Hi Rick, and the whole M gathering, Years ago I found a great "How To" book that is a bible if you want to make / alter / add to your vessels. The title is: Practical Yacht Joinery Fred P. Bingham Published by; International Marine Publishing Camden, Maine ISBN 0-087742-140-4 Starting on page 220 he goes into the problems of building and fitting hatches, giving you several methods. It may be out of print, but perhaps AMAZON might find a copy for you. Connie