Design help needed, Parallel Rig on a Trimaran?

Discussion in 'Multihulls' started by lane, Feb 4, 2010.

  1. lane
    Joined: Dec 2005
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    Location: Austin TX

    lane Junior Member

    Attached is a pic of my Hobie 18 based trimaran. With the current Hobie 16 rig, performance has been good and I feel that she can carry a lot more sail.

    I now have two complete Hobie 16 rigs to play with and am considering a parallel rig setup with one mast on each ama. The boat is 16ft wide and I was thinking about putting the mast steps just inboard of each ama.

    1. What kind of concerns would I have as far as stress on the beams?

    2. Where should I attach the stays?


    Attached Files:

  2. Gary Baigent
    Joined: Jul 2005
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    Gary Baigent Senior Member

    You can freestand them through floats - or you can check out MacApine Downie's setup on Crossbow 11, or Ketterman's Trifoiler; on each example there is a tension/compression spar support across to each hounds position, plus crossed triangulation of the inside rigging shrouds.
  3. Munter
    Joined: Jul 2007
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    Munter Amateur

    The challenges to this rig configuration extend well beyond just holding the mast up. Leech tension on most small cats comes from high mainsheet tension with the traveller down to leeward. If you mount the masts on the outboard hulls you will need to come up with a way of getting leech tension on the leeward rig because you presumably won't have a traveller extending the beam even further out to leeward to pull it tight for you!
    Notice how a lot of the biplane rigs are either sailboard style or have a fixed rigid boom in an attempt to address this problem? Combining a sailboard boom with a rotating mast might be a challenge but that wouldn't be insurmountable.
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