Aluminum mast corrosion

Discussion in 'Materials' started by pkubaska, May 26, 2019.

  1. pkubaska
    Joined: May 2019
    Posts: 3
    Likes: 0, Points: 1
    Location: Croatia

    pkubaska New Member

    Hi everyone,
    I`m new on this forum but I have been reading topics for some time. About a week ago my girlfriend and I bought a 470 class. Its an 1996. Nautivela with everything in great condition except the mast. There is a lot of surface corrosion and few deeper spots. Is there anything I can do to fix it? I wont push that mast hard, and i know there is good tension on the mast when you are sailing... (probably will find a better mast in the next few months). But what is the best thing I can do for now so we can go sailing in winds no more than 10knots?

    [​IMG]
    [​IMG]
     
  2. Blueknarr
    Joined: Aug 2017
    Posts: 674
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum.

    Take a deep breath. The visable corrosion in your pictures shows a mast in not bad condition.
    The anodized surface is disrupted. Navel jelly could restore some cosmetic.

    The fitting shown in the second pic is of some concern. I am tempted to advise drilling out the rivits to check the corrosion behind it. Reinstall with plastic corrosion barrier between it and the mast.

    Take it sailing. It should last many more years.
     
  3. pkubaska
    Joined: May 2019
    Posts: 3
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    Location: Croatia

    pkubaska New Member

    Thanks for the quick answer. The hole in the first picture is somewhere between the spreaders and where the shrouds attach to the mast. What do you think about cleaning the hole and filling it up with metal epoxy or just epoxy mixed with aluminum powder?
    [​IMG]
     
    Last edited: May 26, 2019
  4. Blueknarr
    Joined: Aug 2017
    Posts: 674
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    Location: Colorado

    Blueknarr Senior Member

    If it gives you some peace of mind do it.
     
  5. pkubaska
    Joined: May 2019
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    Location: Croatia

    pkubaska New Member

    Well, Im open for any kind of advice ;) I just want to fix it as much as possible so it does not spread anymore
     
  6. Blueknarr
    Joined: Aug 2017
    Posts: 674
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    Location: Colorado

    Blueknarr Senior Member

    Aluminum corrosion is both faster and slower than iron rusting.

    When raw aluminum is first exposed it immediately forms a dark oxidation coating that effectively prevents further corrosion. Unless...

    Aluminum is very susceptible to galvanic corrosion when in contact with other metals. This is why I suggested inspecting under the stainless steel fitting and electrically isolating them.

    This means that while that's are cosmetic corrosion where the anodized surface was scratched away. The corrosion won't grow without help.
     
  7. djamson
    Joined: Jun 2019
    Posts: 12
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    Location: Fl

    djamson Junior Member

    If you are planning to re-paint it. Zinc chromate is a good primer.
     

  8. Deering
    Joined: Feb 2005
    Posts: 477
    Likes: 22, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    I recently use System3 ‘Metalweld’ on an aluminum hull project and have been impressed. I’d suggest that with a thickener like cabosil.

    I’ve been coating every stainless screw or part in contact with aluminum with anhydrous lanolin and it has worked great in preventing galvanic corrosion. Cheap and easy to use.
     
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