Section 2 Minimum structural requirements

2.1.1 The requirements of this Section, unless specified otherwise, are applicable to all ship types, NS1, NS2 and NS3.

2.1.2 The scantlings of plating and stiffeners determined from the Rule scantling requirements are not to be less than that given in Table 3.2.1 Minimum structural requirements for the ship type. Due consideration is to be given to the vessel type correction factor, ω, as defined in Table 3.2.2 Vessel type correction factor (ω)

2.1.3 In addition, where plating contributes to the global strength of the ship, the thickness is to be not less than that required to satisfy the global strength requirements detailed in Vol 1, Pt 6, Ch 4 Hull Girder Strength

2.2.1 The minimum thicknesses given in Table 3.2.1 Minimum structural requirements are based on the assumption that the correct coatings are used and a proper maintenance regime is employed such that there is negligible loss in strength due to corrosion. Where this is not the case the minimum thickness will be specially considered. For corrosion margins, see Vol 1, Pt 6, Ch 6, 3.8 Corrosion margin

2.3.1 Due consideration is to be given to the scantlings of all structures which may be subject to local impact loadings. For example decks in workshops. Impact testing may be required to be carried out at the discretion of LR to demonstrate the suitability of the proposed scantlings for a particular application.

2.4.1 Areas of shell and deck which are subject to additional wear by abrasion from, i.e. removal or stores routes, working areas, forefoot region, etc. are to be suitably protected by local reinforcement or sheathing. This sheathing may be of timber, rubber, steel, additional layers of reinforcement, etc. as appropriate. Details of such sheathing and the method of attachment are to be submitted for consideration.

2.4.2 The attachment of sheathing by mechanical means such as bolting or other methods is not to impair the watertight integrity of the ship. Through bolting of the hull is to be kept to a minimum and avoided where practicable. The design arrangements in way of any through bolting are to be such that damage to the sheathing will not impair the watertight integrity of the hull.

2.4.3 When decks that are not structurally effective or subject to significant inplane stresses are fitted with approved sheathing, the thickness derived may be reduced by 10 per cent for a 50 mm sheathing thickness, or five per cent for 25 mm, with intermediate values in proportion. The steel deck is to be coated with a suitable material in order to prevent corrosive action, and the sheathing or composition is to be effectively secured to the deck. Inside deckhouses the thickness may be reduced by a further 10 per cent.

2.5.1 Flight decks and structures in way of launcher ramps, gun platforms, etc. will be subject to special consideration.

2.5.2 The minimum plating thickness of ships intended for operation in ice conditions will be specially considered.

2.5.3 Ships with shock enhanced notation are not to be fitted with bar keels. Docking arrangements are to be specially considered.

2.5.4 For large or novel ships, the scantlings of the stern will be specially considered.

2.5.5 Where water jet or sterndrive units are fitted, the scantlings of the plating in way of the nozzles and connections will be specially considered.

2.6.1 The thickness requirements derived from Table 3.2.1 Minimum structural requirements may be specially considered, where direct calculation procedures are adopted to demonstrate the suitability of the proposed alternative, e.g. shear buckling analysis may be performed on girder or floor webs.