Something closed cell for sure. I used a gasket cut from a piece of 3/4" minicell and trimmed to the correct height with a razor blade.

Laszlo

the gasket material sent with the kits worked very well for mine.I put the weather stripping on the hatches then cut it down with a very sharp razor knife. lay the knife flat on a thin piece of scrap wood. Slide the knife and the scrap wood together while cutting the gasket. The gasket material is very easy to bend around the corners.

I thought the gasket material would be too thick also. But it compresses very nicely, and it makes a nice tight hatch. I'm glad I overcame my initial skepticism and used it. Jim

A tip given to me by the guys at Fyne Boat Kits:

The gasket material forms slowly to fit the joint.  If you want to speed this up you can do so by applying more pressure.  To do this, insert a couple of lengths of 1.25" dowelling (bits of broom-handle) underneath the straps and pressing on the side edges of the hatch, then tighten up the straps and leave overnight.

question I posted else where

is the gasket meant to hang over the small hatch rim?.  The postion of my hatch rim doens't is narrower than gasket width, I don't know if this by design or the result of my build. 

thanks in advance

brad

On the subject of hatch covers. When you build your kayak why not laminate some layers of baltic birch on the underside and form it to fit perfectly to the deck. When you cut out the hatch, you now have thicker material to work with. Also, as you only have a saw cut gap it should fit well. Fasten a ledge to bottom of the part still attached to the hull. carefully sand both surfaces and varnish. In the hatch edge cut a round grove and fit an O ring. You may have to epoxy the rubber to the edge of the hatch to stop it from detaching it's self from the hatch. I just wonder if the would work with wood as I'm a Machinist and Turner by trade. 

Just a thought. John

John,

And  good thought it is. Your idea is similar to the way the hatches are formed on some of the boats sold here. Rather than building up a laminate, though, they work with material actually removed from the deck. That way the grain is a perfect match and the sizes match except for the saw kerf.

The ledge is identical to what you propose, but instead of a groove there's a ridge to position and compress the o-ring.

The o-ring is manually built up from an adhesive foam strip glued to the edge of the hatch for exactly the reason you describe - to keep it in place. It can aslo be an actual o-ring/gasket cut from appropriate material.

Your instincts are excellent. It's time for you to build a boat :-)

Happy New Year,

Laszlo

PS - click on the thumbnails to get larger images.