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Old 27-09-2008, 10:48   #1
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Corrosion

When Esconditas was tied up to a Marina and hooked into the electrical grid, The Zincs lasted or 1 1/2 years with little degradation. Last May we took off and started out on a cruise. Money is tight so we spend most of the time (96%) on the hook. in the last 5 months the zincs have been used up. The anchor chain is starting to rust like mad, Over night the chain will develop a layer of rust on the portion of the chain that is under water but not on the bottom. The rust washes off using the wash down pump. The chain in contact with the bottom has a black coating that is near impossable to get off your hands without using Go-Joe hand cleaner. (That may have come from anchoring in Staten Island NY.)

So whats going on. Now that I am not hooked up to the grid, and every other boat in the marina, why are the zincs fizzing off the boat? I am using the SSB more, but would that cause the zincs to be used up. Does operating the boat every day, every other day, have an effect on the zincs?

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Old 27-09-2008, 11:07   #2
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That is a little strange, usually you hear the opposite. Some boats are better without the thru hulls bonded. You may be under zinc'ed. are you running a generator? I'm not sure 5 months is too unusual for some boats. where are your zincs? shaft only? rudder and shaft? etc. I use to snorkel down and change the shaft zinc occasionally. You may have just been in a lucky situation at the dock. Maybe the shoreline balanced everything out....
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Old 27-09-2008, 14:09   #3
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I don't think that I am under zincked. All of the zincs are on the shaft and skage. I have a Max Prop that has it's own zinc, with a donut zinc on the shaft next to the prop and two egg zincs on the shaft and a flat 3 inch on the skage. The through hulls are bonded. And the only gen set is a Honda 2000i. As I wright this I am in Portsmouth Va, and last week I dove on the boat and replaced all of te zincs. We plan to spend the winter in the Bahamas where the water is clear and the checking the zincs every other day is a probility.

One person I brought this up with suiggested that anchoring close by a "cable" area could cause stray voltage, but I don't know about that.
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Old 27-09-2008, 14:17   #4
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I would recommend going around all your connections to metal that connects to fittings that are submerged, and remove the cables, then get a meter on them to see what stray current is causing this.
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Old 27-09-2008, 22:51   #5
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Do you have a metal or a plastic hull?..just to make things clear.

A cable crossing would have nothing to do with it. I agree with Talbot. It's time to get out the multimeter and start disconnecting bonding wires, put the meter across the wire and the anode and start measuring for DC currents on the millivolt scale.
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Old 28-09-2008, 06:35   #6
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Plastic.... it's a Bristol 43.3
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