: Maybe cut the groove with a router and a half round bit so the O-ring would
: fit nicely in the groove. The router could have a guide on it so the
: groove would be the same distance from the edge of the cover all the way
: around. Once the groove is cut, coat it with a layer of epoxy to keep the
: water out of the wood.

: Just make sure you don't screw up, you only have one hatch cover (for each
: hatch) that matches the rest of the kayak. Good luck trying to make a new
: one that matches. Maybe you should practice the technique on scrap first.

: The nice thing about the groove being in the lip instead of the cover is that
: the water has to go up over the foam. If there is an O-ring in the cover,
: the water just has to find a way under the O-ring to get into the kayak.
: In other words the O-ring might not seal as well if it isn't a tight seal
: all the way around.

You can burn a lot of calories going this route if you wish.

I've played with quite a few hatch variations.

The gasket tape Newfound Woodworks sells compresses extremely well.

If you place this tape on your hatch cover so half the tape width will hit the lip the cover rests on and the other half of the tape will be in the opening you have a simple watertight seal.

I strip a panel where each hatch will be after I remove my deck during construction. These panels are cut to a donut shape 1" larger and 1" smaller than the hatch opening. The donuts are glassed under the deck forming a lip for the hatch cover to rest on. The tape compresses so well I don't need to consider it's thickness when installing the hatch lip.

This is what I use on my flush hatches. It's simple and effective, that's all I ask from any technique.

Rob