The discussion of flush hatches has brought up a problem I had with making my last stitch and glue kayak (and I've been trying to mentally solve as I start my second).

How do you make the hatch curve to match the deck?

CLC suggests making small cross frames cut to match the deck curve - epoxied to the back of the hatch (clamp on individually). I was concerned about the hatch twisting so I made a jig - I cut slots in a length of wood (these would hold the cross frames vertical). I supported the hatch cover only along the edges and put the frames and the length of wood over top. Then I winched (by twisting loops of rope on either end) down on the length of wood - slowly bending the hatch too match the shape of the hatch cover. I was then able to glue it in place.

Unfortunately, despite my best intentions the hatches still warped a little - forcing me to try and build up lips of silicone to fill edge gaps, plus by putting the weatherstripping on the deck rather than the hatch cover seemed to help (removing the lip for water to hit with a flush hatch has 2 benefits - 1- reduced splash, 2- waves tend to run over the hatch, and therefore don't force water past the seal).

I plan on making new hatches for my boat as I build my wife a boat this year (I'll be trying flush hatches as well). Any better suggestions? Would I be better off to just clamp the cross frames individually? Or do I just live with some twist in the hatch and try to tighten the straps more?

Mark