Aluminum boat with copper paint problems

2004

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?

Tom Anderson
teacher - Burlington, Washington

affil. link
Marine Aluminum Restorer and Polish

2004

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.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

2005

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.

Roger Heidt
- Belleville, ON, Canada

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.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

2007

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 chromate primer over all. I am then applying epoxy sandable surfacer,then a 3 stage urethane topcoat. I have used it over the years on all bare metal surfaces. It comes in several colors and has never failed me.

Shaun Ramirez
- Clackamas, Oregon

March 30, 2009

Where can I buy PPG-DP-40. Shaun, tell me where I can buy everything that I need to paint my boat? Thank you.

Russ

Russ Hanson
- Belvidere Illinois

November 19, 2009

Hi, Russ. I don't know about the PPG brand, but Awlgrip [affil. link to info/product on Amazon] offers zinc chromate primer. Zinc chromate is labeled "For Professional Use" because of the toxicity of chromates.

Regards,

Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

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