Galvanic corrosion

A

Arnold

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Joined
Oct 14, 2003
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12330
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544
I read that one of the factors contributing to galvanic corrosion for boats kept in salt water is having the boat connected to shore power. Is anyone using a solar panel to keep the batteries charged and not connecting to shore power?
Fell free to tell me that it is a stupid question; I can take it.
 
shore power issues still need to be fixed if there is an issue. if you suspect you have a galvanic corrosion problem, the only solution is a galvanic survey by a qualified marine electrician. anything short of that is looking for a needle in a haystack as there are just too many possible sources for stray current. if there is an issue(s) there can be multiple sources with varying degrees of contribution.

we have had 3 done over the last 10 years and each one has found multiple items that needed attention with varying degrees of necessity.

a galvanic survey is not beyond the reach of a DIY, however it does need some technical skill to properly perform. if you have not done one before, probably better to watch the first one and ask questions.
 
The fun thing about it is that it might not even be your boat that's causing it, but you're suffering the ill effects! Shore power exacerbates the issue when it's present, but there's always some degree of it regardless. Monitor and change your anodes regularly and ensure you have the correct metal type for water application. Zinc for salt, magnesium for fresh, aluminum or zinc for brackish.
 
Arnold,
First off, certainly not a stupid question. Any question you have means you don't know and want to learn. Shore power does not cause galvanic corrosion. Exception is a boat near you or your boat that has "grounding" issues. In other words, with a boat that is using shore power and they don't have grounding or bonding problems all is well. I am sure people more in the know here will elaborate.

Walter
 
Best place to learn more about galvanic corrosion is from youtube.
 
I had similar problem years ago with nearby boats. I installed a galvanic isolator on each incoming 30amp line. did the trick for me.
 
Put in a galvanic isolator at minimum or an isolation transformer. Sooner or later you will run into a nearby boat that will make you wish you did. Going purely solar would not be enough of a reason for me. Galvanic isolators that will break the ground path are vastly less expensive in comparison.
 
At my diver's suggestion, I recently installed a galvanic isolator. It was pretty easy and not too expensive (under $100). My diver says my zincs show nicely today (i.e., a lot less wear). So I'm sold on the galvanic isolator (it's basically two diodes, one running in each direction to stop stray currect -- at least that's how I understand their principle).

V/R
 
FWIW; I've kept shore power connected 24/7 since buying '93, 37C since new. Never had any issues that I am aware of. Vessel was bonded & when I purchased vessel; dealer said I didn't have to add shaft zincs because of bonding. I did it any how; every year I owned boat.
 
quote:
Originally posted by Bob J

FWIW; I've kept shore power connected 24/7 since buying '93, 37C since new. Never had any issues that I am aware of. Vessel was bonded & when I purchased vessel; dealer said I didn't have to add shaft zincs because of bonding. I did it any how; every year I owned boat.

Click to expand...


If shaft bonding brushes are installed in your boat, the dealer is probably correct. But the ONLY way I know of to ascertain if zinc anodes--aluminum is a much better choice--- are needed is to measure the bonding voltages on the submersed metals using a half cell.
 
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