Because the stringers come under tension when bent to the frames, the strong-back will hold the assembly in shape until the panels are attached. The slightly narrower top deck will enable the overlap of the side panels on the top stringers while the float is still on the strongback. A sitka spruce or comparable clear softwood is supplied in the kit. As the stringers function primarily as an attachment point for the plywood skin, strength is not critical. The frames function primarily to create the float shape in construction and to carry some of the compression loads.
Waterproof plywood is supplied with the kit.
The outside panels carry most of the float loads. They provide panel stiffness and resist point loading when mooring or beaching. They are exposed to the environment and of course keep the water out. They are the most important wood material involved. The 3 mm plywood supplied in the kit will provide ample panel stiffness on floats 12 to14 feet long.