Is anyone using aluminum anodes?

Hi,
I am wondering if anyone has switched from zinc anodes to aluminum anodes on the prop shaft in salt water. My reading so far indicates that aluminum anodes should last about half again as long as zincs and protect just as well or better than zinc anodes, with no apparent disadvantages. I don't know if there is a significant cost difference. Can anyone shed light on this?
Thanks,
Frank

Pure Aluminum actualy works better

Puts less toxins in the water too.

Used them for a while on my Maxprop, when maxprop folks were making them. Can't get them anymore. They were a little more expensive when you could.

Hard to come by though as they don't seem to be accepted by most boaters, we are a traditional lot.

Guy

Thanks, Guy!
Yeah, it's interesting that all the reports I read about the aluminum anodes described them as more effective and longer lasting than zinc anodes, lighter weight on the prop shaft, and less polluting than zincs, and yet they haven't become popular. I wonder if it's just a matter of time, or whether zinc anodes will remain the norm.
Frank

Zinc's days are numbered

There are quite a few states, Washington among them that have a schedule to phase out all consumable heavy metals off of the bottom of boats, this includes copper and zinc. Zincs would not be allowed under this law, and aluminum anodes would be the only substitute.

Don't get me going on the bottom paint portion of the same law...... Or the study done here in CA, which is one of the worst I have ever read and the people claiming to be scientists that wrote it should have their diplomas used as toilet paper.

So yes soon they will have to become the norm.... They cost more, because well aluminum takes a lot more energy to manufacture than Zinc.......

Guy

Got any technical references? I'm somewhat skeptical, if only for the certainty that someone must have tried them out decades ago. And the supposition that if they were really superior, they'd be widely used. Just as a guess, I'd imagine that it might be challenging to maintain a good bond with the protected metal. It might be fun to set up some experiments...

And I've been in one end and out the other trying to sort the EPA data on zinc toxicity. In the end, they basically throw out all the data that disagrees with what they want to do (the vast majority) with the one liner, "it must be in error." And it doesn't seem to bother them that the proposed limits are orders of magnitude below the natural background concentrations for streams coming out of west coast mountains. And since when are aluminum ions not toxic?

Anyway, the aluminum smelters that used to be ubiquitous here are long gone. Back in the day, if you had a casting process, they would supply a crucible full of molten aluminum straight from the reduction cell - a huge savings in energy. If most people knew what was in those trucks on the interstate, they'd have freaked out. We still have a small specialty smelter, but I think they specialize in more expensive alloys, out of economic necessity.

Interesting note. I have heard that some zinc anodes have aluminum collars embedded around the mounting holes, to extend the length of time the anode will stay attached.

It is all about the voltage... LOL

http://www.performancemetals.com/anodes/AnodeFAQs.shtml

These folks make all three types of anodes that are currently used in most applications. Zinc, Aluminum, and Magnesium.

Guy

footrope said:

Interesting note. I have heard that some zinc anodes have aluminum collars embedded around the mounting holes, to extend the length of time the anode will stay attached.

Click to expand...

Yep, maxprop zincs which are prone to having the holes for the screws go away first, have aluminum collars.

Guy

toddster said:

And I've been in one end and out the other trying to sort the EPA data on zinc toxicity. In the end, they basically throw out all the data that disagrees with what they want to do (the vast majority) with the one liner, "it must be in error." And it doesn't seem to bother them that the proposed limits are orders of magnitude below the natural background concentrations for streams coming out of west coast mountains. And since when are aluminum ions not toxic?

Click to expand...

Science and bureaucracy don't go together any better than anything else and bureaucracy.

Guy

Well, it's not just about voltage. There's also passivation. Aluminum is notoriously fast to passivate. Which is great in some applications, not so great in electrical applications.

Depends on the alloy

The issue is the alloy used. Some passivate rapidly, and some do not.

The max prop ones were great, I have customers that used some cheap ones, and some that used some expensive ones, the cheap ones were ineffective, I would guess that it was due to passivation of the poorly selected alloy.

Guy

'

where to place Zincs

Can anyone recommend the preferred placement for Zincs and how many are needed for an E 27 in Salt Water, kept at a Marina, in RI?

Thanks.

Bink

Bink,

I just use a single shaft zinc- replace each season on my '27, placed between the hull and strut. I'm on a floating dock with no shore power, so that may be different than your situation.

Don

I would suggest a "collar zinc" (somewhat egg-shaped) around the shaft, and, on either side of the strut, a "button zinc" (a set of two discs that make a "strut sandwich").

These easily last a season in Long Island Sound on my 32 and I would expect would be good for a 27 on Rhode Island too. The mounting hole for my button zinc is relatively small so sometimes that zinc is not a stock item at the marine stores and has to be bought online.

Do not paint the zincs or the metal on which they're mounted.

Thank you!