RULES DET NORSKE VERITAS (DNV) = STRUCTURES = - Boat Design Net

Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011Pt.3 Ch.3 Sec.1 – Page 9402 Engine holdingdown bolts are to be arranged as near as practicable to floors and longitudinal girders.403 In way of thrust bearing and below pillars additional strengthening is to be provided.B 500 Double bottom, if fitted501 Manholes are to be cut in the inner bottom, floors and longitudinal girders to provide access to all partsof the double bottom. The vertical extension of lightening holes is not to exceed one half of the girder height.The edges of the manholes are to be smooth. Manholes in the inner bottom plating are to have reinforcementrings. Manholes are not to be cut in the floors or girders in way of pillars.502 In double bottoms with transverse stiffening, longitudinal girders are to be stiffened at every transverseframe.503 The longitudinal girders are to be satisfactorily stiffened against buckling.C. Side StructureC 100 Stiffeners101 The craft's sides may be longitudinally or vertically stiffened.Guidance note:It is advised that longitudinal stiffeners are used near bottom and strength deck.---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---102 The continuity of the longitudinals is to be as required for bottom and deck longitudinals respectively.D. Deck StructureD 100 Longitudinal stiffeners101 Decks are normally to be longitudinally stiffened.102 The longitudinals should preferably be continuous through transverse members. If they are to be cut attransverse members, i.e. watertight bulkheads, continuous brackets connecting the ends of the longitudinals areto be fitted.103 The plate thickness is to be such that the necessary transverse buckling strength is achieved, or transversebuckling stiffeners may have to be fitted intercostally.D 200 Bulwarks201 The thickness of bulwark plates is not to be less than required for side plating in a superstructure in thesame position.202 A strong bulb section or similar is to be continuously welded to the upper edge of the bulwark. Bulwarkstays are to be in line with transverse beams or local transverse stiffening. The stays are to have sufficient widthat deck level. The deck beam is to be continuously welded to the deck in way of the stay. Bulwarks on forecastledecks are to have stays fitted at every frame.Stays of increased strength are to be fitted at ends of bulwark openings. Openings in bulwarks should not besituated near the ends of superstructures.203 Where bulwarks on exposed decks form wells, ample provision is to be made to freeing the decks forwater.E. Flat Cross StructureE 100 Definition101 Flat cross structure is horizontal structure above waterline like bridge connecting structure between twinhulls, etc.E 200 Longitudinal stiffeners201 Flat cross structures are normally to be longitudinally stiffened.202 The longitudinals should preferably be continuous through transverse members. If they are to be cut attransverse members, i.e. watertight bulkheads, continuous brackets connecting the ends of the longitudinals areDET NORSKE VERITAS AS