Help! I have a '77, 42' Bertram. I need advice on the proper method on sealing the large fiberglass access cover on the exterior top of the salon. Was there originally a preformed gasket that was attached to the edge of the cover? Right now it is caulked in place with Lifeseal and held down with SS screws. We have traced down all leaks and want to prevent new leaks from damaging new headliner and curtains.