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Shaft zincs keep falling off

Discussion in 'Props, Shafts & Seals' started by incoming, Oct 12, 2025.

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  1. incoming, Oct 12, 2025
    #1
    incoming

    incoming Active Member

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    I’ve been struggling with keeping my shaft zincs in place. Never had the problem with other boats. I’ve tried the 4 bolt and the 2 bolt zincs and keep having the same problem - they slide down the shafts after a few hours of running, making me worried about damage to my cutless bearings, then eventually fall off. Anyone have a solution for this? I believe my shafts are 2.5”.
  2. Capt Ralph, Oct 12, 2025
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    Installed on land or by a diver.
    Shaft polished clean before the new install or just where the old zinc was??
    With a BFH*, driving the contact brass button in and re-tightening?
    Quality zincs?
    Checking the screws every cleaning?

    * Big Freaking Hammer
  3. DOCKMASTER, Oct 12, 2025
    #3
    DOCKMASTER

    DOCKMASTER Senior Member

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    As CR mentioned, you have to smack them pretty good with a hammer to make sure they seat well. Then tighten the bolts and smack again then a final tighten of the bolts. A drop or two of loctite never hurts if done with enough time for it to dry.
  4. incoming, Oct 12, 2025
    #4
    incoming

    incoming Active Member

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    These have all been done by a diver, or me holding my breath in the middle of a trip when i realize they are gone or have come loose.

    So is it not really possible to have them done right underwater?
  5. Capt Ralph, Oct 13, 2025
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    Why not?
    Hammers work under water. ♪♫ If I had a hammer ♫♪
    But a breath hold dive probably will not make it.

    But, it takes a quality zinc also.
    Your looking for those brass buttons on the inside, to make that electrical connection and get a bite on the clean shaft.
  6. incoming, Oct 13, 2025
    #6
    incoming

    incoming Active Member

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    Sounds like I should try a new diver
  7. Capt Ralph, Oct 13, 2025
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    Or ask your diver to update his installation and materials.