Life of Zincs

[Trojan]

Bill after rereading your post and looking at your pictures. I don't think that I would make judgment on the conditions of your zincs on how they got that way or how long it took. Since you admit that you had electrical problems in the past. You can never predict, guess the amount removed from the zincs when the trouble occurs. It's just a crap shoot. I would change them out and watch them next spring.

BILL

[yachtsmanbill]

I agree Bill. I get twenty years out my zincs on the Roamer here. Actually the rudders are original (1963). I removed the CAPAC years ago, it turns out it was protecting the steel dock with the boat as the sacrificial anode!
I had to drop a silver chloride half cell in the water and measure (500Mv) that the zincs were producing to protect the boat. FWIW I had to do the math and deteremined it took 120 lbs of zinc to produce that much current.
Once again, check out Yacht Corrosion Control Consultants for a bevy of info! ws

[Nonchalant1]

I got 4 years on zincs in freshwater, and then had to change them after 3 months in saltwater (gulf and keys). We stayed in many marinas and some probably had stray current in the ground wires. Interestingly, it was only my shaft and prop zincs... the engine and genny zincs were still good.

It also matters whether you have isolation transformers or not. If yes, you'll need fewer zincs.

Doug