Bedding parts to mast section...

Discussion in 'Multihulls' started by paxfish, Jan 20, 2016.

  1. paxfish
    Joined: Dec 2014
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    paxfish Junior Member

    Hi Gang, I am about to mount a sprit socket to my forward crossbeam. I could simply slather it up with 4000 UV and bolt it on, but I wonder if there are any tricks to getting a nice professional even layer of bedding material with a clean edge?

    The concave surface conforms very closely to the profile of the crossbeam mast section. Here is the part:

    [​IMG]

    [​IMG]
     
  2. Tom.151
    Joined: Jul 2009
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    Tom.151 Senior Member

    Maybe cut a gasket from something like a thick truck fender flap?
     
  3. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    Even though most of the forces on this thing are in compression, I think I want the added security of a medium adhesive like 4000 UV to augment those 1/4" bolts...
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The trick is to tape the part to be mounted, then leave an even margin and tape the crossbeam. After the bedding compounds oozes out, make a nice fillet and take off the tape.
     
  5. Chuck Losness
    Joined: Apr 2008
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    Chuck Losness Senior Member

    Put a little mineral spirits or turpentine on a rag and then careful wipe around the fitting. The excess goo will come right off leaving a nice, neat clean edge. Works every time for me.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Both Gonzo and Chuck have given the usual and correct advice. If you need a "bed", tape it off carefully, apply a generous bead of goo, knowing much of it will ooze out when you take up the machine screws. When it has oozed out, a solvent damp rag will clean the seam nicely and if you're careful, you can make a little fillet too, before peeling the tape, leaving a crisp line around the seam. Conversely, you can skip the tape and just wipe the ooze out, again with the damp rag, though the seam will have less exposed sealant visible.

    If the fit is close, but not perfect, you can make it perfect, which will transfer loading better. You'd do this by "bonding" the part, to the cross beam, with epoxy. This doesn't have to be a permanent mounting, you can coat the beam and the back of the part with wax, bond it down, then pop off the now perfectly shaped epoxy piece, which is then bedded in the sealant of choice, after the wax is removed from the beam and part.
     
  7. UpOnStands
    Joined: Nov 2015
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    UpOnStands Senior Member

    is your cross beam aluminum?
    what thickness?
    tapping the beam to take the SS screws?
    simple, yes. long-term?
     
  8. PAR
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    PAR Yacht Designer/Builder

  9. paxfish
    Joined: Dec 2014
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    paxfish Junior Member

    Thanks for the responses everyone. I'll post up a pic once I have everything mounted and bobstays attached.
     
  10. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member


  11. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    Just to close out this thread, here a couple of pictures of making a nice base for a cleat on a curved boom. The excess was removed and I made a nice fillet. The bottom of the piece and the fasteners are coated with wax and the tape was removed before curing.

    Thanks for the tutoring, Guys!

    [​IMG]

    [​IMG]
     
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