May 28, 2009

Build a Dinghy: Part 13

After installing the chines and sanding/planing them flat as detailed in last post, its time to dry fit the bottom. The bottom is built oversized. I had already marked centerlines on the bottom, as well as on the transom, the frame and the stem of the boat. So after laying the rough cut bottom atop the upside down boat, I crawled under and lined everything up. Then I came "topside," checked everything again, and tacked the boattom to the chines, transom, stem and center frame with brad nails.
Next, I traced around the bottom overhang. I sanded a pencil flat to make this line as close as possible. Then I removed the bottom and clamped it to a scrap sheet of plywood. I set my circular saw for a shallow and cut out the shape just outside my line. Then I placed it back on the boat, and used a plane and sandpaper to bring the bottom to its exact size, rounding it somwhat at the chine so it will take fiberglass cloth better.
Next, using a shop-built spacer gauge, I pre-drilled the holes in the bottom through which the 1/2" screws into the chine would go. This gauge was the designers suggestion and a good one. Another tip I got from a friend, was to "knock down" the little bumps left by the drill with sandpaper to ensure a flatter fit on the chine ( Thanks Bob!). Finally, I applied a straight coat of expoxy, followed by a thickened mixture and screwed the bottom on. Check back to see the results--I've got squeeze-out to manage!

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