Woulda helped a little, but all boards can be broken with the right impact. A stringer resists some, but the twisting and delam occurs all around anyways, so it’s not a guarantee non break by any means. Plus a bit of weight.
I think you were ‘just unlucky’ - a 9’ board presents so much area combined with length that it’s gonna break on an overhead day if it gets caught wrong. Stringers don’t add all that much strength, especially compared to the rails, additional strength from the veneer skin and glass. Bear in mind that some of the other boards that broke were not surftechs and did have a stringer. But they broke just fine.
Basicly, from the amount of foam stuck to the underside of the veneer, I’d say you got an exceptional bond, veneer-foam, there’s no apparent failures of bond between glass and veneer… you did everything right too.
My guess is that a lip caught it smack dead center and there’s nothing of reasonable weight that would have survived that in a board that size. A center stringer…well, in the same situation it would have busted just fine, maybe sooner, as the inflexibility of the stringer relative to the foam would cause it to fail rather than flex. The moral of the story, if any, is that a longboard is more vulnerable to this sort of thing than a shorter board, simply because of the length and width of it.
what a shame! that looks like it was a beautiful board mate, had you finished it long or had you had years of use out of it? (i’m hoping the latter of the two!)
I went back to your original thread and have an idea that might be worth looking into. It has to do with the orientation of the grain in bending ply. I’m pretty sure that all the grain is aligned in this type of wood in one direction so that it can bend. I noticed that all your grain was vertical in the rails. I wonder if the bending ply in not designed to stand up to being bent that way. Notice how clean your break was… when I try to break real plywood it makes an ugly mess. You might want to look into putting a horizontal stringer in your next on (and maybe moving away from bending ply).
Ahmmm- to be honest with ya, I can’t think of how you’d fix it and have it come out anything but kinda aaaghly, and not especially strong. Let’s say no better than a small wave loaner board at best.
On the other hand… think of all you learned while making that one, and how much better the next one will be. That and the really nice gunny 7’6" you’ll build for those overhead days…
Now, I saw ‘10ft walnut veneer’ - can’t see it from the picture, but would that imply that the bottom was glassed only, say with 4 oz. glass and no veneer?? I’d bump it to at least six ounce all over next time, maybe times two. Not like it’d make a lot of difference, but it wouldn’t add much weight either.
