I can't seem to figure out the reason for these hatches. In the photo, it's on the deck behind the captain's chair. There is another behind the other co-pilot chair.
Any ideas?
If nothing else, they give you access to fasteners for the seats, as well as any wiring and plumbing that may run through the area. Have you opened them?
I'm not near the boat so I can't take a picture of the inside (the photo is from online), but there isn't much room. Looks like channels for water to run, but not sure why they are there.