Composite fittings

Discussion in 'Multihulls' started by catsketcher, Jul 13, 2015.

  1. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    I am about to start building the mast for my 7m trailer sailer cat. I have a nice alloy extrusion but I have to build the masthead, mast base, gooseneck, spreaders sheave boxes and even hounds fittings myself.

    I am not good at welding and am much better at using composite. I would like to make composite fittings to attach onto the ally mast. Has anyone some good pics of someone doing something similar or has anyone done this?

    My idea is that I can make nice moulded parts myself instead of paying expensive prices to mast makers. Also I like the idea of having large composite hounds attachments to take the Dux rigging loops. I can still bolt and screw things on although there is no real reason for me not to make the gooseneck moulded all the way around the section.

    I can engineer the pieces and make them with vac bagging if required. I would just like to see any examples of this.

    I have already made rudder gudgeons, pintles, chainplates, engine nacelle hinges, floor hinges, cleats. sheave boxes, pulley bases, mast band and spreaders and more in composite. I am interested in the design of similar items. Steering wheels, cleats, hinges and chainplates are examples where metal and composite are joined. I would like to broaden the range a bit.

    I did look seriously at buying a carbon section. It was over 5 times the price for a saving of about 25% in weight. So I have the section and need to rig it.

    cheers

    Phil
     
  2. Gary Baigent
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    Gary Baigent Senior Member

    You can do whatever you like combining alloy, carbon, glass ... BUT ... first rough the alloy surface with rasp or 40 grit and then lay on one layer of box weave/epoxy glass (to create a break contact area between higher modulus materials) before building up, layering your carbon fittings. We did this to Jacques old and modified rig for Marguerite Star - is now 30 plus years old, no problems.
     

    Attached Files:

  3. hump101
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    hump101 Senior Member

    When we bond composite to alloy we coat the alloy in epoxy and then sand it with wet-n-dry paper when the epoxy is still wet. Build up the laminate over the epoxy when it is still wet or green so you get a chemical bond. Doing it this way you remove the oxide surface from the alloy but don't allow it to re-oxidise prior to coating. We've not had a failure yet. I think this method was from the WEST system book.
     
  4. Corley
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    Corley epoxy coated

  5. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Definitely tow rather than uni or cloth as it goes round corners without stressing the edges. It also spreads out so there is less fairing required, although building a stop to make an edge is often a better idea.

    Thick tow is a little harder to wet out, but takes much less time.

    I have some ~6kg spools for $50/kg plus postage of 70k standard modulus if you need any. 270m/kg so one spool will build all your fittings for a couple of boats, and then some.

    rob
     
  6. Corley
    Joined: Oct 2009
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    Location: Melbourne, Australia

    Corley epoxy coated

  7. basil
    Joined: Apr 2005
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    basil Senior Member

    Catsketcher,

    Check out this site - he's in Tin Can Bay Queensland I believe. He has fitted composite spreaders to alloy mast sections. From what I've heard he's a very approachable bloke.

    http://www.s-boat.com.au/

    Tony
     
  8. waikikin
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    waikikin Senior Member

    I like the cockpit, I've got a seawind with similar seating (but no cuddy).
    Jeff.
     
  9. cookiesa
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    cookiesa Senior Member

    How did you go? Any further along with the decision?
     

  10. paxfish
    Joined: Dec 2014
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    paxfish Junior Member

    Love to see some of this....

    Catsketcher - Would love to see some pics of the fittings you've done so far. I need to make a new gooseneck soon, and a new mast rotator.

    Just curious about moulding expoy fitting around the aluminum mast. Does expansion come into the picture at all? It would seem that the two materials would behave differently....
     
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