The Seats

The seats for the canoe as designed are open bottom - a piece of plywood over 1" cleats and supports.  I didn't want to leave it open for various reasons - it would be a hiding place for spiders in storage, it would be a pain to clean, and I wanted to experiment with floatation foam chief among them.  So I added a plywood bottom with foam in the middle, providing about 17 pounds of floatation for gear or provisions.  This complicates assembly, because the frame has to be installed after completion instead of being built in place.

After measuring the seat dimensions, I started with the frame on a piece of plywood.  The visible parts of the frame are from scraps of red oak that I have had for 12 years, bullnose trim  left over from stairs I built in a house I used to own.  The newels on those stairs were not loosely nailed to the floor, like in most houses.  They were screwed to the joists.  No one could crash through those rails.  The scraps were not long enough, so I joined pieces to make them long enough, using lap joints.  The hidden cleats were spruce.

This is a learning project, and this is my opportunity to learn about floatation foam.  I have had this flotation foam since 1999, but apparently floatation foam has a shelf life similar to epoxy.  It is still good.  Floatation foam is a Coast Guard approved, two-part polyurethane mixture that foams when mixed, like expensive Great Stuff™.  When mixing this stuff, the mixture is 1:1, so it is convenient to use identical disposable plastic cups (labeled A and B so you can re-use them for each batch) and pour each part to a line molded in the cups.  I mixed thouroughly, just until it started heating, and poured into the seat frame.  Below, you see the result of two pours on the bottom, and the other seat after trimming.  I trimmed using guitar wires, but it took four because they break so easily.

After filling with foam, I glued the plywood tops on.  The assembly is very stiff and light.

Mounting the seats was not as straight forward as I thought initially.  The plans had a measurent to the top of the seat on the centermost edge.  This measurement is different from the other side.  I used a level to make the seat as close to level as possible, smeared the ends thickly with epoxy putty, and screwed the seats into place using two sheetrock screws on each side maintaining 1/8" separation between the seat and hull.  I put 9 ounce woven fibberglass tape on the upper side, wet on wet.

Below, an installed seat.