: I'm working on my 2nd Yost boat, a Sea Otter R. I expect to do a sewn-on
: skin. My combing will be Yost-style plywood buildup with rigid ring on the
: frame, as that's what I'm comfortable at building.

: I see sew-up skins are stitched onto the combings (which float? I have a hard
: time grasping this). So, how are the stitch holes in the combing riser
: sealed? This is probably of extra importance with a plywood riser. Or,
: should I be considering a some method other than stitching to the combing?

Drill your stitch holes through the top of the base ring, and then stretch and stitch your skin to the top of the base ring. Then, you can squeeze some silicon between the coaming and the base ring to keep water from entering the cockpit when you roll, etc.

How far along are you on the Sea Otter? No offense to Tom, but I've built one and was not impressed by it, at all (very unstable, yet difficult to roll). Tom's Sea Rider is a better boat by far, and so too are the Sea Tours, if you need the cargo room.

Good luck, in any case.
Dave