: Bill: I'm going to use marine plywood for the hatch lips. I can put
: those on with clamps after the deck is attached to the hull.
: However, I think I might follow John Caldeira's suggestion on
: cutting out the hatch but leaving 4 tabs to hold it onto the
: deck.

: Charles Robinson

If you've got the plywood lips glued in place that part of the deck would hardly twist at all when you mate the top and bottom halves.
I assume you will have a spacer piece in there as well to accommodate the seal height.
JohnK