Anode Material

My Mercury dealer is selling Navalloy anodes. These anodes are 95% aluminum and 5% zinc. They're advertised as being able to be used in fresh, brackish, and salt water. Since I keep my boat in fresh water but often travel to brackish and salt water these anodes seem to be good for what I do. Does anyone have any experience with these? I've been using aluminum anodes and they seem to work well for the short time I'm in the brackish and salt water.

I have used them exclusively for the past 6 years with excellent success in fresh water.

Bennett