Current Leakage Eating Zincs?

Hi, All. Probably been covered many times, but here goes: Divers replaced my shaft zincs 30 days ago (older Mainship), and today found they've been "consumed." Boat is connected to 30-amp shore power, and only AC equipment that's been running lately are the battery charger and small refrigerator.
I assume it's a current "leakage" (bad ground on boat or shore?).
Suggestions? Where do I start? Thanks.

Start with the DC. AC current won't consume zincs like DC will. You can check for AC shore power leakage with a clamp on AC current probe.



Perhaps a bilge switch that's failing or some DC wiring laying in the bilge that's leaking to a thru hull fitting via the bilge water.

Have a corrosion analysis done by a certified ABYC tech. It’s should take about an hour with you helping. He’ll be able to tell exactly what the problem is plus the remedy.

“Perhaps a bilge switch that's failing or some DC wiring laying in the bilge that's leaking to a thru hull fitting via the bilge water.”

What Steve said. Could also be another boat close by with DC voltage leaking into the water. (DC wire hanging in the water in their bilge) Any new boats around? Ask neighbors if they are consuming zincs.

Maybe have to hire an ABYC guy as stated above.

By one of these until you get it sorted out.
https://www.boatzincs.com/hanging_a...MIjfaQpMvw4AIV2uDICh1t0wLqEAQYAyABEgJd__D_BwE

Larry M said:

Have a corrosion analysis done by a certified ABYC tech. It’s should take about an hour with you helping. He’ll be able to tell exactly what the problem is plus the remedy.

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I like this advice and will follow it myself. Plus, helping him with the work would be very educational since problems are likely to come up again someday. That's an hour worth of billing that will pay dividends.

Bkay said:

I like this advice and will follow it myself. Plus, helping him with the work would be very educational since problems are likely to come up again someday. That's an hour worth of billing that will pay dividends.

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Agreed. Great advise!

What if the problem is the marina or your neighbors boat? Neither may be willing or even able to correct the situation. If that’s the case, maybe one of those auxiliary fish anodes that you clip to the bonding system and hang over the side like previously mentioned will help.

30 days is awfully quick to totally consume shaft zincs. Did your diver report simply that the zincs were gone? If he didn't produce the remnants, how do you know that they didn't fall off due to incomplete installation 30 days before?

I have more questions than answers. First, is there a galvanic isolator installed?

*IF* the problem turns out to be the dock wiring or a nearby boat, a galvanic isolator is one of the best remedies (other than unplugging)

tiltrider1 said:

I have more questions than answers. First, is there a galvanic isolator installed?

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I ordered a 50amp Galvanic Isolator last week for our 'new to us' boat. Easy to install, and can't hurt