Just an idea that worked pretty good for me. I purchased a 2x4 "U" shaped aluminum channel that made an excellent strongback for my guillemot. The corners and surfaces were flat and square, and there isn't a hint of sag along the 16+ foot length (I had to buy a 25' section, so maybe I should do a 9' design next). The material is soft enough to cut with a jig-saw to taper the ends, and you can use 2" aluminum angle to mount the forms. The cost was about $75, but spread over the cost of several boats...