Zinc’s and Corrosion – A Discussion

Galvanic corrosion (also called ‘ dissimilar metal corrosion’ or wrongly ‘electrolysis’) refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte.

When a galvanic couple forms, one of the metals in the couple becomes the anode and corrodes faster than it would all by itself, while the other becomes the cathode and corrodes slower than it would alone. For galvanic corrosion to occur, three conditions must be present:

  1. Electrochemically dissimilar metals must be present
  2. These metals must be in electrical contact, and
  3. The metals must be exposed to an electrolyte


Hi all,

I would appreciate input on the underwater zincs used on my C380.  With the installed Yanmar, I’m aware that it lacks engine and heat exchanger zincs.

Since I’ve only needed to replace our zincs once, during her initial survey in 2007, I’ve forgotten many details.  Before rushing to judgment, about only replacing

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