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Anti Corrosion system

Discussion in 'Technical Discussion' started by Highlander, Apr 22, 2008.

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  1. Highlander, Apr 22, 2008
    #1
    Highlander

    Highlander New Member

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    Hi guys

    I have an "impressed current system" that monitors the voltage of the water vs the boat and somehow adds or subtracts from that to protect the expensive aluminum bits in the water. It has a titainium reference pad and another pad that looks like zinc.
    Last season the indicator lights showed "under protected" and the normal zincs wore very rapidly. Usually they dont wear much at all.

    Over the winter all the connections were checked and cleaned and now- as the boat sits in Rhode Island the light shows green.

    Two weeks ago the boat was tied up at our normal home dock and the lights started flickering green-red.

    The question is where do you start? I assume that the dock power system or a nearby boat can cause the problem. How far away can a boat be and cause corrosion problems to my boat?
    Can you measure a voltage from the dock ground to the water?

    The problem can also come from my boat? Would a similar aproach to the ground fault question be valid?

    Thanks

    Carl
  2. Garry Hartshorn, Apr 22, 2008
    #2
    Garry Hartshorn

    Garry Hartshorn Senior Member

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    I had to deal with a similar issue a few years ago, I would suggest the following to help begin tracking down the problem.

    1. What brand of equipment is installed

    2. What happens when you move the vessel

    3. Are the readings the same when docked, at anchor and underway.

    4. Is it possible that the insulation between the Cathode's and hull is damaged or not working effectively
  3. Marmot, Apr 23, 2008
    #3
    Marmot

    Marmot Senior Member

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    Without really meaning to sound glib, the first place to start is by reading the manual for your cathodic protection system and determine just what the indicators are trying to tell you.

    If you don't have a manual, contact the manufacturer of the system and ask their technical people to explain how the system works and at the same time order the manual.

    Then, find a textbook on marine corrosion protection, or since you have an internet connection, search on those keywords.
  4. Highlander, Apr 24, 2008
    #4
    Highlander

    Highlander New Member

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    Location:
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    corrosion

    Hi guys,

    The unit has three lights, one green and two red- over protected and under protected.
    The electronic controll measures the potential of the boats metal parts relative to the water and inpresses a corrective current. It is supposed to work without any passive zincs but my boat has them as a backup.

    At one dock the light is green. At another dock the light is red- underprotected. I will be doing tests this weekend.

    All the electrodes/cathodes are mounted on the transom and have no effect underway.

    The owner of my marina has not heard of this technology. Is this unusual?
    Ted Hood specified the device and even Hinckley ,using the same Hamilton jets, does not use it.

    Carl
  5. Garry Hartshorn, Apr 24, 2008
    #5
    Garry Hartshorn

    Garry Hartshorn Senior Member

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    Sounds a bit like an ELECTROGUARD system which I have a manual for but we need more information. It is also my understanding that you can not have a passive and active system installed on the same vessel as they will counter each other out.
  6. winesk, Apr 27, 2008
    #6
    winesk

    winesk New Member

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    I have recently installed a Pro Mariner monitor that sounds like the one you describe and have found the same problem. My probe is on the bottom of the boat, probably about 3 feet below water. The unit shows all three lights as green and periodically shows the Underprotect light as red. After a while it retests itself and returns to green. I have tested using an analog meter and the boat is well protected (in the 8 range).

    The boat is in salt water but is subject to some fresh water from a nearby creek but I don't think that is having any impact. Have note had an opportunity to see what happens under way or at a different dock.
  7. Highlander, Apr 28, 2008
    #7
    Highlander

    Highlander New Member

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    Location:
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    Garry,
    Yes that's it. Electro Guard.
    After a bit of testing, an interesting thing popped up.
    At the same dock that previously showed a red -under light- now shows green-safe.

    Milford harbor does not have much current, it is fed by a small stream but the marina owner said that in the spring the runnoff from up state can reduce the salinity at the dock.

    To test this I ran up the Housatonic river at low tide. Anchored in the river, the indicator showed red-under then changed back to green outside the river mouth.

    Winesk- that may be what is happening to you.

    I have noticed this before but only when way up a big river like the Connecticut.

    I am hoping that my problems from last season have been fixed and this is a spring runnoff issue only.

    All in all the Electro guard unit does give you advanced warning of problems before they get expensive.

    Thanks, Carl