Hi Mike, What I did on my KR boat 15 years ago: I made the sides like plans call for except longer and a little taller because I am tall. Once they were flipped upside down on the work table ready for the bottom skin. I took a 1 inch thick piece of Divyncell foam cut close to the bottom shape, laid it on the worktable bowed to simulate the shape of the fuselage bottom sides. I put one layer of biaxial cloth on it (the inside), wet it out with epoxy, let it almost cure so it would not try and fall off the foam once upside down and to let all epoxy cure together at once around the edges, then I painted wet epoxy on the wood bottoms and the edges of the bottom fiberglassed almost cured piece. I then mixed up flox (a mixture of structural cotton fibers and epoxy) and spread it onto the bottom side of the wooden longerons, I then flipped the almost cured foam/glass coverd bottom onto the bottom sides of the sides. I weighted it down to get a good form and snug fit to the sidewall bottoms. I slid in underneath it to wipe off the flox squeeze out. Once it was cured I then sanded a nice radius along the edge and part way into the bottom outside corners of the bottom wooden longerons. Once I had the bottom edges sanded to my satisfaction I layed one layer of biaxial cloth on the bottom with it lapping onto the sides. It is very strong, I can stand up in the bottom of my fuselage with no fear of falling through it. I do not think I added much weight but I am sure it is more heavy than the plywood. I have not made samples to weigh but I will just assime my way is a little more heavy. I originally was building my plane to use a 150 hp Lycoming. I have now decided to use something less, like an 0200 or whatever makes me happy at the time. Larry H.
From: Mike johnson After all the great feedback from the kr club, and talking to a couple of engineers I came up with only one discovery, do nothing! The "boat" is the best part of the kr design. I talked it over with a structural engeneer, and let him no what all your thoughts were as well, and he was quick to say this: " It may seem that a wood frame appears to be prehistoric, but make no mistake about it, it has much more strength than you will ever need, and without much weight penalty." I was actually shocked. This was the same fella that was promoting carbon fiber. Needless to say, I will be starting my boat soon. I have come to realize the "boat" is what makes a kr a kr. Thanks guys, Mike J
