Quadralateral Jibs for Fastboats

Discussion in 'Sailboats' started by Doug Lord, Sep 6, 2012.

  1. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Quadrilateral Jibs for Fast Boats

    Hugh Welbourn has tested many sail combinations and had this quadrilateral built for the Infinity DSS. Thread on SA with more info from Hugh:
    http://forums.sailinganarchy.com/index.php?showtopic=139251

    "This all came about from CFD work I was doing on reaching sail configurations, and from those results we went into the twisted flow wind tunnel in Auckland. The quad that Richard Bouzaid from Doyles designed and built turned out to be a glamour when related to all the other reaching combinations
    we tested."


    click- Infinity 36 DSS with quadrilateral jib/reacher, followed by Ranger's Quad:
     

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  2. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    from Welbourn:

    as a PS - if you look at the video* of the 36 on the DSS site heading off at 20 knots plus - then they are using the quad there. Its great to sail on as you can move the boat wherever you want without those nasty moments where you have to wind on a ton of helm to keep on track.

    And surely mylar/kevlar/carbon have consigned a whole load of sails to scrap bin in the past??!! And continue to do so with each material development.

    Its a sail that is sorely needed - not necesarily by all and sundry, but for the modern quick boats then it really is the missing link where they are sailing so much with apparent wind and resulting angles.

    Progress should not be halted if its useful - and dragging up historical rule remnants and thinking they are all still relevant is ridiculous.

    After all, IOR was killed off and that cost owners a damn sight more than one new sail

    We are already suggesting this as a good general purpose sail for cruising guys as well.



    * here is that video: http://vimeo.com/45635108

    Picture-click-set up in wind tunnel for quad testing:
     

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  3. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    Interesting. Kind of like a Genoa with the clew corner cut off.

    Probably gives it a better set and a higher aspect ratio. Also, the head is fuller, which most likely heightens it's efficiency.

    I don't see very many cruisers using it, though.

    Having to deal with two fussy sheets on each side, rather than one (which have to sheet to different locations on deck, BTW) hardly appeals to the short handed tub sailor.

    I think we are reaching a point in sailboat evolution where 'cruising' boats and 'racing' boats are sailing off on different tacks. And I don't think this trend started recently. I think it started with the IOR in the '70's.

    But now this trend has grown more extreme.

    Much of the recent innovations of the racing world have had questionable value for the cruising community. A lot of these innovations (such as canting ballast keels, and bulbed keels, to a lesser extent) require expensive engineering and materials to work right, and are vulnerable to the rigors of long distance cruising.

    These rigors are: unexpected groundings, casual maintenance (as funds run short), long term service (which allows these things to wear out), and chronic short handed crews, which have to operate their vessel in often unknown waters and under often very difficult conditions.

    Under these conditions, something that is mediocre, or even poor in performance, but inexpensive and lasts a long time, often trumps high performance, but fussy, high cost gear.

    I think that, now days, this applies even to dinghies.

    If I want to be out on the water to relax and do just about anything other than show some other boat my transom, I'm going to want something that is inexpensive, easy to maintain, and can carry a decent payload for it's size.

    Modern 'sport boat', performance dinghies meet none of these criteria.

    But they do offer exciting performance, challenging handling, and often impressive bragging rights.

    To each his own.
     
    Last edited: Sep 8, 2012
  4. sean9c
    Joined: Jan 2011
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    Location: Anacortes,WA

    sean9c Senior Member

    Soon as you crack off the sheet leech control is the big issue, that quad sail gets you better leech control so it's a winner. Hard to believe that the various ruling body's will deem it legal. Especially as it'd pretty much require the rest of the fleet to buy a sail to keep up.
     
  5. philSweet
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    philSweet Senior Member

    Anyone know if the new Ranger has a quad jib?
     
  6. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    It's not hard for me. Racing is about getting the maximum performance out of your boat, even if you're a tub sailor.

    This new sail offers that. And at minimal cost and modification to your boat. Since this sail is really pretty much a Genoa with the clew half cut away, it wouldn't surprise me if a Genoa could be re cut to make a poor man's version.

    The extra sheets are not a problem on race day, as there will probably be plenty of crew on hand to handle the work.
     
  7. Munter
    Joined: Jul 2007
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    Munter Amateur

    Just cutting the clew off would leave the sail with poorly aligned load paths, particularly in some patches around the two new clews. It might work, but it wouldn't work as well as a custom designed sail.

    I wouldn't recommend anyone start hacking their existing sail wardrobe to match this latest fashion just yet.
     

  8. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Infinity 36 DSS Quad

    Another picture:


    click-
     

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