So I’m going to be finishing that bar of soap hybrid board I was asking about painting soon, and I’m finding myself at a crossroads. The board was shaped from an old cut-down so it isn’t as thick as I want it. I’m concerned about bouyancy and I want to shave every ounce off the board I can weight-wise. Would the weight I would save by using lightweight glassed-on fins be enough to offset the risk of a broken fin meaning a major repair instead of a trip to the surf shop?
Also, I Was thinking of shaping the half-moon style fins out of balsa wood and sinking them into the foam before I glass the board. I figured this would add stability to the fins if I can do it right with no bubbles, and will maybe make a break at the base less likely… am I crazy??
As regards buoyancy vs. weight; you’re talking about the weight of the board…plus the weight of you, not just the weight of the board alone. So an ounce…or a pound…won’t really make any meaningful difference in the overall buoyancy.
Now, as to sinking things into foam for strength/stability- not really happening either. You want to ask yourself ‘just how rugged is foam?’. Glassing fins onto bottom glass, good, that strain is spread out over quite a bit of bottom.
Setting fins into .slots in the foam, not so good. You’re kinda setting up a weak point in the bottom glass, y’know? So the glass might well buckle there, with all kinds of unpleasant things after that.