Coating Aluminum Fuel Tanks

I did a quick 'search' and couldn't find anything on the topic so I'll ask the question.
I have the fuel tanks out of Scout and am getting ready to coat them with coal tar epoxy before re-installing. The coal tar epoxy is my choice at the moment but I've been reading about Gluvit and the idea of fiberglassing over.
Tanks are aluminum,*5 years old (installed by PO when the re power was done)*and in great shape. They were painted when new (paint unknown) but it's starting to flake off in a few areas.
Any thoughts on this?
Also looking for something to 'bed' the tanks with where they sit on the fiberglass shelf. I think there was some kind of rubber strips under them when I removed them but it had deteriorated in 5 years.
Thanks
Chip

Why do you feel*the need*to coat them with something?

Prevent further corrosion in the weld joints and bi-metal contact. Condensation. Cosmetics.
Is there a good reason not to?

Anode wrote:
Also looking for something to 'bed' the tanks with where they sit on the fiberglass shelf. I think there was some kind of rubber strips under them

Click to expand...

I did mine with a two part polyester foam.* That was because I didn't know any better. It was what was done when the boat was built.
Now I think I would leave a space under them to allow water to drain. Perhaps some plastic strips. The biggest thing is I didn't want them to move. The foam expands and locked them into place.

SD

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2" Neoprene strips spaced evenly the long way. Any rubber without carbon is ok, but neoprene is best.

I think the industry has gone to the idea that aluminum fuel tanks should be unpainted and mounted in such a way that air can circulate around them. Sitting the tanks on neoprene (solid, not foam) strips that allow air to circulate under the tank sounds like a good idea. I would think you could use strips of Starboard or anything like that as well. Just as long as it won't absorb water. The old practice of foaming tanks in place would cause tanks to fail in less than ten years.

neoprene strips must be*fixed*and sealed around perimeter,*to underside of tanks , any condensation , moisture*between neoprene* and alluminium* will cause oxidisation or pitting* , seen it eat bottom of tank sitting on rubber mat .

cheers danny

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i knew id saved this* hope it helps anode

http://marinesurvey.com/yacht/fueltank.htm

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cheers danny

The old practice of foaming tanks in place would cause tanks to fail in less than ten years.

Foam in place is good practice for those who select PLASTIC tanks , after the tanks have been filled and left to expand a few days.

We service mostly aluminum fuel tanks and fine that the drier they are the better they are. Some are coated with fiberglass and they tend to harbor miosture. Then those that are painted also harbor moisture between the paint and the tank. When called upon to service a tank that is approaching twenty years of age, we normally look for foam. But here lately some tanks are failing before the tenth year. The chemical reaction between the aluminum, salt water, the foam and usually gasoline is very critical. Not to many diesel tanks foamed in, most are either of fiberglass or alumimum. The failures we see in aluminum tank is almost always from the outside and from moisture.

The tank problem is in the process of ending.

No MONEL hasn't suddenly become cheap, but Titanium has.

The tank mfg will need some new gear for welding , but then "forever" tanks will be on sale again , without the Monel price tag.

We had the fuel tanks replaced*on our last boat.* They had rusted thru* from water sitting under them.* The new aluminum fuel tanks were coated with epoxy prior to installation.* Sea View East in Seattle made and installed the tanks.* I asked about the epoxy and they said it was to protect the exterior from*corrosion.* 14 years later,*the tanks looked good and had never leaked.* The bottoms were mostly opened for drainage.*The sides where glassed to the hull to prevent movement.

Yo Danny! Thanks for the link. It was exactly what I was looking for.

I'm looking to build a "house" around the Still Sibsie and shrinkwrap it. Where did you get yours and what is it made of?

Steve

Hey Steve! I almost missed this. My building is a 'Shelter Logic' building I ordered off the internet and had shipped in. It's a steel tube frame and tube purlins. The cover is a vinyl covered fabric that has held up pretty well for the last 3+ years. It has been the best thing I did for the refit/rebuild. No way it would have happened w/o being under cover.

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Steve,

I bought plans from Stimson Marine around 2000 and built my own. It was 20' wide, 44' long. I forget how tall but my 37' flybridge sedan fit in it. Wish I took some pictures. It was not hard to do and the price was very reasonable.

http://www.by-the-sea.com/stimsonmarine/bowroof.html

Rob

37' Sedan

Chip and Rob...thanks very much for the info. I love this site...lol!

Steve