Installation of Aluminum Fuel Tanks

[Mike Sibley]

I am replacing the 46-gallon fuel tank on my 1979 Pearson 365 with two smaller tanks and have a question about the installation of the new tanks.

In an article on how to install aluminum fuel tanks, David Pascoe indicates that two inch strips of Haysite (or other fiber reinforced plastic sheet) should be attached to the bottom of the tanks with 3M 5200 so as to separate the tanks from the supporting platform, thus allowing the circulation of air and the prevention of crevice corrosion.

My problem is that I can’t find a local source of Haysite. Is there another material that will work? King Starboard is a thought, but 5200 won’t stick to it, which appears to be important. Does anyone have any expert advice on the installation of aluminum tanks?

[CaptG]

I replaced my aluminum tanks 1 year ago which had corroded at the point of contact with fiberglass thus trapping moisture. I used 1/4 inch thick by 3 inch wide neoprene rubber strips and 5200. It seems to be working great.

[Mike Sibley]

I guess another alternative is to coat the bottom of the tanks with epoxy, but I have heard both pros and cons of this approach. If I were going to have this done at a good boat yard, how would they do it?

[bobfnbw]

Mike I used 2x2 inch by 60" long strips of HDPE from mcmaster carr. I did not try to glue it but just sat it down in the bilge. The tank I coated with marine tex epoxy and then painted with interlux bilgekote. I believe it would have worked out ok as the weight of the tank with fuel would have kept things down, but before I could finish the installation, the boat sank, the tank filled with sea water and everything got messed up.
I plan on having a new tank built, and painting it with bilgekote. and using the same strips of HDPE to keep the bottom of the tank off the bilge floor. My tank sits in bilge water so its a big problem. I put in a small diaphram pump to try to keep the water level lower than the tank.
Far as I know this stuff can't be glued with any reliability.
Hope this helps.
Bob
McMaster-Carr

[thinwater]

Originally Posted by bobfnbw

Mike I used 2x2 inch by 60" long strips of HDPE from mcmaster carr. I did not try to glue it but just sat it down in the bilge. The tank I coated with marine tex epoxy and then painted with interlux bilgekote. I believe it would have worked out ok as the weight of the tank with fuel would have kept things down, but before I could finish the installation, the boat sank, the tank filled with sea water and everything got messed up.
I plan on having a new tank built, and painting it with bilgekote. and using the same strips of HDPE to keep the bottom of the tank off the bilge floor. My tank sits in bilge water so its a big problem. I put in a small diaphram pump to try to keep the water level lower than the tank.
Far as I know this stuff can't be glued with any reliability.
Hope this helps.
Bob
McMaster-Carr

Those materials can be glued with 5200.

I would hesitate to coat the outside of the tank, as any failures will cause localized and accelerated attack. I have seen this MANY times, specifically in coastal areas, in my work as an API oil tank inspector.

I am curious why internal tank linings are not common, as they are VERY common in industrial oil and gasoline tanks and have proven to be very cost effective and reliable.