-- Last Updated: Mar-22-13 10:05 PM EST --
I tend to deal with general principles more than details, though at times I get persnickity about details and definitions so I don't mind you doing the same regarding the "roughly illustrative" terminology I chose. Anyway, the "near-vertical" portion of fabric on the edge of the foam core IS stabilized on both edges (top edge by the wrap-around over the core, and bottom edge by its junction to the main hull), so don't take the "half-I-beam" term to the extreme of ignoring what that part of the hull actually looks like. My use of a poor name doesn't magically create a free-standing web of material that wasn't there before.
Actually, none of your details about the complex failure of a "Y" shape goes against the overall idea I was getting at, which is that the rather flat, panel-like portions of the hull will be floppy when subjected to even the smallest point loads while those associated with any kind of sharp curvature or three-dimensional shape will be much stiffer. Lightweight hulls like this are still amazingly strong as a whole, and are not that easily damaged EXCEPT on the flat panels, so I can't imagine breaking the stiff parts of the hull with the tension applied to tie-downs (that's already been pointed out and not just by me). The need to stress any part of the boat even remotely close to failure on flatwater just seems like fanciful thinking to me, and if that's the case, the choice boils down to that between a connection that allows the hull to flex all over the place and one that doesn't. Nothing wrong with asking Wenonah, but I suspect all the people who've suggested avoiding the flat-panel parts of the hull in favor of the stiffer areas will turn out to be correct.