No Need for Prop Shaft Anodes in Fresh Water?

Our boat is now at a marina in fresh water and currently does not have any anode protection on the prop shaft. A barrel shaped anode will not fit on the shaft due to installation of a line cutter system. Just got off the phone with a leading marine corrosion company where I asked him about possible solutions and he said I didn't need any. I asked him about possible stray galvanic current in the marina either from your neighbors boat or stray current from shore power pedestals. He said not to worry about it. Am I nuts or is he nuts? Thanks for your comments!!

Based on the cost of a propeller I'd prefer some sort of protection. I use a shaft brush connected to the boats bonding system that seems to be working so far.

They make doughnut sharped zincs about 1 in thick. maybe that might fit.

I am in fresh water and have one magnesium anode on the shaft. While less conducive then salt water still fresh water is not pure water so same principle applies in salt and fresh water.

L

My anode does degrade in fresh water so I think it is doing something. I would not go without any protection. How about a shaft brush and hook it to yourbonding system?

A magnesium anode would be best. Aluminum would be good. Zinc isn't supposed to work although it does deteriorate and may be better than nothing.

Ted

My brother-in-law had to replace the shaft on his Great Lakes only boat due to aggressive corrosion. There had been no anodes on the shaft.

I use aluminum for anodes since I can’t get one size I need in magnesium. I do use magnesium in the engines and generator. I don’t use zinc as it does not work well in fresh water.