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Old 20-02-2017, 07:17   #1
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Zincs wasting away rapidly

The zincs on my drive shaft seem to be deteoriating rapidly. Couple other boats at same dock are seeing same thing. How best to check each boat to see if there is an electrical discharge?
Thanks
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Old 20-02-2017, 08:10   #2
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Re: Zincs wasting away rapidly

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How best to check each boat to see if there is an electrical discharge?
Typically rapid anode depletion is caused by an issue aboard the boat in question. If (as you say) there are multiple boats experiencing the same problem, it is possible that there is something going on with the shorepower system. Hire a qualified marine electrician.
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Old 20-02-2017, 08:19   #3
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Re: Zincs wasting away rapidly

How long should anodes last on average?

When I was docked at the marina for a few months, I was getting 8 weeks out of my prop anodes (aluminum not zinc).
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Old 20-02-2017, 08:24   #4
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Re: Zincs wasting away rapidly

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How long should anodes last on average?
That's tough to say, as those little prop anodes for French boats are notorious for not lasting very long. But you'd hope to get more than two months out of them. Especially since aluminum anodes are supposed to be longer-lived than zinc.
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Old 20-02-2017, 08:51   #5
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Re: Zincs wasting away rapidly

i get a year ususally
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Old 20-02-2017, 09:05   #6
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Re: Zincs wasting away rapidly

Anodes wasting away that quickly are usually as the result of an A/C problem. Do you have a galvanic isolator in between your incoming A/C power source and your panel? If you don't it's a probability that this is causing your problem. On my boat, as a temporary fix until I installed an isolator, I disconnected the green earth wire coming onto my boat and it made an instant difference to the life of the zincs. Of course, I can't recommend you do this otherwise people will be quoting all sorts of ABYC rules at me and you will stick your tongue on a live wire and blame me when your hair sticks up on end.
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Old 20-02-2017, 09:53   #7
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Re: Zincs wasting away rapidly

Thanks, want to check our boat and next would be shore power but dock owner blames the boats.
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Old 20-02-2017, 09:57   #8
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Re: Zincs wasting away rapidly

Can't you get a good evaluation for a vessel by using a multimeter set to read a low voltage with one probe on a bonded rail and the other hanging in the water?
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Old 20-02-2017, 10:06   #9
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Re: Zincs wasting away rapidly

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Can't you get a good evaluation for a vessel by using a multimeter set to read a low voltage with one probe on a bonded rail and the other hanging in the water?
I think you need one of these for that?
Corrosion Reference Electrode Product Specifications

I'm going through anodes now like I had stock in them, and I think I know why, maybe.
I have an isolation transformer.
I now have an Inverter / charger. It is in line with the AC input. AS I'm lazy I extended the AC line from my panel to run through the inverter, and then back to the panel.
I'm thinking that the isolation transformer is now before the inverter / charger, but it needs to be placed after it? That the inverter / charger of course has both AC and DC grounds in it, and that may be my issue?
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Old 20-02-2017, 10:12   #10
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Re: Zincs wasting away rapidly

Unplug. No shore power, no vulnerability.

Assuming you have solar to keep the sump pump happy, just unplug for 2 months. You can plug in for a few hours when you are actually on-site.
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Old 22-02-2017, 01:50   #11
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Re: Zincs wasting away rapidly

If I may:
I have attempting to upload a PDF file of an article I wrote for our local club which had several members having galvanic corrosion issues. It solved several of the members problems when they used it to examine their own AC/DC grounds. no assurance it will do you any good but it can't hurt to read it.


Mark Fay MMC Jr. Engineer QMED AS-E / MSC ET
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File Type: pdf club grounds.pdf (54.6 KB, 95 views)
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