I believe airplanes are typically made with more substantial frames, either solid plywood or plywood with lightening holes in it. The bent ribs of the "geodesic" type boats are relatively flexible. It think this will require a little more reinforcing than more rigid frames.

I have built 18' long hulls with solid foam frames in a tubular structure like a kayak. Before the Kevlar is was very floppy, after it was absolutely rigid. I would not have trusted the dacron to provide this rigidity. I did one time peel the skin to do some work on the boat. The skin was not well bonded to the structure. It may have been bonded well enough, but with the Kevlar roving the structure was very bomb proof. There are things I would do differently if I did it again, but I'm sold on the Kevlar.

Besides, it looks cool. Franky, I don't need any other reason than that. However, I'm all for testing.

: I'd be interested if anyone has actually tested the need for the kevlar. An
: airplane is built with no diagonals, the skin provides all that is needed.
: The Dacron is shrunk, then varnished. There is a lot of Dacron there to
: resist any torsional movement. Another test would be to lay the Dacron on
: the diagonal, since the stringers and ribs provide stiffness in the
: straight directions already. When you consider the area of Dacron, it has
: tremendous load capacity in tension. The question would be, would it
: stretch enough to put enough load on those joints for them to break. My
: guess would be no. If it were my boat, I would have done the tests long
: before this point.

: Al