Got a blog post with some pictures here:
http://dbynoe.blogspot.com/2009/05/skin-on-frame-hatches.html

They are basically just modified comings with plugs that fit in. The hardest thing to figure out was the hold down system. I wanted something traditional looking so hence the way the straps loop over the toggle. (the left and right straps in the picture are separate, the left side one loops over the toggle in the middle and is tightened down). If you were in a hurry nylon webbing would be a lot easier to rig up.

I use them mostly for shoving gear rearward and retrieving things from the ends, they are big enough to fit your head in, so you can shove gear in that way, but its way faster to put the gear in through the cockpit, and reach in through the hatch and pull it towards the ends.

: Great looking baidarka. I especially like the hatches. Can you give
: us some info on them. Huh, can ya, huh?

: Shark