Provides an excellent "temporary" seal for a cast aluminum boat hatch.  The seal is between the boat and the deck. I use a standard hatch seal for the opening part.  I have used a similar arrangement before and found the seal lasted for more than nine years (under demanding conditions), and would have lasted longer if I had not removed the hatch for repainting. However, I would not use the 9/16 foam tape for a plastic hatch or port-light as there is a good chance of distorting the flanges when it is screwed down, thus causing them to crack.