: Using caulking instead of glassing in the bulkheads is going to
: result in weak connections, especially with plywood bulkheads.
: Is there a particular reason you're doing this?

I agree with this, if you are using house caulking.
If you want to bond a bulkhead, you will need to use something like 3M 5200 or the equivalent Sikaflex product. Very strong connection once cured.

It's hard to believe, perhaps, but I found 5200 to be much messier to work with than epoxy - so unless you need a flexible bond, use epoxy.

With wood-glass kayak construction, I think we avoid the 'hard edge' concern that leads some composite builders to soften the bulkhead attachment, or use a foam bulkhead.