In this part I will discuss resawing the glued up side panels and a form to give the hull shape, cutting the top deck profile and adding the stem and stern blocks.
So now we have two 13 foot 8 1/2 inch wide boards made by gluing up strips of Sitka Spruce. Since the first 9 feet of a DN are straight the plans suggest resawing the last 3 feet and filling the sawed out wood with 1/16 inch (1.6 mm) plywood. The stern is bent into shape and the layers glued back together to give it the curve. Les and I resawed the entire length of our boards, planed the surfaces and then glued the layers over a form.
Unless you have access to a saw mill this step is tricky. We found a shop that let us use their large bandsaw. This was a big, powerful machine with a throat that could cut material up to 10 inches thick. Since our boards are almost 9 inches wide this would do. We had some 3/8 inch wide 6 teeth per inch blades and spent some time making sure all the guides were adjusted correctly and the blades tensioned properly. We made a tall fence to push the board against just before entering the blade.
When we were doing the cutting we found that the blade still wandered giving inconsistent thicknesses. Pushing the boards through was very heavy work and produced a very fine cloud of dust.
If I were to attempt this operation again I would use a 1 inch wide blade at 4 teeth per inch. A wider blade can have more tension and therefore should wander less. I would use a 3 person crew, one to push, one to hold the board against the fence and a third to "peel off" or open up the cut to let the dust clear.
A simple form like this can be made using 3/4 plywood and sections of 2 x 4.
We knew we were going to make multiple hulls so Les built a complete box form from 1/2 inch construction grade plywood.
With these large jawed clamps we did not need to use 2 clamps per station. 28 clamps would do for later hulls.
Fresh out of clamping. Maybe too much epoxy!
We cut the top deck profile using a pattern lent to us by John Curtis.
This laminated strand frame, along with the custom angle iron clamps were made specifically for DN hull construction. Two 2 x 6 twelve foot beams with 2 x 6 cross members support 2 x 4 stations predrilled for the clamps. The clamps are 3 1/2 x 5 angle iron cut into 1 inch pieces with welded nuts and holes for 1/2 inch threaded rod. The clamps are used to add sideways pressure for gluing at various stages or just to hold the hull in position. The frame has proved incredibly useful for all kinds of jobs and projects. The whole thing sits on 2 reinforced saw horses. The build could also occur on a flat 12 foot long surface. The stand makes it easy to clamp downward and didn't cost much to build.
The bow and stern blocks were made up out of several layers of high quality plywood laminated together to make a large solid piece. The blocks have slots cut into them ready to receive the stringers. The steering chock post hole was predrilled using a full size drill press. The hole is over bored and will later be filled with an epoxy and carbon mixture poured around the 11/16 post. The post is covered in wax to keep it moving. More on this later.
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