Saturday, May 07, 2011

Building ‘Sharpy’ Part 81

Bracket fixed in place

I made the decision to do my own metal parts; therefore I started on the bracket for the ball bearing pulley that is for hoisting and lowering the keel. Instead of making it as per plan I adapted a bronze Seagull outboard engine clamp. This required ingenuity on my part, but I’m very pleased with the result. The dimensions are similar to the original stainless steel design; however, I believe the bronze fitting will be stronger because the sides that support the spindle are thicker.

Testing the Pulley

Stainless steel and bronze are probably not happy together, but if I make sure there is grease on the pulley I don’t think I’ll have a problem with electrolysis, because the fittings are not below water. They will only be subjected to minimal sea spray and water shed from the cable when the keel is hoisted.

Checking alignment of cable and pulley

I fitted the bracket above the support post so that the ‘v’ of the pulley was directly in line with keel’s Bowden cable. In practice, if there’s a tendency for the cable to jump off the pulley I can easily make a guide to keep it where it should be. As long as it is supporting the keel I don’t think there’s a chance that it will come off the pulley. I’ll have to see how it works.

My next challenge regarding the keel will be devising a quick method of attaching and removing the removable lead weight. My initial thoughts are that I should make two strips of metal about an inch wide by three sixteenths of an inch thick, and drill holes through them to match the holes in the keel weights and the keel itself. One strip will be permanently bolted to the outside of the fixed weight using the same bolts that will retain the weight. The removable weight will slide onto the bolts before the second strip of metal is also slid onto the bolts. To keep the weights in place I can either use washers and nuts, or make holes in the ends of the bolts for retaining pins. The latter is similar to the arrangement shown on the plans, but if I choose this method I shall have to drill holes through the bolts. Incidentally, they would be retained in place by washers and nuts, which means I would have to make recesses in the moveable weight, otherwise the moveable weight would not fit flush with the side of the keel.

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