CONTINUOUSWAVE

In believe the original fuel tank in my 1998 17 Outrage II has a leak (or several leaks). One is at the outer rear port side, side and bottom of corner. I had a new tank fabricated by Alloy Metal Works in Farmingdale, New York.. They were super easy to deal with, had the OEM drawings, and gave great service.

Before the new tank goes in, I'm trying to decide if the newly fabricated fuel tank should be left raw [metal of some unspecified metal, but most likely aluminum of some unspecified alloy].

Q1: should the new metal fuel tank I just had custom fabricated [from some unspecified metal of unspecified composition] be install as-is or some [unspecified] coating applied to it before installation?

Online [many various] opinions can be fiund. The folks at Alloy Metal Works don't do coatings. Their opinion seemed to be that if anything is wrong with the coating, it will trap moisture and accelerate corrosion.

Other people swear by a coating which seems to range from epoxy bottom paint to coal tar epoxy.

Alloy Metal Works said if it gets coated, use an etching primer, possibly zinc chromate.

I'm not doing the installation.

The shop says they will coat it if I want and are waiting on direction from me. The boat is trailered and covered.

The fuel tank that was removed appeared to have a coating on it, and a few spots it had bubbles. The coating was not on the area that leaked, although that may be due to scraping while searching for the leak.

You do not mention what metal was used in fabrication of the new tank.

If aluminum was used you should mention the alloy.

Coating aluminum with a corrosion-resistant sprayed-on paint is common. The color is usually green. Zinc-chromate was often used in the past. Today to find zinc-chromate paint at a retail store may be difficult, apparently due to toxicity. Zinc-phosphate paint may be easier to find.

I do not know what paint Florida Marine Tanks would typically use. If your new tank is aluminum, you could call them and ask what they use.

The aluminum fuel tank in my 1990 Boston Whaler boat was made by Florida Marine Tanks and it has a greenish coating.

ASIDE
In World War II the B29 Super-fortress bomber exterior aluminum skin was left unpainted. An old story attributes that decision to General Curtis LeMay, who found out the paint would add 500-lbs to the weight of the aircraft. He said to skip the paint and he could carry one more 500-lbs bomb on every raid. Of course, the planes only had to last until the end of the war, so corrosion was probably not a big concern.

ALSO
On any internet forum, a thread that is longer than two or three posts will have diametrically opposing opinions. A thread longer than ten posts will have virulent ad hominem attacks, and likely use the term Nazi. This same practice continues today in modern politics, but only needs two posts to reach the same level of rhetorical excess.

Thank you for the reply. The tank was fabricated from 1/8-inch aluminum plate of 5052 alloy.

My old tank had that same [greenish] color coating. Parts of that coating were bubbled up and peeling. I don't know if that means much after more than 26 years.

The “coating” I am describing on my boat’s Florida Marine Tank OEM fuel tank is just a light, sprayed-on layer of paint. I have never seen any evidence of the paint peeling off. The paint appears to remain well bonded to the aluminum, as it is an etching-type paint. The paint is not a separate layer of its own that could bubble or peel away from the aluminum plate of the fuel tank. In order to remove the etched-on, green, zinc-phosphate primer paint you would have to use abrasion to remove it. You could not grab it and “peel” the paint off the aluminum.