Appreciate the input. Now if we were to look at a birds eye view of the boat the bow right, the stern left; this joint runs crosswise, dead-center of the boat. It runs down the port-side, across the bottom, up the starboard side. It seems to me it'll be a hinge, epoxy or not. Details: I'm building with 3/8" Mahogany marine quality plywood. I chose 3/8" for it was the thinnest 5-ply available. I'll S&G the sides to the bottom, and fiberglass the lot. The cross-section will be a square-U, very little rounding (I don't see me developing curve cut panels that will match). The hull will be flat from stern to mid-section then curve upward to the prow about 6-8"; and there'll be a transom.

Here, in Hawaii, the boat is going to sea. Until I've built up confidence in its structural integrity it won't go far to sea. Still there will be some wave jumping. A Hawaiian racing canoe's hull is made of 1/2-3/4" thick fiberglass. It is a U shape and one continual form. Mine is plywood and joined as above. A fiberglass canoe jumped a wave recently (outbound) until the stern alone was in the wave, the rest airborne. When it hit the backside of the wave it blew a hole through the bottom of the U.

I don't plan on a lot of wave jumping, but it is often unavoidable. You can see my consternation with this joint being centered and acting as a "hinge" upon impact. Any advice on support ribbing, etc. running longitudinally with the hull and perpendicular to the joint that may help.

Mike, how should I go about offsetting the joints? Scarf joint full sheets of plywood then cut diagonally across it? Hmmm...hadn't thought of that; I'm very longitudinally focused I guess. Would that be the best way?

Thanks again gentlemen.
> You could either offset them or back the scarfs with fiberglass tape to
> strengthen the joints.

> Mike