Zinc Activity

H

hd2002hd

Member
Jul 20, 2010
457
St. Louis
Boat Info
1996-Sea Ray 215 Express Cruiser/1996-Sea Ray 330 Sundancer/1998-Sea Ray 400 Sundancer/1996-Sea Rayd
Engines
5.7 Mercruiser/454's/454's w/V drive/120HP
Just returned from the marina. They were pulling the boat out to repair the swim platform. I noticed the starboard zincs on the outdrives looked new. However, the port side had a little corrosion building up. Not bad but very noticeable. All zincs were changed a month or so ago. I went to the shop manager and had him take a look. The ground wire seemed to be intact. What issues could be causing this?
 
Maybe electrolysis in the water that is close to the starboard side and that zinc is taking the brunt of it?
 
I assume you are on a fresh water lake. What type of anode did you use? You should be using Magnesium or Aluminum. Make sure that zinc anodes were not used.
 
My magnesium anodes on my starb. engine showed more wear than the port. My only conclusion is that the side closer to the dock (starb) had a bit more electrical activity than the port.

I did notice, upon changing the anodes, that the prior owner at some point, painted over the transom mounted anodes. So.. lot of good they were doing.
 
Yes, it is on a fresh water lake and always has been. Not sure of the alloy but certain it is correct for water. It just seemed odd one side was visibly different after only a out a month. One side was not any closer to the slip than the other. Even the shop manager thought it was unusual. GE said they would look into it. I was just looking for some input from this board. Lots of great knowledge here
 
I read that grounding issues could cause this, esp. if your attached to shore power. Also, is the surface the anodes attach to clean on the anode and the boat parts?
 
I wondered if it had to do with shore power but was confused since it was only the port engine. Good question on the surfaces. I would think the Marinemax mechanics made sure everything had good contact.
 
The whole electrolysis issue in a marina can get absolutely goofy at times.

Knew of a similar circumstance (One side eroding almost entirely and the other side not) - was eventually determined to be a boat in the next slip (on the eroded side) had a shore power grounding issue that 'leaked' electricity that 'found' it's way back to the shore power circuits through my friend's shore power hook up. Crazy!
 
njmello said:
The whole electrolysis issue in a marina can get absolutely goofy at times.

Knew of a similar circumstance (One side eroding almost entirely and the other side not) - was eventually determined to be a boat in the next slip (on the eroded side) had a shore power grounding issue that 'leaked' electricity that 'found' it's way back to the shore power circuits through my friend's shore power hook up. Crazy!
Click to expand...

What sort of metering or other process is used to determine where the leaking voltage is coming from?
i may have a suspect houseboat next to me that is causing problems.
 
I don't know how a marine electrical technician can find out where the problem is - I'm sure they have instruments to do it.

I suggest replacing the bad zinc and if you can, disconnect the boat from shore power and leave the boat in the slip - that will take your boat out of the shore electrical circuits - if there is no noticable corrosion after a month - the problem is not your boat, but originates somewhere else, making it a marina problem. Normally, if the ground fault is on YOUR boat, the corrosion would be equal on ALL of the zincs.
 
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