[h37skipper]

Do not understand your comment about "offshore". I installed them exactly for that reason. These are heavy duty, bolt-through portlights with safety glass. And they look great. I installed six 7x14''s and four 5x12''s.

If installed and maintained properly they do not leak. The two dogs and two hinges are both adjustable to get a tight seal. Whenever I close one I run a damp cloth over the rubber seal and frame. It is a compression seal and dirt will allow leakage.

The downsides are: 1) expense, 2) difficult to install properly(write for detail), 3) require a hanging chain to keep open, and 4) they do not drain. This is a problem for me because of the sloping cabinsides. I sponge out the ones I plan to open when I arrive at the boat.