Electrolysis and Galvanism Electrolysis is a word that is badly abused by boaters who don't really know what it means, so let me correct this right now. First, understand that all boats have an electrical potential. That's because of all the different metals on the boat which, themselves have differing electrical potentials. This is exactly the same principle that makes a dry cell battery generate electricity. This electrical potential is called galvanism and is the reason why we put zincs on boats.
Electrolysis is stray current escaping from the system and is most damaging.
It is an abnormal condition. When this happens, it will eat up the zincs in no time, usually leaving that metal looking bright and shiny. I spent two years putting a meter on every boat that was hauled for survey. Zincs will erode rapidly and underwater metals begin to be affected. The single largest cause of problems with shore power systems results from failure to maintain the connectors on both the cord and the boat connectors.