Put in a row of vertical 3" strips all around the cockpit:
Cut them off an inch above the deck (I used a router with a
block screwed to the base to guide it. Then I cut a piece of 1/8"
marine plywood and glued it to the top. Then trim this piece to 1
inch wide:
On my second kayak I did all of the parts with strips in
redwood as can be seen here - also note the small round hole in
front of the cockpit to mount a compass in:
Cut the hatch openings and fit in some 2 inch wide by 1/4 inch
thick pieces, put a fillet around them, and sand:
Trim these off about .5 inches above the deck and even with
the bottom of the deck. Round over the top edges
To make the hatches take the pieces you cut out and put a rim
around the outside.
On my second kayak I inset round hatches into the deck - here
are some shots of it:
