I completed my hatches for Picara. Made a light wooden frame with one inch ribs spaced about every 6 inches. Cut regular 1 inch bead board foam about 1/8 inch over sized and glued it inside the ribs with epoxy as a force fit, glassed both sides to complete a rain tight hatch. Seems plenty strong for it's purpose. Will also insulate from the hot sun as needed. About 7 pounds for the 32 X 38 inch aft hatch.

Thinking of making a take down Dink in three parts with the same construction ideas, might be able to stow it aft of the footwell on my Picara "Mattie Cooper" -- would be more canoe size, 30 inches X 11 feet than full size Dink. Might use 2 inch foam and ribs with enough plywood on top of the ribs to support 400 pounds or so. Will be light weight. Most of the cost would be in epoxy and cloth, guessing at about 2 gallon epoxy.

The glassing on both sides of the foam seem to add a lot of strength, just used 4 oz cloth for the hatches -- 6 oz might be better for a small boat. The thicker the foam core the stronger the lay up is and the more rigid the foam keeps the ribs.

The foam sanded well with a rotary sanded, but extra care must be used, because it will eat the foam very quickly. Also uneven spots and the edge glueing was prepared with a thin epoxy putty to fill gaps and also to seal the surface before glass was added. The glass glued to the ribs every 6 inches or so seems to be important to get a strong structure.

The foam cut the best with a metal cutting blade in a jig saw.

I am sure better foams might be used, but after the foam is sealed in the glass it seems to fill the bill for hatches at $ 6 per sheet.

David Davis