Friday, December 4, 2009

Transom Build

The transom is built from 3/4" Okoume plywood. The layout lines were transferred to the plywood with carbon paper to show outer contours and added inside frame locations. For some of the curved areas, the added frames allowed using them as a template for final cut of the transom plywood with a router and trimming bit. I angled the motorboard just because I thought it looked better. I also raised the height of the transom at the motorboard to 16.5" from the plan's 15". The "Mustang" boat plans show different dimensions up to 17" depending on make of old outboards and I'm told that performance can be enhanced by tuning the height upwards and the transom can always be cut down if too high. Since I don't have a motor yet, I moved it up, but 17" didn't look good, so I settled on 16.5". The Okoume 3/4" plywood is very dense and heavy and after bending a couple of silicon bronze nails when trying to glue and nail the transom knee together, I increased the diameter of the pre-drilled holes. Bent nails were broke off and another hole drilled adjacent for another nail. Close inspection shows a couple of curious bronze spots in the transom knee....

The bottom of the transom has a shallow "V" cut at a 12 degree bevel. I used the method in the "Boatbuilding with Plywood" book by Glen L. Witt. I added an auxilliary fence suspended about 1/8" higher than the transom thickness off the table saw surface, and then screwed down a straight board to the transom along the line to be cut (one side of the "V" at a time). With the blade angled 12 degrees and the outside of the blade set just below the edge of the aux fence, the cut turned out super. I think the above mentioned book is a "must read" for a new boat builder like me as it answered many questions that I had and hopefully prevented me from making poor choices for materials, assembly and building techniques. I also enjoyed learning about something I knew little about and gave me the confidence to begin and avoid many mistakes that would have happened otherwise.

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