[mitiempo]

If your hatches do not have ribs across the area where the glass goes, they are not "offshore" hatches and need to be replaced. Hatch 2 is an "offshore" hatch, hatch 1 is not.

Bomar is the only company I know of that uses cross bars on their hatches. They are there to keep the Lexan from flexing and breaking the seal - they don't use 1/2" Lexan. Every other hatch manufacturer I know of uses acrylic of a suitable thickness and many are "offshore capable" hatches. Lewmar Ocean series for example.