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Old 19-10-2021, 12:13   #16
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Re: Is this zinc still ok to use

Excellent feedback and all appreciated. It's wire brushed and added to my 'emergency spare' box ... tx again
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Old 20-10-2021, 13:04   #17
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Re: Is this zinc still ok to use

Y'know when you replace an old but unbroken alternator belt, it makes sense to hang on to it as an "emergency spare", because if the new one breaks (as opposed to brakes) you then have a way to get the motor up and running until you get back alongside and can get a replacement. I can't however picture any scenario that would require an "emergency zinc."

As has been alluded to, the actual wear of the zinc depends on a lot of factors - heat, salinity, how much you actually run the engine, etc, etc. So assuming those factors don't change much, you can pretty well estimate your wear-rate. So saying it took a year to erode 20% of the zinc, the same usage in the same environment over the next year will more than likely erode a further 20%. If you do your own maintenance, it's easy enough to mark that info down on your maintenance log, and if you're judicious with your maintenance and don't press it to "Empty" so to speak, you're not likely to run out of zinc between those maintenance intervals. An outside mechanic who doesn't have the intimate knowledge of your engine is advised to replace the zinc at 50% because he can only assume the wear-rate at 50+%/maintenance interval.

Other than a little scrubbing with a wire brush, there's no real difference effort-wise in putting in a new or old zinc - so the "I've taken it out, I might as well change it" argument doesn't hold much water. While they don't cost a lot of $s, remember there is an environmental cost - mining and smelting the zinc, so tossing away a perfectly usable anode is not eco-friendly.

The Westerbeke technical manual has this neat little graphic in it:
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Old 20-10-2021, 13:25   #18
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Re: Is this zinc still ok to use

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Originally Posted by Lodesman View Post
Y'know when you replace an old but unbroken alternator belt, it makes sense to hang on to it as an "emergency spare", because if the new one breaks (as opposed to brakes) you then have a way to get the motor up and running until you get back alongside and can get a replacement. I can't however picture any scenario that would require an "emergency zinc."

As has been alluded to, the actual wear of the zinc depends on a lot of factors - heat, salinity, how much you actually run the engine, etc, etc. So assuming those factors don't change much, you can pretty well estimate your wear-rate. So saying it took a year to erode 20% of the zinc, the same usage in the same environment over the next year will more than likely erode a further 20%. If you do your own maintenance, it's easy enough to mark that info down on your maintenance log, and if you're judicious with your maintenance and don't press it to "Empty" so to speak, you're not likely to run out of zinc between those maintenance intervals. An outside mechanic who doesn't have the intimate knowledge of your engine is advised to replace the zinc at 50% because he can only assume the wear-rate at 50+%/maintenance interval.

Other than a little scrubbing with a wire brush, there's no real difference effort-wise in putting in a new or old zinc - so the "I've taken it out, I might as well change it" argument doesn't hold much water. While they don't cost a lot of $s, remember there is an environmental cost - mining and smelting the zinc, so tossing away a perfectly usable anode is not eco-friendly.

The Westerbeke technical manual has this neat little graphic in it:
Thanks for posting this, I like your argument about how to treat zinc life
Have followed the principle but could have articulated it nearly as well. I've found fresh water flushing on return to the dock helps our raw water cooled engines zinc life too. They aint cheap here from the Yanmar mafia but we buy zinc rod & make our own.
I'm impressed with the westerbeke manual writer too. He would get fired these days as it would be necessary according to corporate mission statement to tell engine owners they need to be replaced with " genuine" westebeke "specially formulated" zinc priced like platinum at 6mth intervals.
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Old 20-10-2021, 15:46   #19
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Re: Is this zinc still ok to use

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The reason you replace it at 50% is because presumably you've used more The zinc itself continues to offer protection until it completely disappears
I don't believe this is correct. The corrosion and calcareous coating on the zinc greatly reduces it's effectiveness as they act as insulation and reduce or even prevent current flow.
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Old 20-10-2021, 16:40   #20
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Re: Is this zinc still ok to use

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I don't believe this is correct. The corrosion and calcareous coating on the zinc greatly reduces it's effectiveness as they act as insulation and reduce or even prevent current flow.
Perhaps you missed the part where I said to "wire brush it to expose clean zinc" or the manual where it says "clean and re-use."
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Old 20-10-2021, 17:29   #21
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Re: Is this zinc still ok to use

They usually are corroded deep but not visibly. They are cheap. Shop these things and buy in bulk. Always replace. The risk from being a skinflint is high.
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Old 20-10-2021, 17:45   #22
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Re: Is this zinc still ok to use

I've removed those zinc pencils only to discover no zinc....it's not a given that the zinc pencil loses material equally along it's length. It could corrode near the thread and the pencil just drop off somewhere inside the exchanger.
As above, clean it and keep as a spare., but replace it. It's not a big ticket item to be dicking around with it.
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Old 21-10-2021, 06:36   #23
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Re: Is this zinc still ok to use

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As above, clean it and keep as a spare., but replace it. It's not a big ticket item to be dicking around with it.
What's the logic in keeping a partly-used spare?
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Old 21-10-2021, 07:50   #24
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Re: Is this zinc still ok to use

What's the logic in keeping a partly-used spare?

you might find yourself in an out of the way place where no spares of any kind are available..a partly-used spare is better than no spare..
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Old 21-10-2021, 09:05   #25
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Re: Is this zinc still ok to use

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What's the logic in keeping a partly-used spare?

you might find yourself in an out of the way place where no spares of any kind are available..a partly-used spare is better than no spare..
Why would I be in an out-of-the-way place doing periodic maintenance without having new spares on hand?
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Old 21-10-2021, 09:33   #26
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Re: Is this zinc still ok to use

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Y'know when you replace an old but unbroken alternator belt, it makes sense to hang on to it as an "emergency spare", because if the new one breaks (as opposed to brakes) you then have a way to get the motor up and running until you get back alongside and can get a replacement.
Yuck, relying on an old, replaced wear item as your emergency back-up sounds horrible. That is one tick up from the theory that the best time to replace something is after the time of failure of the old one.

I keep a brand new spare on board. When it's time to replace, I purchase a new item. The old item is removed and discarded, and the spare is used as it's replacement. The newly purchased item is then placed into the spares pile. If the item fails, the brand new from spares is used. I then immediately replace the spare with a new spare.

replacing a failed item with an old, out of service, about to fail item makes no sense. If the intention is emergency spares, then carry proper emergency spares.
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Old 21-10-2021, 10:08   #27
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Re: Is this zinc still ok to use

Why would I be in an out-of-the-way place doing periodic maintenance without having new spares on hand?

ok, you win....throw it away ....
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Old 21-10-2021, 10:10   #28
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Re: Is this zinc still ok to use

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Yuck, relying on an old, replaced wear item as your emergency back-up sounds horrible. That is one tick up from the theory that the best time to replace something is after the time of failure of the old one.

I keep a brand new spare on board. When it's time to replace, I purchase a new item. The old item is removed and discarded, and the spare is used as it's replacement. The newly purchased item is then placed into the spares pile. If the item fails, the brand new from spares is used. I then immediately replace the spare with a new spare.

replacing a failed item with an old, out of service, about to fail item makes no sense. If the intention is emergency spares, then carry proper emergency spares.
Rubber ages, just sitting there. So slapping a belt that has age-hardened over the last couple of years sitting in your spares-locker onto the engine, is bound to lead to an early failure - and probably at the worst moment if Murphy has his way. Regular inspections (that show age-hardening (cracks, chips) or that it has stretched to near the limit of the tensioner) and/or a logical planned maintenance programme (ie. yearly replacement regardless of wear) allow one to replace the belt before it self-destructs, which permits one to purchase and install a brand-new belt. This gives maximum belt-life and peace of mind.
But even if you do as you do, it still doesn't hurt to hold on to the old unbroken belt. If your belt fails and you put your brand-new spare on, and it turns out to have had a manufacturing flaw that causes it to fail right away (it happens) you'll have an "emergency spare". That's kind of the point of an "emergency spare." I still don't see the point of an emergency spare zinc,
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Old 21-10-2021, 10:13   #29
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Re: Is this zinc still ok to use

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Why would I be in an out-of-the-way place doing periodic maintenance without having new spares on hand?

ok, you win....throw it away ....
Well duh! That's what I do - once I've gotten all the usable life out of it.
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Old 21-10-2021, 10:51   #30
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Re: Is this zinc still ok to use

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I've removed those zinc pencils only to discover no zinc....it's not a given that the zinc pencil loses material equally along it's length. It could corrode near the thread and the pencil just drop off somewhere inside the exchanger.
As above, clean it and keep as a spare., but replace it. It's not a big ticket item to be dicking around with it.

This ^^^^. I have kept records of replacement as I noted earlier and I keep up with it.


The disingenuous part about the photo from the "manual" is that in my experience the zincs do not wear off equally along their length. Sometimes it's the tip sometimes near the threads, but in almost all cases it IS uneven.


The OP's photo is more like just a first month or two worth of "service."


Here's my last one, after five months of a six month interval. Of course, I installed a new one.
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