Bi-Plane rig on a 20m cat

Discussion in 'Multihulls' started by Becaris, Jun 28, 2010.

  1. scape
    Joined: Jan 2012
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    Location: tri-state

    scape Junior Member

    hiya. this thread caught my attention because I'd like to see bi rigs take off for cats, they just make more sense to me; but i think a bi rig in a 20m cat would be tough to do, beyond designing some seriously awesome masts, i'd be curious how you'd tack-- i suppose you could depower one of the mains to assist with some sort of pivot.

    here's a slick schionning radical bay 8000 bi rig with two jibs; looks like he rolls one jib up (towards the end) to help with a tack/not obstruct airflow.
    http://www.youtube.com/watch?v=ciP_xuZHih0
     
  2. Skint For Life
    Joined: Jul 2010
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    Location: CHCH, New Zealand

    Skint For Life Junior Member

    Thanks for the pictures. I am also interested in how this goes. Please keep us updated :D
     
  3. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    I was down at the yard the other day to have a chat to the owner about building space for my next project. Mike has his boat closer to finished but is still waiting on his rigs to arrive.
     
  4. Becaris
    Joined: Aug 2008
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    Becaris Junior Member

    So, could you ask your friend the planned height of his masts off the water? I'm curious as to how much shorter he is going than a single stick. Also, what kind of boom setup is he planning? And... what is the name of the boat? Thanks!
     
  5. Corley
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    Corley epoxy coated

  6. Whimsical
    Joined: Aug 2010
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    Location: Australia

    Whimsical Junior Member

    Name is Bi-Polar
    Mast height is about 17.2 mtrs above W/L. About the same height as the conventional rig
    Boom is 4.5 Mtr???, don't have the drawing in front of me, rigid vang
    Originally it was shorter but a longer boom, pushed the height up a bit to compensate for the shortened boom
    Flexibility is to be 8% at a wind strength to lift the hull with 1 sail up, but i can't remember that either sorry advanced alzheimers i think
    Aiming for about 50 Mtrs of rag including the mast area each stick. Big flat top main
    The wing is 720mm at the base and 390mm at the top

    Mike
     
  7. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Did you ever get that charter of Coolchange in??...seems if you were really interested in that rig you should do that.

    Meanwhile there are some interesting discussions of Derek Kelsall's rig going on over in the forum at 'multihulls@steamradio.com'
    http://www.steamradio.com/mailman/listinfo/multihulls

    http://www.kelsall.com/TechnicalArticles/TheCatRig.pdf
    (a stayed bi-plane rig)
     
  8. prograd
    Joined: Oct 2012
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    prograd Junior Member

    How are jibs attached to unstayed mast?
     
  9. prograd
    Joined: Oct 2012
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    prograd Junior Member

    I stumbled upon this biplane cat:

    [​IMG]

    I think it's Radical Bay with a little bit custom modified (and painted) hulls. It sure looks great.
     
  10. spidennis
    Joined: Feb 2007
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    spidennis Chief Sawdust Sweeper

    Is that another one in the background? Is that another biplane rig I see?
     
  11. Cat2Fold
    Joined: May 2012
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    Location: Felt, Idaho

    Cat2Fold Junior Member

    Sure looks like it... We're taking over the world!
     
  12. prograd
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    prograd Junior Member

    I didn't even notice it before.

    How does light wind performance of biplane cat compare to light wind performance of ordinary sloop cat?
     
  13. Cat2Fold
    Joined: May 2012
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    Location: Felt, Idaho

    Cat2Fold Junior Member

    I can only speak for my boat, but generally speaking, the biplane rig uses significantly shorter masts for a much lower COE.
    My cat is a bit lacking in light air, but I am hoping to resolve this by adding a furling drifter/genoa.
    You can attach a foresail to a freestanding mast just like a rigged mast.
    It might be a bit harder to get the luff super tight, but I've found (at least with my small free-flying jib) it to not be overly important.
    I am just a cruiser and rookie racer, so take anything I say with a grain of salt.
     
  14. prograd
    Joined: Oct 2012
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    prograd Junior Member

    I just found out where that cat in the upper picture is located: it's a charter cat in Thailand.

    SY Crazy Horse

    [​IMG]

    (and it is a Radical Bay 8000)
     

  15. Corley
    Joined: Oct 2009
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    Location: Melbourne, Australia

    Corley epoxy coated

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