Section 6 Ballast keels

6.1.1 The ballast keel may be of lead, cast iron or other suitable material. Cast iron or other ferrous metals are not to be used in wood or composite craft sheathed with copper or other non ferrous metal.

6.1.2 Prior to installation the ballast keel is to be `Dry fitted' to the hull and the top is to be smooth, or slightly concaved in all directions, and well coated with a suitable bedding compound.

6.1.3 In composite yachts care is to be taken to prevent crushing of GRP laminates through overtightening of keel bolts.

6.1.4 A substantial plate washer is to be fitted under the head of the keel bolt. The diameter and thickness are to be not less than 4,0 and 0,25 times the bolt diameter, respectively, but the thickness need not in general exceed 8 mm. The top of the bolt is to have sufficient thread to take double nuts or other suitable locking arrangement. See also Pt 4, Ch 3, 6.3 Keel bolts 6.3.6.

6.1.5 The structure in way of the ballast keel is to be in accordance with the requirements of Pt 6 Hull Construction in Steel, Pt 7 Hull Construction in Aluminium and Pt 8 Hull Construction in Composite for the respective material.

6.1.6 In steel/aluminium alloy yachts all bottom structure in way of the ballast keel(s) is to be welded by means of double continuous welding.

6.1.7 Ballast keels are to be fully supported by floors to distribute the keel loadings to the bottom structure, see Pt 8, Ch 3 Scantling Determination for Mono-Hull Craft. The scantlings of the floors and frames will be specially considered in conjunction with the keel mass together with the size, material and position of the keel bolts.

6.1.8 Canards and lifting keels are outside the scope of the Rules but the structure in way will be specially considered with regard to maintenance of structural and watertight integrity. Full details are to be submitted for appraisal.

6.2.1 Where ballast is to be incorporated in the keel, the internal surface is to be suitably coated prior to filling, and on completion the top surface is to be sealed.

6.2.2 For steel and aluminium alloy yachts the method of installing the internal ballast is not to be detrimental to the plating or internal structure. Details of the installation procedure are to be submitted for consideration prior to implementation.

6.2.3 Internal ballast is to be suitably supported and secured against movement. The supporting structure in way of internal ballast is to be suitably increased in strength.

6.2.4 In steel/aluminium yachts, the ballast is to be totally encapsulated by fully welded plating with a minimum thickness of 6 mm. Alternative arrangements will be specially considered.

6.2.5 In composite yachts, the internal ballast is to be encapsulated by a laminate equivalent in thickness to half the rule bottom shell laminate or 2400g/m² CSM (or equivalent), whichever is the greater.

6.3.1 The keel bolts are to be of a corrosion resistant material. The nuts, washers etc. are to be of a material the same as, or compatible with, that of the keel bolts. The specifications of these materials are to be submitted for appraisal.

6.3.2 The diameter of keel bolts, d _k, is to be that determined from the following formula, or 14 mm, whichever is the greater:

When determining w for the bolt at the ends of the keel, the weight of any overhang is to be included.

6.3.3 Where double bolts are to be fitted, the total cross-sectional area of the bolts is to be not less than 1,2 times the cross-sectional area of the bolt determined in accordance with Pt 4, Ch 3, 6.3 Keel bolts 6.3.2.

6.3.4 Keel bolts are to be fitted alternately on opposite sides of the middle line, and as close as is practicable to the bottom floor structure.

6.3.5 The ballast keel is to be secured by through bolting, but where this is not practicable, short keel bolts or studs may be fitted.

6.3.6 A substantial plate washer is to be fitted under the head of the keel bolt. The diameter and thickness are to be not less than 4,0 and 0,25 times the bolt diameter, respectively, but the thickness need not exceed 8 mm. Washer plates, where square or rectangular, are to have suitably radiused corners. In composite and wood craft the washer plates are to have all edges dressed smooth in addition to being suitably radiused.

6.3.7 The bottoms of short keel bolts are to be secured by nuts and washers fitted in pockets in the keel, or by square plate nuts cast in with the keel. Where cast in, the square plate nuts are to have a breadth and depth not less than 3,0 and 1,0 times the bolt diameter, respectively.

6.3.8 Where studs are fitted, the length of the threaded portion into the cast iron or steel keel is to be not less than 1,5 or 2,5 times the stud diameter where through tapped or blind tapped respectively.

6.3.9 It is recommended that the design of the keel bolt is such that it can be withdrawn for survey and is not cast permanently into the ballast keel.

6.3.10 Details of the proposed torque to be applied to the keel bolts are to be indicated on the relevant plans and submitted.