Can't put it off another day.... to misquote the Chambers Bros. song. I ran out of other things to work on so I finally had to come to grips with whacking a big hole in the deck of my boat. First, the screws and shims that had held the hatch frames in place were removed. Then holes were drilled from underneath at the corners of the hatches to define the margins. Once underway, it seemed like no big deal. The first picture shows the hatch frames put in place before the subdeck and cover planks.Update: The last picture shows primary latch installed. The latch plate will need to be extended since the latch location is too far away from the margin due to not wanting to interfere with perimeter banding.
After finding the corners, I blue taped over the margin areas and drew the margin lines with the aid of a yard stick. With a sabre saw, I cut just the hinge margins, cut the hinges to length and mounted the hinges. Then the remaining fore and aft margins were cut to remove the hatch in one piece.
After cleaning up the edges on the hatch and hatch opening, support pieces were made to support the hatches when closed. These pieces were screwed in place on the boat. Then the hatch center margin was cut on the table saw and back to the boat to install the hinges again.
The center margin and underlying supports were trimmed with a bevel to provide swing clearance when opening.
Secondary latch catches were installed on the underneath side of one hatch and then the perimeter banding was cut and installed.
I still have the primary latch/handle that needs to be installed.