This week, I scarphed together two lengths of soft maple. Why maple? Because I can get it in approximately 8-foot lengths of 1/2" thickness by 8-9" width at an okay price. It is a hard wood destined for a canoe-styled hull. I used an 8/1 scarph ratio which is more than required. The scarph was made initially with a hand power plane for gross reduction, then followed with a belt sander and medium grit. The resulting surfaces were flat and mated well. Epoxy adhesive was followed by clamps. I have three hand belt sanders. Why didn't we have them in junior high shop class! Planes can produce 'chips'; belt sanders never do.
With epoxy and paint, also kept indoors, weather will not be a factor for the maple in this hull. Once scarphed together, I ran the combined board through a thickness planer to bring the thickness down to a uniform 7/16" (0.435"). Why that thickness? Because I wanted a balance of weight, strength, and flexibility for the slight rocker planned. These were rough boards when received, thickness was not uniform, and they initially were not entirely straight. I corrected the side curve with a hand plane and frequent checking with a straight edge. The product now is straight, uniform, and has the flexibility desired while retaining sufficient strength. This will be the plank keel creating a foundation, tying all the frames together.
Today, I bought lumber for the frames: knotty alder. Why knotty alder? It is a beautiful hardwood, but relatively light, and at a reasonable price. Of course, I hand selected the best boards and bought excess (perhaps enough for a next hull). The drawback is the knots present but, for the frames, I will be bonding together rather short lengths of wood. I think I can work around the knots.
