when you put 2 dis-similiar metals in solution you create a battery, the anode is a self sacrificing metal that gets eaten up before the other metals.Mercathode is an electrical system that induces a counter voltage effect to offset the battery potential of the different metals in solution.
In a boat engine (outdrive), you have steel and aluminum . . . put that in water and you get electricity. The 'weakest' metal looses the 'galvanic' battle. So, by introducing a third metal that is 'weaker' than steel or aluminum, the engine is saved from destruction.
This is interesting ....I checked out the above link, wow, talk about an education. I didn't know that they played such an important role not only in safety, but in anti-corrosion of components as well. So from what I read that for fresh water use only....magnesium would be the correct type of anodes to use?
