Section 2 Still water global loads

2.1.1 The still water bending moments and shear force distributions are to be derived using a suitable direct calculation method for a range of loading conditions which cover the operational envelope of the ship.

2.1.2 In general, loading conditions based on amount of fuel, fresh water, stores and payload at departure, arrival and during special operations are to be considered. Loading conditions representing special operational requirements are also to be considered.

2.1.3 As a minimum the following conditions are to be considered in deriving the maximum hogging and sagging still water bending moment and shear force envelopes:

• Deep draught (departure) condition with no growth margin.
• Light draught (arrival) condition with no growth margin.
• Deep draught condition with full growth margin.
• Light draught condition with full growth margin.
• Maximum and minimum operating draught conditions, if different to the above.
• Design draught condition.
• Ballast conditions, where appropriate.
• Any special mid-voyage conditions caused by changes in payload or ballast distribution.
• Other special loading conditions, e.g. emergency evacuation or similar emergency scenario conditions, heavy payloads or cargo, deck cargo conditions, etc. where applicable.

2.1.4 For special loading conditions which may only be required in restricted operational areas, a reduced service area factor, f _s, may be allowable, see Vol 1, Pt 5, Ch 4, 3.3 Vertical wave bending moments 3.3.1.

2.1.5 If the still water bending moment and shear force envelope approach is not appropriate, (as a consequence of the envelope being too severe due to one or two special conditions distorting the envelope) then individual consideration of the bending moment and shear force will be necessary.

2.1.6 A full or half icing allowance in accordance with Vol 1, Pt 5, Ch 2, 4 Guidance for ice environment is to be included in the still water bending moment and shear force calculations.

2.1.7 To account for miscellaneous fittings such as stanchions and rails an additional 5 per cent should be added to the total ice weight calculated for both full and half icing allowances.

2.2.1 The design still water hogging and sagging bending moment distribution envelope, M _S, is to be taken as the maximum sagging (negative) and maximum hogging (positive) still water bending moments, in kN m, calculated at each position along the ship. The maximum moments from all loading conditions are to be used to define the still water bending moment distribution envelope.

2.2.2 It is normal for ships which have low deadweight requirements, e.g. frigates, to have a bending moment distribution envelope which is always hogging. In this case the maximum sagging bending moment envelope may be taken as the minimum hogging bending moment.

2.3.1 The design still water shear force distribution envelope, Q _S, is to be taken as the maximum positive and negative shear force values, in kN, calculated at each position along the ship. The maximum shear forces from all loading conditions, see Vol 1, Pt 5, Ch 4, 2.2 Still water bending moments, are to be used to define the still water shear force distribution envelope.

2.3.2 It is recommended that the minimum shear force value over the midships region should not be less than 50 per cent of the maximum value.