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Paint flaking at raw water pick-ups

Discussion in 'Technical Discussion' started by RRIPP1, Jun 26, 2012.

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  1. RRIPP1, Jun 26, 2012
    #1
    RRIPP1

    RRIPP1 New Member

    Joined:
    Oct 27, 2010
    Messages:
    7
    Location:
    SF BAYAREA
    I have a 38' sport fisher that I am in the process of restoring. Last year (Aug) I had the boat hauled and the bottom painted. I have a diver that cleans and checks the hull about every 4 months. He noticed that around the aft raw water pick-ups the paint is flaking. These raw water pick-ups are for the bait tank pump and the wash down pump. The raw water pick-ups for the engines are fine. I'm thinking this is from stray current. I have been totally through the DC rewired and installed a new panel. AC I'm still working on. Would a galvanic isolator help? If anybody got any suggestions, I need help

    Thanks
    Jim
  2. Bill106, Jun 26, 2012
    #2
    Bill106

    Bill106 Senior Member

    Joined:
    Jan 9, 2010
    Messages:
    390
    Location:
    Beaufort NC
    If she's still overboard during your refit, a check with a silver chloride meter is definitely in order. It is a simple test and will easily tell if there's a stray current issue. Hopefully they are bonded already, if not they definitely should be!

    It is a pure guess at this point but I've seen far too many underwater fittings "just" painted with bottom paint and not properly prepped meaning sanding/blasting, etching if applicable and whichever primer is recommended by the particular bottom paint brand you're using. Anything less and the paint will flake of in short order.

    Any boat with a shore power cord should have either a galvanic isolator or an isolation transformer. At 38' you will probably be better off with the isolator though as the weight and size of a transformer is a pretty significant addition.