Pygmy calls for an interesting method of applying a bead of thickened epoxy to the inside of the shear seam : Take a stick about as long as 1/2 of your boat. Tape a syringe alongside the stick at the very end. Put 2 or 3 eye screws along the length of the stick and run a dowel through them, pushing against the plunger of the syringe. This makes a 'remote control' for your syringe. Tip your boat on it sideand squeeze a bead down the entire length to fill your mystery gap. You can't see exactly what you're doing way down at the ends of the boat, but by applying even pressure and moving the stick at a constant rate, you can get a good bead. Don't thicken the epoxy too much -- you want it to flow into the cracks.

Dean