Hello, I recently had to cut a hole in our 1991 Hunter 28 aft bulkhead to change out a corroded holding tank. I how have the new tank in, but was advised by a marine woodworker that the hole (1.5 ft by 2.5 ft)can not be plugged by screwing in a finished piece of marine plywood without using some sort of glue or fiberglass. He said that the flexing would work out the screws. Since there is limited access throught cockpit lockers, and the forward side of the bulkhead was finished with mellamine (which Tap Plastics said nothing sticks to it), I am not sure the best way to proceed. The bulkhead is 1/2 inch marine plywood. What say any of you who have done this before? Gary Scheier "Serenisea"