To foam or not to foam

[pelican]

Originally Posted by Bushwacker

Shipshape TV is about the LAST resource I would consult on any serious boat work, especially installing a gas tank! Griviskis appears to only know what his sponsors tell him, and I'm not sure he even understands that. Foaming in a gas tank is about the worst way to install it! It allows water to be held in contact with aluminum, causing crevice corrosion. I think most boat builders do it because it's cheap and easy! Even Potter did it on his later models, but Carl Moesly never did. It cost him more because then he had to ventilate the bilge, but he knew that was the right way to do it! Although I've removed my tank a couple times to inspect it, I'm still running the original 1972 tank, which was not foamed in!

Dave Pasco wrote an excellent article on How to Install an Aluminum Fuel Tank that explains the process in great detail. About the only thing I'd add is that I'd paint the tank with an etching epoxy primer and maybe some coal tar epoxy first.

you're quite correct !

ventilation is the key

chemically etch priming ANY aluminum surface,before coating - that's required.