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?

Alfton said:

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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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.

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

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.

I have one I have not gotten around to installing yet.
Steve W.

Moonstruck said:

I still have to change zincs about once a year.

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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.

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.

Dave

Alfton said:

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?

Click to expand...

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.

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.

markpierce said:

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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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.

JD said:

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.

Click to expand...

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

My boat came with one from the factory. I'm surprised any boat with a shore power system would not.

bglad said:

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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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.

rwidman said:

My boat came with one from the factory. I'm surprised any boat with a shore power system would not.

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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.

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.

Is the process for checking the power using a volt meter between the green (ground) and the white (nuetral) coming from the marina?

JD said:

Ron,

Came with a Isolation Transformer or Galvanic Isolator?

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Galvanic Isolator, as per the topic heading.

Phil Fill said:

........ Again the best is to test the AC ground for volts. However, the real danger is the amps which is life threatening ........

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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".

Just for kicks, read this article:

Galvanic Isolator Explained

and this one:

http://yandina.com/electrolysis.htm

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.

Alfton said:

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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Yes! You can also check the water the same way.

We get three years on bottom paint and main zincs. Every time a new boat docks close to us I check. If the reading are high I notify the marina and then they will come a check.

We have an isolator but I do not have much faith in them.

rwidman said:

Galvanic Isolator, as per the topic heading.

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Accordign to the Charles web site they say that the Charles Transformer isolator does not need a Galvanic Isolator."The only true marine isolation transformer available.
Marine ul listing ensures durability and safety. Greatly reduces the potential for in water shock hazard.
Eliminates the need for polarity alarms and galvanic isolators.
Full current carrying shield with encapsulated components and transformer windings.
Terminal blocks fro easy connections mounts to either bulkhead or deck.
Strain kit required for installation. "

JD said:

Accordign to the Charles web site they say that the Charles Transformer isolator does not need a Galvanic Isolator.

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I would not argue with that.

Transformers are heavier and more expensive than isolators. That's probably why they are less common.

rwidman said:

I would not argue with that.

Transformers are heavier and more expensive than isolators. That's probably why they are less common.

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I would think the cost is a big factor as well.

JD said:

I would think the cost is a big factor as well.

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Bingo...depending on models I believe there are other benefits that include adjusting voltage to normal if the dock is a little low...but they are often 10x the cost or more of the more simple diode isolators.

psneeld said:

Bingo...depending on models I believe there are other benefits that include adjusting voltage to normal if the dock is a little low...but they are often 10x the cost or more of the more simple diode isolators.

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I can tell you I will not ever have another boat without them. I never worry about the shore power and the fact that I have not needed outside zincs for over two years says they are doing their job. I now need the zincs replaced after two years and 3 months.

Zincs and galvanic isolators are somewhat a common thing but in reality there's lots of other reasons zincs go fast that have nothing to do with galvanic isolators or isolation transformers. If you took the time to check the ground before you hooked up each time...the chances of needing them would be greatly reduced.

As a live aboard on an old wood boat I have often thought about having an islotaion transformer. But due to noise and space issues I looked at having it on the dock beside the boat under a dock box or boarding step. Something that even being heavy I could move or load onto the boat when in need.

Still think about such but after 10 years here and no issues there there seems no point.

I did install the galvanic isolator however.