Ok, I have had the boat in Saltwater since March, should the zinc already be sacrificed away this quickly??
Zink life has all to do with electrical conditions. Sounds like you or some thing arround you is charging up the water. May not be a good idea to go in the water.
Jim
Yes. Zinc's go so much faster in salt water than fresh. In the brackish water of my marina in the Chesapeake they usually last a season. 3 months in salt water on the trip south, diver checked while he was doing a neighbors boat....said it was totally gone.
If you were getting 3 months out of 1 zinc, would you get 6 months if you installed 2?
Assuming that's not a facetious question, no. It's not linear.
It was a serious question. Would you get longer than 3 months or would both deteriorate in 3 months? Usually get 4 maybe 5 months with a zinc. Some years keep the boat in the water during the winter. Was just wondering if I installed 2 zincs, could I get the remaining 7-8 months out of them?
As Ken Juul said, it depends on the water you're in, the "activity" of boats around you, and in some cases the phases of the moon! :abd: I've been in the same marina with the same neighbors (pretty much) for the past 16 years and have seen significantly various zinc longevity. There simply is no way to tell in advance, hence, a diver service is very useful, 'cuz if your zincs are gone and you don't know it, guess what happens? A diver service will deal with one zinc, two ain't gonna make it any better, and the point could be made that one zinc deteriorating rapidly and being noticed is more beneficial than trying to "hide" a situation with more zincs.
I added a galvonic isolater in my boat to stop eating zincs. I was putting on 2 thinking it would last longer. Not the case. I asked the owner of the "yard" here who said he thought that adding extra zinc accelerated the problem. Just what happened to me.