electrolysis

[skye peak]

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I am losing zincs in 60+ days and started to track down the problem. With an overboard zinc (fish) connected to my shaft, which currently has no zinc attaced underwater, I measure 700 millivolts.

I have read that 200-800 millivolts is acceptable in one article and to the contrary in another article.

Do we have any surveyors or electrical engineers on the forum that could chime in with an opinion?

Thanks
Skye

[Elizabeth Ann]

How and where are you measuring that voltage? 700mV sounds like a lot.

[skye peak]

the 700 mv is measured between the unprotected prop shaft and the overboard zinc on a wire.

Shore power is disconnected, 12volt batteries are disconnected at the terminals.

Boat is on a private dock with the 110v shut off up at the house to eliminate stray currents.