Section 9 Structural details

9.1.1 The shell plating is to be increased in thickness at the fore end of the bulb and in other areas likely to be damaged by the anchors and chain cables. The increased plate thickness is to be the same as that required for plated stems by Vol 1, Pt 6 Hull Construction in Steel.

9.2.1 Hawse pipes, bow rollers and other deck gear, of adequate size and construction, are to be provided for handling and securing the anchors and are to be efficiently attached to the structure and arranged to give an easy lead to the cable.

9.2.2 The hawse pipes are to be of sufficient size and thickness with a minimum diameter not less than 12 times the diameter of the chain cable. The arrangement is to give an easy lead for the cable to the windlass.

9.2.3 Hawse pipes and anchor pockets are to be of ample thickness and of a suitable size and form to house the anchors efficiently, preventing, as much as practicable, slackening of the cable or movements of the anchor being caused by wave action. The shell plating and framing in way of the hawse pipes are to be reinforced as necessary, see Vol 1, Pt 3, Ch 5, 9.4 Local reinforcement 9.4.1. Substantial chafing lips are to be provided at shell and deck. These are to have sufficiently large, radiused faces to minimise the probability of cable links being subjected to high bending stresses. Alternatively, roller fairleads of suitable design may be fitted. Where unpocketed rollers are used, it is recommended that the roller diameter be not less than eleven times the chain diameter. Where hawse pipes are not fitted, alternative arrangements will be specially considered.

9.2.4 The lines of the bow are to be taken into consideration when siting the anchor recesses for conventional bower anchors. Sufficient clearance of the flukes from the hull is to be maintained over the whole of the anchor run, above and below the water, considering the flukes in the most critical position. If a bow sonar dome is fitted, consideration is to be given to the positioning of the anchor recesses to reduce the possibility of the anchor chain rubbing on the dome when the anchor is in the deployed position.

9.3.1 Chain lockers and supporting structures shall be capable of withstanding loads associated with ship motions in the forward region acting on the anchor cable as a lumped mass, see Vol 1, Pt 5, Ch 3, 5.4 Loads for decks designed for cargo or heavy equipment loads, Pcd and Wcd.

9.4.1 The thickness of shell plating determined in accordance with the Rule requirements is to be increased locally by not less than 50 per cent in way of hawse pipes.