I think I saw that a while ago, was doing some work in saginaw and kawkawlin, wandered over to check out the bay. (I'm a wanderer, if there's a direct route somewhere, I prefer finding a more interesting route) Remember trying to figure out what the deal was with it.
Gramp's post clears it up.
The only molds I've seen were for smaller boats, and the stiffening and supports etc were built up out of fiberglass and wood as part of the molds themselves. Now htat it's been pointed out, it's one of those 'duh' moments