Electroplating while sitting in water..... ?

Discussion in 'Metal Boat Building' started by parkland, Oct 30, 2012.

  1. parkland
    Joined: Jul 2012
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    parkland Senior Member

    I have been searching with zero answers,

    Why could a person with a metal boat, put nickel or another corrosion resistant metal in the end of a cable, hang it in the water, and hook electricity up to the boat and the cable, so that electrolysis occurs right in the water, and a metal boat hull becomes plated with a resistant coating?

    It works on a small scale.

    It seems that would "one up" a sacrificial chunk of zinc.
     
  2. michael pierzga
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    michael pierzga Senior Member

    Well...when you haul your boat for antifoul you will notice many tiny Black metal depoits on the copper antifoul and bronze prop. Deposited by the anodes.
     
  3. Frosty

    Frosty Previous Member

    They do not connect the wire to the battery. The zinc on the wire is making Dc current not much but enough to combat the flow the wrong way. So the wire is connected to the part you want to protect. I have massive prps and 2x 2 inch shafts . I need so many zincs I attach them to wires and hang old zincs over the side . The wire is connected to the shaft brush so protecting the shaft and prop. Over the years I have now got a good ballance. As I am all fibre glass I have nowhere to put more zincs even though I have 2 0n the rudders.

    I can eat up a shaft zinc ( the most expensive ) in a year . I feel that is acceptable.

    I have never seen black deposits on my props that I clean monthly from growth and haul every 3 years.
     
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    There are several reasons why it doesn't work:

    1. You cannot electroplate rust or paint, so the person should sandblast the boat before putting it in the water.
    2. Most metals can only be deposited by electrolysis if they are already present in the electrolyte as a salt.
    3. The metal ions should have nowhere else to go, so the boat must be put in a plastic bag.

    Small scale electroplating is done with a carbon electrode wrapped in cotton wool, immersed in the electrolyte containing organic salts of precious metals.
     
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  5. gonzo
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    gonzo Senior Member

    It does work. The system is sold under different names. For example, Mercruiser calls it Mercathode.
     
  6. Frosty

    Frosty Previous Member

    What the hell ---one guy is talking about electro plating and gonzo is talking about Mercathode with is a DC voltage made from the battery to protect engine parts.

    So I don't know what your talking about
     
  7. parkland
    Joined: Jul 2012
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    parkland Senior Member

    I understand the shortfalls of trying to electroplate in the water, such as the paint, rust flakes etc.
    But really, the process applies the sacrificial metal to the path of least resistance (bare metal, scratches), so I think it would still help a lot.

    I'm thinking like direct hooked to a 25w solar panel.

    It would do what is done already, just at an accelerated pace.
     
  8. jonr
    Joined: Sep 2008
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    jonr Senior Member

    You could look up "impressed current cathodic protection".
     
  9. gonzo
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    gonzo Senior Member

    A piece of nickel or silicon bronze over the side connected to DC is probably a home made system similar to a Mercathode.
     
  10. Frosty

    Frosty Previous Member

    But the voltage is critical, its not just 12.5 or 13.9 when running. There is a black box involved.
     
  11. gonzo
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    gonzo Senior Member

    Sure, the OP only saw the metal bar hanging on the side, so there is no way to know what or if it was connected to something.
     
  12. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Tell me there wouldn't be any environmental problems electroplating a boat while floating in public waters.
     

  13. P Flados
    Joined: Oct 2010
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    P Flados Senior Member

    A few years back I recall that we used to have a local firm that did commercial electroplating using item submerged off the side of a dock in our intracoastal waterway. With a closed loop DC circuit, the ions from the sacrificial surface are drawn to the exposed surface across the electrolyte gap. Plating is functional, but the results will not provide a lot of protection of the base material.

    I do not think this would work well for boating applications. To work well as a protective coating, the plating needs to be very uniform and to completely cover the surface that is to be protected. The resultant coating from a do-it yourself plating job will have lots of edges, gaps, porosities and generally in-complete coverage. This allows for concentrated attack at the edges followed by blistering and flaking of the plated surface.

    Although some protection may occur while the current is being maintained, the more simple use of passive protection (zinc) is simpler and has proven to be effective when implemented properly.
     
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