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post #10 of Old 03-07-2013
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Re: Zinc Or Aluminum Anodes On Mid Chessie

Originally Posted by swampcreek View Post
We may very well have this boat a long time, I just want to do whats best for it. Nowhere do I read any technical articles that zinc is better in brackish water, I read just the opposite, the only promotion of zinc over aluminum are the arguments like "that's what we always have done". I've heard of different anodes before but never concerned myself with them but our present boat cost more than all my previous boats combined. I've had some real adventures trying to disassemble old outdrives and lower units, I wonder how much easier some of those jobs might have been if they were protected with aluminum alloy.

To put it another way many cars were produced without oil filters way back when, those kind of caught on too.
I have kept zincs on my boats for many years and never had a problem with galvanic corrosian.

However sacrificial anodes of any matierial zinc or aluminum are not as effective as a galvanic isolator, As the anode deteriorates it loses it abilities. The isolator hhoks in with the shorepower cureent where a lot of the problems may occur.
If you really are truly serious and concerned with protecting your expensive purchase buy a galvanic isolator. It will protect you boat much better. I would still use a sacrificial anode.

Sacrificial zincs corrode away as they protect metal thru hulls, shafts and props from damaging electrolysis. Stray, low voltage current flowing between the AC safety ground and DC bonding system is a principal cause of this "galvanic" action. This type of stray current will normally overload your zinc anodes as they try to protect other near by boats and/or metal objects of the marina.
Marine Galvanic Isolation
A luxury yacht or commercial vessel is an important asset worthy of the best corrosion and safety grounding protection available. While protective coatings and anodes can help protect your boat, a sure method is required to deal with the galvanic corrosion circuit created by the shore power connection. The DEI Galvanic Isolator surpasses all other galvanic isolator electrical ratings.

The Solution:

A simple method which virtually eliminates this galvanic corrosion problem is to insert an appropriately rated and certified fail-safe Galvanic Isolator in series with the grounding conductor of the ship-to-shore power cable. The function of the Galvanic Isolator is to provide AC continuity of the grounding conductor (required for safety in the event of an AC fault) and to block the flow of corrosion-causing galvanic current.

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Last edited by chef2sail; 03-07-2013 at 11:42 PM.
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