Thanks Larry, that wasn't even on my radar. I didn't realize those things would be issues. A dorade box and vent would not be a practical alternative on this boat because of all the clutter on the cabin top. Three lines per side plus rope clutches and winches, and the cabin top jib car tracks.

When I replaced the hatch boards on the Islander I added two round SS louvered vents in one of the top most boards, perhaps that would work on the middle hatch board on this boat as well. That would give a source if air in/out?