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Old 10-11-2012, 05:05 PM   #1
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Galvanic Isolator

How many of you have installed galvanic isolators?
Did you get the results that you wanted?
Is it worth the money invested $500 - $1,000
How many of you do not know what a galvanic isolator is?
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Old 10-11-2012, 05:18 PM   #2
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Originally Posted by Alfton View Post
How many of you have installed galvanic isolators?
Did you get the results that you wanted?
Is it worth the money invested $500 - $1,000
How many of you do not know what a galvanic isolator is?
Yes, Moonstruck has a galvanic isolator. I am not certain that it has been of value, but I am glad it is there. It can help when marina wiring is screwed up. I still have to change zincs about once a year.
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Old 10-11-2012, 05:47 PM   #3
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I don't know about the cost.
I made my own. People think I'm nuts but it works for me.
I used 2 bridge rectifiers wired together so the current sort of loops. I mounted it in a small aluminum box and then Bolted it onto a big piece of aluminum angle as a heat sink.

Does the same thing as the ones you buy.

I have got to be able to fix or repair everything on the boat. This I can fix.

SD
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Old 10-11-2012, 06:15 PM   #4
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The Mainship 34 t's (later models) were built with Charles Isolators. The diver said that when he cleaned the boat this next time he was going to replace the zincs. This is the first time in two and one half years.

I'm guessing they work.
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Old 10-11-2012, 06:55 PM   #5
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I have one I have not gotten around to installing yet.
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Old 10-11-2012, 07:09 PM   #6
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I still have to change zincs about once a year.
No, so far, for all four questions.

After 15 months my zincs were about half gone but had them replaced. The Coot has eleven zincs: four on each side along the hull, two on the rudder, and one on the propeller shaft.

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Old 10-11-2012, 09:01 PM   #7
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We have one, already installed when we got the boat.
Defender sells a dual 30 amp unit by Yandina for $90.
It is hard to determine if it makes any difference, but I guess it is one less thing to worry about except the one time it indicated a fault.

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Old 10-11-2012, 09:34 PM   #8
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Quote:
Originally Posted by Alfton View Post
How many of you have installed galvanic isolators?
Did you get the results that you wanted?
Is it worth the money invested $500 - $1,000
How many of you do not know what a galvanic isolator is?
Not yet...waiting till I change to a 50 amp service..

You don't GET any results unless the marina is backfeeding on their ground.

It would be worth the money if you plugged into a hot ground.

Yes...basically a large diode.
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Old 10-11-2012, 10:09 PM   #9
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We had one installed on our boat. While it protects the boat from stray current in the dock power it does not protect against stray current in the water. For that, you need an isolation transformer, which is way expensive. But a galvanic isolator is a good thing to have, particularly if the marina's or harbor's shorepower system is iffy or if someone on the dock has a faulty electrical system that's letting power leak into the ground leg of the dock power.
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Old 10-12-2012, 12:07 AM   #10
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No, so far, for all four questions.

After 15 months my zincs were about half gone but had them replaced. The Coot has eleven zincs: four on each side along the hull, two on the rudder, and one on the propeller shaft.


How fast a zinc deteriorates depends on many things. Salinity of the water, how "hot" the marina is, and how the boat is bonded. Moonstruck sits a couple of miles from the Atlantic in very salty waters. We cruise into many marinas of which some have questionable power ( especially the Bahamas). When zincs deteriorate it is a good thing. It means they are doing their job. That is if your wiring is set up correctly on your boat.
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Old 10-12-2012, 06:03 AM   #11
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Quote:
Originally Posted by JD View Post
The Mainship 34 t's (later models) were built with Charles Isolators. The diver said that when he cleaned the boat this next time he was going to replace the zincs. This is the first time in two and one half years.

I'm guessing they work.
What you have there are isolation transformers. They block stray DC current from coming aboard because it can't pass through them. They also insure the current working aboard will be properly polarized. It doesn't matter if the dock power comes in normal or reversed polarity the boat side of the windings will always be the same. So dock power hot/neutral revesed no problem, hot/ground reversed transformer will not function.

Galvanic isolator is different and a less expensive option. It is a switch that blocks low voltages of which DC is the corrosion problem. Stray AC current is the dangerous one. The GI keeps the low voltage DC current out and if a serious fault occurs from AC current it makes a connection and allows the green safety ground to do its job.

By the way the galvanic isolator works in both directions so it should keep your own boat from causing trouble in the marina. Ony bad thing about that is you have to maintain your own zincs. No plugging into the marina to use your neighbors
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Old 10-12-2012, 09:28 AM   #12
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My boat came with one from the factory. I'm surprised any boat with a shore power system would not.
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Old 10-12-2012, 09:44 AM   #13
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What you have there are isolation transformers. They block stray DC current from coming aboard because it can't pass through them. They also insure the current working aboard will be properly polarized. It doesn't matter if the dock power comes in normal or reversed polarity the boat side of the windings will always be the same. So dock power hot/neutral revesed no problem, hot/ground reversed transformer will not function.

Galvanic isolator is different and a less expensive option. It is a switch that blocks low voltages of which DC is the corrosion problem. Stray AC current is the dangerous one. The GI keeps the low voltage DC current out and if a serious fault occurs from AC current it makes a connection and allows the green safety ground to do its job.

By the way the galvanic isolator works in both directions so it should keep your own boat from causing trouble in the marina. Ony bad thing about that is you have to maintain your own zincs. No plugging into the marina to use your neighbors
Thanks for the explanation. When I realized that I had not called them by their proper name it was too late to edit the post.

As I understand it they (Isolation Transformers) give the same end result without the need for the Galvanic Isolators in addition.

in any case I do change the zincs on the engine about every six months. I change them all, even the ones that have some material remaining. It isn't that hard nor that expensive as I have two complete sets. So I pull the old insert the news and put the old into an acid bath for a day or so. Then refurbish the old with new zinc and six months later do it again. My Yanmar 6LYA-STP has seven including the trans oil cooler. About a half hour job. Cost about $15 and great therapy. Also cheaper than the replacement heat exchanger or oil cooler would be.
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Old 10-12-2012, 10:05 AM   #14
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My boat came with one from the factory. I'm surprised any boat with a shore power system would not.
Ron,

Came with a Isolation Transformer or Galvanic Isolator? The Charles Transformers are pricey and are not on a lot of boats due to that. The two on my boat are a little over $1k each list. So that means a builder has an extra $1.7k or so in their cost to build.

I give Mainship a lot of credit for using items like this throughout the boat yet maintaining a somewhat entry level price point.
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Old 10-12-2012, 11:20 AM   #15
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Are they worth the money? That is a hard question to answer? Maybe for peace of mind! It depends on the level of stray current in the shore power ground, green wire. The purpose of the isolator is to prevent stray current going INTO the boat, while allowing stray current OUT of the boat However, they only bock 1.2 volts, so volts over still go into the boat and chances are blow out the diodes.

A better bet is to periodically test the shore ground, green wire for stray electricity, and to make sure the boats zinc protect loop is working. The isolator does not prevent your boat from producing, and/or coming through the water. Again the best is to test the AC ground for volts. However, the real danger is the amps which is life threatening which the isolate protect agasint. If there is corrosion, then the fitting/prop will turn pink because the zinc in the bronze is being used up. So there are signs and preventive measures weather boat has one or not.

Which reminds me I need to do some testing tonight.
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Old 10-12-2012, 11:33 AM   #16
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Is the process for checking the power using a volt meter between the green (ground) and the white (nuetral) coming from the marina?
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Old 10-12-2012, 11:41 AM   #17
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Ron,

Came with a Isolation Transformer or Galvanic Isolator?
Galvanic Isolator, as per the topic heading.
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Old 10-12-2012, 11:46 AM   #18
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........ Again the best is to test the AC ground for volts. However, the real danger is the amps which is life threatening ........
Please explain that statement. "Amps" (amperes) is a measurement of the flow of current. "Volts" is a potential. Without voltage, there will be no current flow and thus no "amps".
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Old 10-12-2012, 11:50 AM   #19
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Just for kicks, read this article:

Galvanic Isolator Explained

and this one:

http://yandina.com/electrolysis.htm
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Old 10-12-2012, 11:57 AM   #20
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I installed an isolation transformer fairly early in the process.
My boat lives in brackish water, so that plus the transformer has me on a 3 year cycle for both bottom paint and zincs.

I think ABYC states that if you have a galvanic isolator, you also need to have a 'display' which indicates that the unit is still working. So, the newer ones have this feature.
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