Building ‘Sharpy’ Part 3

Profile and Plan View

Sketch of the Keel

The Keel

The 42 inch keel is made from plywood, aluminium, mahogany and lead. Both the leading edge and the trailing edge underwater sections are tapered and they are shaped from mahogany that is screwed and bonded to the plywood so that they overlap the aluminium sheathing on either side. A Bowden cable attached to the bottom of the keel fits in a groove on the leading edge. When in use, the cable is clipped to a tackle on the foredeck so that the keel can easily be raised or lowered. When fully raised, the top of the keel protrudes 23” above the cockpit coaming; this does not interfere with the sail, although I doubt the keel would be fully raised when the boat is being sailed. For optimum speed downwind, that may be the case, and should an involuntary gybe occur, the boom would be clear of the keel.


The ballast keel bulb is laminated from sheets of lead that are shaped with shears or scissors. Each piece is joined to the other with flexible impact glue and they are clamped together with locating pins. The starboard ballast is permanently attached to the keel, and the port ballast can be removed for convenient transportation. Derek designed the keel so that it would be able to flex, and if it were subjected to exceptional strain the plywood core may possibly fracture, but the keel and ballast would not be lost.


The keel snugly fits into a vertical keel box that is at located at the forward end of the cockpit. There is room either side of the keel box for the crew’s legs to pass under the foredeck so that his feet can rest on the steering bar.