I thought it was unlikely too, to get water through the stitching holes, since I filled them with thickened epoxy, and then added cloth and layers of epoxy over them....but I did fill the holds with water, and that's where I'm getting the leaks.

I drilled 1/16 holes (as specified in the Coho manual). After wiring the planks together, and gluing the seams, I removed the wires. Then I sanded down the plank seams, and put another coat of thickened epoxy over the seams, and in the wire holes. Then, I sanded the whole hull, and put another coat of thickened epoxy where needed. After another sanding, I then applied the fill coats, epoxy cloth and more fill coats.

I think I have to assume that at least one of the batches of thickened epoxy was "bad" (i.e., operator error in mixing up the epoxy) - otherwise, why the hole failures only below the waterline, where presumably there's the greater water pressure?

Anyway, as mentioned earlier, I could drill out and refill the holes, or slap small patches over the holes. But, I think I'll try another batch of thickened epoxy (using wood floor - I don't know what carbosil is). I'll try to squirt it in with a syringe, and also press some down with flat pressure using a popsicle stick. I'll also try to get inside the hull, as well.

Worst comes to worst, next spring when I sand the boat again in preparation for varnishing, I'll down to the cloth, and apply some patches, and then fair them in and put on a few more fill coats of epoxy.

Any other suggestions are appreciated!

TIA
Ed
(Of course, what I may do is just slap some duct tape on temporarily, take it out on the water, and make sure I've got all the holes...)