compliant with damage stability through application of approved critical KG/GM
data should be regarded as approved loading conditions.]


25      The correspondence group noted that cCritical GMfGM/KGfKG data may be derived
for compliance with both intact and damaged stability requirements, and that all conditions of
loading must meet both limits. The group further recalled existing guidance in MSC/Circ.920
which advises that stability information should include limiting curves for both intact and
damaged stability where these are available.


26      TIhe correspondence group concluded that operational guidance on the use of critical        Formatted: Bullets and Numbering
KG/GM data should emphasise thatt is not permissible to use verification against critical
intact GMfGM/KGfKG data in isolation, where this data is provided in the approved stability
information, as compliance with critical damage GMfGM/KGfKG data must also be
demonstrated. .


2726 Critical GMf/KGf data may not be used to verify stability unless approved damaged              Formatted: Bullets and Numbering
GMf/KGf data are provided. Where such approved data are available, it is recommended that
the approved stability information should include a single combined set of critical data which
incorporates both intact and damaged stability.


2827 To assist production of critical damaged GMfGM/KGfKG data the correspondence
group recognised , it may have been necessary for the a designer or shipyard to make
assumptions in respect of the a loading condition or to apply initial limitations on the loading,
such as minimum or maximum filling levels or counter-ballasting of wing tanks outboard of
empty or part filled cargo tanks.


2928 The correspondence group concluded the operational guidelines should emphasise
that wWhere such initial assumptions or limitations are have been applied during the
derivation of critical damaged GMfGM/KGfKG data, these should be stated on the approved
critical data and the critical data should not be usapplied unless the live loading condition is
first verified as meeting these initial assumptions.


3029 The correspondence group also considered the use of stability software, and
concluded that fFlexibility of operation may also be increased if the live loading conditions is
are subject to direct verification for compliance with both intact and damaged stability, using
stabilitysuch software. In all such cases it isThe correspondence group recalled the
recommendedguidance contained in the addendum to MSC/Circ.456 that the application use
of such software on ships should may be authorised by the flag state, or recognised
organisation (RROO) acting on its behalf, for the verification of stability on board where this
is deemed to be desirable with any conditions imposed for its use.


3130 The correspondence group further recalled the recommendations contained in
MSC/Circ.891 and MSC.1/Circ.1229 in relation to Conditions forthe use of stability software
on board ships and the approval of stability instruments and considered that they may form
may a reasonabley basis include requirements for authorising the specification of theuse of
such software in relation to its accuracy, and its approval to an appropriate standard, the use
of verification checks to ensure its continued accuracy in service, and the maintenance of
appropriate records on board for examination during audits and inspections..


32Existing standards applied by IACS through unified requirement for load line URL5                 Formatted: Bullets and Numbering
provide for the approval of two types of stability software. Type 2 software, which is capable
of making an intact stability verification supplemented by damage stability verification using
stored critical damage GMf/KGf data, and Type 3 software which makes both intact and
damage stability verification by direct calculation. These standards are also reflectred in the
Intact Stability Code, Part B, Chapter 4.


3331 The correspondence group has considered the possibility of verification of stability
being undertaken ashore using critical GMfGM/KGfKG data or stability software, either at
the operators shore office or through subcontracted consultancy services.


32      The correspondence group concluded that shore based verification may be accepted
subject to its authorisation by the flag state (or RO acting on its behalf) and suitable
arrangements being made for the provision of records on board the vessel and at the operators
shore office for examination during ISM audits and inspections.


33       The correspondence group further considered that where verification is being
undertaken remotely, including by the flag state (or RO acting on its behalf) particular care
must be taken to ensure the transmission of data between the vessel and shore office is
reliable with regard to the ability to send and receive data when required and also to ensure all
relevant loading data is provided accurately.


34      The correspondence group concluded that as an additional safeguard, in the case             Formatted: Indent: Left: 0", First line: 0",
where verification is made remotely, the operational guidelines should recommend a cross            Numbered + Level: 1 + Numbering Style: 1, 2,
                                                                                                    3, … + Start at: 7 + Alignment: Left + Aligned
check is made between the predicted floating position of the vessel from the calculated             at: 0.25" + Tab after: 0.75" + Indent at:
loading condition and that of the vessel when observed from the quay.                               0.75", Tab stops: 0.5", List tab + Not at 0.75"
                                                                                                    Formatted: Bullets and Numbering

34       Shore based verification may be accepted subject to its authorisation by the flag state    Formatted: Bullets and Numbering
or RO and suitable arrangements being made for the provision of records on board the vessel
and at the operators shore office, for examination during audits and inspections as required. It
is considered that particular care must be taken in ensuring that the transmission of data
between the vessel and shore office is reliable with regard to both the ability to transmit data
when required and also to ensure that all relevant loading data is provided.
35
35In this respect it is considered that an additional safeguard which could be employed is to       Formatted: Bullets and Numbering
cross check the predicted floating position of the vessel from the calculated loading condition
with that of the vessel when observed from the quay. Any differences should be minimised by
cross-checking the input data.


Consider in particular clarification of the terms and conditions for use of stability
software and documentation which demonstrates that the software is appropriate for its
purpose
3635 Having considered the use of stability software for verification of intact and damaged
stability, on board or remotely ashore, as an alternative to loading only to approved loading
conditions, the correspondence group has agreed considered the following clarifications :


    1.      Use The need for use of stability software for verification of intact and damaged
            stability toshould be authorised by the Flag State or RO, and for a record of the
            authorisation should to be provided on board the vessel with any conditions
            which apply.


    2.      The need for the authorisation shall to include details of the specification of the
            stability software and any approval standard applied to by Flag State or RO
            requirement and for cs. Copies of software specification and approval
            documentation toshould be provided on board the vessel.


    3.      Unless otherwise providedThe need for, the authorisation shall to include specify
            details of any check calculations required to be undertaken to ensure the
            continued satisfactory operation of the stability software, and any records to be
            maintained.


    4.      The need for the authorisation shall includeto specify details of any records of
            stability verifications which are required to be maintained on board or ashore for
            audit and inspection purposes.


Advise on any other relevant issues raised in the course of the group's discussion


Approved variation in loading conditions




3736 Presently left blank for insertionsThe correspondence group has considered the
practicality of how a vessel may be loaded “in accordance with” an approved loading
condition which has been verified compliant with damage stability by the Flag State (or RO
acting on its behalf) and approved for inclusion in the approved stability information.


37      In considering this issue it is the conclusion of the correspondence group that loading
“in accordance with” an approved loading condition must allow for some variation in loading
to account for differences in minor deadweight items such as consumables, variations in SG
of cargo or sea water, and minor differences in tank filling levels from those stated in the
approved condition which is being loaded.


38       It is further concluded by the correspondence group that it is desirable for the
operational guidelines attached at Annex C to include limits on the maximum variation which
may be permitted from an approved loading condition before the vessel is no longer regarded
as being loaded “in accordance with” that loading condition, and details of the live loading
condition are required to be submitted to the Flag State (or RO acting on its behalf) for
individual approval. Such “default” limits have been proposed for the guidance of ships
officers, ship operators, flag and port states and port state control inspectors
39       In the course of its deliberations on this issue, the correspondence group has
expressed a desire that further consideration should be given to the approval of loading
conditions for inclusion in the approved stability information. In particular, it is proposed that
consideration should be given to evaluating individual loading conditions during the approval
process to determine the extent of variation which may occur before damage stability criteria
are no longer met.


3840 The correspondence group proposes that in place of the fixed “default” limits on
variation in loading presently included in the operational guidelines, each approved loading
condition would have a maximum variation defined during the approval process, and this
would be stated on the condition for the information of ships crew, port state control
inspectors and others and take precedence over the “default” limits. Vessels with higher
margins of damaged stability compliance would be anticipated to be permitted larger
variations on loading, giving greater flexibility of operation. Presently left blank for insertions


Action requested of the Sub-Committee


4138 The Sub-Committee is invited to consider the report of the correspondence group and
is requested to adopt the proposed design and operational guidelines to promote application of
consistent methodologies for tanker damage stability appraisal during stability information
and stability software approval, and for the maintenance of adequate operational stability of
such vessels in service.information contained in this document, and to take action as
appropriate
                                       Annex A

Existing IMO instruments and relevant references relating to the
issue of verification of damage stability requirements



Conventions
MARPOL 1973 - Annex 1
SOLAS 1974 – Chapter II-1
Load Lines, 1966/1988 - International Convention on Load Lines, 1966, as Amended by the
Protocol of 1988


Codes
International Code for the Construction and Equipment of Ships Carrying Dangerous
Chemicals in Bulk (IBC Code)
Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk
(BCH Code)
International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in
Bulk (IGC Code)
Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (GC
Code)
International Code on Intact Stability, 2008 (2008 IS Code)


MSC Circulars
MSC/Circ.406/Rev.1                                             MSC/Circ.891
MSC/Circ.456                                                   MSC/Circ.920
MSC/Circ.854                                                   MSC.1/Circ.1229
The following extracts are provided for information and ease of reference, but are not
comprehensive. Definitive guidance should be obtained by making reference to the full
text all relevant documents, noting that the applicable regulations for an individual
vessel will depend on the vessel type, size, and year of construction. It should be noted
that for practical applications, the authoritative document is the stability information
provided on board which has been approved by the Administration or its Recognised
Organisation (Normally the classification society).                                                                                                       Comment [A1]: Some proposed introductory
                                                                                                                                                          comment to provide clarity rather than just quoting
                                                                                                                                                          the bare text.


A.-SOLAS, regulations 5 and 5-1


Regulation 5 Intact stability *(For ships constructed from 2009-01-01)
_____________
* Refer to the Code on Intact Stability for All Types of Ships covered by IMO Instruments, adopted by the Organization by resolution A.749(18)

1 Every passenger ship regardless of size and every cargo ship having a length (L) of 24 m and
upwards, shall be inclined upon its completion and the elements of its stability determined. In addition
to any other applicable requirements of the present regulations, ships having a length of 24 m and
upwards constructed on or after 1 July 2010 shall as a minimum comply with the requirements of part
A of the 2008 IS Code.

Regulation 5-1 Stability information to be supplied to the master* (For ships constructed from 2009-01-01)
_________________________
* Refer also to the Guidelines for the preparation of intact stability information (MSC/Circ.456); Guidance on the intact stability of existing tankers
during transfer operations (MSC/Circ.706); and the Revised guidance to the master for avoiding dangerous situations in following and quartering
seas (MSC.1/Circ.1228). (MSC/Circ.707).


1 The master shall be supplied with such information satisfactory to the Administration as is
necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of
the ship under varying conditions of service. A copy of the stability information shall be furnished to
the Administration.
2 The information should include:
      .1     curves or tables of minimum operational metacentric height (GM) versus draught which
            assures compliance with the relevant intact and damage stability requirements, alternatively
            corresponding curves or tables of the maximum allowable vertical centre of gravity (KG)
            versus draught, or with the equivalents of either of these curves;
      ….
B.- LOADLINE CONVENTION (regulations 1, 10 and 27)
Regulation 1 Strength and intact stability of ships (For ships constructed on or after 2005-01-01).
General
The regulations assume that the nature and stowage of the cargo, ballast, etc., are such as to secure
sufficient stability of the ship and the avoidance of excessive structural stress.
The regulations also assume that where there are international requirements relating to stability or
subdivision, these requirements have been complied with.
(1) The Administration shall satisfy itself that the general structural strength of the ship is adequate
for the draught corresponding to the freeboard assigned.
(2) A ship which is designed, constructed and maintained in compliance with the appropriate
requirements of an organization, including a classification society, which is recognized by the
Administration or with applicable national standards of the Administration in accordance with the
provisions of regulation 2-1, may be considered to provide an acceptable level of strength. The above
provisions shall apply to all structures, equipment and fittings covered by this annex for which
standards for strength and construction are not expressly provided.
(3)        Compliance
          (a) Ships constructed before 1 July 2010 shall comply with an intact stability standard
          acceptable to the Administration.
          (b)    Ships constructed on or after 1 July 2010 shall, as a minimum, comply with the
          requirements of part A of the 2008 IS Code.
…
Regulation 10 Information to be supplied to the master (For ships constructed on or after 2005-01-
01).


(1) The master of every new ship shall be supplied with information to arrange for the loading and
ballasting of his ship in such a way as to avoid the creation of any unacceptable stresses in the ship' s
structure, provided that this requirement need not apply to any particular length, design or class of ship
where the Administration considers it to be unnecessary.
(2) Information shall be provided to the master in a form that is approved by the Administration or a
recognised organization. Stability information, and loading information also related to ship strength
when required under paragraph (1), shall be carried on board at all times together with evidence that
the information has been approved by the Administration.
(3) A ship which is not required under the International Convention for Safety of Life at Sea in force
to undergo an inclining test upon its completion shall:
         (a)    be so inclined and the actual displacement and position of the centre of gravity shall be
                  determined for the lightship condition;
         (b)    if the Administration so approves, have its inclining test on completion dispensed with,
                  provided basic stability data are available from the inclining test of a sister ship and it is
                  shown to the satisfaction of the Administration that reliable stability information for the
                  ship can be obtained from such basic data;
         (c)    if the Administration decides that the performance of an inclining experiment is not
                  practicable or safe or yields inaccurate results due to the specific proportions,
                  arrangements, strength or hull form of a ship, have the ship' s lightship characteristics
                  determined by a detailed weight estimate confirmed by a lightweight survey;
         (d)    have such information* supplied for the use of its master as is necessary to enable the
                 master, by rapid and simple processes, to obtain accurate guidance as to the stability of
                 the ship under all conditions likely to be encountered in normal service; and
                  _______________
                  * Refer to the Code on Intact Stability for All Types of Ships covered by IMO Instruments, adopted by the Organization by
                  resolution A.749(18), as amended.

         (e)   carry on board at all times its approved stability information together with evidence that the information has been
                   approved by the Administration.
(4) Where any alterations are made to a ship so as to materially affect the loading or stability information supplied to the
master, amended information shall be provided. If necessary the ship shall be re-inclined.

Regulation 27 Types of ships (For ships constructed on or after 2005-01-01).

(2-4/11-13): Type "A" ships (Tankers).
(3): Type "A" ships with length over 150 metres.
(5/7): Ordinary type "B" ships.
(5/6): Increase type "B" / type "B+".(Other than Tankers).
(5/7-9/11-13): Reduced type "B" ships / type "B-60".
(5/7/8/10-13): Reduced type "B" ships / type "B-100".

…
(1)   For the purposes of freeboard computation, ships shall be divided into type ' A' and type ' B' .

          Type ' A' ships

(2)   A type ' A' ship is one which:
         (a) is designed to carry only liquid cargoes in bulk;
         (b) has a high integrity of the exposed deck with only small access openings to cargo
         compartments, closed by watertight gasketed covers of steel or equivalent material; and
            (c)     has low permeability of loaded cargo compartments.

(3) A type ' A' ship, if over 150 m in length, to which a freeboard less than type ' B' has been
assigned, when loaded in accordance with the requirements of paragraph (11), shall be able to
withstand the flooding of any compartment or compartments, with an assumed permeability of 0.95,
consequent upon the damage assumptions specified in paragraph (12), and shall remain afloat in a
satisfactory condition of equilibrium, as specified in paragraph (13). In such a ship, the machinery
space shall be treated as a floodable compartment, but with a permeability of 0.85.
…
          Type ' B' ships

(8) Any type ' B' ship of over 100 m in length may be assigned freeboards less than those required
under paragraph (7), provided that, in relation to the amount of reduction granted, the Administration is
satisfied that:
         (a) the measures provided for the protection of the crew are adequate;
         (b) the freeing arrangements are adequate;
         (c) the covers in position 1 and 2 comply with the provisions of regulation 16(1) through (5)
                         and (7); and
        (d) the ship, when loaded in accordance with the requirements of paragraph (11), shall be able
              to withstand the flooding of any compartment or compartments, with an assumed
              permeability of 0.95, consequent upon the damage assumptions specified in paragraph
              (12), and shall remain afloat in a satisfactory condition of equilibrium, as specified in
              paragraph (13). In such a ship, if over 150 m in length, the machinery space shall be
              treated as a floodable compartment, but with a permeability of 0.85.
…
(13) The condition of equilibrium after flooding shall be regarded as satisfactory provided:
….
C.- THE INTERNATIONAL CODE ON INTACT STABILITY, 2008
Part A.
PREAMBLE

      1     This Code has been assembled to provide, in a single document, mandatory requirements in
             the introduction and in part A and recommended provisions in part B relating to intact
             stability, based primarily on existing IMO instruments. Where recommendations in this
             Code appear to differ from other IMO Codes, the other Codes should be taken as the
             prevailing instrument. For the sake of completeness and for the convenience of the user, this
             Code also contains relevant provisions from mandatory IMO instruments.
      2     ….

INTRODUCTION

Purpose

1.1 The purpose of the Code is to present mandatory and recommendatory stability criteria and other
measures for ensuring the safe operation of ships, to minimize the risk to such ships, to the personnel
on board and to the environment. This introduction and part A of the Code address the mandatory
criteria and part B contains recommendations and additional guidelines.

…
Part B.
RECOMMENDATIONS FOR CERTAIN TYPES OF SHIPS AND ADDITIONAL GUIDELINES.
CHAPTER 4 – STABILITY CALCULATIONS PERFORMED BY STABILITY INSTRUMENTS
4.1       Stability instruments 25
________________
25
   Refer to the Guidelines for the approval of stability instruments (MSC.1/Circ.1229).
A stability instrument installed onboard should cover all stability requirements applicable to the ship.
The software is subject to approval by the Administration. Active and passive systems are defined in
4.1.2. These requirements cover passive systems and the off-line operation mode of active systems
only.

4.1.1 General

4.1.1.1       The scope of stability calculation software should be in accordance with the approved
stability booklet and should at least include all information and perform all calculations or checks as
necessary to ensure compliance with the applicable stability requirements.

4.1.1.2       An approved stability instrument is not a substitute for the approved stability booklet, and
is used as a supplement to the approved stability booklet to facilitate stability calculations.

4.1.1.3       The input/output information should be easily comparable with the approved stability
booklet so as to avoid confusion and possible misinterpretation by the operator.

4.1.1.4      An operation manual should be provided for the stability instrument.

4.1.1.5       The language in which the stability calculation results are displayed and printed out as
well as the operation manual is written should be the same as used in the ship’s approved stability
booklet. A translation into a language considered appropriate may be required.

4.1.1.6      The stability instrument is ship specific equipment and the results of the calculations are
only applicable to the ship for which it has been approved.

4.1.1.7      In case of modifications of the ship which cause alterations in the stability booklet, the
specific approval of any original stability calculation software is no longer valid. The software should
be modified accordingly and re-approved.

4.1.1.8     Any change in software version related to the stability calculation should be reported to
and be approved by the Administration.

4.1.2 Data entry system

4.1.2.1      A passive system requires manual data entry.

4.1.2.2       An active system replaces partly the manual entry with sensors reading and entering the
contents of tanks, etc.

4.1.2.3       Any integrated system which controls or initiates actions based on the sensor-supplied
inputs is not within the scope of this Code except the part calculating the stability.

4.1.3 Types of stability software

Three types of calculations performed by stability software are acceptable depending upon a vessel’s
stability requirements:

Type 1

Software calculating intact stability only (for vessels not required to meet a damage stability criterion).

Type 2

Software calculating intact stability and checking damage stability on basis of a limit curve (e.g., for
vessels applicable to SOLAS part B-1 damage stability calculations, etc.) or previously approved
loading conditions.

Type 3

Software calculating intact stability and damage stability by direct application of pre-programmed
damage cases for each loading condition (for some tankers, etc.). The results of the direct calculations
performed by the stability instrument could be accepted by the Administration even if they differ from
the required minimum GM or maximum VCG stated in the approved stability booklet.

Such deviations could be accepted under the condition that all relevant stability requirements will be
complied with by the results of the direct calculations.

4.1.4 Functional requirements

4.1.4.1       The stability instrument should present relevant parameters of each loading condition in
order to assist the master in his judgement on whether the ship is loaded within the approved limits.

The following parameters should be presented for a given loading condition:

            .1      detailed deadweight data items including centre of gravity and free surfaces,
                     if applicable;

            .2     trim, list;

            .3     draught at the draught marks and perpendiculars;

            .4     summary of loading condition displacement, VCG, LCG, TCG, VCB, LCB, TCB, LCF,
                     GM and GML;

            .5     table showing the righting lever versus heeling angle including trim and draught;

            .6     down-flooding angle and corresponding down-flooding opening; and

            .7     compliance with stability criteria: Listings of all calculated stability criteria, the limit
                     values, the obtained values and the conclusions (criteria fulfilled or not fulfilled).

4.1.4.2      If direct damage stability calculations are performed, the relevant damage cases according
to the applicable rules should be pre-defined for automatic check of a given loading condition.

4.1.4.3       A clear warning should be given on screen and in hard copy printout if any of the
limitations are not complied with.

4.1.4.4          The data should be presented on screen and in hard copy printout in a clear unambiguous
manner.

4.1.4.5          The date and time of a saved calculation should be part of the screen display and hard copy
printout.

4.1.4.6    Each hard copy printout should contain identification of the calculation program including
version number.

4.1.4.7      Units of measurement should be clearly identified and used consistently within a loading
calculation.

4.1.5 Acceptable tolerances

Depending on the type and scope of programs, the acceptable tolerances should be determined
differently, according to 4.1.5.1 or 4.1.5.2. Deviation from these tolerances should not be accepted
unless the Administration considers that there is a satisfactory explanation for the difference and that
there will be no adverse effect on the safety of the ship.

The accuracy of the results should be determined using an independent program or the approved
stability booklet with identical input.

4.1.5.1       Programs which use only pre-programmed data from the approved stability booklet as the
basis for stability calculations should have zero tolerances for the printouts of input data.
Output data tolerances should be close to zero, however, small differences associated with calculation
rounding or abridged input data are acceptable. Additionally differences associated with the use of
hydrostatic and stability data for trims and the method calculating free surface moments that differ
from those in the approved stability booklet are acceptable subject to review by the Administration.

4.1.5.2      Programs which use hull form models as their basis for stability calculations should have
tolerances for the printouts of basic calculated data established against either data from the approved
stability booklet or data obtained using the Administration’s approval model.

4.1.6 Approval procedure

4.1.6.1        Conditions of approval of the stability instrument

The software approval includes:

          .1     verification of type approval, if any;

          .2     verification that the data used is consistent with the current condition of the ship (refer
                   to 4.1.6.2);

          .3     verification and approval of the test conditions; and

          .4     verification that the software is appropriate for the type of ship and stability calculations
                   required.

          The satisfactory operation of the stability instrument is to be verified by testing upon
          installation (refer to 4.1.8). A copy of the approved test conditions and the operation manual
          for the stability instrument are to be available on board.

4.1.6.2        Specific approval

          4.1.6.2.1 The accuracy of the computational results and actual ship data used by the
          calculation program for the particular ship on which the program will be installed should be to
          the satisfaction of the Administration.

          4.1.6.2.2 Upon application for data verification, minimum of four loading conditions should
          be taken from the ship’s approved stability booklet, which should be used as the test
          conditions. For ships carrying liquids in bulk, at least one of the conditions should include
          partially filled tanks. For ships carrying grain in bulk, one of the grain loading conditions
          should include a partially filled grain compartment. Within the test conditions each
          compartment should be loaded at least once. The test conditions normally should cover the
          range of load draughts from the deepest envisaged loaded condition to the light ballast
          condition and should include at least one departure and one arrival condition.

          4.1.6.2.3 The following data, submitted by the applicant, should be consistent with
          arrangements and most recently approved lightship characteristics of the ship according to
          current plans and documentation on file, subject to possible further verification on board:

                    .1      identification of the calculation program including version number.
                             Main dimensions, hydrostatic particulars and, if applicable, the ship’s
                             profile;

                    .2     the position of the forward and aft perpendiculars, and if appropriate, the
                             calculation method to derive the forward and aft draughts at the actual
                             position of the ship’s draught marks;

                    .3     ship’s lightweight and centre of gravity derived from the most recently
                             approved inclining experiment or light weight survey;
                  .4     lines plan, offset tables or other suitable presentation of hull form data
                           including all relevant appendages, if necessary to model the ship;

                  .5     compartment definitions, including frame spacing, and centres of volume,
                           together with capacity tables (sounding/ullage tables), free surface
                           corrections, if appropriate; and

                  .6    cargo and consumables distribution for each loading condition.

         Verification by the Administration does not absolve the shipowner of responsibility for
         ensuring that the information programmed into the stability instrument is consistent with the
         current condition of the ship and approved stability booklet.

4.1.7 User manual

A simple and straightforward user manual written in the same language as the stability booklet should
be provided, containing descriptions and instructions, as appropriate, for at least the following:

         .1    installation;
         .2    function keys;
         .3    menu displays;
         .4    input and output data;
         .5    required minimum hardware to operate the software;
         .6    use of the test loading conditions;
         .7    computer-guided dialogue steps; and
         .8    list of warnings.


A user manual in electronic format may be provided in addition to the written manual.

4.1.8 Installation testing

4.1.8.1       To ensure correct working of the stability instrument after the final or updated software
has been installed, it is the responsibility of the ship’s master to have test calculations carried out
according to the following pattern in the presence of an Administration’s surveyor. From the approved
test conditions at least one load case (other than light ship) should be calculated.
Note : Actual loading condition results are not suitable for checking the correct working of the stability
instrument.

4.1.8.2     Normally, the test conditions are permanently stored in the stability instrument. Steps to
be performed:
         .1   retrieve the test load case and start a calculation run; compare the stability results with
                 those in the documentation;
         .2   change several items of deadweight (tank weights and the cargo weight) sufficiently to
                 change the draught or displacement by at least 10%. The results should be reviewed
                 to ensure that they differ in a logical way from those of the approved test condition;
         .3   revise the above modified load condition to restore the initial test condition and compare
                 the results. The relevant input and output data of the approved test condition should
                 be replicated; and
         .4   alternatively, one or more test conditions should be selected and the test calculations
                 performed by entering all deadweight data for each selected test condition into the
                 program as if it were a proposed loading. The results should be verified as identical to
                 the results in the approved copy of the test conditions.

4.1.9 Periodical testing

4.1.9.1      It is the responsibility of the ship’s master to check the accuracy of the stability instrument
at each annual survey by applying at least one approved test condition. If an Administration’s
representative is not present for the stability instrument check, a copy of the test condition results
obtained by this check should be retained on board as documentation of satisfactory testing for the
Administration’s representative’s verification.

4.1.9.2      At each renewal survey this checking for all approved test loading conditions should be
done in the presence of the Administration’s representative.

4.1.9.3       The testing procedure should be carried out in accordance with paragraph 4.1.8.

4.1.10        Other requirements

4.1.10.1 Protection against unintentional or unauthorized modification of programs and data should be
provided.

4.1.10.2 The program should monitor operation and activate an alarm when the program is incorrectly
or abnormally used.

4.1.10.3 The program and any data stored in the system should be protected from corruption by loss
of power.

4.1.10.4 Error messages with regard to limitations such as filling a compartment beyond capacity or
more than once, or exceeding the assigned load line, etc., should be included.

4.1.10.5 If any software related to stability measures such as sea keeping abilities of the vessel,
evaluation of in-service inclining experiments and processing the results for further calculation, as well
as the evaluation of roll period measurements is installed on board, such software should be reported to
the Administration for consideration.

4.1.10.6 Program functionalities should include mass and moment calculations with numerical and
graphical presentation of the results, such as initial stability values, righting lever curve, areas under the
righting lever curve and range of stability.

4.1.10.7 All input data from automatically measuring sensors, such as gauging devices or draught
reading systems should be presented to the user for verification. The user should have the possibility to
override faulty readings manually.

D.-MARPOL ANNEX I, rRegulation 28


1. Every oil tanker delivered after 31 December 1979, as defined in regulation 1.28.2, of 150 gross
tonnage and above, shall comply with the subdivision and damage stability criteria as specified in
paragraph 3 of this regulation, after the assumed side or bottom damage as specified in paragraph 2 of
this regulation, for any operating draught reflecting actual partial or full load conditions consistent with
trim and strength of the ship as well as relative densities of the cargo."

          UNIFIED INTERPRETATION 46 Operating draught

           With regard to the term "any operating draught reflecting actual partial or full load
          conditions", the information required should enable the damage stability to be assessed under
          conditions the same as or similar to those under which the ship is expected to operate."

          …

          " 5 The master of every oil tanker to which this regulation applies and the person in charge of
          a non-self-propelled oil tanker, to which this regulation applies shall be supplied in a approved
          form with:

                   .1 information relative to loading and distribution of cargo necessary to ensure
                   compliance with the provisions of this regulation; and
                        .2 data on the ability of the ship to comply with damage stability criteria as
                        determined by this regulation, including the effect of relaxations that may have been
                        allowed under subparagraph 1.3 of this regulation”.

            PREVIOUS UNIFIED INTERPRETATION of Operating draft for vessels built between
            1979 and 1984
            11.4.1 With regard to the term "any operating draft reflecting actual partial or full load
            conditions", the information required should enable the damage stability to be assessed under
            conditions the same as or similar to those under which the ship is expected to operate. For this
            purpose, until 2 October 1984, in addition to the calculation for the full load condition, a
            limited number of partial load conditions should be investigated. After 2 October 1984, more
            detailed information covering partial operational load conditions would be required depending
            upon more varied operational demands.”


E.- INTERNATIONAL CODE FOR THE CONSTRUCTION AND EQUIPMENT OF SHIPS
CARRYING DANGEROUS CHEMICALS IN BULK

CHAPTER 2 SHIP SURVIVAL CAPABILITY * AND LOCATION OF CARGO TANKS.

2 Freeboard and intact stability (For ships constructed from 1986-07-01 to 2007-01-01)_______
* Reference is made to the Guidelines for the Uniform Application of the Survival Requirements of the Bulk Chemical Code and the Gas Carrier
Code.
….
2.2.5 The master of the ship should be supplied with a Loading and Stability Information booklet. This
booklet should contain details of typical service and ballast conditions, provisions for evaluating other
conditions of loading and a summary of the ship's survival capabilities. In addition, the booklet should
contain sufficient information to enable the master to load and operate the ship in a safe and seaworthy
manner.

Conditions of loading (For ships constructed from 1986-07-01 to 2007-01-01) ______
* Reference is made to the Guidelines for the Uniform Application of the Survival Requirements of the Bulk Chemical Code and the Gas Carrier
Code.


 Damage survival capability should be investigated on the basis of loading information submitted to
 the Administration for all anticipated conditions of loading and variations in draught and trim. Ballast
 conditions where the chemical tanker is not carrying products covered by the Code, or is carrying only
 residues of such products, need not be considered.

IBC Chapter 2 Ship survival capability and location of cargo tanks (For ships constructed from
2007-01-01)

2.2.5 The master of the ship shall be supplied with a loading and stability information booklet. This
booklet shall contain details of typical service and ballast conditions, provisions for evaluating other
conditions of loading and a summary of the ship's survival capabilities. In addition, the booklet shall
contain sufficient information to enable the master to load and operate the ship in a safe and seaworthy
manner.

2.4 Conditions of loading
Damage survival capability shall be investigated on the basis of loading information submitted to the
Administration for all anticipated conditions of loading and variations in draught and trim. Ballast
conditions where the chemical tanker is not carrying products covered by the Code, or is carrying only
residues of such products, need not be considered.

F.-INTERNATIONAL CODE FOR THE CONSTRUCTION AND EQUIPMENT OF SHIPS
CARRYING LIQUEFIED GASES IN BULK.
CHAPTER 2 SHIP SURVIVAL CAPABILITY * AND LOCATION OF CARGO TANKS.
__________
* Reference is made to the Guidelines for Uniform Application of the Survival Requirements of the
Bulk Chemical Code and the Gas Carrier Code.

Paragraph 2 Freeboard and intact stability.

2.2.5 The master of the ship should be supplied with a Loading and Stability Information booklet. This
booklet should contain details of typical service conditions, loading, unloading and ballasting
operations, provisions for evaluating other conditions of loading and a summary of the ship' s survival
capabilities. In addition, the booklet should contain sufficient information to enable the master to load
and operate the ship in a safe and seaworthy manner.

Paragraph 4 Conditions of loading.

Damage survival capability should be investigated on the basis of loading information submitted to the
Administration for all anticipated conditions of loading and variations in draught and trim. The survival
requirements need not be applied to the ship when in the ballast condition *, provided that any cargo
retained on board is solely used for cooling, circulation or fuelling purposes.
___________
* The cargo content of small independent purge tanks on deck need not be taken into account when
assessing the ballast condition.


G.-Draft IGC Revised Code (SLF 53/INF 2)
2.2.5 The Master of the ship shall be supplied with a loading and stability information
booklet. This booklet shall contain details of typical service conditions, loading, unloading and
ballasting operations, provisions for evaluating other conditions of loading and a summary of the ship's
survival capabilities. In addition, the booklet shall contain sufficient information to enable the Master
to load and operate the ship in a safe and seaworthy manner.

In addition, the Master is to be given an approved loading computer to assess:
      the intact stability
      the damage stability condition according to the standard damage cases and the
      actual damage condition of the ship
      bending moment and shear force in intact condition.


The loading computer input data and output results have to be approved by the Administration.
H.-CODE FOR THE CONSTRUCTION AND EQUIPMENT OF SHIPS CARRYING
LIQUEFIED GASES IN BULK (GC Code) A 328 (IX)- Spanish version only-

2.2.3 The master of the ship should be supplied with a loading and stability information booklet. This
booklet should contain details of typical service conditions, loading, unloading and ballasting
operations, provisions for evaluating other conditions of loading and a summary of the ship’s survival
capabilities. In addition, the booklet should contain sufficient information to enable the master to load
and operate the ship in a safe and seaworthy manner.

I.-CODE FOR THE CONSTRUCTION AND EQUIPMENT OF SHIPS CARRYING
DANGEROUS CHEMICALS IN BULK (BCH Code)

Chapter 4

4.3. In addition to the usual loading information required under intact stability requirements the master
should be supplied with the following information pertaining to damage stability.

        .1. data relative to loading and distribution of cargo and ballast necessary to ensure
        compliance with damage survival requirements;
        .2. data relative to the ship’s survival capabilities;
          .3. a damage control drawing showing the position of important fittings and listing instructions
          for their control;
          .4. data relating to the effect of free surface or liquid heeling moments of cargo tanks at all
          stages of filling;
          .5. example calculations and standard blank forms to facilitate calculations.


J.-MSC/Circ 406/Rev 1 (29 june 1980) GUIDELINES FOR THE UNIFORM APPLICATION OF
THE SURVIVAL REQUIREMENTS OF THE BULK CHEMICAL CODE AND THE GAS
CARRIER CODE (approved by the Maritime Safety Committee at its forty-second session, 1980)- For ships constructed
from 1986-07-01 to 2007-01-01-


          2.1 A systematic investigation of damage survival characteristics should be undertaken by
          making calculations to obtain the minimum required GM or maximum allowable KG at a
          sufficient number of draughts within the operating range to permit the construction of a series
          of curves of "required GM" or "allowable KG" in relation to draught and cargo tank content in
          way of the damage. The curves must be sufficiently comprehensive to cover operational trim
          requirements.

          2.2 Each of the curves thus constructed relates to one position of assumed damage only and
          the calculations should be repeated for each damage and lesser extent of damage to be
          assumed at any part of the ship.

          2.3 Where it can be determined by inspection that the effect of certain assumed damage will
          be less onerous than other assumed damage, for which calculations are provided and curves
          prepared, then the investigation of such damage cases may be dispensed with.

          2.4 The damage calculations should take account of:

                    .1 tanks in way of the assumed damage filled with liquid at increments of
                    about 25% between empty and the maximum weight of liquid, or liquids,
                    intended to be carried in the particular tanks under consideration;

                    .2 the distribution of liquids in the adjacent tanks concerned which will give
                    the most severe result, taking into account trim;

                    .3 a number of draughts over the operating range, up to and including the
                    tropical freeboard mark. The fresh water freeboards need not be considered;

                    .4 the effect of damage involving the machinery space and adjacent tanks
                    containing liquids over a number of draughts as in 2.4.3;

                    .5 the ship in either the departure or the arrival condition, whichever will
                    give the most severe result;

                    .6 the ship without trim and a sufficient number of trims covering the
                    operating range, in order to permit interpolation.
                                     Annex B

Identify any ambiguities in the existing requirements and consider
the need for clarifications and/or make recommendations for
amendments to mandatory instruments




The Correspondence Group has considered existing mandatory instruments and
proposes that the Sub-Committee gives consideration to the following proposed
amendments :


1) ICLL reg 27(11)(b)(iv)


To avoid possible misinterpretation of the meaning of this regulation, as it defines the
treatment of consumables and provisions in deriving intact loading condition to which damage
shall be applied in accordance with reg 27(3) and also regs 27(8) and 27(10), the following
change is proposed to the first sentence.


Original Text – “50% of the individual total capacity of all tanks and spaces fitted to contain
consumable liquids and stores is allowed for.”


Revised Text – [“50% of the ships total capacity of all tanks and spaces fitted to contain
consumables and stores is allowed for”] or [“50% of the ships total capacity of all tanks and
spaces fitted to contain each type of consumables and stores is allowed for”].


2) ICLL reg 27(11)(b)


Treatment of ballast water is not specifically addressed within the existing text of reg 27(11()b)
as this defines how the intact loading condition to which damage shall be applied in
accordance with reg 27(3) and also regs 27(8) and 27(10) shall be derived. To avoid
misinterpretation the following additional text is proposed for insertion between after existing
regulationsparagraph 27(11)(b)(iv) with existing paragraphs 27(11)(b)(v) and 27(11)(b)(vi)
being renumbered.


 “Ballast water tanks shall normally be considered to be empty and no free surface
correction shall be made for them. [However, in cases where carriage of ballast (in
addition to maximum homogeneous cargo at maximum cargo SG) is necessary to
maintain adequate stability at the summer load waterline, this may be permitted and
accounted for in the loading condition along with any applicable free surface]”.
“Ballast water tanks shall normally be considered to be empty and no free surface
correction shall be made for them. [However, where carriage of ballast is required to
maintain adequate stability of the maximum cargo condition at the summer load
waterline, this may be permitted and accounted for in the loading condition with any
applicable free surface correction]”.


3) ICLL reg 27(11)(b)


The Correspondence Group are requested to consider which, if any, options for treatment of
the intact stability condition and calculation method for applying damage is preferred for
inclusion as an amendment to ICLL with reference to the three alternative proposals made by
Germany and having regard to the related advice in SLF 53/8/3 and SLF 53.INF.9.


4) ICLL reg 27(13)
The Correspondence Group is invited to consider whether they wish to recommend an
amendment to the ICLL is made in respect of addition of a statement into reg 27(13)
advising that it is not necessary to apply damage stability criteria to live service
loading conditions using a loading stability instrument, stability software or other
method. A proposed text follows.


“(g) Compliance with the residual stability criteria specified in paragraphs (a), (c), (d)
and (e) above is not required to be demonstrated in service loading conditions using a
loading stability instrument, stability software or other approved method.”


5) MARPOL Annex 1, reg 25(1)


To clarify and harmonise guidance on the requirement to evaluate damage stability up to the
highest subdivision draught, including draughts which correspond to freeboards less than the
summer freeboard, the following modification is proposed to reg 25(1).


Existing Text – “for any operating draught”


Revised Text – “ all anticipated conditions of loading and variations in draught and
trim, up to and including operation at the tropical freeboard mark where such a
freeboard mark is assigned”.


6) IBC and IGC Codes, Chapter 2, paragraph 2.4


To clarify and harmonise guidance on the requirement to evaluate damage stability up to the
highest subdivision draught, including draughts which correspond to freeboards less than the
summer freeboard, the following modification is proposed to reg 25(1).
Existing Text – “all anticipated conditions of loading and variations in draught and trim”


Revised Text – “ all anticipated conditions of loading and variations in draught and
trim, up to and including operation at the tropical freeboard mark where such a
freeboard mark is assigned”.


7) Marpol Annex 1, reg 1 – Definition of Approved Loading Condition


To clarify the status of loading conditions included within the approved stability
information, it is proposed a new definition is included in Annex 1, reg 1 which
defines an approved loading condition and the limitations on its use.


.35.(32) Approved loading condition is a unique condition of loading, taking account
of the combination of lightship and all individual deadweight items, which has been
verified by the flag State (or recognized organization acting on its behalf) as
complying with both intact and damaged stability criteria and is included within
approved stability information supplied to the Master in accordance with reg 28(5) for
use in service of the vessel. Approval of an individual approved loading condition is
granted for the purpose of loading in accordance with that unique condition and does
not confer approval of other loading conditions which vary from it. [Loading
conditions which are verified in service and shown to lie within the boundary of
approved limiting KG/GM curves included within approved stability information
supplied to the Master in accordance with reg 28(5) shall also be regarded as
approved loading conditions.]


8) Marpol Annex 1, reg 1 – Definition of In Accordance With an Approved
Loading Condition


To clarify what is meant by loading in accordance with an approved loading
condition, it is proposed a new definition is included in Annex 1, reg 1


(33) To be loaded in accordance with an approved loading condition it is necessary
tor a vessel to be loaded within the following limitations :
        a) the loading of any individual cargo tank, slop tank or water ballast tank in
the loading condition under consideration should not differ from that of the approved
loading condition by more than [1% or 2% or 3% or 5%] by mass, and
        b) the GMfGM of the loading condition under consideration should not less
than that of the approved condition by more than [2cm], or, the KGfKG of the loading
condition under consideration should not exceed that of the approved loading
condition by more than [2 cm].
9) IBC and IGC Codes, 1.3 – Definition of Approved Loading Condition


To clarify the status of loading conditions included within the approved stability
information, it is proposed a new definition is included at section 1.3 of each Code
which defines an approved loading condition and the limitations on its use.


1.3.31 Approved loading condition is a unique condition of loading, taking account of
the combination of lightship and all individual deadweight items, which has been
verified by the flag State (or recognized organization acting on its behalf) as
complying with both intact and damaged stability criteria and is included within
approved stability information supplied to the Master in accordance with 2.2.5 for use
in service of the vessel. Approval of an individual approved loading condition is
granted for the purpose of loading in accordance with that unique condition and does
not confer approval of other loading conditions which vary from it. [Loading
conditions which are verified in service and shown to lie within the boundary of
approved limiting KG/GM curves included within approved stability information
supplied to the Master in accordance with 2.2.5 shall also be regarded as approved
loading conditions.]



10) IBC and IGC Codes, reg 1.3 – Definition of In Accordance With an
Approved Loading Condition


To clarify what is meant by loading in accordance with an approved loading
condition, it is proposed a new definition is included at section 1.3 of each Code


1.3.32 To be loaded in accordance with an approved loading condition it is necessary
tor a vessel to be loaded within the following limitations :
        .1) the loading of any individual cargo tank, slop tank or water ballast tank in
the loading condition under consideration should not differ from that of the approved
loading condition by more than [1% or 2% or 3% or 5%] by mass, and
        .2) the GMfGM of the loading condition under consideration should not less
than that of the approved condition by more than [2cm], or, the KGfKG of the loading
condition under consideration should not exceed that of the approved loading
condition by more than [2 cm].


11) Marpol Annex 1 – Requirement for carriage of Type 2 stability program on parcel
tankers which have approved critical KG or GM data.


To facilitate this proposal it shall also be necessary to include a definition of parcel tanker
within the Convention :
In relation to Annex 1, reg 1


.36. Parcel tanker means a vessel arranged to carry a wide range of cargoes of differing SG,
often in combination, and where variation between individual cargoes makes carriage of repeat
loading conditions unlikely.


In relation to Annex 1, reg 28(5)


.3     in the case of parcel tankers, where the calculations submitted to satisfy paragraph 1 of
       this regulation include critical KG or GM data for inclusion in stability information
       provided in accordance with this paragraph, the vessel shall be fitted with a stability
       instrument employing stability software of Type 2.


12) IBC Code – Requirement for carriage of Type 2 stability program on parcel tankers
which have approved critical KG or GM data.


To facilitate this proposal it shall also be necessary to include a definition of parcel tanker
within the IBC Code :


In relation to Chapter 1, reg 1


Insert new regulation - 1.3.26 Parcel tanker means a vessel arranged to carry a wide range of
cargoes of differing SG, often in combination, and where variation between individual cargoes
makes carriage of repeat loading conditions unlikely.


Subsequent regulations to be renumbered


In relation to Chapter 2


Insert new regulation - 2.2.6 In the case of parcel tankers, where the calculations submitted to
satisfy regulation 2.9 include critical KG or GM data for inclusion in stability information
provided in accordance with regulation 2.2.5, the vessel shall be fitted with a stability
instrument employing stability software of Type 2.



13) ICLL, regs 27(12) and 27(13)
To clarify the method required to conduct damage calculations made in accordance with
reg.27in respect of ships which carry liquid cargoes, the following modification is proposed to
reg 27(12).


[(g). In the case of damage being assumed to any cargo compartment initially containing fluid
cargoes, the fluid cargo in the compartment shall be considered to be lost and replaced by
seawater to the level of the equilibrium waterline] .                                       Formatted: Font: Not Bold




Critical intact GMf/KGf data
Critical damage GMf/KGf data


It is probable that this information will be taken in part from Annex 4 to the operational
guidelines.



And also for recommended amendments to mandatory instruments and other existing
guidance as proposed below :


These to be proposed.



To clarify the derivation of residual stability characteristics where damage calculations are   Formatted: Font: Not Bold
made in accordance with reg.27 in respect of ships which carry liquid cargoes, the following    Formatted: Left
modification is proposed to reg 27(13)(e)


[ Add the following text to reg 27(13)(e). “For the purpose of this paragraph, in the case where
the damage case being considered includes compartments initially containing fluid cargo, the
residual stability may be determined using the intact displacement of the vessel minus the
weight of lost fluid cargo.”]
                               Annex C
                                                                             Formatted: Centered

Draft Guidelines for the verification of damage stability requirements for
                                  tankers




     GUIDELINES FOR VERIFICATION OF
         STABILITY ON TANKERS




                            PART 1




   GUIDELINES FOR PREPARATION AND
APPROVAL OF TANKER DAMAGE STABILITY
           CALCULATIONS
Guideline for Scope of Damage Stability
Verification on new oil tankers, chemical
tankers and gas carriers *)
1        Application

This recommendation applies for new oil tankers, chemical tankers and gas carriers
contracted for construction* on or after 1st January 2010 subject to review of impact
on ships undergoing approval and delivering after said date.

* The ‘contracted for construction’ date means the date on which the contract to build the
vessel is signed between the prospective owner and the shipbuilder. For further details
regarding the date of ‘contract for construction’, refer to Procedural Requirement (PR) No. 29.

2        Reference

2.1      IMO Instruments

2.1.1 General Instruments

     SOLAS Chapter II-1, Regulations 4.1, 4.2, 5-1 and 19;

     Res. MSC.143(77) "Adoption of amendments to the Protocol of 1988 relating to
      the International Convention on Load Lines, 1966", Regulations 27(2), 27(3),
      27(11), 27(12) and 27(13) 1);

     Res. MSC.281(85) "Explanatory Notes to the SOLAS Chapter II-1 Subdivision
      and Damage Stability Regulations" - special attention should be paid to
      Guidelines for the Preparation of Subdivision and Damage Stability Calculations
      specified in the Appendix;

     Res. MSC.245(83) "Recommendation on a Standard Method for Evaluating
      Cross-Flooding Arrangements";

     MSC.1/Circ.1245 "Guidelines for Damage Control Plans and Information to the
      Master"; and

     MSC.1/Circ.1229 "Guidelines for the Approval of Stability Instruments",
      paragraph 4.


Footnotes:

*)    Excluding combination carriers.

1)    The application of ICLL Protocol 1988, Reg.27 is explained in Annex 1.


Note:
Rev.1 applies for new oil tankers, chemical tankers and gas carriers contracted for
construction on or after 1 January 2011 subject to review of impact on ships
undergoing approval and delivering after said date.
2.1.2 Instrument applicable to oil tankers

     MARPOL Annex I, Regulation 28.

2.1.3 Instruments applicable to gas carriers

     International Code for the Construction and Equipment of Ships Carrying
      Liquefied Gases in Bulk (IGC Code), Chapter 2, Paragraphs 2.1, 2.4, 2.5, 2.6.2,
      2.6.3, 2.7, 2.8 and 2.9; and

     MSC/Circ.406/Rev.1 "Guidelines on Interpretation of the International Code for
      the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk
      (IBC Code) and the International Code for the Construction and Equipment of
      Ships Carrying Liquefied Gases in Bulk (IGC Code) and Guidelines for the
      Uniform Application of the Survival Requirements of the IBC and IGC Codes".

2.1.4 Instruments applicable to chemical tankers

     International Code for the Construction and Equipment of Ships Carrying
      Dangerous Chemicals in Bulk (IBC Code), Chapter 2, Paragraphs 2.1, 2.4, 2.5,
      2.6.2, 2.7, 2.8 and 2.9; and

     MSC/Circ.406/Rev.1 “Guidelines on Interpretation of the International Code for
      the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk
      (IBC Code) and the International Code for the Construction and Equipment of
      Ships Carrying Liquefied Gases in Bulk (IGC Code) and Guidelines for the
      Uniform Application of the Survival Requirements of the IBC and IGC Codes”.

2.2      IACS Resolutions

     UR L5 “Onboard Computers for Stability Calculations”;

     PR7 “Procedure for the Training and Qualification of Survey and Plan Approval
      Staff”; and

     UI SC 156 “Doors in watertight bulkheads of cargo ships and passenger ships”.

3        General

3.1      Education and training

3.1.1 Plan approval staff engaged in damage stability verification of new oil tankers,
chemical tankers and gas carriers should have as minimum the following formal
educational background:

      - a degree or equivalent from a tertiary institution recognized within the field of
        marine engineering or naval architecture; and

      - competent in the English language commensurate with their work.

3.1.2 Plan approval staff engaged in damage stability verification of new oil tankers,
chemical tankers and gas carriers should be trained according to theoretical and
practical modules defined by the Administration or RO to acquire and develop
general knowledge and understanding applicable to the a/m types of ship and
stability assessment according to the IMO and IACS Rules and Instruments and
Resolutions referred in paragraph 2 above.
3.1.3 Methods of training may include monitoring, testing, etc. on regular basis
according to the Administration or RO’s system. Evidence of training provided should
be documented.

3.1.4 Updating of qualification may be done through the following methods:

      - self-study;

      - extraordinary seminars in case of significant changes in the International
        Conventions, Codes, etc.; and

      - special training on specific work, which is determined by a long absence of
        practical experience.

Maintenance of qualification should be verified at annual performance review.

3.2      Scope of stability verification

The scope of damage stability verification is determined by the required damage
stability standards (applicable damage stability criteria) and aims at providing the
ship’s master with a sufficient number of approved loading conditions to be used for
the loading of the ship. In general, for non approved loading conditions (by the
Administration or RO), approved KG/GM limit curve(s) or approved stability
instrument software satisfying the stability requirements (intact and damage) for the
draught range to be covered should be used to verify compliance on board.

Within the scope of the verification determined as per the above, all potential or
necessary damage scenarios should be determined and assessed taking into
account the damage stability criteria.


Damage stability verification and approval requires a review of submitted calculations
and supporting documentation with independent check calculations to confirm
damage stability calculation results comply with relevant stability criteria.


Examination and approval of the stability instrument software installed on board (and
to be used for assessing intact and damage stability) should also be carried out. A
stability instrument comprises hardware and software. The accuracy of the
computation results and actual ship data used by the software is to be verified.

3.3      Assumptions

For all loading conditions, the initial metacentric height and the righting lever curve
should be corrected for the effect of free surfaces of liquids in tanks.

Superstructures and deckhouses not regarded as enclosed can be taken into
account in stability calculations up to the angle at which their openings are flooded.
Flooding points (including windows) incapable of weathertight closure to be included
in any list determined in accordance with paragraph 3.4.2.6. Full compliance with
residual stability criteria must be achieved before any such point becomes immersed.

When determining the righting lever (GZ) of the residual stability curve, the constant
displacement (lost buoyancy) method of calculation should be used (see paragraph
6.1).

Conditions of loading and instructions provided by the submitter for use of the
applicable KG/GM limit curve(s) and variation of loading patterns and representative
cargoes are taken to be representative of how the ship will be operated.
3.4    Documentation to be submitted for review

3.4.1 Presentation of documents

The documentation should begin with the following details: principal dimensions, ship
type, designation of intact conditions, designation of damage conditions and pertinent
damaged compartments, KG/GM limit curve(s).

3.4.2 General documents and supporting information

.1     lines plan, plotted or numerically;

.2     hydrostatic data and cross curves of stability (including drawing of the
       buoyant hull);

.3     definition of watertight compartments with moulded volumes, centres of
       gravity and permeability;

.4     layout plan (watertight integrity plan) for the watertight compartments with all
       internal and external opening points including their connected sub-
       compartments, and particulars used in measuring the spaces, such as
       general arrangement plan and tank plan;

.5     Stability Booklet/Loading Manual including at least fully loaded homogeneous
       condition at summer load line draught (departure and arrival) and other
       intended operational conditions;

.6     coordinates of opening points with their level of tightness (e.g., weathertight,
       unprotected) 2), including reference to the compartment that the opening is
       connected to.

.7     watertight door location;

.8     cross and down flooding devices and the calculations thereof according to
       resolution MSC.245(83) with information about diameter, valves, pipe lengths
       and coordinates of inlet/outlet. Cross/down flooding should not be considered
       for the purpose of achieving compliance with the stability criteria (see also
       paragraph 9.2);

.9     pipes in damaged area when the breaching of these pipes results in
       progressive flooding (see paragraph 10.1);

.10    damage extents and definition of damage cases; and
.11    any initial conditions or restrictions which have been assumed in the
       derivation of critical KG or GM data, and which must therefore be met in
       service.


Footnote:

2) Details of watertight, weathertight and unprotected openings should be included in the
Damage Control Plan and Damage Control Booklet in accordance with MSC.1/Circ.1245.

The cases and extent of progressive flooding assumed in the damage stability analysis
should be indicated in the Damage Control Booklet and the Documents for Submission in
accordance with the Appendix to MSC.281(85). Arrangements to prevent further flooding are
to be indicated on the Damage Control Plan and in the Damage Control Booklet.

3.4.3 Special documents

.1     Documentation

Design documentation: damage stability calculations (including residual stability
curves), the arrangements, configuration and contents of the damaged
compartments, and the distribution, relative densities and the free surface effect of
liquids.

Operational documentation: loading and stability information booklet (stability
booklet), Damage Control Plan; and Damage Control Booklet 2).

.2     Special consideration

For intermediate flooding stages before cross-flooding (see paragraphs 6.8 and 9.2)
or before progressive flooding (see paragraph 6.9), an appropriate scope of the
documentation covering the aforementioned items is needed in addition. The
intermediate stages for cargo outflow and sea water inflow should be checked. If any
stability criteria during intermediate stages shows more severe values than in the
final stage of flooding this intermediate stages should also be submitted.

4      Operating Limits – Descriptions/Assumptions

In considering the scope of the verification to be conducted, consideration of the
operating limits is needed.

The following loading options should be permitted:

a)    Service loading conditions identical to the approved loading conditions of the
      stability booklet (see paragraph 4.2); or

b)    Service loading conditions complying with the approved intact and damage
      stability limiting curves (where provided) (see paragraph 4.3); or

c)    Service loading conditions which have been checked with an approved on-
      board stability software with the capability to perform damage stability
      calculations (Type 2 or Type 3 of IACS UR L5, Rev.2, Corr.1 Nov 2006) either
      based on KG/GM limit curve(s) or based on direct damage stability assessment
      (see paragraph 4.5).
If above mentioned proof of compliance is not possible, then the intended loading
conditions should be either prohibited or be submitted for specific approval to the
Administration or RO. Suitable instructions to this effect should be included in the
stability booklet/loading manual.
An approved loading condition is one which has been specifically examined and
endorsed by Administration/RO.

4.1    Specific loading patterns

Ship specific design loading patterns and loading restrictions should be clearly
presented in the stability booklet. The following items should be included:


a)     Any required and intended loading conditions (including the ones
       corresponding to multiple freeboards when so assigned to the vessel), i.e.
       symmetrical/unsymmetrical, homogeneous/alternating or ballast/partial/full;


b)     Types (e.g. oil, noxious liquid substances and LNG) of liquid cargo allowed to
       be carried;
c)     Restrictions to different liquid loads to be carried simultaneously;


d)     Range of permissible densities of liquid loads to be carried; and


e)     Minimum tank filling levels required to achieve compliance with the applicable
       stability criteria.


For the verification of damage stability all loading conditions presented in the stability
booklet except for ballast, light ship and docking conditions are to be examined.

4.2    Matrix of permissible loading conditions

In the absence of stability software and KG/GM limit curve(s), in lieu of approved
specific loading conditions, a matrix clearly listing the allowable range of loading
parameters (draft, trim, KG, cargo loading pattern and SG) that the vessel is allowed
to load in order to be in compliance with the applicable intact and damage stability
criteria can be developed for the stability booklet when a greater degree of flexibility
than that afforded by approved specific loading conditions is needed.

4.3    KG/GM Limit Curve(s) 3)

The preparation of KG/GM limit curves for tank vessels, especially for gas/chemical
tank vessels, should include a comprehensive calculation as described in
MSC/Circ.406/Rev.1, paragraph 2.1:

”A systematic investigation of damage survival characteristics should be undertaken
by making calculations to obtain the minimum required GM or Maximum allowable
KG at a sufficient number of draughts within the operating range to permit the
construction of a series of curves of “required GM” or “allowable KG” in relation to
draught and cargo tank content in way of the damage. The curves must be
sufficiently comprehensive to cover operational trim requirements.”

The verification of KG/GM limit curves should be conducted without any free surface
correction. The actual loading condition uses the free surface correction (see
paragraph 6.5) when comparing actual and allowable KG values.

It is to be noted that any change of filling level, draught, trim, cargo density might
have a major influence to the results of a damage case; therefore the following items
should be considered carefully for the calculation of the KG/GM limit curves:

a)    Intact and damage stability criteria applicable to the vessel;

b)    The maximum required damage extent and lesser extents of damage which
      provide the most severe damage cases;

c)    Draught range of the vessel (up to tropical freeboard if required);

d)    Trim range of the vessel (see paragraph 6.6);

e)    Full and empty cargo tanks;

f)    Partially filled cargo tanks (consideration of increments as necessary);

g)    Minimum tank fillings in tonnes if required;

h)    Maximum/minimum densities of cargoes; and

i)    Ballast tank filling levels as necessary to achieve compliance.

Damage stability calculations, on which the KG/GM limit curve(s) is(are) based,
should be performed at the design stage. The KG/GM limit curve(s) drawn out taking
stability criteria (intact and damage) into account should be inserted in the stability
booklet.

Footnote:

3) To avoid difficulties associated with developing suitable KG/GM limit curves and their
restriction on operational capacity it is recommended that an approved Type 3 stability
software is fitted on board.


4.4    Initial heel

The stability booklet should contain a note for the master to avoid initial heel greater
than 1 degree. A steady heeling angle may have major influence to the stability of the
vessel especially in case of damage.

4.5    Direct calculation onboard (Stability software)

The use of stability software for stability calculations is not a class requirement.

However, stability software installed onboard should cover all stability requirements
(intact and damage) applicable to the ship.
The following types of stability softwares, if approved by an Administration or RO,
(according to IACS UR L5, Rev.2, Corr.1 Nov 2006) are applicable for calculation of
service loading conditions for tank vessels:

a)      Type 2: Checking intact and damage stability on basis of a KG/GM limit
        curve(s) or previously approved loading conditions; and

b)      Type 3: Checking intact and damage stability by direct application of pre-
        programmed damage cases for each loading condition, including capability for
        calculation of intermediate damage stages.

The software should be approved by the Administration or RO. The software is not a
substitute for the approved stability documentation, but used as a supplement to
facilitate stability calculations.

Sufficient damages, taking into account lesser damages, and variation of draft, cargo
density, tank loading patterns and extents of tank filling should be performed to
ensure that for any possible loading condition the most onerous damages have been
examined according to relevant stability criteria.

The methodologies for determining compliance with relevant stability criteria should
be as set out in these Guidelines.


5        Hull and Compartment Modelling Tolerances

Acceptable tolerances should be in accordance with Table 1.

Deviation from these tolerances should not be accepted unless the Administration or
RO considers that there is a satisfactory explanation for the difference and that there
will be no adverse effect on the capability of the ship to comply with the stability
criteria.

No deviation is generally allowed for input data, however, small differences
associated with calculation rounding or abridged input data are acceptable.

Table 1:


               Hull Form Dependent                          Tolerances

     Displacement                                2%
     Longitudinal centre of buoyancy, from AP    1% / 50 cm max
     Vertical centre of buoyancy                 1% / 5 cm max
     Transverse centre of buoyancy               0.5% of B / 5 cm max
     Longitudinal centre of flotation, from AP   1% / 50 cm max
     Moment to trim 1 cm                         2%
     Transverse metacentric height               1% / 5 cm max
     Longitudinal metacentric height             1% / 50 cm max
     Cross curves of stability                   5 cm
             Compartment Dependent                             Tolerances

     Volume or deadweight                          2%
     Longitudinal centre of gravity, from AP       1% / 50 cm max
     Vertical centre of gravity                    1% / 5 cm max
     Transverse centre of gravity                  0.5% of B / 5 cm max
     Free surface moment                           2%
     Level of contents                             2%

Deviation in % = [(base value - applicant’s value)/base value]*100

where the “base value” may be taken from the approved stability information or the
computer model.


6         Methodology

6.1       Method of analysis

Independent analysis uses the "constant displacement"/"lost buoyancy" method.

Within the scope of damage stability analysis with the deterministic approach,
depending on the subdivision of the ship, the result of applying the standard of
damage as specified in the applicable requirements is the creation of a number of
damage cases, where one or more compartments are open to sea.

The compartment(s) once damaged, are not considered as contributing to the
buoyancy of the ship. Consequently, a new condition of equilibrium occurs. In order
to define the new equilibrium condition and to assess the stability of the ship after
damage the lost buoyancy/constant displacement method is used.

The new floating position can be determined by assuming that the damaged
displacement is equal to the intact displacement (constant displacement) minus the
weight of liquids which were contained in the damaged compartments.

Due to the lost buoyancy of the damaged compartment(s), the remaining intact ship
has to compensate by sinkage, heel and trim until the damaged displacement is
reached. Once the equilibrium has been reached and the final waterline is
determined, the metacentric height (GM), the righting lever curves (GZ) and the
centre of gravity positions (KG), can be calculated in order to verify the stability of the
ship against the applicable requirements.

For the intermediate stages of flooding and the equalisation with compartments
cross-connected by small ducts, i.e. not opened to the sea directly, the added weight
method is used.

6.2       Arguments used in calculations

The Arguments used in the calculation for the verification of damage stability are the
following:

.1        Trim: The calculation should be done for the ship freely trimming;
.2    Heel angle at equilibrium: The heel angle at equilibrium, due to unsymmetrical
      flooding should not exceed the maximum values as indicated in the applicable
      requirements. Concerning the range of positive righting levers (GZ), this
      should be calculated beyond the position of equilibrium to the extent as so
      required by the applicable requirements;

.3    Free surface of liquid: For the calculation of the position of the centre of
      gravity (KG), the metacentric height (GM) and the righting lever curves (GZ),
      the effect of the free surfaces of liquids (see paragraph 6.5) should be taken
      into account;

.4    Immersion of weathertight and unprotected openings (see paragraph 6.7 and
      10.1)

      Unprotected openings:

      -   The positive range of righting levers is calculated from the angle of
          equilibrium until the angle of immersion of the unprotected openings
          leading to intact spaces;

      Weathertight points: see paragraph 10.1 (ii);
.5    Progressive flooding through internal pipes: In case of damage of an internal
      pipe which is connected to an undamaged compartment, the undamaged
      compartment should also be flooded, unless arrangements are fitted (e.g.
      check valves or valves with remote means of control), which can prevent
      further flooding of the undamaged compartments;

.6    Permeabilities: Care should be taken to apply the permeabilities as specified
      in the applicable regulations. Special attention should be paid in case
      compartments which are separated by weathertight boundaries are modeled
      as one compartment. This simplified method of modeling the compartments
      should apply only to compartments belonging to the same category (same
      permeability); and

.7    Heel angles for the calculation of the GZ curve: Evaluation of damage stability
      criteria should generally be determined from data calculated over a range of
      angles from 0 to 60 degrees. It is recommended to use an increment not
      exceeding 5 degrees.

6.3   Adjustments for cargo run-off

.1    In cases where the damage involves the cargo hold, it is assumed that cargo
      is flowing out and that water starts to ingress. During the intermediate stages
      of flooding it is considered that both cargo and sea water are existing in the
      damaged tank (see paragraph 9.3).

      At the final stage it is assumed that the cargo is completely lost and that the
      tank is filled with sea water up to the level of the waterline.

.2    The impact on the stability of the ship, due to the inflow and outflow of liquid
      cargo is also dependent on the following parameters:

      -   the density of the cargo: Liquid cargo with density greater than 0.95 t/m3
          should be considered as heavy liquid cargo. In case of lesser vertical
                extent of damage, i.e. damage above the tank top (see Annex 4), the
                release of heavy liquid cargo might lead to large angle of heel on the
                intact side of the ship. Depending on intact draught and cargo tank filling
                level, outflow of cargo of lesser density may also cause heel to the
                opposite side; and

            -   the permeability of the cargo space, taking into account that permeabilities
                smaller than the those specified in the applicable rules can be applied if
                justified.

     6.4    Handling of permeabilities

     .1     Permeability of a space means the ratio of the volume within that space,
            which should be assumed to be occupied by water to the total volume of that
            space. The total volume should be calculated to moulded lines and no
            reduction in total volume should be taken into account due to structural
            members (i.e stiffeners, etc.). Account of structural members is taken in the
            applicable permeabilities (see also MSC/Circ.406/Rev.1, paragraph 3.11).

     .2     Depending on the applicable requirements, the permeabilities assumed for
            spaces flooded as a result of damage should be as shown in the Table 2.


     Table 2:

                                                            Permeabilities
                Spaces
                                         MARPOL         ICLL 1)        IBC             IGC
Appropriated to stores                      0.6          0.95          0.6             0.6
Occupied by accommodation                   0.95         0.95          0.95            0.95
Occupied by machinery                       0.85         0.85          0.85            0.85
Voids                                       0.95         0.95          0.95            0.95
Intended for consumable liquids          0 to 0.95*      0.95       0 to 0.95*     0 to 0.95*
Intended for other liquids               0 to 0.95*      0.95       0 to 0.95*     0 to 0.95*
* The permeability of partially filled compartments should be consistent with the amount
   of liquid carried in the compartment.
1)
     Regarding application of ICLL damage stability requirements please refer to Annex 1.

     .3     Whenever damage penetrates a tank containing liquids, it should be assumed
            that the contents are completely lost from that compartment and replaced by
            sea water up to the level of the final plane of equilibrium.

     .4     Other figures for permeability may be used for the damaged case both during
            cargo run-off and the final equilibrium condition under the following provisions:

     .4.1   The detailed calculations and the arguments used for determining the
            permeability of the compartment(s) in question, is to be included in the
            damage stability booklet;

     .4.2   The water tightness/resistance to water pressure and the means by which
            internal fittings/material are secured to the tank should substantiate the use of
            such fittings/material in reducing the permeability of a compartment. Where a
       ship is fitted with significant quantities of cargo insulation, the permeabilities of
       the relevant cargo spaces and/or the void spaces surrounding such cargo
       spaces may be calculated by excluding the volume of insulation material in
       those spaces from the flooded volume, provided that the insulating material is
       shown to comply with the following conditions:

       .1     it is impermeable to water under hydrostatic pressure at least
              corresponding to the pressure caused by the assumed flooding;

       .2     it will not crush or break up due to hydrostatic pressure at least
              corresponding to the pressure caused by the assumed flooding;

       .3     it will not deteriorate or change its properties over the long term in the
              environment anticipated in the space it is installed;

       .4     it is highly resistant to the action of hydrocarbons, where relevant; and

       .5     it will be adequately secured so that it will remain in position if
              subjected to collision damage and consequent displacement, distortion
              of its supporting and retaining structure, repeated rapid ingress and
              outflow of seawater and the buoyant forces caused by immersion
              following flooding;

.4.3   The applied permeability should reflect the general conditions of the ship
       throughout its service life, rather than specific loading conditions; and

.4.4   Permeabilities other than those indicated in Table 2 should be considered
       only in cases, where it is evident that there is a significant discrepancy
       between the values shown in the regulations and the actual values (i.e. due to
       specific tank structure or insulating material).

6.5    Free-surface calculation (upright, as vessel heels and after cargo run-off)

With respect to the approval of actual loading conditions the following should be
applied:

.1     The free surfaces of liquids lead to the increase of the centre of gravity (KG)
       and the reduction of the metacentric height (GM) and the righting arm (GZ
       curve) of the ship. Therefore corrections should be made, taking into account
       the change of the centre of gravity of the ship due to the moving of the centre
       of gravity of the liquids.

       Depending on the filling level, free surfaces can exist in tanks with
       consumable liquids, sea water ballast and liquid cargo.

.1.1   For consumable liquids account on the free surfaces should be taken
       whenever the filling level is equal to or less than 98%.

.1.1.1 In calculating the free surface effects in tanks containing consumable liquids,
       it should be assumed that for each type of liquid at least one transverse pair
       or a single centreline tank has a free surface and the tank or combination of
       tanks taken into account should be those where the effect of free surfaces is
       the greatest.
.1.1.2 Taking into account .1.1.1 the free surfaces should correspond to the
       maximum value attainable between the filling levels envisaged.

.1.2   During ballasting between departure and arrival condition, the correction for
       the free surfaces should correspond to the maximum value attainable
       between the filling levels envisaged. This applies also for the situation where
       in the departure condition the filling level of a ballast tank is 0% and in the
       arrival 100% (or the opposite).

.1.3   For the category of liquids referred under paragraph .1.1 and .1.2, as an
       alternative intermediate loading conditions may be considered, as deemed
       necessary, covering the stage where the free surfaces are the greatest. It
       may be calculated with varying free surface moments (i.e. actual liquid
       transfer moments), taking into account actual heel and trim, depending on the
       interval angles of the GZ curve. This is a more accurate method.

.1.4   Except as indicated in 1988 LL/27(11)(v), for liquid cargo the effect of free
       surface should be taken into account for filling level equal or smaller to 98%. If
       the filling level is fixed actual free surfaces can be applied.

       The following two methods can be used for the calculation of the GZ curve
       taking into account the effect of the free surface moments for the intact
       compartments:

       -   Calculation with constant effect of free surfaces, without taking into
           account the change in heel and trim, for the interval angles of the GZ
           curve.

       -   Calculation with varying free surface moments, actual liquid transfer
           moments, taking into account actual heel and trim, depending on the
           interval angles of the GZ curve (see Annex 2).

.2     For the damaged compartments, whenever the damage is involving cargo
       tanks, account should be taken on the following:

       -   The impact on the stability of the ship due to the outflow of cargo and
           ingress of sea water can be verified with the calculation of the
           intermediate stages of flooding (see Section 9); and

       -   At the final equilibrium the free surface correction should exclude the free
           surface moment of the lost cargo.

.3     The free surface effect should be calculated at an angle of heel of 5 degrees
       for each individual compartment or as per paragraph 6.5.1.3.

6.6    Treatment of operational trim

.1     For the assumed damage and the resultant damage cases, the damage
       stability should be assessed for all anticipated conditions of loading and
       variations in draught and trim.

.2     Significant trim values (greater than 1% Lpp) can appear in the aft/fore part of
       the ship in the departure and arrival condition. In that case, damage cases
       involving the aft/fore part of the ship might be critical for achieving compliance
       with the applicable criteria. In order to limit the trim ballast water is used
       during the voyage, as deemed necessary. Under the provision of paragraph
       6.5.1.2 and 6.5.1.3, for taking account of the free surface effect during
       ballasting, if intermediate stages of the voyage are considered then the
       loading conditions representing these stages, should be also calculated for
       damage stability.

6.7    Downflooding points

Downflooding point is the lower edge of any opening through which progressive
flooding may take place. Such openings should include air-pipes, ventilators and
those which are closed by means of weathertight doors or hatch covers and may
exclude those openings closed by means of watertight manhole covers and flush
scuttles, small watertight cargo tank hatch covers which maintain the high integrity of
the deck, remotely operated watertight sliding doors, and sidescuttles of non-opening
type.

All openings through which progressive flooding may take place should be defined:
both weathertight and unprotected. As an alternative it might be accepted to consider
only the most critical openings, which are considered to be the openings with the
lowest vertical position and close to the side shell. Concerning the longitudinal
position it depends on the aft or fore trim of the initial condition and the trim after
damage at equilibrium. Unprotected openings should not be immersed within the
minimum range of righting-lever curve required for the ship. Within this range, the
immersion of any of openings capable of being closed weathertight may be
permitted.

6.8    Cross-flooding time

Cross-flooding time should be calculated in accordance with Recommendation on a
standard method for evaluating cross-flooding arrangements (resolution
MSC.245(83)).

If complete fluid equalization occurs in 60 seconds or less, the equalized tank should
be assumed flooded with the tanks initially to be flooded and no further calculations
need to be carried out. Otherwise, the flooding of tanks assumed to be initially
damaged and equalized tank should be carried out in accordance with paragraph
9.2. Only passive open cross-flooding arrangements without valves should be
considered for instantaneous cases.

Where cross-flooding devices are fitted, the safety of ship should be demonstrated in
all stages of flooding (see paragraph 9.2 and Section 10). Cross-flooding equipment,
if installed, should have the capacity to ensure that the equalization takes place
within 10 min.

Tanks and compartments taking part in such equalization should be fitted with air
pipes or equivalent means of sufficient cross-section to ensure that the flow of water
into the equalization compartments is not delayed.

Spaces which are linked by ducts of a large cross-sectional area may be considered
to be common, i.e. the flooding of these spaces should be interpreted as
instantaneous flooding with the equalization of duration of less than 60 seconds.

6.9    Progressive flooding (internal/external) (see also paragraph 10.1 and 10.2)
     Progressive flooding is the flooding of compartments situated outside of the assumed
     extent of damage. Progressive flooding may extend to compartments, other than
     those assumed flooded, through downflooding points (i.e. unprotected and
     weathertight openings), pipes, ducts, tunnels, etc.

     The flooding of compartment(s) due to progressive flooding occurring in a predictable
     and sequential manner through a downflooding point which is submerged below the
     damage waterline may be permitted provided all intermediate stages and the final
     stage of flooding meet the required stability criteria.

     Minor progressive flooding through the pipes situated within the assumed extent of
     damage may be permitted by the Administration, provided the pipes penetrating a
     watertight subdivision have a total cross-sectional area of not more than 710 mm2
     between any two watertight compartments.

     If the opening (unprotected or fitted with a weathertight means of closure) connects
     two spaces, this opening should not be taken into account if the two connected
     spaces are flooded or none of these spaces are flooded. If the opening is connected
     to the outside, it should not be taken into account only if the connected compartment
     is flooded.

     7       Extents of Damage Considered

     7.1     Maximum extents

     The following provisions regarding the maximum extent and the character of the
     assumed damage should be applied:

.1         Side damage:       MARPOL / IBC / IGC                 ILLC (Type A ships)
                                  2/3
.1.1 Longitudinal             1/3L      or 14.5m, whichever is   Single compartment
     extent:                  less                               between adjacent transverse
                                                                 bulkheads as specified in
                                                                 ILLC paragraph 12(d) 1)
.1.2 Transverse extent: B/5 or 11.5m, whichever is               B/5 or 11.5, whichever is the
                        less (measured inboard from              lesser (measured inboard
                        the ship’s side at right angles          from the side of the ship
                        to the centreline at the level of        perpendicularly to the
                        the summer load line)                    centreline at the level of the
                                                                 summer load waterline) 1)
.1.3 Vertical extent:         upwards without limit              From baseline upwards
                              (measured from the moulded         without limit
                              line of the bottom shell plating
                              at centreline)
.2         Bottom damage      MARPOL / IBC / IGC
           2)
             :                For 0.3L from the forward          Any other part of the ship
                              perpendicular of the ship
.2.1 Longitudinal             1/3 L2/3 or 14.5m, whichever is    1/3 L2/3 or 5m, whichever is
     extent:                  less                               less
.2.2 Transverse extent: B/6 or 10m, whichever is less            B/6 or 5m, whichever is less
.2.3 Vertical extent:         MARPOL / IBC:                      MARPOL / IBC:
                              B/15 or 6m, whichever is less      B/15 or 6m, whichever is
                               (measured from the moulded          less (measured from the
                               line of the bottom shell plating    moulded line of the bottom
                               at centreline)                      shell plating at centreline)

                               IGC:                                IGC:
                               B/15 or 2m, whichever is less       B/15 or 2m, whichever is
                               (measured from the moulded          less (measured from the
                               line of the bottom shell plating    moulded line of the bottom
                               at centreline)                      shell plating at centreline)
.3         Bottom raking       MARPOL
           damage 3):
.3.1 Longitudinal              in tankers of 75,000 tonnes deadweight and above:
     extent:                   0.6L(m) measured from the forward perpendicular of the ship
                               in tankers of less than 75,000 tonnes deadweight:
                               0.4L(m) measured from the forward perpendicular of the ship
.3.2 Transverse extent: B/3 anywhere in the bottom
.3.3 Vertical extent:          Breach of the outer hull
1)
     See Annex 3
2)
     Bottom damage is not required in the ICLL
3)
     Bottom raking damage is required only for oil tankers of 20,000 tonnes deadweight and above

     7.2     Lesser extents

     7.2.1 If any damage of a lesser extent than the maximum damage specified in 7.1
     would result in a more severe condition, such damage should be considered (see
     paragraph 4.5).

     7.2.2 In the case of gas carrier, local side damage anywhere in the cargo area
     extending inboard 760mm measured normal to the hull shell should be considered
     and transverse bulkheads should be assumed damaged when also required by the
     applicable sub-paragraphs of 2.8.1 of the IGC Code.

     7.3  Rationale for reviewing lesser extents including symmetrical vs.
     unsymmetrical tank arrangement/geometry - Calculation on weakest side

     For a given loading condition, following examples of damages of lesser extent may
     result in a more severe situation than that caused by a maximum damage specified
     in 7.1:
     .1       Example of damage on double bottom tanks with watertight centre girder:

             -   Damage of lesser extent which could occur at the bottom plate of the ship,
                 without damaging the centre girder, will lead to flooding of the double
                 bottom tank on one side of the ship only . This is the case of
                 unsymmetrical flooding. For the same location, damage of maximum
                 extent would cause damage on the centre girder and therefore flooding of
                 the double bottom tanks on both sides. This is the case of symmetrical
                 flooding. (see Annex 4).

             Compared to the symmetrical flooding in the case of maximum damage
             extent, unsymmetrical flooding of spaces, caused by damage of lesser extent
             might lead to a more severe situation. Of course, in case of non-watertight
       centre girder, the effect of damage of lesser and maximum extent would be
       the same.

.2     Example of damage with lesser vertical extents:

       -   Damage starting from above a tank top would flood the spaces only above
           the double bottom (see Annex 4). This may result in a more onerous
           residual stability or heeling angle.

Taking into account above examples, it is necessary to review damages of lesser
extents considering the symmetrical or unsymmetrical nature of tank arrangements of
the ship and geometry of the ship. The ship’s damage stability is to be ensured, in
the most severe or weakest case of damage of lesser extents.

8      Rationale Applied for Loading Pattern Evaluation

For damage stability calculations of tank vessels the following effects due to different
loading methods should be taken into account in determining the scope of verification
and specific cases of damage to be investigated.

8.1    Homogeneous vs. alternate/partial loading

For homogeneous loading conditions the damage of cargo tanks may have a major
effect on residual stability. Outflow of the loaded cargo liquids (and less inflow of sea
water) may reduce the vessels displacement and cause heel to opposite side of the
damage. For alternate loading conditions the residual stability depends on the
damaged cargo tank. Damage of a fully loaded cargo tank might cause reduction of
the initial displacement and heel to the opposite side, but damage on an empty cargo
tank might cause the opposite effect. For the damage of two adjacent cargo tanks,
one filled and one empty, the total effect might be less severe due to two (partly)
neutralizing effects.

Partial loading of liquid cargo tanks will cause a high free surface moment when the
surface does not intersect with the tank overhead and will increase the heel in case
of damage. However, reductions of the initial displacement and heel to the opposite
side may not be as significant. Trim to the vessel as consequence of damage can be
significant due to many partially filled cargo tanks.

8.2    Symmetrical and unsymmetrical loading pattern

In general damage stability calculations should be performed for both ship sides.
However, the damage stability calculation for one side of the ship may be accepted
for symmetrical load (alternate, homogeneous, full, partial or empty), if the ship and
all openings are also symmetrical and initial heel to portside or starboard is zero.

8.3    MSC/Circ.406, Rev.1

Additional information regarding intact and damage stability matters for tank vessels
can be found in MSC/Circ.406/Rev.1 which also recommends application of the
“Guidelines for the Uniform Application of the Survival Requirements of the Bulk
Chemical Code (BCH Code) and the Gas Carrier Code (GC Code)” to the IBC and
IGC codes.

9     Intermediate Stages of Flooding Including Equalization, if any, and
Cargo Run-off
Intermediate stages of flooding cover the flooding process from the commencement
of flooding up to but excluding the final equilibrium damage condition (see also
paragraph 3.4.3.2).

Intermediate stages should be comprehensively checked for all ships at the design
appraisal stage.

9.1     Basis for checking intermediate stages of flooding and Minimum
Stability Criteria Applied

The stability criteria applicable to the final equilibrium stage should also be satisfied
for all intermediate stages. If any stability criteria during intermediate stages shows
more severe values than in the final stage of flooding this intermediate stages should
also be submitted.

9.2    Number of intermediate stages considered

A sufficient number of intermediate stages should be examined for all damage cases.
It is generally recommended to apply 5 intermediate stages of flooding (see also
paragraphs 6.8, 6.9 and 10.1).

If the vessel is equipped with non-instantaneous (greater than 60 secs) passive
equalization arrangements or non-passive equalization arrangements of any size the
following procedure is to be used:

1)    Compliance with the relevant criteria should be demonstrated without using
      equalisation arrangements for intermediate and final stages; and

2)    For subsequent equalisation additional 2 intermediate stages and final stages
      the compliance should also be demonstrated.

9.3    Cargo outflow and flood water inflow

During intermediate flooding stages a practical method of calculating the floating
position and residual righting moments is the added weight method where the intact
condition is corrected for the weights of inflowing floodwater and outflowing cargo.

During each stage an assumed amount of added floodwater and/or cargo outflow
should be used. The following method is recommended:

i)    For a loaded tank an equal loss of liquid cargo mass and equal inflow of
      floodwater mass at each stage resulting in a total loss of liquid cargo at and
      total inflow of floodwater to the final damage equilibrium waterline; and

ii)  For an empty tank an equal inflow of floodwater mass at each stage resulting in
     total inflow of floodwater to the final damage equilibrium waterline.
See Annex 5 for example calculation.

[Alternative methods may be accepted, for example:

i)    For a loaded tank the loss of liquid cargo mass and inflow of floodwater mass is
      based on a linear change of total tank content density over each intermediate
      stage from pure cargo at the intact condition to pure floodwater at the final
      damage equilibrium waterline.
ii)     For an empty tank an increasing depth of water at each stage based on the
        difference between the depth of water in the tank and the depth to the waterline
        in way of the tank, divided by the number of remaining stages, resulting in total
        inflow of floodwater to the final damage equilibrium waterline.]

Noting that calculation of stability in the final damage condition assumes both the
liquid cargo and the buoyancy of the damaged spaces to be lost it is therefore
considered both reasonable and consistent to base the residual GZ curve at each
intermediate stage on the intact displacement minus total liquid cargo loss at each
stage.

9.4       Treatment of free surface and KG adjustment

Taking due account of the requirements of paragraph 6.5.1.1 it is generally
recommended to apply actual liquid transfer moments for all tank filling levels in
determining compliance with the relevant damage stability criteria through direct
calculations of actual loading conditions.

With regard to the treatment of free surfaces of flooded spaces and noting that there
will be combinations of empty and loaded tanks within the damaged extent all
damaged compartments should be considered individually flooded during the
intermediate stages – i.e. individual free surfaces. (The compartments are
considered open to the sea in the final damage condition).

10        Final Stage of Flooding (Resolution MSC.281(85) to be referred to)

10.1      Watertight and weathertight integrity

The mandatory instruments referenced in paragraph 2.1 require the final waterline,
taking into account sinkage, heel and trim, shall be below the lower edge of any
opening through which progressive flooding may take place. Such openings shall
include air-pipes (irrespective of closing devices) and those which are closed by
means of weathertight doors or hatch covers and may exclude those openings
closed by means of watertight manhole covers and flush scuttles, small watertight
cargo tank hatch covers which maintain the high integrity of the deck, remotely
operated watertight sliding doors, and sidescuttles of the non-opening type.

Within the required range of residual stability, the immersion of any of the openings
listed above and other openings capable of being closed weathertight may be
permitted.

In the final equilibrium condition watertight escape hatches should not be submerged
below the equilibrium damage waterline and should be treated as weathertight
openings 4).



Footnote:

4)     This specification applies only to the escapes from spaces other than tanks.

For emergency generator room the lowest point of the room should remain above the
final equilibrium damage waterline. Any opening leading to this room should be
treated as unprotected or weathertight, as applicable.
The following principles apply:

i)     Watertight doors under the final waterline after flooding

All watertight doors under the final waterline after flooding should be remotely
operated sliding watertight doors. Installation of a hinged watertight door (e.g.
between the steering gear compartment and engine room) is subject to acceptance
by the Administration.

ii)    Progressive flooding due to damage or submersion of air pipes

Progressive flooding may be accepted subject to the air pipes leading to relatively
small compartments which are progressively flooded in a predictable and sequential
manner in which all intermediate stages of flooding (with the exception on no
progressive flooding) and the final stage of flooding meet the required stability
criteria.

iii)   Watertight doors on the aft wall of forecastle under the final waterline after
flooding

Hinged watertight doors at the aft bulkhead of a forecastle space are permitted to be
submerged after damage only when possible progressive flooding is limited to one
relatively small compartment which is progressively flooded in a predictable and
sequential manner in which all intermediate stages of flooding (with the exception of
no progressive flooding) and the final stage of flooding meet the required stability
criteria. No further progressive flooding is permitted beyond the initial flooding of the
forecastle. This approach is only permitted after all other options, such as increasing
the sill height, relocating the door, only providing access from above, have been
shown to be unworkable in practice.

10.2   Unprotected openings

Residual GZ curves should be terminated at the lowest angle of submersion of an
unprotected opening.
                                    ANNEX 1

DAMAGE STABILITY REQUIREMENTS APPLICABLE TO NEW OIL TANKERS,
            CHEMICAL TANKERS AND GAS CARRIERS


                          ASSIGNED
      SHIP TYPE                                     LENGTH                RULES
                         FREEBOARD
                                                                        MARPOL,
                                                    L ≤ 150 m
                      Type “A” ship with                                ANNEX I
                      assigned freeboard                                 MARPOL,
     OIL TANKER 1)    less than type “B”           L > 150 m            ANNEX I +
                                                                       ICLL, Reg.27
                      Not less than type                                MARPOL,
                                              Regardless of length
                      “B”                                               ANNEX I
                      Type “A” ship with            L ≤ 150 m              IGC
                      assigned freeboard                                IGC +ICLL,
 LIQUEFIED GAS        less than type “B”           L > 150 m
                                                                          Reg.27
   CARRIER 1)
                      Not less than type
                                              Regardless of length         IGC
                      “B”
                      Type “A” ship with            L ≤ 150 m               IBC
                      assigned freeboard                                IBC +ICLL,
      CHEMICAL        less than type “B”           L > 150 m
                                                                          Reg.27
      TANKER 1)
                      Not less than type
                                              Regardless of length          IBC
                      “B”
1)
   Ships complying with the above Regulations do not need to comply with the damage
stability requirements of SOLAS, Chapter II-1, Part B-1.
                                      ANNEX 2

   EXPLANATORY NOTES TO THE FREE SURFACE CALCULATION WITH
VARYING FREE SURFACE MOMENTS, ACTUAL LIQUID TRANSFER MOMENTS,
  TAKING INTO ACCOUNT ACTUAL HEEL AND TRIM, DEPENDING ON THE
                INTERVAL ANGLES OF THE GZ CURVE

In the figure below it is shown that the free surface moments can be reduced
significantly, depending on the filling level and on the heel. Therefore calculations
according to the actual liquid transfer moment represent a more realistic situation. In
cases where the effect of free surfaces has a significant impact (i.e. large tanks) this
method provides a more realistic account and can be used for the calculations of
damage stability.




    WL                                                                                 WL




     WL                                                                                WL
                                   ANNEX 3

DESCRIPTION OF THE LONGITUDINAL EXTENT OF DAMAGE ACCORDING TO
             ICLL PROTOCOL 1988, REGULATION 27(12)(d)

The longitudinal extent of one compartment may vary depending if transversal wing
tank bulkheads exceed B/5 (or 11.5m, whichever is less) or not. Please see the
damages of sketch below.

1.     Normal B/5 or 11.5m damage;

2. and 3.Transverse bulkhead exceeding B/5 or 11.5 m undamaged (two single one
       compartment damage cases); and

4.     Transverse bulkhead not exceeding B/5 or 11.5m damaged (one single one
       compartment damage case).
                    ANNEX 4

EXAMPLE ON HOW TO DEFINE DAMAGES OF LESSER EXTENT
                                       ANNEX 5

    EXAMPLE CALCULATION OF THE LOSS OF LIQUID CARGO MASS AND
                  INFLOW OF FLOODWATER MASS


Initial filling = 540 tonnes at SG = 1.800


Final filling at equilibrium = 240 tonnes at SG = 1.025


Stage     Assumed total       Assumed         Assumed      Total volume   SG assumed in
             mass in           mass at       Mass of sea    assumed in     compartment
          compartment        original SG       water       compartment
  0             540              540             0            300.0           1.800
  1             490              450             40           289.0           1.695
  2             440              360             80           278.0           1.583
  3             390              270            120           267.1           1.460
  4             340              180            160           256.1           1.328
  5             290               90            200           245.1           1.183
  6             240               0             240           234.1           1.025
GUIDELINES FOR VERIFICATION OF DAMAGE
        STABILITY FOR TANKERS




               PART 21




       OPERATIONAL GUIDELINES
[OptionSection A-1-1 - Compliance with damage stability regulations


Original text based upon SLF 53/8 and SLF53/8/2 modified in accordance
with first round comments



1 BACKGROUND


1.1 Scope of Guidelines


These Operational Guidelines have been developed to provide Tanker Masters and Tanker
Managers with information and guidance on compliance with the requirements of damage
stability and on providing verification of such compliance to relevant authorities.


The Master should be supplied with information appertaining to the stability of the tanker
under various conditions of service. The basic requirements for provision of stability
information under SOLAS, MARPOL and the IBC and IGC Codes are shown at Annexes 1, 2
and 3 respectively.


This information should enable the Master to ensure compliance with the relevant intact and
damage stability requirements in relation to the studied (approved) cargo loading conditions.


All references to “approved loading conditions” made within this document shall also be
taken to refer to loading conditions which lie within the prescribed boundaries of approved
limiting KG or GM curves, or to loading conditions verified using an approved stability
program whose use is authorised by the flag administration (or an RO acting on its behalf) for
this purpose.


In the case where curves of minimum operational GMfGM or maximum operational KGf are
included in stability information the ability to verify intact and damage stability compliance
for other conditions of loading should also be ensured.


However, the provision of limiting operational GMfGM or KGf data is not always practicable
for tankers and such data may not be provided. In this case the advice at SOLAS Chapter II-1
reg 5-1(5) applies.


Considerations on the scope and type of stability information are given at Part 3 of Annex 4


1.2 Introduction


1.2.1 Responsibility
It is required under MARPOL and SOLAS to ensure that the vessel is loaded in accordance
with all relevant stability criteria, prior to proceeding to sea. This responsibility is identified
in the relevant provisions of SOLAS and MARPOL. There are additional provisions and
requirements for certificates issued under the provisions of the IBC and IGC Codes.


In order to understand this issue the terms Intact Stability, Damage stability and Stability in
the damaged condition should be understood and are explained below.


1.2.2 Compliance with intact stability


The International Code on Intact Stability* provides information and criteria which must be
complied with by cargo and passenger ships. This Intact Stability information is provided to
the master as per SOLAS chapter II-1, regulation 5-1.


During normal operations the intact stability of a ship is assessed by either using an intact
stability function attached to a loading computer program oor stability instrument or by
manual calculations.


Compliance with intact stability shall be demonstrated before proceeding to sea and evidence
of this documented.


1.2.3 Compliance with damage stability


Damage stability requirements in SOLAS, chapter II-1, parts B-1 to B-4, must be complied
with by all cargo ships above 80 m length other than those which are required to comply with
subdivision and damage stability regulations in other IMO instruments.


In the case of oil tankers, chemical tankers and gas carriers the damage stability provisions of
Marpol Annex 1, the International Code for the Construction and Equipment of Ships
Carrying Dangerous Chemicals in Bulk (IBC Code) and the International Code for the
Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code), apply
respectively in place of the damage stability requirements of SOLAS Chapter II-1, Parts B-1
to B-4.


Information provided to the Master in the form of a stability booklet contains loading
conditions (including ballast conditions) which have been verified to ensure compliance with
both intact and damage stability requirements relative to its vessel type. When the tanker is in
an operational condition which is not covered by one of the loading conditions contained in
the stability booklet then compliance with damage stability must be verified prior to
proceeding to sea and evidence of this documented.


       Refer to the International Code on Intact Stability, 2008 (2008 IS Code), adopted by resolution
        MSC.267(85).
1.2.4 The Stability of the vessel in the damaged condition


This is the residual stability of the vessel after an actual damage to its structure, and
consequent flooding, has occurred. Damages of varying size and layout are evaluated during
approval of stability information, up to the damage of maximum extent as defined within the
rRegulations which apply to a particular vessel.


Compliance with basic intact stability criteria does not necessarily ensure compliance with
damage stability requirements and intact stability characteristics well in excess of the
statutory minimum may be necessary for a particular loading condition to ensure compliance
with damage stability.


Compliance with damage stability requirements should always be verified prior to sailing, and
is required to ensure a vessel shall survive a damage of any extent up to the maximum extent
required by the Regulations which apply to it, should such a damage occur. Use of a shore
side contractor, retained to provide emergency evaluation and assistance in the event that a
damage does occur in service, is not an accepted means to make such pre-departure
verification.


It is important to note that in the event of ANY damage occurring to the vessel which requires
reporting to the Flag Administration, Port State and Classification Society, specialist advice
should always be sought to verify the continued structural integrity.


2   COMPLIANCE


It is the responsibility of the Master to ensure the vessel is loaded in accordance with the
applicable intact and damaged stability criteria during all operational cargo conditions. The
Master [could/may] also be required to demonstrate compliance with these stability criteria to
different surveying and inspecting authorities.


Regulations governing damage stability requirements are contained in various instruments
developed by the IMO (refer to Part 4 of Annex 4 for further detail).


2.1 Compliance with Rregulations


The Master will need to be provided with sufficient documentation information to
demonstrate that their vessel is loaded in a manner which will ensure compliance with the
relevant RegulationsRegulations which apply to it’s type, size and age. This Information to be
provided should include:


       Load Line information;
       shear force and bending moments information;
       draft information;
       intact stability information; and
       damage stability information.


3   METHODS TO DEMONSTRATE VERIFICATION OF COMPLIANCE


There are various methods available to the Master which can be used to demonstrate
compliance with the RegulationsRegulations, as follows:


        .1      to load the vessel only in accordance with the approved loading conditions as
                given in the approved Stability Information Booklet (refer to Parts 1 and 2 of
                Annex 4) ; or
        .2      where the vessel is not loaded in accordance with an approved loading
                condition from the approved Stability Information Booklet, obtain approval
                from the Administration or, a recognized organization (RO) acting on its
                behalf for the proposed loading condition. It is recommended in this case that
                the accuracy of the of the verified loading condition is validated by cross-
                checking the predicted floating position with the observed condition viewed
                from the quay ; or
        [.3     where the vessel is not loaded in accordance with an approved loading
                condition from the approved Stability Information Booklet, when authorised
                by the Administration (or RO acting on its behalf) obtain confirmation from
                the shore-based operating company that the proposed loading condition
                complies. It is recommended in this case that the accuracy of the of the
                verified loading condition is validated by cross-checking the predicted
                floating position with the observed condition viewed from the quay. ; or]


        .4      to     use     an     approved     sStability   pProgram       (stabilityLoading
                Computerinstrument*) or other acceptable method to verify that intact
                stability ands well as damage stability criteria are satisfied for this operating
                condition. When an approved sStability pProgram (Loading Computer) is
                used for such verification then use the approval of this programme must be
                specified in the ship's approved Stability Information Booklet or on the ship's
                certificate of fitness. It is recommended that an approved stability computer
                is used. ASuch approved computers stability programs may beare usually an
                approved as IACS URL5 damage stability softwarecalculation program of
                Ttype 2 or 3Type 3 ; or
        .5      the use of simplified stability data, for example curves of maximum KGfKG
                or minimum allowable GMfGM, to demonstrate compliance, noting that
                w.here such simplified data are used it is necessary to ensure that any
                restrictions applied in their development are also fulfilled in the actual
                loading condition being assessed. Use of simplified intact stability data for
                this purpose is not sufficient and verification must also be made against
                approved damage stability data. In the case of parcel tankers it is
                recommended that such checks are made using an approved Type 2 stability
                program as provided for in the 2008 IS Code, Part B, Chapter 4.


4   WHEN COMPLIANCE IS NOT INITIALLY DEMONSTRATED
The Master should not sail until the vessel is in full compliance with all stability
requirements. In a situation where it has not been possible to demonstrate compliance by any
of the previously mentioned methods, there are a number of choices available, as follows:


          .1        to adjust the loading of the vessel so that it complies with an approved
                    condition from the vessel's approved Stability Information Booklet (refer to
                    Parts 1 and 2 of Annex 4); or


          .2        to adjust the loading of the vessel until the loading computer intact and
                    damage stability modules show that compliance has been achieved, whilst
                    ensuring that all other requirements of the voyage such as load line and
                    strength requirements are met ; or


          .3        to contact shore-based operating company when authorised by the
                    Administration (or RO acting on its behalf) and request assistance in the
                    calculation of the intact and damage stability for an adjusted loading
                    condition to ensure compliance with the Regulations. It is recommended in
                    this case that the accuracy of the of the verified loading condition is validated
                    by cross-checking the predicted floating position with the observed condition
                    viewed from the quay ; or


          [.4       to contact the RO acting on behalf of the Administrationship's classification
                    society and request assistance in the calculation of the intact and damage
                    stability for an adjusted loading condition to ensure compliance with the
                    Regulations. It is recommended in this case that the accuracy of the of the
                    verified loading condition is validated by cross-checking the predicted
                    floating position with the observed condition viewed from the quay ]



5    DOCUMENTATION


All checks and diligence carried out in ensuring that the ship is in compliance with the
Rregulations should be documented in accordance with the company's operating procedures
and the company's safety management system.


It is important that any manual calculations done to ensure compliance or printouts from an
approved Loading Computer used for this purpose should be kept on file to maintain an audit
trail and to be able to demonstrate compliance to company auditors, surveyors, port state
control inspectors, etc.


* There are three types of Approved Stability Programmes/Software, (Loading Computers) details of which are
provided in IACS Unified Requirement no. 5 for Load Line (UR L5) and 2008 IS Code, Chapter 4. A brief
description of the 3 types is as follows. Three types of calculations performed by stability software are acceptable
depending upon a vessel's stability requirements:


          Type 1: Software calculating intact stability only (for vessels not required to meet a damage stability
                  criterion);
Type 2: Software calculating intact stability and checking damage stability on basis of a limit curve
        (e.g., for vessels applicable to SOLAS Part B-1 damage stability calculations, etc.) or
        previously approved loading conditions; and
Type 3: Software calculating intact stability and damage stability by direct application of pre-
        programmed damage cases for each loading condition (for some tankers, etc.).
                                           ANNEX 1


    SOLAS REQUIREMENTS FOR PROVISION OF STABILITY INFORMATION
             INCLUDING DAMAGE STABILITY INFORMATION


                        (Based on SOLAS 2009 Consolidated Edition)


                                      "Part B-1 Stability”


Regulation 5-1 – Stability information to be supplied to the master


1        The master shall be supplied with such information satisfactory to the Administration
as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to
the stability of the ship under varying conditions of service. A copy of the stability
information shall be furnished to the Administration.


2       The information should include:


        .1      curves or tables of minimum operational metacentric height (GM) versus
                draught which assures compliance with the relevant intact and damage
                stability requirements, alternatively corresponding curves or tables of the
                maximum allowable vertical centre of gravity (KG) versus draught, or with
                the equivalents of either of these curves;


        .2      instructions concerning the operation of cross-flooding arrangements; and


        .3      all other data and aids which might be necessary to maintain the required
                intact stability and stability after damage.


3       The stability information shall show the influence of various trims in cases where the
operational trim range exceeds ± 0.5% of Ls.


4        For ships which have to fulfil the stability requirements of part B-1, information
referred to in paragraph 2 are determined from considerations related to the subdivision index,
in the following manner: Minimum required GM (or maximum permissible vertical position
of centre of gravity KG) for the three draughts ds, dp and dl are equal to the GM (or KG
values) of corresponding loading cases used for the calculation of survival factor si. For
intermediate draughts, values to be used shall be obtained by linear interpolation applied to
the GM value only between the deepest subdivision draught and the partial subdivision
draught and between the partial load line and the light service draught respectively. Intact
stability criteria will also be taken into account by retaining for each draught the maximum
among minimum required GM values or the minimum of maximum permissible KG values
for both criteria. If the subdivision index is calculated for different trims, several required GM
curves will be established in the same way.
5        When curves or tables of minimum operational metacentric height (GM) versus
draught are not appropriate, the master should ensure that the operating condition does not
deviate from a studied loading condition, or verify by calculation that the stability criteria are
satisfied for this loading condition."
                                          ANNEX 2


          REQUIREMENTS FOR DAMAGE STABILITY INFORMATION.


                                 MARPOL Annex 1, reg 28


"5      The master of every oil tanker to which this regulation applies and the person in
charge of a non-self-propelled oil tanker to which this regulation applies shall be supplied in
an approved form with:


        .1     information relative to loading and distribution of cargo necessary to ensure
        compliance with the provisions of this regulation; and


        .2     data on the ability of the ship to comply with damage stability criteria as
        determined by this regulation, including the effect of relaxations that may have been
        allowed under subparagraph 1.3 of this regulation."
                                           ANNEX 3


     INFORMATION ON STABILITY TO BE PROVIDED UNDER RELEVANT
                CLAUSES OF THE IBC AND IGC CODES


The extracts below are provided for guidance only. Reference should be made to chapter 2 in
each of the particular Codes. Particular attention is to be given to the certificate requirements
listed at the end of this annex.


IGC Code, clause 2.2.5:


The master of the ship should be supplied with a loading and stability Information booklet.
This booklet should contain details of typical service and ballast conditions, loading,
unloading and ballasting operations, provisions for evaluating other conditions of loading and
a summary of the ship's survival capabilities. In addition, the booklet should contain sufficient
information to enable the master to load and operate the ship in a safe and seaworthy manner.


IGC Code, clause 2.4:


Damage survival capability should be investigated on the basis of loading information
submitted to the Administration for all anticipated conditions of loading and variations in
draught and trim. The survival requirements need not be applied to the ship when in the
ballast condition, provided that any cargo retained on board is solely used for cooling,
circulation or fuelling purposes.


(NB; this clause should be read in conjunction with the certificate requirements below)


IBC Code, clause 2.2.5:


The master of the ship shall be supplied with a loading and stability Information booklet.
This booklet shall contain details of typical service and ballast conditions, provisions for
evaluating other conditions of loading and a summary of the ship's survival capabilities. In
addition, the booklet shall contain sufficient information to enable the master to load and
operate the ship in a safe and seaworthy manner.


IBC Code, clause 2.4:


Damage survival capability shall be investigated on the basis of loading information
submitted to the Administration for all anticipated conditions of loading and variations in
draught and trim. Ballast conditions where the chemical tanker is not carrying products
covered by the Code, or is carrying only residues of such products, need not be considered.


(NB; this clause should be read in conjunction with the certificate requirements below)
Requirements on the Certificates of Fitness for the IBC and IGC Codes


The Certificates of Fitness issued under both of these Codes contain the following clauses:


        That the ship must be loaded:


        .1      in accordance with the loading conditions provided in the approved loading
                manual, stamped and dated ............................ and signed by a responsible
                officer of the Administration, or of an organization recognized by the
                Administration;


        .2      in accordance with the loading limitations appended to this Certificate.


Where it is required to load the ship other than in accordance with the above instruction, then
the necessary calculations to justify the proposed loading conditions shall be communicated
to the certifying Administration who may authorize in writing the adoption of the proposed
loading condition.
                                        ANNEX 4


                     DEFINITIONS AND INTERPRETATIONS


Part 1 - Approved Loading Condition


.1     In relation to a tanker certified under MARPOL Annex I or the IBC or IGC Codes, an
       approved loading condition is a unique individual condition of loading, taking
       account of the combination of lightship and all individual deadweight items, which
       has been verified by the flag State (or recognized organization acting on its behalf) as
       complying with both intact and damaged stability criteria and is approved for use in
       service of the vessel.


.2     The approval of an individual loading condition is granted for the purpose of loading
       to that unique condition and cannot be taken to confer any acceptance or approval of
       other loading conditions which vary from it, given that the margin of compliance
       against the applicable intact or damage stability criteria may be zero.


.3     [Loading conditions which are verified in service and shown to lie within the
       boundary of approved limiting KG/GM curves shall also be regarded as approved
       loading conditions.]


Part 2 -– Loading “iIn accordance with”, “closely loaded to” or “not significantly
different from” – an Approved Loading Condition


.1     For tankers which do not have an approved loading stability instrument, or critical
       GMfGM or KGfKG data, which enable damage stability verification of the live
       loading condition to be made on board prior to departure, loading should always be
       made strictly in accordance with an approved loading condition unless the loading
       condition is first verified as compliant by the Flag State or a recognized organization
       prior to departure.


.2     However, to permit practical operation of such tankers, having regard to small
       variations in cargo SG, stores and minor tank fillings, it is necessary to permit some
       variation in loading from an approved condition.


.3     Although variation of a loading condition could result in the condition becoming non-
       compliant with damage stability criteria, it is accepted that the probability of this
       occurrence is low where such variations in loading are small.


.4     For the purpose of determining whether a tanker is loaded "in accordance with" an
       approved loading condition, the following limits should be applied:
      .1      the filling of any individual cargo tank, slop tank or water ballast tank should
              not vary by more than [1% ] or [2 2%] or 3% or 5%] by mass from that
              assumed in the approved loading condition; and


      .2      [the condition KGfKG should not exceed that of the approved loading
              condition by more than 2cm or the condition GMfGM fall below that of the
              approved loading condition by more than 2cm].




Part 3 -– Approved Range of Loading Conditions


.1    In limited circumstances it is acceptable to load to a condition of loading which lies
      within an approved range of loading conditions, even though the individual loading
      condition may vary from all of these individual conditions.


.2    For an approved range of loading conditions to be valid it must offer a clear
      indication how intermediate cargoes are to be loaded. In this respect it should be clear
      when loading to a condition which lies between two approved conditions within the
      range of conditions, how the cargo is to be distributed and whether any ballast should
      be carried. The range of loading conditions may carry additional guidance in this
      respect for advice of the master.


.3    In this respect, inclusion of conditions with all cargo tanks 98% filled for a range of
      single SG cargoes, and with progressive filling of ballast tanks to maintain trim
      and/or draught may provide adequate guidance for loading single cargoes of an
      intermediate SG.


.4    Conversely, the inclusion of loading conditions for a range of different single SG
      cargoes each of which exhibit different distributions of cargo and ballast, and from
      which it is not possible to infer the transitional distribution of cargo or ballast at
      intermediate cargo SGs, is not acceptable.




Part 4 - Minimum number of loading conditions required in Approved Stability
Information


.1    For the purpose of making a submission of stability information for approval, the
      minimum number of loading conditions which should be submitted for approval is a
      function of the mode of operation intended for the vessel.


.2    MSC/Circ.406/Rev.1 offers guidance in this respect, and identifies the concepts of the
      "dedicated service tanker" and "parcel tanker" for the purpose of undertaking stability
      approval of vessels certified under the IBC and IGC Codes.
.3    This guidance has equal relevance to tankers certified under MARPOL Annex I and
      makes a distinction between vessels which are procured to undertake long-term
      service on fixed routes, where the likely range of variation in cargoes and cargo
      distribution is small and may be predicted, and those procured to undertake a parcel
      service on the spot market where the range of cargoes and cargo distribution is
      unlimited and impossible to predict with any certainty.


.4    Difficulties in making satisfactory damage stability verification prior to departure
      may result if a vessel changes its mode of operation, particularly from dedicated
      service tanker to parcel tanker.


.5    For tankers which do not have an approved loading stability instrument, or approved
      critical GMfGM or KGfKG data covering intact and damage stability, enabling
      damage stability verification of the live loading condition to be made on board prior
      to departure, loading should always be made strictly in accordance with an approved
      loading condition.


.6    Where the dedicated service of a tanker is known in advance the operator should seek
      to ensure enough loading conditions are submitted for approval to cover all
      anticipated cargoes, their potential range of SG, anticipated operational variations in
      trim and any requirement to carry part loads (e.g., in the case of tankers intended to
      discharge part cargoes).


.7    If it is desired to change the service of a dedicated service tanker to include additional
      cargoes or routes, additional loading conditions may be submitted for approval and
      appended to the approved stability information.


.8    Where a tanker is intended for service as a parcel tanker and the variation in cargoes
      and cargo distribution is not possible to predict, MSC/Circ.406/Rev.1 proposes that
      the range of potential tank fillings and cargo SGs should be systematically examined
      and limiting curves of critical GMfGM or KGfKG developed and approved covering
      intact and damage stability compliance over the full operational draught and trim
      envelope of the vessel.


.9    This provides a means for verification of damage stability prior to departure for a
      parcel tanker where an approved loading stability instrument capable of damage
      stability verification of the live loading condition is not fitted. However, the use of
      critical GMfGM or KGfKG data is itself conditional upon any restrictions applied in
      their development being met in the live condition under consideration (e.g., minimum
      ballast filling in voids outboard of an empty cargo tank) and such restrictions should
      be stated in the stability information.


.10   Where the stability information submitted for approval includes critical GMfGM or
      KGfKG data for the purpose of verifying intact and damage stability, there is no
      necessity to include a substantial range of typical loading conditions for approval as
      these have limited practical value. However, it is necessary to submit the matrix of
      calculations which have been employed to derive the critical GMfGM or KGfKG
      data for examination.
.11     Where the stability information submitted for approval relates to a tanker where it is
       the intention to provide an approved loading stability instrument capable of verifying
       intact and damage stability directly, there is similarly no necessity to include a
       substantial range of typical loading conditions for approval as these shall also have
       limited practical value.


.12    For parcel tankers it is recommended to submit loading conditions for approval which
       encompass light and deep draughts, high and low cargo SG, ballast conditions, and
       any conditions which highlight loading restrictions which have been used to
       determine the critical GMfGM or KGfKG data for the general guidance of the master,
       particularly where strength considerations may be relevant.


.13    The minimum number and range of loading conditions required to be submitted for
       approval is determined by a tankers service, not its size or type, and the scope of
       approved stability information deemed suitable for use on a dedicated service tanker
       may not enable damage stability verification to be made should the vessel
       subsequently be engaged in service as a parcel tanker.


Part 54 -– Dedicated Service Tanker and Parcel Tanker


.1     A dedicated service tanker is a vessel which is arranged to carry a limited range of
       cargoes in terms of the cargo distribution or SG, and typically carries these cargoes
       repeatedly over the duration of a significant charter period.


.2     Loading conditions normally comprise a single SG cargo, or a limited combination of
       cargoes of different SG. Stability verification on such vessels may be ensured by
       always loading to an approved loading condition.


.3     A parcel tanker is a vessel arranged to carry a wide range of different cargoes of
       differing SGs, often in combination, Such vessels commonly trade on the spot market
       and wide variation in loading makes carriage of repeat cargoes unlikely.


.4     Ensuring stability verification by always loading to an approved loading condition
       may not be a practical option for a parcel tanker due to the number of potential cargo
       distributions and consequent difficulty in predicting such loading conditions in
       advance. Other means of verification, such as application of critical KG/GM data or
       direct calculation using a stability instrument, may be more appropriate for such
       vessels.


Part 6 - Requirements for damage stability verification contained within mandatory
instruments


.1     SOLAS requirements for stability information to be supplied to the master provided
       by chapter II-1, part B-1, regulation 5-1(2) specify these should include critical intact
     GMfGM or KGfKG data which ensure compliance with both intact and damage
     stability criteria.


.2   In the case of tankers the damage stability requirement is determined from the
     application of the relevant provisions of MARPOL Annex 1 or the IGC and IGC
     Codes and not the application of part B-1 to B-4 of chapter II-1, as provided for by
     regulation 4.1.


.3   SOLAS requirements for stability information to be supplied to the master provided
     by chapter II-1, part B-1, regulation 5-1(5) make specific provision that where critical
     GMfGM data (and by implication critical KGfKG data) are not appropriate, the
     master shall ensure the operating condition of the vessel does not deviate from the
     conditions contained in the stability information unless such an alternative loading
     condition has been verified by calculation.


.4   Noting the difficulty in developing critical GMfGM or KGfKG data for tankers,
     where the filling level and SG of the content for all tanks needs to be taken into
     consideration over the range of operational draught and trim, and the number of
     loading permutations which may result on parcel tankers, provision of this data may
     prove to be inappropriate when compared to an alternative method of demonstrating
     compliance, such as direct calculation using an approved loading stability instrument.


.5   MARPOL Annex I, regulation 28(5.1) requires that the master or person in charge of
     an oil tanker shall be provided with approved stability information which provides
     "information relative to the loading and distribution of cargo necessary to ensure
     compliance with the provisions of this regulation", i.e. regulation 28 (Subdivision and
     damage stability).


.6   In the case of a dedicated service tanker this requirement provides for the provision of
     approved intact loading conditions which ensure compliance with damage stability
     criteria should any damage case of the prescribed extent occur.


.7   In the case of a parcel tanker this requirement also provides for the provision of
     approved critical GMfGM or KGfKG data applicable to the anticipated operation
     range of draught, trim, tank filling and cargo SG, supplemented by approved intact
     loading conditions which comply with these critical GMfGM or KGfKG limits and
     therefore with damage stability criteria should any damage case of the prescribed
     extent occur.


.8   MARPOL Annex 1, regulation 28(5.2) further requires that the master or person in
     charge shall also be provided with approved "data on the ability of the ship to comply
     with damage stability criteria".


.9   In the case of a dedicated service tanker this may be taken to mean the margin of
     compliance with damage stability criteria should any damage of the prescribed extent
     occur. In the case of a parcel tanker for which critical GMfGM or KGfKG data have
      been developed, this may also be taken to mean an indication of the damage stability
      criterion which defines the critical limit for a given loading condition.


.10   The above requirements of MARPOL Annex 1 specifically provide for the provision
      of approved loading conditions and/or approved critical GMfGM or KGfKG data
      which may be used by the master or person in charge to safely load the vessel. In this
      context, only loading conditions which closely reflect the approved loading
      conditions or which comply with the GMfGM or KGfKG limits may safely be
      loaded.


.11   The requirements of the IBC and IGC Codes with regard to the provision of approved
      stability information are similar, and detailed in chapter 2 of each instrument.


.12   Paragraph 2.2.5 of each Code requires that the master is provided with stability
      information which includes typical service and ballast conditions, makes provision
      for evaluating other conditions of loading, gives a summary of the survival
      capabilities and contains sufficient information to enable the master to safely load the
      vessel.


.13   These provisions can be satisfied by paragraphs .6, .7 and .9 as these relate to a tanker
      to which MARPOL Annex 1 applies. The provision of guidance to the master to
      safely load the vessel would extend to clear instruction on how to apply critical
      GMfGM or KGfKG data, where these are appropriate and have been developed, or to
      restrict operation to the typical service conditions unless an alternative condition has
      first been verified by calculation.


.14   Paragraph 2.4 of each Code requires that damage survival capability is investigated
      on the basis of the loading information submitted for all anticipated conditions of
      loading and variations in draught and trim. Where a submission is restricted in scope,
      and does not contain critical intact GMfGM or KGfKG data which ensure compliance
      with intact and damage stability criteria over a range of draught and trim,
      investigation of damage survival capability would be limited to the submitted loading
      conditions and operation of the vessel would necessarily be restricted to these
      conditions only.


.15   The standard text of the certificates of fitness for IBC and IGC Codes provide for
      two forms of stability approval. Use of sub-paragraph 1 may be appropriate where
      operation shall be restricted only to the approved loading conditions, and sub-
      paragraph 2 may be appropriate if it is desired to specify conditions for verifying
      intact and damage stability using an approved loading stability instrument.


.16   Both clauses are supplemented by the footnote which requires any other loading
      conditions not verified by the approved method to be submitted for authorization by
      the certifying Administration, as required by SOLAS chapter II-1, part B-1,
      regulation 5-1(5).]
[OptSection A-2 - Compliance with damage stability regulations


Revised text proposed by the United States



   DRAFT OPERATIONAL GUIDELINES FOR THE VERIFICATION OF
       DAMAGE STABILITY REQUIREMENTS FOR TANKERS



Introduction


1      These Guidelines are intended to provide additional information and guidance
on the methods used to verify tanker compliance with the applicable damage stability
requirements.


2       It is the responsibility of the Master to ensure the ship is loaded in accordance
with the applicable damage stability requirements during all operational conditions
where cargo is carried. It is critical to verify a ship’s damage stability characteristics
before departing port because, in the unlikely event that damage does occur during a
voyage, there may be insufficient time for the crew to take effective action to restore
the ship’s stability. Familiarity with the ship’s damage stability characteristics will
help the Master and crew to determine whether or not to abandon ship, and to decide
what measures are reqired to mitigate the effects of damage and, where possible,
improve the situation.


Definitions


3      The stability and buoyancy characteristics of a ship typically include, but are
not limited to, the draft, trim, heel, height of the center of gravity (KG), righting arm
(GZ) and metacentric height (GM).


4      The term intact stability refers to the stability and buoyancy characteristics of
an undamaged ship in a static condition, which are evaluated during approval of the
ship’s stability information and must also be verified prior to the ship’s departure
from port.


5       The term damage stability refers to the residual stability and buoyancy
characteristics of a damaged ship in a static condition, which are evaluated during
approval of the ship’s stability information and must also be verified prior to the
ship’s departure from port. Damage stability compliance assures that the ship has
sufficient reserves of intact stability to withstand a specified extent of damage.
Damages of varying size and layout are applied during evaluation of damage stability,
up to the maximum extent of damage defined in the applicable Regulations, and
confirm whether or not the ship has adequate residual stability characteristics to meet
specified minimum criteria after flooding.


6       The term stability in the damaged condition refers to the residual stability and
buoyancy characteristics of a ship after an actual damage to its structure has occurred,
the initial contents of any damaged compartment have been lost and flooding of all
damaged compartments is completed.


7      A stability instrument is an instrument installed on board a particular ship by
means of which it can be ascertained that stability requirements specified for the ship
in the stability booklet are met in any operational loading condition. A stability
instrument comprises hardware and software.


General


8       Compliance with basic intact stability criteria does not ensure compliance
with damage stability requirements. In a particular loading condition, a vessel may
need intact stability characteristics well in excess of the statutory minimum to ensure
compliance with damage stability.


9        Compliance with damage stability requirements does not ensure stability in
the damaged condition shall be sufficient to ensure survival following any case of
damage, but only damages up to the maximum extent considered by the applicable
Regulations. The actual extent of damage and flooding must be determined during an
incident in order to compare this with the standard damage cases used to confirm
regulatory compliance in accordance with these Guidelines. If the actual case of
damage exceeds the maximum extent applied by the Regulations, then the case must
be specially evaluated prior to taking remedial action. Information on the actual extent
of damage will also be required to determine whether a ship has sufficient structural
integrity in the damaged condition.


10     It should be noted that damage stability is normally calculated for individual
loading conditions based upon the ship’s specific draft and trim, the specific gravity
and level of liquids in each tank, and value of the condition KG or GM. The result is
also dependent upon maintenance of the watertight and weathertight boundaries of the
buoyant hull. If any of these factors change, or the boundary of the hull is not
maintained watertight or weathertight, the calculations are no longer valid and the
ship may not meet the survival criteria.


Regulatory requirements
11       The regulations which require tankers to verify compliance with damage
stability requirements are contained in various instruments developed by the IMO, as
follows:


Vessel Type                                Regulation
Cargo ships of 80 m in length and SOLAS 2009, Chapter II-1, regulation 5-
upwards*, keel laid on or after 1 Jan 2009 1
Cargo ships over 100 m in length*, SOLAS 90, Chapter II-1, regulation 25-1
constructed on or after 1 Feb 1992 &
Cargo ships 80 m in length and up, but
not over 100 m*, constructed on or after 1
Jul 1998
Oil tankers of 150 gross tonnage and MARPOL, Annex I, regulation 28
above, delivered after 31 Dec 1979
Ships carrying dangerous chemicals or IBC Code, Chapter 2, regulation 2.2.5
noxious liquid substances in bulk, keel
laid on or after 1 Jul 1986
Ships carrying liquefied gases in bulk, IGC Code, Chapter 2, regulation 2.2.5
keel laid on or after 1 Oct 1994 1 July
1998
BG Code ???


* If a cargo ship is shown to comply with subdivision and damage stability
regulations in another IMO instrument, the ship is not required to comply with the
SOLAS damage stability requirements.




Assessment of a ship’s loaded condition


12     The first step in verifying damage stability compliance is to make a careful
assessment of the ship’s actual condition, once it is loaded and/or ballasted for
departure. As a minimum, the assessment of the ship’s actual condition should
include the following steps:


       1. Determine the ship’s forward and after drafts, along with the midships
          draft, if available;

       2. Confirm that the cargo measuring devices (gauges) are working and
          accurate;
       3. Gauge the levels of all cargo and ballast tanks;


       4. Confirm the specific gravity of the loaded cargo(es); and


       5. Record the above information.


13      Once the data above is obtained and recorded, it should be used to calculate
other variables required to verify damage stability compliance, such as trim, GM or
KG. There should be instructions available to assist in calculating any necessary
variables.


14       There are various methods available to verify compliance with damage
stability regulations, as described in the four sections below. If a ship is not in full
compliance with the damage stability regulations, then the loading of the vessel must
be adjusted to ensure compliance is achieved prior to departure from port.


Use of approved loading conditions


15     The stability information supplied to the Master will include various loading
conditions which have been verified by the Administration (or recognized
organization acting on its behalf) as complying with stability requirements, including
damage requirements, and have been approved for use in service of the ship. It is
important to confirm that the approved loading conditions cover both intact stability
and damage stability requirements.


16      At any time the operator of a ship may request the Administration (or
recognized organization acting on its behalf) to approve additional loading conditions
for use in service of the ship and to append these approved conditions to the stability
information.


17       If a ship is loaded in accordance with one of the approved conditions provided
in, or appended to, the stability information, the ship complies with the damage
stability requirements.


18     Any variation from an approved loading condition will reduce the accuracy of
the approval and may result in non-compliance with the damage stability
requirements. However, it is accepted that the probability of such non-compliance
occurring is low when the differences in loading are very small, and minor variations
from an approved loading condition are permissible to allow for small variations in
loading.
19     A ship may be considered to be loaded in accordance with an approved
condition provided none of the following limits are exceeded:


       .1      [1% or 2% or 3% or 5%] by mass for the filling of any individual
               cargo tank, slop tank or water ballast tank;


       .2      [+2 cm][+5 cm or 1% KG (whichever is less)] for the condition KG
               or [-2cm][-5cm or 1% KG (whichever is less)] for the condition GM;


       .3      [10 cm] for the mean draft; and


       .4      [30 cm] for the trim.


20      A ship may not exceed the variations discussed in this section unless the
revised condition is verified as compliant with damage stability using a method from
one of the following three sections


Use of curves or tables of minimum operational GM versus draft or maximum
allowable KG versus draft


21       The stability information supplied to the Master may also include simplified
stability data, such as curves or tables of minimum operational GM versus draft or
maximum allowable KG versus draft, which has been verified by the Administration
(or recognized organization acting on its behalf) as complying with stability
requirements, and has been approved for use in service of the ship. It is important to
confirm that any such simplified stability data covers both intact stability and damage
stability requirements prior to using it to verify a loading condition other than an
approved loading condition.


22      Simplified stability data establishes limits for some of the ship’s stability
characteristics. Once the ship is loaded and/or ballasted for departure, it complies
with damage stability requirements if it’s stability characteristics fall within the limits
specified in the simplified stability data. Depending on the ship, simplified stability
data may be defined by a single curve or table, but in other cases there may be many
curves or tables to address each damage case as these apply to a single loading
condition. There should always be specific instructions describing how to use
simplified stability data and to interpret the results.


23      If any restrictions were assumed or applied in the development of the
simplified stability data, then those restrictions also apply to the ship’s actual loading
condition (e.g., minimum ballast filling in voids outboard of an empty cargo tank).
Any restrictions associated with use of the simplified stability data should be clearly
stated in the stability information, and any use of the simplified stability information
should include a process to ensure that any such restrictions are met in the loading
condition being assessed for compliance.


24     In the case of parcel tankers for which curves of minimum operational GM or
maximum operational KG are approved, it is recommended that stability verification
using this data is undertaken using an approved stability instrument of Type 2 as
provided for in the 2008 IS Code, Part B, Chapter 4.



Use of a stability instrument


25       A stability instrument may be used to verify compliance with damage stability
regulations, provide the instrument has been verified by the Administration (or
recognized organization acting on its behalf) as complying with stability requirements
and its use has been authorised in service of the ship. It is important to confirm that
any authorisation for the stability instrument covers both intact stability and damage
stability requirements.


26      There should be specific instructions describing how to check the accuracy of
the stability instrument, and how often this must be done (e.g., prior to use, once a
week, once a month).


27       Once the ship is loaded and/or ballasted for departure, the ship’s actual
stability characteristics can be entered into the stability instrument to verify that the
ship complies with the damage stability requirements. There should be specific
instructions describing how to use the stability instrument, the tolerances used by the
software, and how to interpret the results.


28     Stability instrument calculations may be less conservative than those made
during approval of loading conditions or simplified stability data. [If necessary, there
should be specific instructions describing the required level of accuracy for tank
gauges, and describing whether additional underway calculations are needed to verify
continued compliance with the damage stability requirements.]


Use of shore-based support


29     Once the ship is loaded and/or ballasted for departure the ship’s actual stability
characteristics may be sent to a company support office ashore or the classification
society for remote verification of compliance with damage stability requirements,
where this is authorized,or sent to the Administration (or recognized organization
acting on its behalf) for direct approval of the loading condition. Where this type of
verification is employed, the vessel should not sail until a copy of the damage stability
approval has been received.


Documentation


30      Verification of compliance with damage stability requirements should be
documented in accordance with the company’s operating procedures and the
company’s safety management system. This should include a method of retaining
manual calculations and/or stability instrument printouts used to verify compliance, so
that this information can be provided to third parties, such as company auditors,
surveyors or port state control inspectors. It is recommended that records are retained
on board for a minimum of three years to ensure they are available at the next SMC
audit.


Introduction


1      These Guidelines are intended to provide additional information and guidance
on the methods used to verify tanker compliance with the applicable damage stability
requirements.


2        It is the responsibility of the Master to ensure the ship is loaded in accordance
with the applicable damage stability requirements during all operational conditions. It
is critical to calculate a ship’s damage stability characteristics before departing port,
because in the unlikely event that damage does occur during a voyage, there will be
no time for computations and the crew will probably not be in a condition to conduct
a careful analysis of the ship’s stability. As such, familiarity with the ship’s damage
stability characteristics will help determine whether or not to abandon ship, and help
determine what measures are needed to mitigate the effects of damage and, where
possible, improve the situation.


Definitions


3      The stability and buoyancy characteristics of a ship typically include, but are
not limited to, the draft, trim, heel, height of the center of gravity (KG), righting arm
(GZ) and metacentric height (GM).


4      The term intact stability refers to the pre-calculated stability and buoyancy
characteristics of an undamaged ship in a static condition, which are evaluated during
approval of the ship’s stability information or prior to the ship’s departure from port.


5      The term damage stability refers to the pre-calculated stability and buoyancy
characteristics of a damaged ship in a static condition, which are evaluated during
approval of the ship’s stability information or prior to the ship’s departure from port.
Damages of varying size and layout are applied, up to the maximum extent of damage
defined in the applicable regulations, to determine whether the ship has adequate
stability characteristics to attain a specified equilibrium after absorbing the damage
and whether the ship has sufficient reserve buoyancy to withstand flooding.


6     The term stability in the damaged condition refers to the residual stability and
buoyancy characteristics of a ship after an actual damage to its structure has occurred.


7      A stability instrument is an instrument installed on board a particular ship by
means of which it can be ascertained that stability requirements specified for the ship
in the stability booklet are met in any operational loading condition. A stability
instrument comprises hardware and software.


General


8       It should be noted that compliance with basic intact stability criteria does not
ensure compliance with damage stability requirements. In a particular loading
condition, a vessel may need intact stability characteristics well in excess of the
statutory minimum to ensure compliance with damage stability.


9        It should also be noted that compliance with damage stability requirements
does not ensure adequate stability in the damaged condition. The actual extent of
damage and flooding must be identified during an incident in order to compare the
stability in the damaged condition with the pre-calculated scenarios used to confirm
regulatory compliance in accordance with these guidelines. The actual extent of
damage will also be needed to verify that a ship has sufficient structural integrity in
the damaged condition.


10      It should be noted that a ship’s damage stability is calculated for specific
loading conditions based upon the ship’s draft, maintenance of watertight integrity,
specific liquid levels in each tank, specific gravity of cargo, and specific values of KG
and/or GM. If any of these factors change, the calculations are no longer valid, and
the ship may not meet the survival criteria.


Regulatory requirements


11       The regulations which require tankers to verify compliance with damage
stability requirements are contained in various instruments developed by the IMO, as
follows:


Vessel Type                                  Regulation
Cargo ships of 80 m in length and SOLAS 2009, Chapter II-1, Regulation 5-
upwards*, keel laid on or after 1 Jan 2009 1
Cargo ships over 100 m in length*, SOLAS 90, Chapter II-1, Regulation 25-1
constructed on or after 1 Feb 1992 &
Cargo ships 80 m in length and up, but
not over 100 m*, constructed on or after 1
Jul 1998
Oil tankers of 150 gross tonnage and MARPOL, Annex I, Regulation 28
above, delivered after 31 Dec 1979
Ships carrying dangerous chemicals or IBC Code, Chapter 2, Regulation 2.2.5
noxious liquid substances in bulk, keel
laid on or after 1 Jul 1986
Ships carrying liquefied gases in bulk, IGC Code, Chapter 2, Regulation 2.2.5
keel laid on or after 1 Oct 1994


* If a cargo ship is shown to comply with subdivision and damage stability
regulations in another IMO instrument, the ship is not required to comply with the
SOLAS damage stability requirements.




Assessment of a ship’s loaded condition


12     The first step in verifying damage stability compliance is to make a careful
assessment of the ship’s actual condition, once it is loaded and/or ballasted for
departure. At a minimum, the assessment of the ship’s actual condition should
include the following steps:


       1.Determine the ship’s forward and after drafts, along with the midships draft,   Formatted: Bullets and Numbering
          if available;

       2.Confirm that the cargo measuring devices (gauges) are working and               Formatted: Bullets and Numbering
          accurate;


       3.Gauge the levels of all cargo and ballast tanks;                                Formatted: Bullets and Numbering




       4.Confirm the specific gravity of the loaded cargo(es); and                       Formatted: Bullets and Numbering




       5.Record the above information.                                                   Formatted: Bullets and Numbering
13      Once the data above is obtained, the information should be recorded, and then
used to calculate other variables which will be needed to verify damage stability
compliance, such as trim, GM or KG. There should be instructions available to assist
in calculating any necessary variables.


14       There are various methods available to verify compliance with the damage
stability regulations, as discussed in the four sections below. If a ship is not in full
compliance with the damage stability regulations, then the loading of the vessel must
be adjusted so that compliance is achieved prior to departure from port.


Use of approved loading conditions


15     The stability information supplied to the Master will include various loading
conditions which have been verified by the Administration (or recognized
organization acting on its behalf) as complying with stability requirements and have
been approved for use in service of the ship. It is important to confirm that the
approved loading conditions cover both intact stability and damage stability
requirements.


16     At any time, the Administration (or recognized organization acting on its
behalf) may approve additional loading conditions for use in service of the ship and
append these conditions to the stability information.


17      If a ship is loaded in accordance with one of the approved conditions provided
in the stability information, the ship complies with the damage stability requirements.


18       Any variation from an approved loading condition could result in non-
compliance with the damage stability requirements. However, it is accepted that the
probability of non-compliance is low when the differences in loading are very small,
so it is allowable to permit minor variations from an approved loading condition.


19     A ship may be considered to be loaded in accordance with an approved
condition if the variation is less than:


       .1      [1%][2%] by mass for the filling of any individual cargo tank, slop
               tank or water ballast tank;


       .2      [2 cm][5 cm or 1% KG (whichever is less)] for the overall GM or KG;


       .3      [10 cm] for the mean draft; and
       .4      [30 cm] for the trim.


20      A ship may exceed the variations discussed in the paragraph above and still be
considered to be loaded in accordance with an approved condition, if the
Administration (or recognized organization acting on its behalf) has evaluated the
variations, confirmed that the ship will still comply with damage stability
requirements, and approved the variations for use in service of the vessel.


Use of curves or tables of minimum operational GM versus draft or maximum
allowable KG versus draft


21       The stability information supplied to the Master may also include simplified
stability data, such as curves or tables of minimum operational GM versus draft or
maximum allowable KG versus draft, which has been verified by the Administration
(or recognized organization acting on its behalf) as complying with stability
requirements and has been approved for use in service of the ship. It is important to
confirm that the simplified stability data covers both intact stability and damage
stability requirements.


22       The simplified stability data establishes limits for some of the ship’s stability
characteristics. Once the ship is loaded and/or ballasted for departure, if the ship’s
stability characteristics fall within the simplified stability data limits, then the ship
complies with the damage stability requirements. Depending on the ship, the stability
characteristic limits for a loading condition may be defined by one curve or table, but
in other cases, there may be many curves and tables to address one loading condition.
There should be specific instructions describing how to use simplified stability data
and how to interpret the results.


23       If any restrictions were applied in the development of the simplified stability
data, then those restrictions will also apply to the ship’s actual loading condition (e.g.,
minimum ballast filling in voids outboard of an empty cargo tank). Any restrictions
associated with use of the simplified stability data should be clearly stated in the
stability information.



Use of a stability instrument


24       A stability instrument may also be used to verify compliance with the damage
stability regulations, provide the instrument has been verified by the Administration
(or recognized organization acting on its behalf) as complying with stability
requirements and has been approved for use in service of the ship. It is important to
confirm that the stability instrument covers both intact stability and damage stability
requirements.
25      There should be specific instructions describing how to check the accuracy of
the stability instrument, and how often this must be done (e.g., prior to use, once a
week, once a month).


26       Once the ship is loaded and/or ballasted for departure, the ship’s actual
stability characteristics can be entered into the stability instrument to verify that the
ship complies with the damage stability requirements. There should be specific
instructions describing how to use the stability instrument, the tolerances used by the
software, and how to interpret the results.


27      Stability instrument calculations may be less conservative than the
calculations used to create approved loading conditions or simplified stability data. If
necessary, there should be specific instructions describing the required level of
accuracy for tank gauges, and describing whether additional underway calculations
are needed to verify continued compliance with the damage stability requirements.


Use of shore-based support


28       Once the ship is loaded and/or ballasted for departure, the ship’s actual
stability characteristics may be sent to a company shore-based support or
classification society for assistance in verification of compliance with the damage
stability requirements, or sent to the Administration (or recognized organization
acting on its behalf) for approval of the loading condition.


Documentation


29      Verification of compliance with damage stability requirements should be
documented in accordance with the company’s operating procedures and the
company’s safety management system. This should include a method of retaining
manual calculations and/or stability instrument printouts used to verify compliance, so
that this information can be provided to third parties, such as company auditors,
surveyors or port state control inspectors.]
DRAFT GUIDELINES FOR VERIFICATION OF
   DAMAGE STABILITY FOR TANKERS




               PART 3




     GUIDELINES FOR SECTION B –
DEMONSTRATION OF DAMAGE STABILITY
COMPLIANCE AT 2ND AND 3RD PARTY AUDIT
 AND INSPECTIONS, ISM INTERNAL AND
 EXTERNAL AUDITS, VETTING AND PORT
     STATE CONTROL INSPECTION
1   MANDATORY REQUIREMENT


It is a requirement of paragraph 1.2.3 of the ISM Code that all vessels to which the SOLAS
Convention applies shall be operated in a manner which ensures compliance with all
international instruments, national and other legislation which applies to them.

This provision includes the need for tankers to be operated in a manner which ensures
compliance with the damage stability requirements of MARPOL - Annex 1, or the IBC and
IGC Codes as applicable.

Section 7 of the ISM Code further obliges the operating company to ensure there are adequate
procedures in place to ensure compliance with these requirements, including the use of
checklists as appropriate, and that any task is only undertaken by duly qualified personnel.

Such operating procedures should include the maintenance of adequate records to
demonstrate to internal and external ISM auditors and to PSC inspectors, that all relevant
mandatory requirements are being met during service of the vessel.

For non-SOLAS vessels, it is the expectation that operational guidance on board shall be to
no lesser standard than that required for Convention sized vessels, having regard to the
application of “no less favourable treatment” and the extension of MARPOL - Annex 1 and
the IBC and IGC Codes to vessels of less than SOLAS convention size.

2   ACCEPTED METHODS                TO     DEMONSTRATE            DAMAGE         STABILITY        Formatted: Font: 11 pt
    COMPLIANCE


The following methods are acceptable formay be used demonstrateing that damage stability
requirements of MARPOL – Annex 1 or the IBC and IGC Codes are met :

       2.1     The vessel must may load only to an approved loading condition from the
               approved stability information

       2.2     Where approved critical damaged GMfGM/KGfKG data are provided within
               the approved stability information or damage stability calculations, then these
               may be employed to demonstrate compliance with damage stability using
               either a manual calculation, or through the use of stability software of 2008 IS
               Code, Chapter 4 or IACS URL5 Type 2 (or an equivalent standard specified
               by the Flag State or RO).

               Where 2008 IS Code, Chapter 4 or IACS URL5 Type 2 (or equivalent)
               stability software is employed to verify damage stability compliance, this may
               be undertaken on board the vessel or at an authorised shore location. In the
               case of parcel tankers for which curves of minimum operational GM or
               maximum operational KG are approved, it is recommended that stability
               verification using this data is undertaken using an approved stability
               instrument of Type 2.



       2.3     The vessel may load to a condition other than an approved condition from the
               approved stability information provided that this condition is submitted to the
               Flag State or RO for approval, and that such approval is obtained prior to the
               vessel proceeding on its voyage.

       2.4     The vessel may load to a condition other than an approved condition from the
               approved stability information provided that the damage stability of the
               condition is verified compliant before the vessel proceeds on its voyage
               through the use of stability software of 2008 IS Code, Chapter 4 or IACS
               URL5 Type 3 (or an equivalent standard), and that this means of verification
               is authorised by the Flag State or RO.

               Where 2008 IS Code, Chapter 4 or IACS URL5 Type 3 (or equivalent)
               stability software is employed to verify damage stability compliance, this may
               be undertaken on board the vessel or at an authorised shore location.


3   DOCUMENTATION REQUIRED WHICH MAY BE USED TO DEMONSTRATE
    VERIFICATION OF COMPLIANCE WITH DAMAGE STABILITY
    COMPLIANCEREQUIREMENTS


The following documentation should be available on board the vessel may be used to
demonstrate that compliance with damage stability requirements when available on board the
vessel, are met :

       3.1     In the case where the vessel is loaded in accordance with an approved loading
               condition from the approved stability information.

                      Approved stability information (If approval is subject to conditions
                       given by letter or in a design appraisal document, a copy of this letter
                       or document in addition).
                      Approved damage stability calculations (If approval is subject to
                       conditions given by letter or in a design appraisal document, a copy
                       of this letter or document in addition).
                      The recorded loading condition.
                      Confirmation of the approved loading condition upon which
                       compliance is based.

               Comparison of the two conditions should confirm the following.

                      The re is no significant difference between the content of the cargo       Formatted: Bullets and Numbering
                       and ballast tanks (determined as a proportion of the weight of their
                       content in the approved loading condition) and that of the recorded
                       loading condition shall not exceed [1% or 2% or 3% or 5%].
                      There is no substantial difference between the KG or GM of the
                       recorded loading condition and that of the approved condition upon
                       which it is based. In this respect the KG shall not exceed, or the GM
                       fall below, that of the approved loading condition by more than [1cm
                       or 2cm or 5cm]. Where necessary, the KG or GM of the approved
                       loading condition may be interpolated for displacements which lie
                       between those of the approved departure and arrival conditions.

       3.2.1   In the case where a vessel is loaded to a condition which is not an approved
               loading condition, and the verification is made on board using a manual check
               of critical GMfGM/KGfKG data.
              Approved stability information (If approval is subject to conditions
               given by letter or in a design appraisal document, a copy of this letter
               or document in addition).
              Approved damage stability calculations which incorporate critical
               damage GMfGM/KGfKG data, where these critical data clearly
               indicate if their derivation is dependent upon any initial assumptions
               or restrictions in the loading condition (If approval is subject to
               conditions given by letter or in a design appraisal document, a copy
               of this letter or document in addition).
              The recorded loading condition.
              Confirmation that the recorded loading condition complies with any
               initial assumptions or restrictions used to simplify derivation of the
               critical damaged GMfGM/KGfKG data.
              Check calculation or record sheets confirming the GMfGM/KGfKG
               of the recorded loading condition meets the approved critical damage
               GMfGM/KGfKG data for every possibleall relevant case of damage
               cases, including lesser cases (such as one compartment damage cases
               for two compartment ships) where relevant. For example, the
               approved critical GMf/KGf data used to make the verification should
               consider one compartment damage cases for two compartment ships
               and damages up to and beyond a longitudinal bulkhead for some twin
               hulled vessels.

3.2.2   In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made ashore using a manual check
        of critical GMfGM/KGfKG data.

              Approved stability information (If approval is subject to conditions
               given by letter or in a design appraisal document, a copy of this letter
               or document in addition).
              Approved damage stability calculations which incorporate critical
               damage GMfGM/KGfKG data, where these critical data clearly
               indicate if their derivation is dependent upon any initial assumptions
               or restrictions in the loading condition (If approval is subject to
               conditions given by letter or in a design appraisal document, a copy
               of this letter or document in addition).
              Authorisation from the Flag State or RO accepting the use of critical
               GMfGM/KGfKG data at the shore office to verify damage stability.
              The recorded loading condition and evidence of transmission of this
               loading condition to the shore office for approval.
              Confirmation that the recorded loading condition complies with any
               initial assumptions or restrictions used to simplify derivation of the
               critical damaged GMfGM/KGfKG data. This check may not be made
               by the stability software and a manual check must be made in this
               case.
              Check calculation or record sheets confirming the GMfGM/KGfKG
               of the recorded loading condition meets the approved critical damage
               GMfGM/KGfKG data for every possible case ofall relevant damage
               cases, including lesser cases (such as one compartment damage cases
               for two compartment ships) where relevant.where relevant. For
               example, the approved critical GMf/KGf data used to make the
               verification should consider one compartment damage cases for two
               compartment ships and damages up to and beyond a longitudinal
               bulkhead for some twin hulled vessels.


3.3.1   In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made on board against critical
        GMfGM/KGfKG data using stability software of 2008 Intact Stability Code,
        Part B, Chapter 4 or IACS URL5 Type 2 (or an equivalent standard specified
        by the Flag State or RO).

              Approved stability information (If approval is subject to conditions
               given by letter or in a design appraisal document, a copy of this letter
               or document in addition).
              Approved damage stability calculations which incorporate critical
               damage GMfGM/KGfKG data, where these critical data clearly
               indicate if their derivation is dependent upon any initial assumptions
               or restrictions in the loading condition (If approval is subject to
               conditions given by letter or in a design appraisal document, a copy
               of this letter or document in addition).
              The recorded loading condition.
              Confirmation that the recorded loading condition complies with any
               initial assumptions or restrictions used to simplify derivation of the
               critical damaged GMfGM/KGfKG data. This check may not be made
               by the stability software and a manual check must be made in this
               case.
              Authorisation from the Flag State or RO accepting the use of the
               stability software to verify conditions of loading on board the vessel.
              Copy of any approval for the stability software specified in the
               authorisation issued by the Flag State or RO.
              Evidence of any check calculations specified in the authorisation
               issued by the Flag State or RO to demonstrate that the stability
               software remains accurate.
              Output data from the stability software confirming the                     Formatted: Bullets and Numbering
               GMfGM/KGfKG of the recorded loading condition meets the
               approved critical damage GMfGM/KGfKG data for every possible
               case ofall relevant damage cases, including lesser cases (such as one
               compartment damage cases for two compartment ships) where
               relevant.
              where relevant. For example, the approved critical GMf/KGf data
               stored in the software should consider one compartment damage
               cases for two compartment ships and damages up to and beyond a
               longitudinal bulkhead for some twin hulled vessels.


3.3.2   In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made ashore against critical
        GMfGM/KGfKG data using stability software of 2008 Intact Stability Code,
        Part B, Chapter 4 or IACS URL5 Type 2 (or an equivalent standard specified
        by the Flag State or RO).

              Approved stability information (If approval is subject to conditions
               given by letter or in a design appraisal document, a copy of this letter
               or document in addition).
               Approved damage stability calculations which incorporate critical
                damage GMfGM/KGfKG data, where these critical data clearly
                indicate if their derivation is dependent upon any initial assumptions
                or restrictions in the loading condition (If approval is subject to
                conditions given by letter or in a design appraisal document, a copy
                of this letter or document in addition).
               The recorded loading condition and evidence of transmission of this
                loading condition to the shore office for approval.
               Confirmation that the recorded loading condition complies with any
                initial assumptions or restrictions used to simplify derivation of the
                critical damaged GMfGM/KGfKG data. This check may not be made
                by the stability software and a manual check must be made in this
                case.
               Authorisation from the Flag State or RO accepting the use of the
                stability software to verify conditions of loading on board the vessel.
               Copy of any approval for the stability software specified in the
                authorisation issued by the Flag State or RO.
               Output data from the stability software confirming the                     Formatted: Bullets and Numbering
                GMfGM/KGfKG of the recorded loading condition meets the
                approved critical damage GMfGM/KGfKG data for all relevant
                damage cases, including lesser cases (such as one compartment
                damage cases for two compartment ships) where relevant.
               every possible case of damage, including lesser cases where relevant.
                For example, the approved critical GMf/KGf data stored in the
                software should consider one compartment damage cases for two
                compartment ships and damages up to and beyond a longitudinal
                bulkhead for some twin hulled vessels.

3.4     In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made by submission of this loading
        condition directly to the Flag State or RO for approval.

               Approved stability information (If approval is subject to conditions
                given by letter or in a design appraisal document, a copy of this letter
                or document in addition).
               Approved damage stability calculations (If approval is subject to
                conditions given by letter or in a design appraisal document, a copy
                of this letter or document in addition).
               The recorded loading condition and evidence of transmission of this
                loading condition to the Flag State or RO for approval.
               Response from the Flag state or RO confirming that the loading
                condition has been verified for compliance with damage stability and
                is approved for departure.

3.5.1   In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made on board using stability
        software of 2008 Intact Stability Code, Part B, Chapter 4 or IACS URL5
        Type 3 (or an equivalent standard specified by the Flag State or RO).

               Approved stability information (If approval is subject to conditions
                given by letter or in a design appraisal document, a copy of this letter
                or document in addition).
               Approved damage stability calculations (If approval is subject to
                conditions given by letter or in a design appraisal document, a copy
                of this letter or document in addition).
               The recorded loading condition.
               Authorisation from the Flag State or RO accepting the use of the
                stability software to verify conditions of loading on board the vessel.
               Copy of any approval for the stability software specified in the
                authorisation issued by the Flag State or RO.
               Evidence of any check calculations specified in the authorisation
                issued by the Flag State or RO to demonstrate that the stability
                software remains accurate.
               Output data from the stability software confirming the loading
                condition meets intact and damaged stability. All relevant damage
                cases should be considered on both sides of the vessel unless the
                vessel is upright, symmetrical and has symmetrical loading. For
                example, the software should consider one compartment damage
                cases for two compartment ships and damages up to and beyond a
                longitudinal bulkhead for some twin hulled vessels.

3.5.2   In the case where a vessel is loaded to a condition which is not an approved
        loading condition, and the verification is made ashore using stability software
        of 2008 Intact Stability Code, Part B, Chapter 4 or IACS URL5 Type 3 (or an
        equivalent standard specified by the Flag State or RO).

               Approved stability information (If approval is subject to conditions
                given by letter or in a design appraisal document, a copy of this letter
                or document in addition).
               Approved damage stability calculations (If approval is subject to
                conditions given by letter or in a design appraisal document, a copy
                of this letter or document in addition).
               The recorded loading condition and evidence of transmission of this
                loading condition to the shore office for approval.
               Authorisation from the Flag State or RO accepting the use of the
                stability software at the shore office to verify conditions of loading on
                board the vessel.
               Copy of any approval for the stability software specified in the
                authorisation issued by the Flag State or RO.
               Output data from the stability software confirming the loading
                condition meets intact and damaged stability. All relevant damage
                cases should be considered on both sides of the vessel unless the
                vessel is upright, symmetrical and has symmetrical loading. For
                example, the software should consider one compartment damage
                cases for two compartment ships and damages up to and beyond a
                longitudinal bulkhead for some twin hulled vessels.




                                                                                End      of
                                                                                Document

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:16
posted:8/6/2012
language:
pages:91