Section 2 Hull construction

2.1.1 The basic structural scantlings are, unless specified within this Section, to be as indicated in Pt 8 Hull Construction in Composite.

2.1.2 The shell weight/thickness determined from Pt 8 Hull Construction in Composite, is to be maintained throughout the length of the craft, with the bottom shell weight extending to the chine line or 150 mm above the static load waterline, whichever is the greater.

2.1.3 The keel plate thickness for sailing yachts is to be 1,1 times the keel thickness for motor craft as determined in Pt 8 Hull Construction in Composite. In no case is the thickness of keel to be taken less than the thickness of the adjacent bottom shell or fin and tuck as appropriate.

2.1.4 The fin and tuck thickness is not to be less than 0,9 times the keel thickness for motor craft as determined in Pt 8 Hull Construction in Composite. In no case is the thickness of the fin and tuck to be taken less than the thickness of the adjacent bottom shell.

2.1.5 The construction of hull to deck connections is to be in accordance with Pt 8, Ch 2, 5 Details and fastenings.

2.1.6 The hull laminate is to be strengthened in way of the attachment of chainplates etc. See Pt 8, Ch 2, 5 Details and fastenings.

2.1.7 The stern or transom is to be the same weight as the side shell and is to be adequately stiffened with special consideration being given to the transmission of backstay loadings.

2.1.8 Where twin bilge keels are fitted, the bottom laminate in way of the bilge keels is to be formed by extending the keel reinforcement to a distance not less than 25 per cent the width of the keel, as required by Pt 8 Hull Construction in Composite, outside the line of the outboard edge of the bilge keels or to the supporting structure whichever is the greater, prior to being tapered in accordance with the Rules to the adjacent bottom shell laminate. See also Pt 4, Ch 3, 2.1 Hull scantlings (composite materials) 2.1.10.

2.1.9 The hull and deck are to be locally increased in thickness in way of fittings for rudder tubes, propeller brackets etc. The increase is not to be less than 50 per cent of the adjacent plate laminate. Details of such reinforced areas are to be submitted for consideration.

2.1.10 Local reinforcement is, in general, to extend under the adjacent supporting structure and then be tapered gradually to the base laminate thickness in accordance with Pt 8, Ch 3, 3.14 Local reinforcement.

2.2.1 Sailing yachts with a conventional rig, are to be provided with suitably increased scantlings in floors, frames, beams and brackets adjacent to each mast.

2.2.2 In general, beams at the heads of web frames and four beams in way of each mast in sailing and auxiliary yachts are to have their scantlings increased by a factor of two. Where practicable, masts are to be located in way of transverse bulkheads or other primary stiffening.

2.2.3 Keel mounted masts are to be mounted on a suitable mast step secured to three floors at a height sufficient to provide the necessary structural integrity and to keep the heel of the mast clear of any bilge water.

2.2.4 Keel mounted masts are to be fitted with mast partners running fore and aft on either side of the mast to join the transverse beams. The strength of the mast partners is to be the same as for the beams.

2.2.5 Deck mounted masts are to be housed in a mast step positioned directly over a bulkhead or a web frame/deep beams with a pillar fitted under the mast.

2.3.1 Conventional masts mounted on mast steps as in Pt 4, Ch 3, 2.2 Transversely framed yachts 2.2.3 are to be fitted with heavy transverse web frames as required by Pt 4, Ch 3, 2.2 Transversely framed yachts 2.2.2.

2.4.1 The structure in way of non-conventional mast configurations will be specially considered.