Aluminum Anodes

Google "aluminum anodes," read articles that show up, including stuff by experts like Steve D'Antonio. Why aren't we all using aluminum anodes? Caution: when changing them out, change all the ones in the same bonding system.

Good question. Cost maybe?

It shouldn't be cost. We changed to Al and the cost was within $20 for the 3 anodes on Hobo and they last longer. Right now were in brackish water but we'll stay with Al and monitor when we go back to salt. Here's a source and a brief discussion. Scroll down to question T7 and open the two PDF tables. BoatZincs.com Frequently Asked Questions

They cost about the same. An interesting disadvantage from someone who said they didn't think they last as long as zinc. That may be because when the zinc gets into fresh or brackish water it developes some coating which makes them ineffective, so they might last forever. So would a piece of plastic, but it may not protect the boat. I can't see any reason to have zinc anodes at all. (Supposedly the ones in the engine and genes are in a different "lake," bonding wise, and don't need to be changed at the same time as the others.

Sitting in fresh water I know aluminum is the preferred material for anodes on my shaft and rudders... In fact, I just replaced them this month... (though the discussion on not lasting as long could also be a result of sitting in a "hot" marina with lots of stray charge around you eating them away faster)

but does the same go for the engine and generator anodes? Aluminum there too?

Coming up time to inspect and replace, so got to thinking about it.

I put aluminum anodes on my boat last year but haven't hauled again and don't know what shape they are in. Problem is finding aluminum shaft anodes. Haven't found any yet.

tmiller1116 said:

Sitting in fresh water I know aluminum is the preferred material for anodes on my shaft and rudders...

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Nope.

hmmm, and yet nobody in this area recommends Mg.

I'm not sure the Al vs Mg in fresh water is a yes/no or will/won't work type of answer. Mg is probably the best for fresh but quality Al will work from what I can tell. There are a lot of opinions out there and here are a couple.

This is from Performance Metals web site.

Anode FAQs

and this is from Martyr's web site. http://www.martyranodes.com/content/martyr-products-services/pleasurecraft-anodes/Mag.php

The common anode for fresh water is magnesium. Aluminum is a good "catch all" anode meaning a boat that frequents both fresh and salt has decent protection in either environment. The quality of the anode and the purity of the aluminum or magnesium is also important. On this topic, experience (water type, boat location) is your best reference.
John Adey | Technical Director | ABYC Master Technician

Interesting, considering the graphic I posted is also from the Martyr web site.

Xsbank said:

I put aluminum anodes on my boat last year but haven't hauled again and don't know what shape they are in. Problem is finding aluminum shaft anodes. Haven't found any yet.

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Try zincwarehouse.com.

mike66 said:

Try zincwarehouse.com.

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BoatZincs.com (978-841-9978) – The Online Superstore for Zinc Anodes

Engine anodes are available in Aluminum, but don't have to be replaced at the same time, as they are in a different "lake."

jjanacek said:

Engine anodes are available in Aluminum, but don't have to be replaced at the same time, as they are in a different "lake."

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Do you have a source for the engine pencil anodes in Al? I can only find Mg or Zn.

Performance metal. they also have a tech bulletin about why we should all be using them.

Thanks

Just replaced all my anodes with Performance Metal Anodes including the hull and prop shaft. I purchased them through Go2Marine. It will be interesting to sea how they hold up. The boat will be in freashwater.

Larry M said:

Do you have a source for the engine pencil anodes in Al?...

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jjanacek said:

Performance metal...

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The heat exchanger anode was the last for all Aluminum. Thanks jjanacek.

I do like that there is a central core. They advertise that it prevents the end from breaking off. Historically when I change the heat exchanger zinc, I find pieces on the face. We'll see.

Below is the zinc with the brass head and the Al with the SS head. Less than $5 each.

Probably a stupid question, however...

Is using Al anodes for the heat exchangers/oil coolers but zinc for shaft etc anodes ok or should all anodes on the boat be the same material?

I ask because I've just fitted a fresh water flush system and only just found out the zinc anodes won't work in the exchangers once fresh water is in there.

Should be okay to use different anodes; they wouldn't be working to protect the same metals. I can't see the problem of mixing them on the same metal either, the zinc and Al would be eaten away at different rates, but both would still be protecting the SS or bronze until they are used up.

Martyr, a manufacturer, says not to mix:

http://www.martyranodes.com/content/martyr-resources/Aluminum Anodes.pdf

​

Don’t Mix Anode Types[FONT=Garamond,Garamond][FONT=Garamond,Garamond]. If you install different anode materials like zinc and aluminum, the more active anode (aluminum) will spend part of its effort protecting the less active metal (zinc). This will reduce the overall protection that you are getting. A classic mistake is adding a zinc transom anode to a Sterndrive equipped with aluminum anodes. Transom anodes are connected through the bonding system so make sure you install aluminum replacements. [/FONT][/FONT]
[FONT=Garamond,Garamond][FONT=Garamond,Garamond][/FONT][/FONT]

Hmm.. gets confusing after digesting the graphic Fstbttms posted.



As my raw water system will be full of fresh now (since installing the fresh water flush system) - it would seem that neither zinc nor Al anodes will be effective in the heat exchanger and oil cooler. Seems Mg is the ones I shold be using. Of course, they will be no good when the boat is in use - but effective whislt it sits in it's berth (which is the majority of the time - even during our most active boating months).

So do I just use the Al (just in the raw water system OR all over), keep the Zn or go for Mg?

What to do? Opinions?

Bloody hell - you think you solve one issue, just to find an even more complicated decision.

Opinions?

THERE'S REALLY NO POINT IN USING ZINC ANYMORE FOR EITHER, NOW THAT ALUMINUM IS AVAILABLE. Sorry about caps. West Marine still doesn't carry them in the stores, but recommends using them. Most boaters still use zinc because their forefathers came across the Atlantic with them on their paddles and see no reason to change.

I remember reading that if you use Al anodes, they need to ALL be swapped. Don't recall the specifics, but I can try and look it up.

Shufti, Al should be fine because you really don't need much protection once the HE has been flushed and full of fresh water. If there is still brackish water in there you will be protected. Zn will get messed up unless in salt water.

Thanks guys for the responses. I also got a response from Tony Athens at boat diesel saying to not worry about it and stick with zinc.

As I've just put the boat back in the water last week with all new Zn anodes (just days before reading all about these Aliminium anodes which I'd never even heard of before), I'll stick with the Zn for now, and change to Al when I do the next bum clean.

In salt water, what is the advantage of using Al over Zn. How about those with steel vessels where the builder insists on Zn. How about those with engine, hydraulic and cooling system Al pieces where the builder insists on Zn.

Lots going on here and not wise to assume one hat fits all, possibly damaging in fact.

FYI: Here's an Al heat exchanger anode from our FL SP135 after 185 hours and 4 plus months. I like that the anode has a wire through the center so when it's removed, it doesn't break off. I Know could go to a smaller diameter anode but now that we are 100% Al why not use the specified size?

I did pull the cover to see what was there. Some debris but it not require cleaning the face of the tubes but I will probably do it every other anode change to be safe.

jjanacek said:

because their forefathers came across the Atlantic with them on their paddles

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I know this is a somber subject, but.... hahahahahahahahahahaha... :lol:

Greetings,
With regards to the chart in post #22...I didn't realize the sacrificial anodes were alloys. Just what alloys are they and how much of the "active" ingredient do they contain? Could one machine an aluminum anode out of rod stock?