Thanks ...
Thanks very much for the quick comeback. Both Lewmar and Bomar are shown in my Defender catalog and Lewmar makes hatches that may fit. Problem is, I just don't trust myself to measure super-accurately, and then there is the question of the radiused corners. I'm hoping someone has already been down this road and can cite, from actual experience, model numbers of hatches that worked. Failing that, I may try mailing templates made from the existing holes to Defender. They've always proven to be very customer friendly folks. Unlike H-R, which I have tried (a couple of times) to contact via email, but from whom I have yet to receive a response (maybe b/c I don't speak Swedish).