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

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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
Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Amended July 2011, see page 3Pt.3 Ch.3 Sec.1 – Page 10to be fitted or welds are to be dimensioned accordingly.203 Longitudinal stiffeners are to be supported by bulkheads and web frames.F. Bulkhead StructuresF 100 Transverse bulkheads101 Number and location of transverse watertight bulkheads are to be in accordance with the requirementsgiven in Ch.1 Sec.1 B200.102 The stiffening of the upper part of a plane transverse bulkhead is to be such that the necessary transversebuckling strength is achieved.F 200 Corrugated bulkheads201 Longitudinal and transverse bulkheads may be corrugated.202 For corrugated bulkheads the following definition of spacing applies (see Fig. 1):s= s 1 for section modulus calculations=1.05 s 2 or 1.05 s 3 for plate thickness calculations.Fig. 1Corrugated bulkheadG. Superstructures and DeckhousesG 100 Definitions101 Superstructure is defined as a decked structure on the freeboard deck, extending from side to side of theship or with the side plating not inboard of the shell plating more than 4% of the breadth (B).102 Deckhouse is defined as a decked structure above the strength deck with the side plating being inboardof the shell plating more than 4% of the breadth (B).Long deckhouse - deckhouse having more than 0.2 L of its length within 0.4 L amidships.Short deckhouse - deckhouse not defined as a long deckhouse.G 200 Structural continuity201 In superstructures and deckhouses, the front bulkhead is to be in line with a transverse bulkhead in thehull below or be supported by a combination of girders and pillars. The after end bulkhead is also to beeffectively supported. As far as practicable, exposed sides and internal longitudinal and transverse bulkheadsare to be located above girders and frames in the hull structure and are to be in line in the various tiers ofaccommodation. Where such structural arrangement in line is not possible, there is to be other effective support.202 Sufficient transverse strength is to be provided by means of transverse bulkheads or girder structures.203 At the break of superstructures, which have no set-in from the ship's side, the side plating is to extendbeyond the ends of the superstructure, and is to be gradually reduced in height down to the deck or bulwark.The transition is to be smooth and without local discontinuities. A substantial stiffener is to be fitted at the upperedge of plating. The plating is also to be additionally stiffened.204 In long deckhouses, openings in the sides are to have well rounded corners. Horizontal stiffeners are tobe fitted at the upper and lower edge of large openings for windows.Openings for doors in the sides are to be substantially stiffened along the edges. The connection area betweendeckhouse corners and deck plating is to be increased locally.Deck girders are to be fitted below long deckhouses in line with deckhouse sides.DET NORSKE VERITAS AS
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RULES DET NORSKE VERITAS (DNV) = STRUCTURES = - Boat Design Net

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