Section 3 Vehicle decks

3.1.1 Where it is proposed to construct vehicle decks in FRP composite materials, each case will be subject to individual consideration. The scantlings are to be determined by direct calculation or on the basis of the requirements of Pt 8, Ch 3 Scantling Determination for Mono-Hull Craft, in conjunction with the procedures, loadings and general requirements for vehicle decks of aluminium alloy construction, as indicated in Pt 7, Ch 5 Special Features.

3.1.2 It is recommended that single skin laminate construction incorporating longitudinal or transverse stiffening be adopted. Where it is proposed to use sandwich skin construction, particular care is to be given to the selection of the core material. Such proposals will require to be specially considered, and testing may be required to demonstrate the suitability of the panels.

3.1.3 The deck and supporting structure are to be designed on the basis of the maximum loading to which they may be subjected in service. Where applicable, the hatch covers are to be similarly designed. In no case, however, are the scantlings to be less than would be required for a weather or cargo deck or hatch cover, as applicable.

3.1.4 Details of the deck loading resulting from the proposed stowage or operation of vehicles are to be supplied by the Builder. These details are to include axle and wheel spacing, the wheel load, type of tyre and tyre print dimensions for the vehicles. The vehicle types and wheel loads for which the vehicle decks, including hatch covers where applicable, have been approved are to be included in the craft's documentation and contained in a notice displayed on each deck. For design purposes, the wheel loading is to be taken as not less than 3,0 kN.

3.1.5 The scantling requirements are based on structural strength and limitations on stress and deflection, with no allowance made for wear and tear. Local reinforcement as given in Pt 8, Ch 3, 3.14 Local reinforcement is to be fitted as necessary, particularly in way of vehicle lanes and passenger routes.

3.1.6 Deck fittings in way of vehicle lanes are to be recessed.

3.2.1 Details of the loads and connections to the hull of vehicle securing arrangements are to be indicated on the plans submitted with the Designer`s calculations.

3.3.1 Where access to the vehicle deck is provided by bow, side and stern doors, these openings are to comply with the requirements of Pt 3, Ch 4, 4 Side and stern doors and other shell openings.

3.3.2 Doors providing pedestrian access between vehicle decks and accommodation spaces are to be gastight, and have scantlings and fire restricting characteristics equivalent to the surrounding structure, see also Pt 17 Fire Protection, Detection and Extinction.

3.4.1 The scantlings and arrangements of hatch covers located within vehicle decks are to be not less than those required by the Rules for the supporting structure in which such hatches are fitted. In general, the end fixity of primary stiffening members is to be taken as simply supported. Local and secondary stiffening members may be either partially or fully fixed at their end connections dependent upon the proposed arrangement.

3.4.2 In no case, however, are the scantlings of plate or sandwich laminates and stiffeners to be less than would be required for a weather or cargo deck, or hatch cover, as applicable.

3.4.3 Where unusual arrangements of hatch cover stiffening are proposed, the scantlings of plating and stiffeners may be determined by direct calculations using a two-dimensional grillage determination.

3.5.1 Where heavy or special loads are proposed to be carried, the scantlings and arrangements of the deck structure will be individually considered on the basis of submitted calculations.

3.5.2 Due account is to be taken of the acceleration levels due to craft motion applicable to particular items of heavy mass such as vehicles, containers, pallets, etc.

3.6.1 LR will consider direct calculations for the derivation of vehicle deck scantlings as an alternative and equivalent to those derived by Rule requirements. The assumptions made and the calculation procedures used are to be submitted for appraisal in accordance with Pt 3, Ch 1, 2 Direct calculations.