I had to go to a ACE hardware b/c HD had nothing usable. Since then, I have found it at automotive stores and even Wal-Mart.

I went with the 3/8 X 1/8 for the layup and 3/8 X 1/4 for the seal. It worked fine. The hatch protruded for a few days, then set flush as the foam compressed.

The foam was for "windows, doors, and automotive" use. Not really sure if high or low density. Have played much in waves and wet exiting with no more than a few drops in either hatch and I think that was due to a gap that formed b/c of poor gasket installation. Have since fixed it and have not had problems with leakage.

Hope this helps, and good luck.

Brian