The forward deck hatch on our project boat, Keywaydin, a 1967 Allied Seabreeze, did not let much light into our dark and dingy forepeak. There was no mechanism to hold the molded fiberglass hatch open, and it was hard to adequately secure from the inside. We decided to replace it with a new waterproof hatch.
The Vetus hatch we chose was slightly larger than the original hatch, which meant we needed to rework the opening in the deck to accommodate it. To accomplish this we decided to remove the original interior wooden hatch frame and build a new mahogany frame that would fit on top of the opening’s fiberglass lip and form a base on which we could mount the new hatch.
To create the new frame, I first made templates of each side of the frame out of poster board. Once I was happy with the fit, I cut out the four pieces slightly oversize. The next step was to figure out at what angle each piece joined the other. While the joints were simply end-grain to face-grain, the corners were not square and the flange was out of plumb, creating a compound miter. I made a few different corner joints out of scrap wood before I was satisfied with the fit. Once the correct angles were cut on the final boards, I used dowels and West System epoxy to secure the joints.
One of the biggest issues was the fact that the hatch opening was curved in its vertical plane so as to follow the camber of the cabin coachroof. The new hatch, however, was flat. To accommodate it, I made the new hatch frame deep enough so that it could sit flush with the highest point of the cambered raised flange on the coachroof while still following the curve on the interior. This created a gap the width of the fiberglass laminate and about 3/4 in high at the corners.
In hindsight, it would have been much easier to borrow a reciprocating saw and trim the original flange flat. Instead, I made filler blocks, planed these to fit the curve, and trimmed the whole top edge with 3/8 in x 1 3/8 in wide strips to create a flat surface. This was then routed out to create a rabbet for the hatch to sit in.
