Hatching out a project
There is a decent set of pictures of making a homebrew seahood in Spurr's Boatbook, pages 171 thru 175. Seven Seas Press, 1983.
Nowadays, I would start with a perfect mockup in MDF and putty filler, and make a female mold from it, and then lay up the hatch.
If it looked decent, make some more of 'em on a break-even basis for other owners, maybe...
Note that any good OEM boatyard (lucky us, we have two in Portland!) could do this project in a day or three in balsa or honeycomb coring, and the cost would be resonable albeit not cheap.
Write me privately and I can give you the email addy of the former E27 owner that built a new wood hatch, and perhaps he could pass along some pointers to start you out... he has a fairly complete wood shop at home, BTW. He's still kind of an Ericson guy in his heart.