Could be you got a fresh/brackish water zinc vs one for salt. I don't remember the base metals but I'm sure Norm will respond. Bob PDQ 36 Peace
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Peter Kafer Sent: Monday, October 26, 2009 5:47 PM To: [email protected] Subject: [Liveaboard] Lifespan of zincs I recently had an interesting experience with my prop shaft mounted zinc. It had been on the shaft for 22 months and had replaced an earlier zinc that had been on for only 4 months. The zinc that the present zinc replaced had been badly corroded, nearly half eaten away. During the 22 months that the present zinc was on the shaft, I had a diver check it periodically and he consistently told me that it was in fine shape. Finally, after 22 months I decided that I would have him replace it with a new one. When he gave me the old one, I could hardly believe it, it was almost in brand new condition, even sporting the original price tag! It was a bit spongy in a couple of places where I could dig out some of the material with a fingernail. It had obviously been making good electrical contact with the shaft. It was the same brand as the one it replaced 22 months earlier. Why such a long life? Admittedly, I am rarely hooked up to shore power for more than a week or so at a time--maybe a total of one month over the past 22 months. The boat has, however spent most of the past 18 months in a marina. The only thing that is different about the two zincs is that I installed a galvanic isolator shortly before installing the one that lasted for so long. Since the boat spends so little time hooked up to shore power, I wouldn't think that this would have a great impact. Is it normal for zincs to last so long? Most people in my marina say theirs last from as little as 2 months to as much as 6 months. Peter s/v Now or Never!
_______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
