: Just a little more details here. I am a woodworking, so I am familiar with
: wood movement due to moisture. I don't think that was what happened.

: I had glassed the top on the form, 3-4 days before. I had removed the top and
: done some work on the hull. Few minor things left to do before jointing
: the two. Had sat it back on the hull a few times so there was no problem
: with the fit. A minor amount of movement but nothing that hand pressure
: wouldn't pull down in place.

: Move it outside. Disk sanding the underside of the hull. Knocking down any
: high spots and glue squeeze out. Moved it inside and glassed and epoxied
: it. 12 hours or so latter I discovered it had curled up. It will come back
: down but it is going to take some serious pressure with some straps. Hand
: pressure will not longer flatten it out. I need to try out a couple of
: things but I think I am going to have to clamp it in place and then run
: tape along the outside edge between the straps. I don't see just putting
: epoxy on the sheer clamps and ever being able to get that deck in place
: and shape without a huge mess. The ends where it was mostly flat I can,
: but not around the cockpit.

: Speaking of which I am thinking of opening up the small hole I left for the
: cockpit. Not full size opening yet, but that should relieve some of the
: stress at the back bulkhead and make it easier to flatten that section.

: Next time I think I will just coat the inside and not glass it. Be ready to
: put it on hull just as soon as I the epoxy starts to set up too. Probably
: didn't need the glass but I just wasn't sure and didn't want to regret it
: latter.

"Glue squeezed out" I remember reading that glue should be left for at least a week for it to cure properly. Even though it hardens quickly, there is still quite a bit of moisture locked in there & if the timber then gets a temperature change then your problem may be the result.
I think this may be the cause but I certainly don't have the solution, that needs to come from somebody with experience.
At least if you know the cause then it may open up more possibilities for a fix.
Glen G.