Brent. A separate gasket ( rubber?) may not give you a good enough seal if you ever leave the sub at the dock, even for a short period. It looks in the pictures like the RTV has held up well considering it's age. I'd be careful about maintaining a good seal at that point. Always thought it would be better to have complete envelope tanks attached so a leak can't occur. My tanks, although a different shape, are separate complete tanks bolted on. I will be able to crash into stuff without fear of losing the ability to rise. They are made of 12 gage stainless, and will get a huge dent long before they fail. Frank D.