Bill, what a great project.

because your glue joints do not flex(you used epoxy instead of a flex joint like tied or silicone or sikaflex or flex polyurethane) you have to take steps to keep the yak from deforming and cracking these jts - its stiff now b/c you built it to be stiff. first use the roving - it'll help keep each and every(there'll be failures) module rectanglar. second, strongly strongly consider central vetical foam pillars running from near the stern up to the cockpit, and one from near the bow up to the front cockpit and slightly beyond. this is typical setup for ww yaks, and you'd get used to it real quick. you need to keep the stiffness going.

the other weak point will be buckling right at the cockpit sides. I would also strongly recommend vertical foam at ea cockpit side running say 2 ft past the cockpit. from the side it's like 2 opposing 'D' tubes.

my guess would be that failure would happen in buckling at or near the cockpit sides, so if theres any way of curving some more stringers from just ahead of the cockpit around it to the back for some distance, might be worth considering.

but good for you!!

-mick