Is there a better way to install an aluminum fuel tank than foaming it in place?

google marine fuel tank david pascoe. he has a very good write-up. apparently the neoprene foam i used on my moeller polyethylene tanks is also not such a good idea for aluminum. he glues hard plastic strips to the tank bottom with 5200 so air can get under tank and water can drain out.

fixx
 

not only that the foam acts as a cushion to support the bottom of the tanks to keep them from splitting,,the bottom of the fuel tanks need the support when your going over waves,the pounding will knock the tank loose with all the fuel sloshing around inside them..

The coal tar is used to coat the tanks in case you get any water around the tank in the foam. It acts as a barrier coat. Obviously there are arguments for and against foaming in fuel tanks, and obviously it has been done for years, sometimes with failures, sometimes without.

I personally foamed in my fuel tank when I rebuilt my boat, but I also made a few changes to the original design of the fuel tank cavity. The key to keeping water out of the foam, is keeping water out of the fuel tank cavity.

1) The area where my fuel tank is, is completely sealed off from the bilge area and cabin. Not even a drain tube from the cabin back to the bilge. I did this for two reasons, 1) if my tank should leak the fuel will be contained in this area, not in the bilge, 2) no bilge water can get into the fuel tank cavity. I also sealed around the fuel cavity access panel to keep water from getting in. I have pulled the access hatches after getting caught in the rain and have yet to see any water in there.

2) I made fiberglass strips to lift the fuel tank off of the bottom of the hull prior to foaming in. I dont' recall the exact size but around 12"x3" and a 1/2 thick. I put them at the ends of the tank and wherever there was a baffle for support and to allow the foam to get underneath the tank, 10 total, 5 on each side.

My tank was originally screwed into the stringers and had 6 mounting plates, 3 on each side (100 gallon tank). When I removed the tank, 3 of the plates were broken off at the welds from hull flex.

Personally, I like the way Superboat foams in the tanks and then fiberglasses them in. I wish I would have done that myself but I had already gel coated my fuel tank cavity and painted my tank with Por 15. If I were to do it again, that is exactly how I would do it.

How many Superboats have you heard of with failed fuel tanks? :D

Here are some pics of my fuel tank cavity...

http://www.offshoreonly.com/forums/3095069-post83.html

Install photos. I left the straps around the tank, just in case I do ever have to pull it again: