Alpha 1 Outdrive Anodes

[samsciacca]

I have a 1988 Alpha 1 (4.3LX engine) that I use only in fresh water. When I bought the boat, it had no anodes on the outdrive whatsoever and looked pretty clean. When I took the boat out of the water at the end of the season, I had some paint blistering with white residue. I did charge the battery a couple of times without and isolation. Did the charging create the problem or do I need anodes? If anodes, zinc or magnesium?