Aluminum boat with copper paint problems

Q. I have recently purchased a used 16 foot aluminum boat. It had previously had the bottom painted with a copper-based paint. Now, under the barnacles, there is oxidation and corrosion. The hull does not leak and the rivets appear solid. What must I do to ensure longevity and integrity with this bottom?

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A. The first thing you need to do is get the copper off there because it causes galvanic corrosion. Copper-based bottom paint is used as a biocide to deter marine build-up, it is not a corrosion inhibitor. It is only appropriate for use on plastic. It is probably impractical to test the hull integrity of a small boat like this, but a marine surveyor could look at it to make you more comfortable.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.

Q. What do you suggest I use to remove the copper paint on my aluminum boat. There are no real signs of corrosion yet. I also want to remove the paint over anodized on the sides of the boat. It is a classic FeatherCraft I have begun to restore.

Hi. When you folks speak of "copper paint", I'm assuming you mean ablative bottom paint that has copper in it, rather than copper colored paint. I imagine that it can be removed either with Aircraft Stripper or by abrasive blasting. But as far as I know, bottom paint is a hazardous material, so the blasting service may need to do something about containment. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.

Q. I am currently restoring an aluminum hull boat I have DA sanded it completely with 80 grit paper and a stainless steel wire wheel. I am applying PPG DP-40 zinc dust ⇦ on eBay or Amazon [affil link] . Zinc chromate is labeled "For Professional Use" because of the toxicity of chromates.

Regards,