Ralph, I have just been in the dungeon to disconnect the batteries for the winter lay-up. I confirm that it is a gesket and not a sealant. Seabuilt makes different sizes and I went with the 10'' to make access easier. When I installed the sender for the Wema fuel gauge the cover seemed like a natural place to put it. And it was easy to remove so I could drill the access hole right in the center of it. Wiring is long enough that I can easily put the cover aside without disconnecting when needing to clean the tank.
