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Old 07 December 2005, 19:02   #1
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Electrolysis - How far?

I have a non RIB technical question regarding electrolysis. We have all heard of wrongly electrically connected boats in marinas causing serious damage to surrounding shafts etc through acting as sacrificial anodes, but has anyone on the forum any idea as to roughly the maximum distance other boats can be affected? Or is it purely to do with the amount of current discharging into the water. I have known of boats affected within a 20-30' radius for example, but is this the maximum?

Your assistance would be appreciated.
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Old 08 December 2005, 06:23   #2
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ttt
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Old 08 December 2005, 07:39   #3
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A lot would depend on the type of water it is in - ie it's salinity and also how still the water is - massive difference between a small closed marina and a big one with loads of water movement.
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Old 08 December 2005, 08:03   #4
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[QUOTE=codprawn] A lot would depend on the type of water it is in - ie it's salinity and also how still the water is - massive difference between a small closed marina and a big one with loads of water movement. [/QUOTE

Salinity - Salty, Marina - British. Water Movement - Average. Pontoon Space - Average. Harbourmaster - Grumpy. Grey Mullet - Abundant. Electrical Supply - Shocking. Anodes - Fkd.
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Old 08 December 2005, 08:13   #5
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Quote:
Originally Posted by hard1
I have a non RIB technical question regarding electrolysis. We have all heard of wrongly electrically connected boats in marinas causing serious damage to surrounding shafts etc through acting as sacrificial anodes, but has anyone on the forum any idea as to roughly the maximum distance other boats can be affected? Or is it purely to do with the amount of current discharging into the water. I have known of boats affected within a 20-30' radius for example, but is this the maximum?

Your assistance would be appreciated.
My wife has electrolysis treatment, 15 a go, can I attach her to the hull and obtain the same results?
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Old 08 December 2005, 08:18   #6
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Originally Posted by fred bolton
My wife has electrolysis treatment, 15 a go, can I attach her to the hull and obtain the same results?
Is that the same as the Electrotherapy I have to undergo as condition of my "Care in the Community" status?..... perhaps I could tell 'em I'm going to live on a boat?... All this electrickery makes my hair stand on end..and I can't do a thing with it.....
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Old 08 December 2005, 08:28   #7
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Thank you for your replies. I thought there might be someone on this forum who knows something about marine electrolysis - a friend has suffered serious damage to shafts and P brackets and suspects the presence of a dumb lighter in the marina, which has electrical power to welding sets and zero anodes as the likely cause, but has been faced with denials by marina officials and the barge owners. He is looking at repair bills in the order of '000's even though his boat is correctly protected as verified by a marine surveyor. I hasten to add that this is not local to me (we have several dredgers and barges in local marinas as I speak).

This seems to be a growing problem in the UK. I just wondered if there was any similar experiences out there, as an aluminum outboard/outdrive leg on a RIB would be eaten in double quick time given the same circumstances, and how would one check, verify and protect against such likelyhoods.
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Old 08 December 2005, 08:43   #8
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Try talking to a good surveyer. The efficiency of your cathodic protection can be measured and checked. I believe that Aluminium can be "over protected" which can also cause big problems. I don't in anyway claim to have any knowledge of the "mechanics" of it all, but it's worth searching for the information. I looked because I was half interested in building metal boats at one time.....
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Old 08 December 2005, 08:50   #9
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Here's a Yank paper on it. It's talking about AC marina systems but you'll notice that they talk about being connected to "every boat in the marina" not physical distance.... Are the welding sets powered off the Marina electrics or are they welding generators?

http://www.boatus.com/seaworthy/galvanic/default.asp
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Old 08 December 2005, 09:03   #10
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Quote:
Originally Posted by Jono
Here's a Yank paper on it. It's talking about AC marina systems but you'll notice that they talk about being connected to "every boat in the marina" not physical distance.... Are the welding sets powered off the Marina electrics or are they welding generators?

http://www.boatus.com/seaworthy/galvanic/default.asp
Fantastic site. Thanks and it explains a lot, I'll forward it on to my mate. The welding sets are powered from the Marina electrics, and it looks as if he may have an insurance claim, either his or theirs if the survey report on his install holds up. It is also worth noting (for the benefit of members who keep their boats in marinas) that often, the berthing contract small print carries and indemnity against these events but I'm sure there's a "duty of care" issue which may override it.
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