I have inherited a strongback that was used to build a Bear Mountain Endeavor. It is all set up but can be used for any canoe or kayak with some modifications. Hate to see it turned into firewood (Lord knows I already have enough of that). If you are planning to start a project and want a head start, email me off line. It is in the Vancouver, B.C. area.
It is a supported plank and not a box beam, but it looks pretty stable.