Any knowledge of whether a Galvanic Isolator would have been standard on a 2010 OA 60?

[l00smarble]

A contractor says it looks like galvanic corrosion from interaction with dock and they recommend an isolator. I would think a yacht of this caliber would already have one or even better an isolation transformer.

 

[tiltrider1]

If you bought it new and didn’t specify it as an option then it didn’t come with it.

If you bought the boat second hand then I would be surprised if it didn’t have one.

However, a galvanic isolator protects your zincs from stray dock currents. If your running gear is showing signs of galvanic corrosion it is due to a lack of zinc changes or poor bonding.

An Isolation Transformer means you have no ground connection to the dock so you don’t need a galvanic isolator. While you read a lot about isolation transformers here, they are rather rare in the boating world.

Your first question should be why are my zincs not being changed often enough.

 

[Bmarler]

Maybe share a little more information about the specific corrosion issue you have?
Also, A good electrical survey of the underwater metals will tell if you’re protected. I check mine every couple of years to see if there’s any changes.

 

[l00smarble]

Maybe share a little more information about the specific corrosion issue you have?
Also, A good electrical survey of the underwater metals will tell if you’re protected. I check mine every couple of years to see if there’s any changes.

The boat does not have "corrosion" though he thinks it does. It is suffering from cathodic disbondment of the bottom paint (likely copper based) around the thru-hulls and other underwater metals. The metals are not damaged in any way. If anything, zinc is plated onto the protected metals. This is most likely not related to interaction with the dock/other boats on dock so even if there is or isn't a GI it may not make any difference.

The question is just about whether OA builds boats without galvanic isolation. In this size/class of yacht I would think a GI would be a minimum standard with a Isolation transformer really being the preferred solution.

 

[tiltrider1]

I get it. Your bottom paint is Pettit Trinidad which is a 70% copper paint. Your boat has a lot of zinc and you are suffering a halo affect around all the through hull fittings.

What you need is Electro-guard. It regulates the zinc so that your boat is not over protected. Over protection is what causes the halo effect.

 

[Diep]

Tiltrider is onto it.

You may be able to reduce the number of zincs you have or change them to smaller sizes. The best way to assess the situation would be with a silver-silver chloride reference electrode. They're probably a few hundred bucks these days. Nigel Calder has good info and instructions on the issue and how to assess it in his book.

 

[l00smarble]

I get it. Your bottom paint is Pettit Trinidad which is a 70% copper paint. Your boat has a lot of zinc and you are suffering a halo affect around all the through hull fittings.

What you need is Electro-guard. It regulates the zinc so that your boat is not over protected. Over protection is what causes the halo effect.

Hey thanks for the response but just to be clear once again it's not my boat and I'm helping the owner with the problem. I'm not in need of finding an explanation for the paint damage as I understand the causeú and I deal with this pretty regularly. I'm just curious about ocean Alexander either making galvanic isolation standard or not on their builds.

But you are correct that over protection can and will cause cathodic disbondment of the paint though it isn't just a simple as the guy put on more zinc this year than he was supposed to. The other big factor is how well coated the underwater metals are. The whole process can be slowed down by reducing the effective surface area of protected metals with high quality barrier coatings and top coatings. Conversely if the underwater metals lose the barrier coating they got years ago then this year the same amount of zinc anodes are doing much more work to protect them and producing much more of the ions that are caustic to the paint. There are many other variables as well including water temperature, currents, anode composition, etc

But I didn't mean to start a thread in the OA forum about cathodic disbondment. I just wanted to know if they put galvanic isolators in their boat or not.

 

[tiltrider1]

Can’t help you with that question. Never saw an OA with out a Galvanic Isolater. Can’t imagine some one ordering a boat with out one.