Opinions on my anode location plans please.

Discussion in 'Boat Design' started by rsimon, Jan 6, 2012.

  1. rsimon
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    rsimon Junior Member

  2. CDK
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    CDK retired engineer

    So you have an epoxy coated aluminum hull with an aluminum outboard....

    As long as you keep shore power ground isolated from the hull, all you need is a small zinc nut or ring on the stainless outboard prop shaft.
    If the stainless bolts for the 'anodes' are already in place and cannot be removed, coat them with a durable compound and put plastic caps over them. They are the only enemies of your hull.
     
  3. gonzo
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    gonzo Senior Member

    Passivated stainless would be better. The difference in price shouldn't be too great.
     
  4. michael pierzga
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    michael pierzga Senior Member

  5. CDK
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    CDK retired engineer

    No Gonzo, annealed, passivated or even TiN coated doesn't matter here, only the chemical composition counts.
    The stainless steel is much more noble than the aluminum, so at the first scratch in the epoxy coating, the hull will become the sacrificial electrode.

    Of course zinc could be used here, but isolating or removing the bolts is cheaper and more effective.
     
  6. gonzo
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    gonzo Senior Member

    It is my understanding that passivated stainless steel is non-reactive.
     
  7. CDK
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    CDK retired engineer

    The process removes traces of iron and carbon left by the cutting tools and yields a homogenous oxide layer. It also enhances the general appearance and makes cleaning easier when used for kitchenware etc.
    Electrically connected to a less noble metal and submerged in an electrolytic solution it behaves just as untreated stainless does.
     

  8. viking north
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    viking north VINLAND

    I.E. it's still a conductor regardless and as such will act to complete the closed circuit.
     
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