Zinc or copper

Just came from a "chewing the fat" session with a group of guys down at our boat club. There was a lot of talk re copper anodes. Seems that now that much of the anti fouling is copper based, it doesn`t sit well with zinc. Guys gave their experience of getting rid of all their hull and shaft zincs and putting one copper strip on the transom, in place of a normal zinc - guys are claiming its a better invention than sliced bread - no barnacles/growth on any metal parts after a year or so. Earthed to the engine.

Anyone with any knowledge of this?

No. Zincs are used as sacrifices to avoid electronic erosion. Copper is nearly ideal for avoiding marine growth. If correct, I'm wondering about the boating knowledge of your club members. Are we talking saltwater?

Mark - No I dont have any knowledge of this or No I disagree?
Definitely salt - and lots of collective boating boating knowledge amongst them.

Brisyboy said:

Mark - No I dont have any knowledge of this or No I disagree?
Definitely salt - and lots of collective boating boating knowledge amongst them.

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Where did they get that collective wisdom?

Sitting around the dock discussing things?

Or are there some professional maintainers and drivers in the bunch?

I usually feel pretty up on new boating tech for smaller vessels and haven't heard of copper anodes.

I may be all wet but I think they are flirting with disaster, especially in saltwater.

Maybe the copper will reduce fouling but copper will also promote corrosion of the underwater metals such as S.S., maybe even somewhat less noble metals such as some 'bronzes'.

Copper is more noble than most metals meaning those other metals will corrode to protect the copper.

That is why zincs or aluminum anodes in some cases, are used. The anode, zinc/alum., corrodes instead of the very expensive metals.

These guys would seem to have reversed the process at the possible expense of the hardware.

Thanks C Lectric - the discussion started after a comment about electronic growth control - dangling electrodes over the side - worried a few people and the ultrasonic systems which are installed internally.

The copper discussion included the idea re noble metals and how logically it shouldn`t work but there were guys there that had converted to it and reckoned it worked. They did admit though that they didn`t understand how it worked.

Thus my question. After the comments re my friends I`m sorry I mentioned them, rather than just ask the question.

George-seems we are talking about two different things. First, whether copper prevents growth, it does. That is no secret, hence the copper in the paint. But, as far as I am aware, it is the direct contact with copper that prevents growth. Copper release copper ions that are antimicrobial and algeacidal and prevent attachment to hulls. Thus the need for direct contact. From your comment, it appears that the underwater metal parts are not connected in any way to the copper on the hull. Even if they were grounded to the copper plate, I can't see where that could possibly have any effect. If there were an effect, with a connection, it would seem it would almost have to be electrical. That is, the immersion of the copper plate in salt water is creating a small current that keeps bad things from attaching. that is the only explanation I can see.

The second issue is the corrosion issue. Again, here I think whether or not the metal parts are connected to the copper plate would be important. No secret that current flows to the lesser noble metal, in this case, the matel parts. That would seem to me to accelerate, not retard any corrosion issues with those parts. If there is no connection, again I cannot see how the copper plate could have any effect. It should be not different than simply not having zincs on the metal parts.

Not sure if any of this makes any sense, I am not an electrician or corrosion person, but it just seems logical to me.

Brisboy....your friends are no different than dock talk anywhere else.

The reason I brought up having someone I the group being in the boating biz is because I thought I knew a lot being an active boater for 40 years, even living aboard for 6 of them.

Well....the first year I was working in a marina, I learned more good stuff, and more current stuff than in the previous 40 years of recreational boating...and I was a pretty rabid learner. Plus, I learned just how many old wives tales were out there and how many got started all the time. Many as simple as someone would learn something worked in one situation (like cayenne pepper in bottom paint) and would swear by it in other situations that were different enough that event the worst bottom paint was good enough.

This copper discussion sounds like the classic transfer of an idea...where something that works for one task, apparently worked for something else, and now it is proof that it's a good idea (revalation). Yet no writings in the marine industry or offerings from companies that specialize in sacrificial anodes? If there are, forgive my ignorance and please post a link. I truly want to catch up in this possibility.

Copper won't work as well as zinc to protect your boat's metal parts. There are any number of good articles on the net and good books to explain corrosion. The image below comes from

Metal Parts for Boats

The chart is easy to use. Metals above and to the right of a given metal, in this discussion copper, will be protected. Metals below and to the left will be sacrificed.

History shows others that have tried to take advantage of the anti-fouling properties of copper... just sayin'

"Over 200 years ago, the British naval frigate Alarm recorded the effects of galvanic corrosion on its hull, which had been plated with copper sheets to prevent damage.

Just two years after attaching the copper sheets, the iron nails that were used to hold the copper to the ship's underside were already severely corroded, causing the copper sheets to fall off.

In this case, two metals of different nobility (copper and iron), immersed in an electrolyte (sea water), created an electrolytic, or galvanic, cell."

This is apparently from ABYC.

dimer2 said:

This is apparently from ABYC.

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Not quite, its an ad' from Performance Metals, anode manufacturers.

Thanks guys for your contributions so far.
Check out this web site:

Kleenhull Antifouling Anode System

Interesting....never head or read about it in the 18 years of their testing.

It is also more than "using copper anodes"....

What, I am not sure of but will wait for the current industry of zinc anode providers to dispute or validate this new tech.

Brisyboy said:

Thanks guys for your contributions so far.
Check out this web site:

Kleenhull Antifouling Anode System

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Went through their whole site and am still not sure what they are selling. The first hint of snake oil is their incorrect use of the term "electrolysis" among other terms. they don't appear to have a scientific grounding in the subject.

Smells like a smoke, mirrors, BS and snake oil stew akin to the Algae-X magnet or Dr. Ho's copper bracelet.

boatpoker said:

Went through their whole site and am still not sure what they are selling. The first hint of snake oil is their incorrect use of the term "electrolysis" among other terms. they don't appear to have a scientific grounding in the subject.

Smells like a smoke, mirrors, BS and snake oil stew akin to the Algae-X magnet or Dr. Ho's copper bracelet.

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True breakthroughs usually get some press...this didn't so I agree that it smells like snake oil.

But I' ll keep an open mind for a bit longer.....