SUB-COMMITTEE ON STABILITY AND LOAD LINES AND ON FISHING VESSELS by x8M625X

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


     GUIDELINES FOR VERIFICATION OF DAMAGE STABILITY REQUIREMENTS
                     FOR 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 under agenda item
    53/8 has considered the terms of reference drawn up by the drafting group during the
    intercessional period, co-ordinated by 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, set out in the report of the
   drafting group (SLF 53/WP.7), instructed the group to :


           .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 guidelines are separated into two
sections 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 1 of the Draft Operational Guidelines


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      It is further considered that the operational advice contained in Part 1 of the draft
Guidelines applies equally to both existing and to new vessels, as the technical standards
applied by the relevant instruments are the same for both and it is only being sought to
harmonise the guidance on application between them.


13      Conversely, the technical guidance in Part 2 of the draft Guidelines is only expected
to apply 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 7 and 5 respectively of the model forms of
International Certificate of Fitness for the carriage of chemicals and liquefied gases in bulk.


16       It is the opinion of the correspondence group that, unless otherwise provided for, 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 are made :


            a. If no variation is permissible 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 “100% departure” and “10% arrival”
               cargo loading conditions for approval, but there is no certainty that a vessel
               will depart port in the 100% condition or arrive in port in the 10% condition.


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 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. However,
this should not be interpreted as excluding the use of, for example, approved curves of
maximum KGf/minimum GMf


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, it is further considered that some
variation in the loading of cargo and ballast tanks shall be permissible to account for minor
variations in cargo and seawater SG from those considered in the approved loading condition
under consideration.


20       In thjs respect it 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 [2%] [3%] by weight] from that assumed in
the approved loading condition being replicated., and [the condition KGf should not exceed
that of the approved loading condition by more than 2cm or the condition GMf fall below that
of the approved loading condition by more than 2cm] unless larger approved variations are
given within the approved stability data.


21       Provided the approved loading condition which is being loaded is approved for both
100% departure and 10% arrival capacity of consumables and stores, 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 further verification of the stability, 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, KGf/GMf 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
existing international instruments provide for the approved stability information to be the
definitive guidance to the Master for determining adequacy of stability and that provided that
a vessel is loaded in accordance with the approved stability information, no further
verification of stability is required.
22       Approval of a range of loading conditions with variation of cargo SG or cargo
distribution 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.


23        The correspondence group considered s that guidance on verification of compliance
should clarify that the carriage of a loading distribution for a particular SG cargo which is not
included either directly or within an approved range in the approved stability information
provided on board may be non-compliant with damage stability requirements, even if another
distribution of the same SG cargo was approved and included in the approved stability
information.


24      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 use of critical GMf/KGf data, where these are approved during the initial
approval of stability information and supporting damage stability calculations.


25       Critical GMf/KGf data may be derived for compliance with both intact and damaged
stability requirements, and all conditions of loading must meet both limits. It is not
permissible to use verification against critical intact GMf/KGf data in isolation, where this
data is provided in the approved stability information, as compliance with critical damage
GMf/KGf data must also be demonstrated..


26      Critical GMf/KGf data may not be used to verify stability unless approved damaged
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.


27       To assist production of critical damaged GMf/KGf data, it may have been necessary
for the designer or shipyard to make assumptions in respect of the loading condition or to
apply initial limits on the loading, such as minimum or maximum filling levels or counter-
ballasting of wing tanks outboard of empty or part filled cargo tanks.


28      Where such assumptions or limitations are applied during the derivation of critical
damaged GMf/KGf data, these should be stated on the approved critical data and the critical
data should not be applied unless the live loading condition is first verified as meeting these
assumptions.
29      Flexibility of operation may also be increased if the live loading condition is subject
to direct verification for compliance with both intact and damaged stability, using stability
software. In all such cases it is recommended that the application of such software should be
authorised by the flag state or RO with any conditions imposed for its use.


30       Conditions for use of stability software may reasonably include requirements for the
specification of the software 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.


31       Existing standards applied by IACS through unified requirement for load line URL5
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.


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


33       Shore based verification may be accepted subject to its authorisation by the flag state
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.


34      In this respect it is considered that an additional safeguard which could be employed
is to 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


35       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 considered the following clarifications :


    1.      The need for use of stability software for verification of intact and damaged
            stability to be authorised by the Flag State or RO, and a record of the
            authorisation should be provided on board the vessel with any conditions which
            apply.
     2.       The authorisation shall include details of the specification of the stability
              software and any approval standard applied to Flag State or RO requirements.
              Copies of software specification and approval documentation should be provided
              on board the vessel.


     3.       Unless otherwise provided for, the authorisation shall include 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 authorisation shall include 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




36        Presently left blank for insertions


37        Presently left blank for insertions


Action requested of the Sub-Committee


38      The Sub-Committee is invited to consider the report of the correspondence group , to
note the progress made and to take action as appropriate
                                                               Annex A

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



The extracts provided below are provided for information and ease of reference. The
applicable regulation 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 will be the stability information provided on board that has been approved by
the Administration or its Recognised Organisation (Normally the classification society).



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
                                                                                                         25
4.1                                         Stability                                     instruments
________________
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 Regulation 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 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 existing
regulations 27(11)(b)(iv) and 27(11)(b)(v).


“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]”.
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, by loading 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 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.


(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.


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%] by mass, and
        b) the GMf of the loading condition under consideration should not less than that of
the approved condition by more than [2cm], or, the KGf 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.


11) 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%] by mass, and
        .2) the GMf of the loading condition under consideration should not less than that of
the approved condition by more than [2cm], or, the KGf of the loading condition under
consideration should not exceed that of the approved loading condition by more than [2 cm].




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.
                               Annex C

Draft Guidelines for the verification of damage stability requirements for
tankers




 DRAFT GUIDELINES FOR VERIFICATION OF
        STABILITY ON TANKERS




                            PART 1

             OPERATIONAL GUIDELINES
[Section A-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.


In the case where curves of minimum operational GMf 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.
It is to be understood throughout this document that where reference is made to approved
stability conditions this also includes conditions within the prescribed boundaries of limiting
curves etc.


However, the provision of limiting operational GMf 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 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 or some other cause of 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 Regulations 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.


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 regulations


The Master will need to be provided with sufficient means to demonstrate that the vessel is
loaded in a manner which will ensure compliance with the relevant Regulations which apply
to it’s type, size and age. 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 Regulations, 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, a recognized organization (RO) acting on its behalf
               for the proposed loading condition ; or
       [.3     where the vessel is not loaded in accordance with an approved loading
               condition from the approved Stability Information Booklet, obtain
               confirmation from the shore-based operating company that the proposed
               loading condition complies ; or]


       .4      to use a Stability Program (Loading Computer *) or other acceptable method
               to verify that intact stability as well as damage stability criteria are satisfied
               for this operating condition. When a Stability Program (Loading Computer)
               is used for such verification then 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. Such approved computers are usually an approved IACS URL5
               damage stability calculation program of type 2 or 3 ; or
       .5      the use of simplified stability data, for example curves of maximum KGf or
               minimum allowable GMf, to demonstrate compliance.


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 and request assistance in the
               calculation of the intact and damage stability and compliance with the
               regulations ; or


       [.4     to contact the ship's classification society and request assistance in the
               verification of compliance of the intact and damage stability [for an
               adjusted][for the actual] loading condition and compliance with the
               Regulations.]
5   DOCUMENTATION


All checks and diligence carried out in ensuring that the ship is in compliance with the
regulations 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). 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     Conditions that are within the approved boundaries of limiting KGf or GMf curves
       are to be considered as approved conditions.




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


.1     For tankers which do not have an approved loading instrument, or critical GMf or
       KGf 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%] [3%] by mass from that assumed in the
              approved loading condition; and


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




Part 3 - 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 instrument, or approved critical
      GMf or KGf 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 GMf or KGf 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 instrument capable of damage stability
       verification of the live loading condition is not fitted. However, the use of critical
       GMf or KGf 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 GMf or KGf
       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 GMf or KGf 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 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 GMf or KGf 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 4 - 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
       GMf or KGf 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
     GMf data (and by implication critical KGf 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 GMf or KGf 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 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 GMf or KGf 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 GMf or KGf 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 GMf or KGf 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 GMf or KGf 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 GMf or KGf 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 GMf
      or KGf 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 GMf or KGf 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 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).]
[Section 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. 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, 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, 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.]
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   METHODS TO DEMONSTRATE DAMAGE STABILITY COMPLIANCE



The following methods can be used for demonstrating that damage stability requirements of
MARPOL – Annex 1 or the IBC and IGC Codes are met :

       2.1     The vessel could load only to an approved loading condition from the
               approved stability information; or

       2.2     Where approved critical damaged GMf/KGf 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 IACS
               URL5 Type 2 (or an equivalent standard specified by the Flag State or RO).;
               or

               Where 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.

       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.; or

       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 IACS URL5 Type 3 (or an equivalent
                standard), and that this means of verification is authorised by the Flag State or
                RO.

                Where 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 THAT CAN BE USED TO DEMONSTRATE VERIFICATION OF
    COMPLIANCE WITH DAMAGE STABILITY REQUIREMENTS



The availability on board of the following information will assist in the demonstration of
compliance
       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 there is no significant
                difference between the content of the cargo 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.

        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 GMf/KGf 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 GMf/KGf 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 GMf/KGf data.
              Check calculation or record sheets confirming the GMf/KGf of the
               recorded loading condition meets the approved critical damage
               GMf/KGf data for all relevant damage cases , including lesser cases
               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 GMf/KGf 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 GMf/KGf 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
               GMf/KGf 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 GMf/KGf 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 GMf/KGf of the
               recorded loading condition meets the approved critical damage
               GMf/KGf data for all relevant damage cases           case of damage,
               including lesser cases 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
        GMf/KGf data using stability software of 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 GMf/KGf 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 GMf/KGf 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 GMf/KGf of
               the recorded loading condition meets the approved critical damage
               GMf/KGf data for all relevant damage cases. 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.


3.3.2   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
        GMf/KGf data using stability software of 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 GMf/KGf 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 GMf/KGf 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 GMf/KGf of
               the recorded loading condition meets the approved critical damage
               GMf/KGf data for all relevant damage cases 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 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 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.
DRAFT GUIDELINES FOR VERIFICATION OF
STABILITY ON TANKERS




                              PART 2

   GUIDELINES FOR PREPARATION AND
APPROVAL OF TANKER DAMAGE STABILITY
           CALCULATIONS




 Copy of IACS Recommendation 110 rev.1 (SLF53.INF9) to be inserted here.

								
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