Fixing fittings to mast section?

Discussion in 'Boatbuilding' started by Eliseviv, Jan 21, 2011.

  1. Eliseviv
    Joined: Jan 2011
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    Location: Darwin

    Eliseviv Junior Member

    Hi peeps done some googling, but didnt come up trumps.

    What is the technique for fixing fittings attached to mast section that are 3 metres up the mast section (Im looking to fit a prodder gooseneck to the middle of a crossbeam in a cat.) Is it tapped into the aluminium and expoxyed, or is it a plate with threaded holes pasted up the mast section and captured by some long threads on the fixture?
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Each design has its own method. The type of section, the type of fitting and the load will determine it.
     
  3. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Not much thickness on small mast sections for tapping threads, normally you pop rivet fittings in shear or compression.. A trick to making a strong gooseneck connection is to perfectly mate the gooseneck saddle's form to the mast wall. Fit the gooseneck, drill the rivet holes. Next Carefully cover the mating surface...the backside of the gooseneck , with Mylar tape...poke holes thru the tape for the rivets, trim edges with a razor knife. . The mylar tape acts as a insulator for the ss to aluminum joint . Now cover the backside of the gooseneck with a thick layer of micro fiber epoxy bog. then rivet the bogged up gooseneck fitting to the mast wall and wipe off the squeezed out epoxy . You have now created a perfectly machined fit between gooseneck and mast wall with all pop rivets equally stressed and a mylar insulator between the ss and aluminum. I just installed a ss goosneck fitting on a boom this way.

    The other solution is a backing plate inside the mast then drill and tap. Not easy and many times not necessary on a small boat. Always bed in epoxy
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I've never seen any professionally rigged mast with epoxy bedding under the fittings. A proper fitting will fit well. Some fittings are through bolted across the section too.
     
  5. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Well Gonzo...you obviously haven't seen very much !!!!!!!!!!!!!!..Every fitting on this mast and every fitting bolted to this deck are epoxy bedded. Yup..Every single fitting. Its called custom boatbuilding.

    I challenge you Gonzo to fabricate a saddle gooseneck fitting with one hundred percent surface contact on the mating surfaces.
     
  6. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Eliseviv: do yourself a favor and look at the many websites from rigging and spar suppliers. you will see that none have that nonsense of epoxy. I have only seen that done by amateurs because they can't fit.
    Michael: I am a professional and can fit anything. Spar fittings are a piece of cake compared to scarfing a plank on a lapstrake repair or fitting babbit bearings.
     
  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    An before Michael gets his panties in a knot, here is a photo of a scarf I did last month.
     

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  8. Eliseviv
    Joined: Jan 2011
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    Location: Darwin

    Eliseviv Junior Member

    Thanks for the comments fellas,

    Ive fired off the parts order for the section im using so hopefully it'll all fit. Wandered about the local marina early this morning and just had a look at attachment methods - so should be fine! :)

    Cheers
     
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