Friday, March 11, 2011

Building 'Sharpy' Part 38

Initial shaping

Early this afternoon I set about shaping the marine plywood for the keel. I used one of the aluminium pieces as a template; then I cut out the plywood with a jigsaw. The job only took an hour, including the final shaping with a plane and sandpaper.

Planed and sanded

This evening I intend bonding the ‘sandwich’ together with Evo-stik impact adhesive. The original ‘Sharpy’ keel was sandwiched in this way, and it is still going strong after several years. I questioned Derek Munnion, the designer of the boat, to assure myself before joining the parts that I would do it correctly. He did not advise scoring the wood, or severely abrading the aluminium parts. He used a plastic kitchen scouring pad to slightly roughen surfaces of the aluminium parts that would come into contact with the Evo-stik. He also cleaned the metal surfaces with white spirit before spreading the adhesive. I think I shall clean them with acetone in preference to white spirit. Derek slightly sanded and vacuum cleaned the plywood surfaces, and I shall do the same.

The sandwich

Finally, I’ll clamp them together to ensure they are properly bonded.

My next job will be making a template for cutting the sheet lead pieces that will be laminated together with Evo-stik to form the keel weights. These will be streamlined like a torpedo or fish.

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