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Old 09-16-2014, 02:00 PM   #21
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I've had great success with BoatZincs.com (978-841-9978) – The Online Superstore for Zinc Anodes

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Old 09-16-2014, 02:13 PM   #22
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Its a long treatise that most wont understand or believe. Bonding is a holdover from wooden boat days and has no place on modern fg boats. Read Nigel's books. I assume that most of us here would consider him an "expert". Dont just read it, try to really understand it, study it. When you actually "know" what it says and means you will understand bonding, and why its a bad idea. BTW, his personall boat is unbonded, just like mine, with no adverse effects.
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Old 09-16-2014, 02:22 PM   #23
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The European theory on bonding underwater metalsoften is the opposite of ours.

They believe that an unbounded bronze underwater thru hull that's totally isolated is in little danger of dezincification. P148 of Nigel Calder's second edition of Mech and Elect Manual...if interested.

I have seen plenty of examples of this and believe bonding is necessary for only some parts and certainly there needs to be a good grounding system for AC systems and bleeding off unwanted RF and lightning potential.
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Old 09-16-2014, 02:45 PM   #24
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Bonding is totally different from grounding or lightning dissapation. The only reason there is a requirement for bonding is to prevent delignification of wood around thru hull fittings on wooden boats. PS, what parts do you think need to be bonded ? I am a proponent of no bonding of underwater fixtures at all, but, I've been wrong a couple of times this year already.
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Old 09-16-2014, 04:30 PM   #25
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Any part that is not totally isolated from another that has dissimilar metal or the possibility of electric current or is in close proximity (say less than a couple feet) to others that do need bonding.

Shaft and prop, due to proximity the rudder...after that not much but the smart thing is to check each fitting with a silver/silver chloride electrode...

Corrosion Reference Electrode Product Specifications
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Old 09-16-2014, 05:24 PM   #26
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Our last sailboat, a Pearson, wasn't bonded. Came that way from the factory. The surveyor noted it as a deficiency, so the insurance company wanted us to bond everything. I directed the insurance company to the chapter in Calder's book, and they removed the requirement. His analysis made total sense to me. Seven years and we never had a single problem, yet several boats with aluminum outdrives in our marina had serious issues. I chalk it up to the fact that we only had bronze and stainless in the water, so the outdrive boats acted like our zincs (which, by the way, eroded very, very slowly). Not sure if it made a difference, but I did install a galvanic isolator on that boat. Anyway, that said, our current Nordic Tug is bonded, and we have decided to keep it this way. So far, no issues, yet one of my friends in the marina just spent 20K replacing outdrives and transome plates on his boat (aluminum parts).
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Old 09-16-2014, 08:12 PM   #27
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If your shaft is isolated from the engine with a "drive saver" type of device that is non conductive the only requirement for a sacrificial anode is due to the SS shaft and bronze or nibral prop. Even without the non conductive device (which just removes the batteries from the shaft) the protection is for the prop. If the rudder (s) are also isolated (read not bonded) they cannot influence the shaft/prop electrically. Insurance Co.s require bonding, and some still do, because wooden boats were sinking at the dock regularly due to delignification around underwater (thru hull) metal, mostly bronze alloys. This was back when dock side power was first starting to be utilized on boats. This was caused by the fact that wet wood is a semicondutor, and ferro resonant battery chargers used then were non or poorly regulated compared to better chargers today. La Marche comes to mind. The excess dc current had to go some where and the nearest and most conductive path was it. Tie everything together and give it more paths instead of just one best path. It worked, albeit kinda round about. But I am coming to grips with the fact that most folks have there minds made up and dont want to be confused with facts.
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Old 09-17-2014, 12:12 AM   #28
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Back to the origional post, and please talk to me slooooowly as this talk of bonding and isolation has worn out the google on my device.

I move back and forth mooring 7-8 winter months in fresh and 4 - 5 summer months in the salt. What anode for me?

Thanks
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Old 09-21-2014, 12:07 PM   #29
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Back to the origional post, and please talk to me slooooowly as this talk of bonding and isolation has worn out the google on my device.

I move back and forth mooring 7-8 winter months in fresh and 4 - 5 summer months in the salt. What anode for me?

Thanks
IMHO, best applications regarding anodes: Salt = Zinc / Fresh = Magnesium

Caveat: I believe that zinc is OK for freshwater (many will disagree with this) as long as you dive under and scrape and wire brush scrub (bronze BBQ brush with scraper end works well) its surfaces clear of any build-up that occurs on zinc in freshwater. Scraping should happen at least in 3 month or sooner increments. From freshwater months-time you mention above... looks to me that once in mid freshwater time and at very end would suffice. More zinc surface cleanings is always better.
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Old 09-21-2014, 12:28 PM   #30
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Originally Posted by kulas44 View Post
Even without the non conductive device (which just removes the batteries from the shaft) the protection is for the prop. If the rudder (s) are also isolated (read not bonded) they cannot influence the shaft/prop electrically. Insurance Co.s require bonding, and some still do, because wooden boats were sinking at the dock regularly due to delignification around underwater (thru hull) metal, mostly bronze alloys.
My boat is un-bonded, no zinc plate from the factory. Two shaft zincs on each shaft, a zinc on each rudder and one pencil zinc in each cooler. I re-zinc every year and am running the original shafts, props and rudders. I suppose it depends on your marina and the local environment, but I believe many fiberglass boats are way over zinc'd.
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