Normally a lurker on this list, since I don't own a C&C, but thought I'd post this link to a paper on corrosion issues by Stan Honey. http://honeynav.com/grounding-on-sailboats/
West Marine has a version of this on their website. From my perspective as a EE (but certainly not a corrosion expert), Stan's suggestions seem to sum up the issues and possible remedies pretty well. There is no perfect solution, particularly regarding stray currents. At my "hot" marina, I go through two oversized shaft anodes every 5-6 months. David Castor Port Angeles, WA On Mon, Aug 13, 2018 at 9:53 PM, ALAN BERGEN via CnC-List < cnc-list@cnc-list.com> wrote: > Hi Mike: > > A good book for you is Nigel Calder's "Boatowner's Mechanical and > Electrical Manual". In the book, it says: "All equipment should have an > insulated ground that leads back to a central ground bus bar in the main > distribution panel, which in turn leads to a common ground point or bus." > In other words, don't connect one ground to another, and then to the ground > bus. Each piece of equipment must have it's own ground going to the ground > bus. > > Alan > > > On Mon, Aug 13, 2018 at 4:25 PM, Mike via CnC-List <cnc-list@cnc-list.com> > wrote: > >> Hi Alan >> >> >> >> The readings I posted are at anchor in the Thousand Island area. I >> almost never plug in during the cruising season. I only use shore power to >> charge the batteries during winter layup when the solar and wind are >> removed, every 6 to 8 weeks >> >> >> >> So today I did more testing. I disconnected the positive cable for the >> start battery and I still saw 0.02V at the prop shaft. So I ruled out that >> as an issue. I disconnected the battery charger and still saw voltage. >> Next I took the wind generator out of the equation and the results were the >> same. Next I disconnected the windlass, same results. Next I moved inside >> and checked for voltage on the tube for the centre board pendant. Saw 0.25 >> V. I removed the positive cable to the house electrical panel. Still saw >> voltage. >> >> >> >> Am I doing this right. My memory tells me that the way I’m testing might >> be creating some kind of battery but my memory might be tricking me. >> >> >> >> Could really use some help from any electricians or corrosions specialist >> out there. >> >> >> >> >> >> Mike >> C&C 37 K/CB Shoal draft >> Persuasion >> Stormont Yacht Club >> >> >> >> *From: *ALAN BERGEN via CnC-List <cnc-list@cnc-list.com> >> *Sent: *August 9, 2018 5:23 PM >> *To: *C&C <cnc-list@cnc-list.com> >> *Cc: *ALAN BERGEN <trya...@alumni.usc.edu> >> *Subject: *Re: Stus-List Galvanic corrosion >> >> >> >> You can use aluminum anodes in fresh water. That's what I use. They're >> cheaper than magnesium. >> >> >> >> To test for stray currents, borrow a clamp on ammeter. Then check the AC >> line supply for your boat, and for the boats in nearby slips. The ammeter >> should read zero amps. Use the lowest scale, as stray currents could be >> pretty low. If the reading isn't zero, some of the current is finding a >> return path, other than through the AC supply line. >> >> >> Alan Bergen >> >> 35 Mk III Thirsty >> >> Rose City YC >> >> Portland, OR >> >> >> >> >> >> On Thu, Aug 9, 2018 at 6:01 AM, Mike Taylor via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >> Hi Bob >> >> >> >> I started the season with 1.5 anodes. I’m in fresh water, Lake Ontario >> and St. Lawrence river. I believe I have the correct anodes for fresh >> water. I really don’t want to go the galvanic isolator route >> >> >> >> Mike >> >> >> On Aug 9, 2018, at 12:04 AM, Robert Boyer via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >> What is the condition of your shaft zincs? >> >> >> >> Are you in fresh water or salt water & do you have the correct zincs for >> the type of water your boats in? >> >> >> >> Sounds like you may need a galvanic isolator... >> >> >> >> Bob >> >> Bob Boyer >> >> S/V Rainy Days (1983 C&C Landfall 38 - Hull #230) >> >> Blog: dainyrays.blogspot.com >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__dainyrays.blogspot.com&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=fJAQMdpX2dTSopdOWc3l9uX5S1WMFKlmsA86BrWxBCw&s=Wa3qqugmtpAwXVFKMv4mxeeuUh8qI-Q-QEkwBjxxvQo&e=> >> >> Email: dainyr...@icloud.com >> >> Annapolis, MD >> >> >> On Aug 8, 2018, at 8:10 PM, Persuasion37 via CnC-List < >> cnc-list@cnc-list.com> wrote: >> >> >> Hey folks >> >> >> >> I’m looking for some help. Persuasion is suffering from galvanic >> corrosion or stray current corrosion or something. When I connect a multi >> meter, ground to engine and positive lead to various place like keel bolt, >> mast and through hull I see ~0.5V. Today I changed out the controller on >> the wind generator, with the circuit breaker open I saw 2.4V on the battery >> leads. Also the prop shaft was tarnished looking as well as the prop when >> I hauled out to do the centre board. >> >> >> >> Before I call in the calvary can anyone advise me how to tackle this >> methodically and what I should look for. >> >> >> >> >> >> Thanks in advance >> >> Mike >> >> PERSUASION >> >> C&C 37 *(k/cb) *shoal draft >> >> Long Sault >> >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each >> and every one is greatly appreciated. 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Each >> and every one is greatly appreciated. If you want to support the list - >> use PayPal to send contribution -- https://urldefense. >> proofpoint.com/v2/url?u=https-3A__www.paypal.me_stumurray&d= >> DwICAg&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7 >> Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=c8oAg3HufEQQhnh3c0T >> UBiMhBe_f6MUw10PjHiFfa0w&s=o2DCU1_NuNDtcks9SUOkET3y4RHvykWw6MSK4trVGuI&e= >> >> >> > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > >
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