Monday, March 21, 2011

Building ‘Sharpy’ Part 44

Glued surfaces

Well, I’m back on the job again, continuing with making the keel weights. I first did some experiments to test laminating lead with epoxy and drilling through lead. Before gluing four offcuts together I cleaned them with white spirit. I shall try tearing them apart tomorrow after they have been clamped together for 24 hours.

To test my Black and Decker battery operated drill, I bored a hole through an offcut of lead. At slow speed it cut a clean hole through the lead with little resistance, which means I shouldn’t have a problem when it comes to drilling through the assembled keel weights, but as I don’t have a bench drill, I’ll need to take great care that both holes for the retaining pins are at right angles to the outer and inner surfaces of the weights.

Joined in pairs

Having tested joining offcuts of lead with Evo-stik I felt confident to go ahead with laminating the actual keel weights. I started by laminating 12 pieces together. These I lightly clamped and set aside until I can continue adding more pieces. I noted that their total thickness was approximately 18 millimetres, which confirmed that individually they were 1.5 millimetres thick. I now know that I shall need at least 80 pieces to make the required combined thickness of the lead weights. Derek Munnion, the designer of the boat, laminated 96 of them, so somewhere there is a discrepancy of 16 pieces, and as each piece weighs about 13 oz my keel would be 13 lbs lighter than his. I’ll have to see what actually happens when they have been made to the correct dimensions. Perhaps my lead flashing is slightly thicker than Derek’s.

Twelve pieces laminated together

Incidentally, I’ve made contact with the chap who may be able to make the stainless steel parts for the keel. He is now in possession of photos of the drawings, and I await what he has to say.

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