Aluminum tube sectioned mast

Discussion in 'Multihulls' started by Onefish, Jan 29, 2020.

  1. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    After much thought I am pretty much set on building a Woods Design Quattro 16.

    My initial plan was to just buy a used Hobie 16 mast, but when I started looking into where to keep the boat after I build it, I realized that keeping it my garage is probably the most practical option, but my garage wont accommodate a 26 foot mast, which brings me to the option of building a sectioned mast in stead. So even though building my own mast is more effort(and possibly more money) in the short term, long term it would be the cheaper/easier option.

    My thinking was to use aluminum tubing to make the mast in two sections with an insert that is one to two feet long inside it. Additionally I was thinking of riveting or having welded on a track for the main sail and then wrapping it in fiberglass for aerodynamic purposes.

    My primary concern is that the Quattro 16 is meant to be a dual trapeze design and I'm not sure if a trapeze would put too much stress on the mast for that or is most of the strain from a trapeze handled by the shrouds?

    Thanks in advance.
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Mixing metal and fiberglass on a mast is not impossible, but really hard to do. Most likely it will delaminate. You can make a two piece mast out a Hobie 16 one.
     
  3. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    I was thinking that the fiberglass would be held in place by a combination of the fasteners holding the standing rigging on the mast and some rivets attached to the sides of the mainsail luff track. That way I wouldn't be drilling any more holes into the mast than absolutely necessary. The fiberglass wouldn't be doing much load bearing, so my primary concern would be preventing it from slipping up or down the mast.

    As I understand it, aluminum needs to be acid etched to prepare it for bonding with epoxy resin, which is not something I'm keen on doing myself.

    That being said, your suggestion of sectioning a hobie mast would probably be a lot easier.

    Do you have any resources for performing such a process? I imagine I'd want to get most of the worlndone by a metalworking shop, since I'd want a pretty precise fit.
     
  4. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    Okay, so I've been looking into it some. It looks as though the Hobie 16 mast does not taper, so it should be feasible to do the following:

    Have the mast cut a few feet below where the shrouds attach to the mast. Take two pieces of aluminum tube that matches the inside radius of the leading edge of the mast. They should be about 14-18" in length each. Insert each tube into their respective mast sections until they are flush. Using one to two pairs of rivets, secure each length of tube in place. Take a single length of aluminum tube that fits snugly inside of the other two tube lengths and insert it into the mast. Then drill a hole through each mast section closer to the seam between them and then use either a pair of cotter pins of bolts to secure it together and prevent the sections from twisting independent of each other.

    How does that sound?
     
  5. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Thinking in left field, would it be feasible to stow a one piece mast on top of the roof, or maybe standing vertically alongside the garage?
     
  6. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    Already considered that. I live in a townhouse. Got some garage space, a very small front yard, and that's it. Dont want to lean it up against the house, too much risk it might fall over and hurt someone.
     
  7. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    How about a flag pole in the front yard?., If you glue in aluminium tube, let it dry, wrap the protruding tube in plastic film[no wrinkles], assemble mast, drill a hole where the tube finishes and inject resin up up to that level you will have a solid fit. adding a spreader to the join may help.
     
  8. redreuben
    Joined: Jan 2009
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    Location: Beaconsfield Western Australia

    redreuben redreuben

    The Gougeon method to bond to aluminium is to clean down the aluminium, paint it with epoxy and then abrade with wet and dry so the surface abraded is protected from oxidation by the resin. Thing is glass and aluminium have quite different expansion coefficients, could be a problem.
    My solution would be to join the local yacht cub and keep it on the hard stand perhaps. If you have to assemble a mast, re-tension diamond stays etc it’s going to be a pain and the boat won’t get used.
    I’d be talking to you local mast/rigging people first.
     
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  9. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    have you considered the ceiling hypotenuse in the garage?

    my brother has a lovely Windward 15 sailboat and he stores it on a mooring, but generally, the storage requirements are part of the SOR

    a mast can be so much a pain in the rear, extending one sounds awful to me

    you can probably get about 24 feet across the ceiling of the garage the long way...probably...perhaps you need to adjust the sail plan vertically a couple feet...have you asked Richard?
     
  10. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Evidently Hobie sells a two piece mast kit for the 16
     
    Last edited: Jan 30, 2020
  11. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    The primary issue here is that getting inside the mast to prepare the surface of the aluminum would be extremely difficult.
     
  12. Onefish
    Joined: Oct 2019
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    Location: Pennsylvania

    Onefish Junior Member

    Thought of that too. Diagonally, inciuldnonky fit something up to about 22 feet.
     
  13. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    If you did lean it up against the house, it should be fairly easy to secure the base (in a box perhaps?) and to have a bracket on the garage wall to lash / attach the mast to, to ensure that it cannot fall over?
    It could then also do double duty as a flag pole for 4th July and other auspicious occasions?
     
  14. gonzo
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    gonzo Senior Member

    What is the maximum length you can store in the garage?
     

  15. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Are you unable to drill a 10 inch hole in your garage wall on each end of garage up under the eave, install a 10 inch pvc pipe and screw capped end and just slide the entire mast into it. If you have a couple of feet of overhang on each end you may only have to have the pipe extend a bit beyond the eave and perhaps it would be hidden from view.
    Alternatively if you have a 26 foot eave continuous horizontal section of eave on the house, you could hinge a 22 foot piece of pvc pipe, one end on a hinge under the eave, the other end
    attached to a pulley, slide the mast in and then just hoist the low end up under the eave and tie it off,

    I would be concerned about your mast carrying the loads with a joint in the middle especially if it is a high performance craft. Due to the loading from the sail and the point load
    from the spreader, compression loads from the stays and additional loading from the trapeze, the mast will be under a lot of loading. Once you make the mast discontinuous due to the cut in the middle, you need to be able to carry the stresses across the joint or invite failure, buckling, etc.

    I would do everything that I could to keep the mast length intact and keep it simple
     
    Last edited: Jan 30, 2020
    fallguy and bajansailor like this.
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