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#11
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Cleaning Zinc Anodes
Rich,
No, it does not. The problem in your neighbor's boat affecting your boat IS the common bonding. Without that, there is no circuit! Secondly, a ground isolator is not a cure, it is an inhibitor because the leakage current through that diode is still very damaging. These measures only address stray current corrosion. Galvanic corrosion on the other hand, causes identical damage, but is caused by dissimilar metals in a common electrolyte and sacrificial anodes are another band aid, not a cure. These anodes can actually encourage galvanic corrosion. This is a very complex subject and if you are suffering from this, the goal should be elimination, not a band aid. On another point, there is a lot of advise out there in print that is either incomplete or unadulterated b-ll s---t and propagating it without a thorough understanding does no one any good. Steve "RichH" wrote in message ... Opppps, Brain Fart !!! Zinc (-1.0v) less reactive than Mg (-1.6v). Still the rest applies: galvalnic isolator, common bonding through the AC ground, reference cell, etc., etc. |
#12
posted to rec.boats.cruising
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Cleaning Zinc Anodes
On Aug 21, 12:19*am, "Steve Lusardi" wrote:
Rich, No, it does not. The problem in your neighbor's boat affecting your boat IS the common bonding. Without that, there is no circuit! Secondly, a ground isolator is not a cure, it is an inhibitor because the leakage current through that diode is still very damaging. These measures only address stray current corrosion. Galvanic corrosion on the other hand, causes identical damage, but is caused by dissimilar metals in a common electrolyte and sacrificial anodes are another band aid, not a cure. These anodes can actually encourage galvanic corrosion. This is a very complex subject and if you are suffering from this, the goal should be elimination, not a band aid. On another point, there is a lot of advise out there in print that is either incomplete or unadulterated b-ll s---t and propagating it without a thorough understanding does no one any good. Steve "RichH" wrote in message ... Opppps, Brain Fart !!! Zinc (-1.0v) less reactive than Mg (-1.6v). Still the rest applies: galvalnic isolator, common bonding through the AC ground, reference cell, etc., etc.- Hide quoted text - - Show quoted text - OK ... I've read thru the posts, and now I'm MORE confused than ever. A bit of background; my previous vessel had been stored in the very same lake we visit from time to time (Summersville, WVa). When I plopped it into the Kanawha River, it seemed the zincs didn't really do a great deal, more the lower end of the outdrive took the hit. So now I have this brand new vessel (2007 260DA) .. don't know if the "zincs" are Zinc or Magnesium .. I'm guessing Zinc, but you know what guessing does. I've cleaned the gunk off 'em with a small steel brush, down to the shiny. I expect I'll replace 'em when I pull the vessel out of the water for winterizing, but that still doesn't answer the questions in my mind. 1) I have Sea Ray's Galvonic Isolator (standard install) .. 2) if I have troubles with shore power in my slip, what's next? I can't very well leave the vessel unplugged, can't very well dictate the wiring practices used by the marina. What's next? And thanks! ~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~= john burton Bach 50B3 Bass Trombone Kanawha Valley Community Band / Slide-by-Slide South Charleston, West Virginia |
#13
posted to rec.boats.cruising
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Cleaning Zinc Anodes
On Aug 20, 10:50*pm, RichH wrote:
Opppps, Brain Fart !!! Zinc (-1.0v) less reactive than Mg (-1.6v). Still the rest applies: galvanic isolator, common bonding through the AC ground, reference cell, etc., etc. , while you are plugged in to shore you are only using a very small amount of current; just say, a few watts an ISOLATING transformer might be the answer? The transformer might not handle anything really heavy but a small trickle charger to keep up the battery only takes a few a watts on the AC side. For example 12 volts at say 3 amps = 36 watts. That's no more than some laptops, or a model train set! However to run a fridge all the time might require 360 watts. That's still not that impossible except that the transformer must be bigger/ heavier. And it must be able to handle the starting loads of a fridge compressor. An Isolation transformer has completely separate input and output windings. So that it prevents the flow of electricity from even the 'ground' system on shore, which is also most likely, connected to other boats etc.; through the metal parts of your boat into the water. Even so called freshwater is slightly conductive. Also if you have two dissimilar metals on your boat which are connected together electrically both being in the water you have an electrolytic cell. See note. Current will flow, even so slightly and the less noble metal will slowly corrode. Some early batteries, now called 'Alkaline cells' were invented by LeClanche. They consisted of a glass jar with a weak alkaline solution of water and sal ammoniac. The positive electrode was usually a carbon rod which did not suffer any erosion. The negative (and less noble) electrode was zinc and if was consumed and eaten away. Back then people could go to a hardware store and buy new zinc (which was sometimes used for roof flashings anyway) and the stuff to mix with water to make the alkaline electrolyte. A similarity to two metals on a boat. There are two likely conditions. 1) Leakage through boat into the water and/or other boats with their leakage into the water going to ground through YOUR boat. 2) Electrolytic corrosion on YOUR boat regardless of whether it is l plugged in to shore. So for example a zinc (or magnesium) clamped and in metallic contact to say an outboard is designed to be eaten away, thus protecting the metal outboard motor from being eroded. |
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