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Old 12-18-2017, 07:45 AM   #1
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Time for a galvanic isolator??

See attached photo. These zincs were replaced about 5 weeks ago. My mechanic sent the pic. I'm not sure where the really bad one was. Should I install a galvanic isolator?
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Old 12-18-2017, 08:16 AM   #2
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Absolutely install one and make sure all your grounds are good.
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Old 12-18-2017, 08:32 AM   #3
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All engine zincs, huh? Weird. I wonder what your hull zincs look like. I would have to wonder if it's an engine wiring/electrical leak or if it's coming from the shore power side. A galvanic isolator wont hurt but you want to find where its coming from first. I would've thought your Mainship Pilot had one (an isolator) already.
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Old 12-18-2017, 09:36 AM   #4
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a galvanic isolator generally has nothing to do with engine zincs as they are usually in what is considered a totally isolated body of water and are not specifically bonded .....just to the protected part. (usually).

have your engines been running?

running they wear in 5 weeks on my boat but hardly when sitting.
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Old 12-18-2017, 09:37 AM   #5
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Not weird at all. Same thing happened to me. I redid all my grounds and installed a galvanic isolator. Problem solved. This was on the advice of my diver.
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Old 12-18-2017, 10:36 AM   #6
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Quote:
Originally Posted by JackD View Post
See attached photo. These zincs were replaced about 5 weeks ago. My mechanic sent the pic. I'm not sure where the really bad one was. Should I install a galvanic isolator?
Why is the mechanic pulling them after just 5 weeks?
Are you chasing an ongoing problem?
What do the external zinc (s) look like on your boat?
How long do they (external zincs) last?
Do they erode at about the same rate?
Do you have any dc wires in bilge water?
Any neighboring boats with zinc issues?
Are you continually connected to shore power?

The good news is the zincs in the picture are doing their job. Maybe just working a little harder then they should.
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Old 12-18-2017, 10:44 AM   #7
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Till the OP states engine usage, zinc wear is impossible to estimate.
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Old 12-18-2017, 11:27 AM   #8
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Just speculation.....but any engine zincs that are on the salt water side would be on the same ground plane as the other zincs that are exposed to salt water. The saltwater “stream” on an idle engine usually remains uninterrupted (due to vacuum) back through the engine intake side to the surface water at the intake strainer thus completing a path to ground. Also the bonding system (connecting all non engine zincs) is usually connected to the engine block (dc ground) in one form or another. Not sure if the engine running or not would come into play here?
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Old 12-18-2017, 04:05 PM   #9
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Erosion....not corrosion...big time..... especially running in sedimented water..

Just my experience and what i have read and learned from pros.....someone might have different experience.
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Old 12-29-2017, 11:31 AM   #10
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My Yanmar 6LPA is in a lift-kept boat and gets a freshwater rinse after every outing. Even so, after about 150 engine hours over 2.5 years, the lower three zincs, which are always wet, require semi-annual replacement, while the upper two (fuel cooler and intercooler) are always dry when checked and remain pristine looking. The excellent mechanic I occasionally allow on the boat tells me he thinks the raw water drains from the upper parts of the system through the Tides dripless shaft seal cooling line from engine to shaft seal.
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Old 12-30-2017, 07:16 AM   #11
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Owner's reply

Hi folks,

Somehow I missed all of the great responses here. To answer some questions :
- zincs on the hull last a long time
- replaced engine zincs a month or so ago. Went fishing for a few hours one day. Besides that, not running.
- always connected to shore power
- we noticed the issue because my mechanic had some time this month and I wanted him to clean my coolers

Thanks for the input!
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