Bonding Or grounding in the engine compartment

Discussion in 'Electrical Systems' started by RhuntIII, Feb 14, 2012.

  1. RhuntIII
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    RhuntIII Junior Member

    I've purchased a wake board boat and I'm planning on running it in salt water. I would like to take every step in protecting my boat. I've purchased anodes for several metal parts that will be in direct contact with the salt water. One of the anodes is a hull type that the manufacturer sent. This anode bolts to the fiberglass hull. What does that protect? I've furthered my research and found that I should bond all metal parts (engine, trany, through hull fittings, etc.) in the engine compartment to one of the anode through bolts. Is this so and how would I go about doing this?
     
  2. michael pierzga
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    michael pierzga Senior Member

  3. RhuntIII
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    RhuntIII Junior Member

    A wake board boat is like a ski boat just the hull is designed to produce a larger wake. The engine is a Mercruiser 350 inboard and is cooled with raw water. Not a jet drive.

    Thanks for the reply Michael.
     
  4. Ike
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    Ike Senior Member

  5. michael pierzga
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    michael pierzga Senior Member

    Just as its possible to have to little anode protection its possible to have to much anode. More is not better. Always a good idea to be aware . Keep an eye on your underwater metalic parts and the anode wear rate.
     
  6. Ike
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    Ike Senior Member

    right. You want your anodes to be used up on an annual basis. If your anode isn't being used then you have too much, or something else is being eaten.
     
  7. CDK
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    CDK retired engineer

    Are we talking about a true inboard or a stern drive?

    The inboard doesn't have much in the water that needs protection, just a zinc nut on the prop shaft. A stern drive needs a lot more, but nowadays comes standard with zincs and a Mercathode unit.
     
  8. RhuntIII
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    RhuntIII Junior Member

    This Boat is a true inboard with a Walter v-drive.
     
  9. CDK
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    CDK retired engineer

    OK, you're lucky then.
    The zinc nut on the prop shaft will already be installed, if not, do so while the boat is still on the trailer. If the prop is stainless, the smallest zinc is enough.

    There probably also is a rudder that needs some protection. Again, if it is stainless steel, the smallest zinc is enough. If there is a mounting hole on the rudder, mount the zinc there, so you don't need any ground wiring at all.
     
  10. RhuntIII
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    RhuntIII Junior Member

    CDK,
    I spoke to the company that built the boat about running in salt water. They sent anodes for the rudder, the prop shaft, a trim tab and a hull type anode. "This is what we put on all are boats sent over seas." They said. I could understand all the anodes except the hull anode, it's through bolted in the fiberglass. What would that protect? I did some research on hull anodes and have found out that they are for bonding in the bilge and through hole intakes. My boat has bronze through hole intakes, water pumps for filling ballasts and of course the engine and transmission. Both engine, tranny, and exhaust are cooled with raw water. These won't need protection? The boat will be kept on a trailer and at the most left in the salt water for a weekend.

    Thanks to all you guys for the info
     
  11. michael pierzga
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    michael pierzga Senior Member

    I dont know small trailer boat systems. On bigger boats, all metal like seacocks are bonded together and ultimately protected by the anode. . Generally zinc anodes are for sea water and aluminum anodes for fresh.
     
  12. CDK
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    CDK retired engineer

    That the builder puts all this stuff on his boat doesn't mean it makes sense.

    In this case it surely doesn't. The hull doesn't take part in any galvanic process, you cannot protect it with electrodes.
    The bronze through hulls are best left "floating". My boat was built in 1980 and remains in seawater nearly all the time; the bronze through hulls have never been replaced and are still in good condition.

    The engine, exhaust and -to a far lesser degree - the gearbox will be subject to corrosion no matter how many lbs of zinc you have on the hull. Only internal zinc electrodes in the coolant circuit can postpone that, but I do not know whether or not Merc installs any or has plugs in strategic positions that you can replace with a zinc electrode.
    My own experience with Merc is limited to 3.0LX engines; they have no internal protection at all and are eaten by seawater within a few years, starting with the exhaust manifold and riser. For a boat on a trailer, flushed after every use, they of course last a decade or more.
     
  13. michael pierzga
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    michael pierzga Senior Member

    Even on big boats we contrust a flush fitting on the seachest to flush seawater from all systems before storing for winter. Take a short time, costs little and it works
     
  14. RhuntIII
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    RhuntIII Junior Member

    CDK & pierzga,
    Thanks again for the info. I do agree with you on the hull anode. I've already installed a flush kit on the engine and will be flushing after every use in the salt water. It's just this hull anode they sent me that has me torn. I think I'll be leaning towards no hull anode and thorough inspections of the through holes when washed after salt water use.
     

  15. georgepetsas
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    georgepetsas Junior Member

    Would this be a good idea on a 80 ft steel hull that sits at the dock for a month at a time. Considering you have the time. And if so after fresh water flushing could you turn the flush fitting back to excepting sea water and not have it dilute the fresh water in the system?
     
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