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 150 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 ] k 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- tion. 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 ensured. 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 100 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. 60 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: 120 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. Note 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 Certificate. 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.