(a) With the aid of a sketch describe the method of attachment for a bilge keel and hence explain why provision is made to reduce the possibility of the hull being punctured in the event of damage to the keel.
(6)
(b) State why the keel does not extend for the length of the ship.
(5)
(c) Evaluate the effectiveness of bilge keels for large wall sided vessels.
(5)
Reference Answer
### (a) Bilge Keel Attachment and Hull Safety **Method of Attachment:** The bilge keel is a passive anti-rolling device, typically a flat plate or a flanged plate, attached externally to the hull at the turn of the bilge. Its attachment is specifically designed to be robust for normal operational loads but sacrificial in the event of grounding or contact, thereby protecting the main hull's watertight integrity. 1. **Foundation Bar (Ground Bar/Doubler Plate):** A continuous flat bar, known as a ground bar or doubler plate, is first welded directly to the hull plating along the intended line of the bilge keel. This welding is a full-strength, continuous fillet weld on both sides, ensuring a solid connection and distributing stresses evenly into the hull structure.
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