I have a couple of very old Bomar
hatches on Boracay.
Assuming you mean the soft rubber seal that goes on the upper (moving) part I replaced mine with a "suitable" automotive strip of "e" section foam rubber.
It just slides into place (with only a little all round persuasion). I trimmed to slightly oversize with scissors after all but the last bits were in place, then pushed the ends into place. No glue.
Seems to work fine.