Attaching Fittings to Carbon Mast

Discussion in 'Fiberglass and Composite Boat Building' started by granite, Aug 15, 2006.

  1. granite
    Joined: Oct 2005
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    granite Junior Member

    I need to attach some fittings to a Carbon Fiber mast and I can not see an alternitave to using Blind Rivets

    The Rivets used already on the mast are Stainless Steel and as is typical they have a bit of staining from corrosion but do not seem to have been structuraly affected by the corrosion.

    I have not been able to find any Stainless Steel rivets but have found some Monel ones.

    Does anyone have any experiance of using Monel rivets in Carbon Fiber with regard to corrosion?

    Are they comperable to Stainless Steel in strength?
  2. SeaSpark
    Joined: Mar 2006
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    SeaSpark -


    I have little experience with carbon masts but the most logical approach to me seems laminating fittings to them.
  3. Sander Rave
    Joined: May 2005
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    Sander Rave Senior Member

    Just for reference and not a direct answer to your question:
    Maybe you can do some investigation in the field of racing bicycles.
    This field of sports is also on the leading edge of carbons and alloys, and the attachment of components is really ingenious.
    2nd: SS rivets are widely used in offshore appliences. If you can't find them at the hardwearstore, try the Hobie importer or something like that.
    Good Luck!
  4. frosh
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    frosh Senior Member

    I have fitted out two carbon masts. I have only used stainless fittings and fastenings. You need to minimize the galvanic corrosion that is always trying to happen between carbon and metal in the presence of salt water.
    Personally I wont use rivets at all. On the mast that is smaller and under low stress I have bolted right through the mast.
    On the more highly stressed one I have not drilled it at all. All fittings are custom made to encircle the mast and are epoxy glued and laminated on. I have used dynel to reinforce a glued stainless fitting to the mast. The dynel is very tough and wont split, and absolutely prevents the possibility of the metal collar sliding.
    Also glue between metal and carbon (thin layer) seems to prevent almost all corrosion.
  5. granite
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    granite Junior Member

    Thanks for the answers,
    I found some interesting stuff looking up the bikes, not all of it relevent like the guy who built a bamboo and carbon mountin bike. Possibly the next project.

    Most of the fittings are going to be carbon and laminated in place, I will be laminating some SS fittings in place as well but there are some that would be difficult due to the shape so I was looking at rivets.

    Interestingly Monel is described as being a nickel copper alloy that is extremely resistant to corrosion and acids

    I have not seen anything describing its resistence to galvinic corrosion so I may put one somewhere non critical and see how it goes.
  6. Karsten
    Joined: Jun 2004
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    Karsten Senior Member

    According to my table Monel has a electrochemical potential of -0.04V - -0.14V. The potential for 300 Series stainless steel is 0V - -0.15V if they are passivated (have a chromium oxide layer on the surface). The potential of graphite (carbon) is +0.2V - +0.3V. So the "battery" you are creating between the two materials has about 0.2V and Monel and Stainless Steel are almost the same. The only metals better in combination with carbon are Titanium, Inconel or Platinum. Anybody seen any Platinum boat fittings lately?

    The tip to insulate the two materials is a good one. This way your "battery" is interrupted and galvanic corrosion can't happen. Another tip is to inspect the rivets regularly. They are not going to disappear over nicht and it's quite easy to just drill them out and replace them with new ones.


  7. John ilett
    Joined: Nov 2003
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    John ilett Senior Member

    Avoid the holes if possible. Failures in carbon parts often happen/start where there are holes. Some things you know will be safe due to small loads or just plain experience but carbon + carbon is safe if done right.

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