: Mike-
: Another approach to this problem (you are not far from dead flat @
: 1/16") is (starting with a clean deck and hatch rim) to put
: a few (fingernail-size) shims on the deck to hold the hatch rim
: flat. (Glue the shims in place on the deck-make sure they will
: be covered completely with your sealant/adhesive).
: You can even glue the shims in place and then sand flat with a
: piece of (flat) plywood with sandpaper attached.
: Apply sealant/adhesive and bolt/screw/weight the hatch rim in place
: with minimal pressure. The shims will keep the hatch rim from
: flexing. Clean up excess adhesive.
: Let the adhesive/sealant cure well (days to weeks, depending on the
: goop) then tighten up the fasteners.

: I used this method for making epoxy pads for stanchion bases on a
: sailboat project, and I've also used it with inspection ports
: & hatches with 3M5200 and Sikaflex.

: BTW, I've also been surprised at how flexible glass/CF layups are-
: it takes quite a bit of glass/CF to make a stiff flat panel.

: Cheers
: John

This is why there are few truely flat areas in production glass boats, only takes a tiny bit of camber to make a nearly flat panel stiff.

Bill H.