_I-1-1_ Section 31 Barges and Pontoons

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					I - Part 1    Section 31     C    Barges and Pontoons                                                    Chapter 1
GL 2010                                                                                                  Page 31–1

                                                   Section 31

                                           Barges and Pontoons

A.       General                                           calculations. For barges of less than 90 m in length,
                                                           the scantlings of longitudinal members are to be gen-
                                                           erally determined according to Section 7, A.4.
1.       Definitions

1.1      Barges as defined in this Section are un-         2.       The midship section modulus may be 5 %
manned or manned vessels, normally without self-           less than required according to Section 5.
propulsion, sailing in pushed or towed units. The ra-
tios of the main dimensions of barges are in a range
usual for seagoing ships; their construction complies      3.       The scantlings of the primary longitudinal
with the usual construction of seagoing ships; their       members (strength deck, shell plating, deck longitudi-
cargo holds are suitable for the carriage of dry or liq-   nals, bottom and side longitudinals, etc.) may be 5 %
uid cargo.                                                 less than required according to the respective preced-
                                                           ing Sections of this Chapter. The minimum thickness
                                                           and critical thickness specified in these Sections are,
1.2      Pontoons as defined in this Section are un-       however, to be adhered to.
manned or manned floating units, normally without
self-propulsion. The ratios of the main dimensions of
pontoons deviate from those usual for seagoing ships.      4.        Longitudinal strength calculations for the
Pontoons are designed to usually carry deck load or        condition "Barge, fully loaded at crane" are required,
working equipment (e.g. lifting equipment, rams etc.)      where barges are intended to be lifted on board ship
and have no holds for the carriage of cargo.               by means of cranes. The following permissible
                                                           stresses are to be observed:
2.       Validity
                                                                 bending stress:       σb =             [N/mm 2 ]
The requirements given in Section 1 – 24 apply to                                                k
barges and pontoons unless otherwise mentioned in
this Section.                                                                                   100
                                                                 shear stress:         τ    =           [N/mm 2 ]
3.       Character of Classification
                                                           k     = material factor according to Section 2, B.2.
3.1     Vessels built in accordance with the require-
                                                           Special attention is to be paid to the transmission of
ments of this Section will have the Notation BARGE
                                                           lifting forces into the barge structure.
or PONTOON affixed to the Character of Classifica-
                                                           5.        For pontoons carrying lifting equipment,
3.2       Barges built for the carriage of special cargo   rams etc. or concentrated heavy deck loads, calcula-
(e.g. liquid or ore cargo) will have the respective No-    tion of the stresses in the longitudinal structures under
tations affixed to the Characters of Classification (see   such loads may be required. In such cases the stresses
also Part 0 – Classification and Surveys, Section 2).      given under 4. are not to be exceeded.

4.       General indications
Where barges are intended to operate as linked push        C.       Watertight Bulkheads and Tank Bulk-
barges proper visibility from the tug forward is to be              heads

                                                           1.       For barges and pontoons, the position of the
                                                           collision bulkhead is to be determined according to
B.       Longitudinal Strength                             Section 11, A.2.

                                                           Where in barges and pontoons, the form and construc-
1.      The scantlings of longitudinal members of          tion of their ends is identical so that there is no deter-
barges and pontoons of 90 m and more in length are to      mined "fore or aft ship", a collision bulkhead is to be
be determined on the basis of longitudinal strength        fitted at each end.
Chapter 1      Section 31     G     Barges and Pontoons                                                      I - Part 1
Page 31–2                                                                                                    GL 2010

2.       On barges intended to operate as linked push        E.         Rudder
barges, depending on the aft ship design, a collision
bulkhead may be required to be fitted in the aft ship.       The rudder stock diameter is to be determined accord-
                                                             ing to Section 14, C.1. The ship's speed speed v0 is not
                                                             to be taken less than 7 knots.
3.        A watertight bulkhead is to be fitted at the aft
end of the hold area. In the remaining part of the hull,
watertight bulkheads are to be fitted as required for the
purpose of watertight subdivision and for transverse         F.         Pushing and Towing Devices, Connecting
strength.                                                               Elements

4.       The scantlings of watertight bulkheads and of       Devices for pushing and towing of linked barges as
tank bulkheads are to be determined according to             well as the connecting elements required for linking
Sections 11 and 12 respectively.                             the barges are to be dimensioned for the acting exter-
                                                             nal forces.
Where tanks are intended to be emptied by com-
                                                             The forces are to be specially determined for the re-
pressed air, the maximum blowing-out pressure pv
                                                             spective service range. When determining the scant-
according to Section 4, D.1. is to be inserted in the        lings of these devices and elements as well as of the
formulae for determining the pressures p1 and p2.            substructures of the barge hull, the following permis-
                                                             sible stresses are to be observed:

                                                             –      bending and normal stress:
D.       Structural Details at the Ends
                                                                    σ      =                [N/mm 2 ]
1.       Where barges have typical ship-shape fore                               k
and aft ends, the scantlings of structural elements are
to be determined according to Section 8, A.1.2 and           –      shear stress:
Section 9, A.5. respectively.
                                                                    τ       =               [N/mm 2 ]
The scantlings of fore and aft ends deviating from the                          k
normal ship shape are to be determined by applying the
formulae analogously such as to obtain equal strength.       –      equivalent stress:

2.       Where barges are always operating with hori-               σv      =    σ2 + 3τ2 =             [N/mm 2 ]
zontal trim, in consideration of the forebody form,                                                k
relaxations from the requirements concerning strength-
ening of the bottom forward may be admitted.
                                                             G.         Equipment
3.       Where barges have raked ends with flat bot-
toms, at least one centre girder and one side girder on      1.        Barges and pontoons are to be provided with
each side are to be fitted. The girders shall be spaced      anchor equipment, designed for quick and safe opera-
not more than 4,5 m apart. The girders shall be scar-        tion in all foreseeable service conditions. The anchor
phed into the midship structure. A raked fore-end with       equipment shall consist of anchors, chain cables and
a flat bottom is to be strengthened according to             a windlass or other equipment (e.g. cable lifter with
Section 6, E.                                                a friction band brake, by means of which the anchor
                                                             can be lifted using an auxiliary drum or a crank han-
4.       In pontoons which are not assigned a Nota-          dle) for dropping and lifting the anchor and holding
tion for restricted service area or which are assigned       the ship at anchor. The requirements of the GL Rules
the Notation RSA (200), the construction of the fore         for Machinery Installations (I-1-2), Section 14, D. are
peak is to be reinforced against wash of the sea by          to be observed.
additional longitudinal girders, stringers and web
frames. In case of raked bottoms forward, the rein-          2.       Unless otherwise specified in this Section, the
forcements are, if necessary, to be arranged beyond          required equipment of anchors and chain cables and
the collision bulkhead. If necessary, both ends are to       the recommended ropes 1 for manned barges and pon-
be reinforced, see also C.1.                                 toons are to be determined according to Section 18. A
                                                             stream anchor is not required.
Also for pontoons sailing only temporarily, for the
purpose of conveyance to another port, within the
region RSA (200) or beyond that region, the rein-
forcements given in 4. are required.                         1    See also Section 18, F.
I - Part 1    Section 31    G    Barges and Pontoons                                                  Chapter 1
GL 2010                                                                                               Page 31–3

3.        The equipment numeral Z for determining the    7.       If necessary for a special purpose, for barges
equipment according to Table 18.2, is to be deter-       and pontoons mentioned under 6., the anchor mass
mined for pontoons carrying lifting equipment, rams      may be further reduced by up to 20 %. Upon Owner's
etc. by the following formula:                           request the anchor equipment may be dispensed with.
                                                         The notation "Without anchor equipment" will be
      Z      = D2 3 + B ⋅ f b + f w                      entered into the Certificate and Register in such cases.
                                                         Additionally the notation "For sea voyages anchor
D     = displacement of the pontoon [t] at maximum
                                                         equipment is to be available" will be entered into the
        anticipated draught
fb    = distance [m] between pontoon deck and wa-
        terline                                          8.      If a wire rope shall be provided instead of a
                                                         chain cable, the following is to be observed:
fw    = wind area of the erections on the pontoon
        deck [m2] which are exposed to the wind          8.1      The length of the wire rope is to be 1,5 times
        from forward, including houses and cranes in     the required chain cable length. The wire rope is to
        upright position                                 have the same breaking load as the required chain
                                                         cable of grade K1.
4.       Where more than two anchors are required
the third anchor (spare anchor) may be used as a stern   8.2       Between anchor and wire rope, a chain cable
anchor.                                                  is to be fitted the length of which is 12,5 m or equal to
                                                         the distance between the anchor in stowed position
5.         Pontoons having a machinery of sufficient     and the windlass. The smaller value is to be taken.
power which are assigned the Notation RSA (20) or
RSA (50) need not have a spare anchor (3rd anchor).      8.3       A winch has to be provided which is to be
The power of the machinery will be regarded as suffi-    designed in accordance with the requirements for
cient if it is not less than:                            windlasses (see also the GL Rules for Machinery In-
                                                         stallations (I-1-2), Section 14, D.).
      N      = 0, 08 ⋅ L ⋅ B ⋅ H + 40 [kW]
                                                         9.      Push barges not operating at the forward or
6.       In special cases, upon Owner's request, for     aft end of pushed or towed units need not have any
unmanned barges and pontoons the number of anchors       equipment.
may be reduced to one and the length of the chain
cable to 50 % of the length required by Table 18.2.      10.      Anchor equipment fitted in addition to that
The notation "special equipment" will be entered into    required herein (e.g. for positioning purposes) is not
the Certificate and Register in such cases.              part of Classification.