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I have shaft zincs (2) as well as a zinc at the end of my maxprop. I have started to also put a large zinc over the side when on the mooring connected to the grounded system.

I noted that the zincs on the shaft are lasting much longer with this latest change but the prop zinc still disappeared quickly.

Is the prop zinc more active, or its position unique that causes it go faster than the zincs on the prop? My goal was to have the prop zinc last all season so I didn't need to have a diver replace it mid-season.

Thanks for any insights.
 

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Can't give you a technical reply, but I have a similar setup and my max-prop zinc goes first. Personally, I think a full season out of zincs is unrealistic. I'm good, if all I need is one mid-season replacement.
 

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My suspicion is that the proximity of the bronze in the prop accelerates the prop zinc consumption. Even given the shaft zincs are there... Next time you pull the boat you could try slathering the prop with a dielectric goop, but I have had mixed results with this.
 

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My suspicion is that the proximity of the bronze in the prop accelerates the prop zinc consumption. Even given the shaft zincs are there... Next time you pull the boat you could try slathering the prop with a dielectric goop, but I have had mixed results with this.
If you disrupt the electrical connection between the prop and the zinc, you may indeed slow down or stop its corrosion. However, you've also defeated its purpose, as something else must become the anode. The stainless parts within the prop are not electrically connected to the shaft zinc.
 

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I have shaft zincs (2) as well as a zinc at the end of my maxprop. I have started to also put a large zinc over the side when on the mooring connected to the grounded system.

I noted that the zincs on the shaft are lasting much longer with this latest change but the prop zinc still disappeared quickly.

Is the prop zinc more active, or its position unique that causes it go faster than the zincs on the prop? My goal was to have the prop zinc last all season so I didn't need to have a diver replace it mid-season.

Thanks for any insights.
Having installed many hundreds of Max Prop zincs, I can tell you that my experience is that on many boats they do not last as long as other zincs, regardless of manufactured them. Why this is, I cannot say.
 

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We have a collar zinc on one of our Gori props, and it wears much more quickly than the others (which don't turn, as the prop zinc does). Our theory is that the friction of the water and what it carries wears on the zinc as the prop is turning.
 

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because its on the point. last point of contact, and smallest, with surrounding "cathode/ground. CNT remember name of principle? me be an EE can help?
 

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Why would current between the shaft and prop travel to a hanging zinc, or even a zinc on the shaft, when it is so much easier to go to the zinc on the prop?

That's why the prop zinc is always going to waste first.
 

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funny you understood it pretty good on the other forum
I'm pretty sure neither you or anybody else made that statement on the other forum. But since you've made it here and it's about as clear as mud, maybe you can enlighten me as to why electrical current would find it "so much easier to go to the zinc on the prop" as opposed to the shaft.
 

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Nearly an Old Salt
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I have shaft zincs (2) as well as a zinc at the end of my maxprop. I have started to also put a large zinc over the side when on the mooring connected to the grounded system.

I noted that the zincs on the shaft are lasting much longer with this latest change but the prop zinc still disappeared quickly.

Is the prop zinc more active, or its position unique that causes it go faster than the zincs on the prop? My goal was to have the prop zinc last all season so I didn't need to have a diver replace it mid-season.

Thanks for any insights.
I suspect the primary reason is that the whatver metal the zinc on the end of the Maxprop is protecting, is not that well electrically connected to your grounding/bonding system. There must be a good electrical connection between the zinc over the side and the metal you are trying to protect
 
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