How do AC yachts handle their wing sail

Discussion in 'Sailboats' started by hprasmus, Sep 22, 2011.

  1. hprasmus
    Joined: Sep 2010
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    hprasmus Junior Member

    I am curious how 600 sqm's of fixed wing sails are handled when the cat/trimarans are moored. Does anyone know ?
     
  2. masalai
    Joined: Oct 2007
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    masalai masalai

    They are disassembled when not racing...
     
  3. CutOnce

    CutOnce Previous Member

    Actually, the AC teams employ wing sail experts to "live" on the boats at the dock, watching the wing full time and making sure it is feathered into the wind. One of Canada's C Class catamaran team worked as a wing watcher at the last AC. The boats are NOT disassembled in between race days.

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    CutOnce
     
  4. CutOnce

    CutOnce Previous Member

    I was talking about the last real America's Cup competition and Magnus Clarke worked for BMW Oracle as on-boat wing monitor betweens races. Although the new boats are labeled as AC 45's, they have not participated in an actual America's Cup contest.

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    CutOnce
     
  5. BobBill
    Joined: Oct 2009
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    Location: Minnesotan wakes up daily, in SE MN, a good start,

    BobBill Senior Member

    There is some info on mooring one of those AC boats in SF, maybe past issue of sailing mag, that said they tethered boat in some way so it weather-vanned to wind, rudders and boards up, and left the wing up, in the water.

    I know it sounds tricky and foolhardy, considering the cost of a carbon wing etc. but...

    I do not know if it was for one night or all the time, but the piece was informative...I will check later.
     
  6. DGreenwood
    Joined: Aug 2004
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    DGreenwood Senior Member

    In Caiscais they were moored with wings up. They did fine.
     
  7. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    mooring

    I was mostly wrong and "once" and DGreenwood were mostly right:

    Concerns about approaching storms led to the AC45 yachts being hauled out overnight rather than left on their moorings, as is typical for the wingsail cats. http://www.cupinfo.com/en/americas-cup-world-series-plymouth-fleet-racing-day-2.php under "Sunday Outlook"

    There is video somewhere of the boats being hauled out but I mistakenly assumed that to be the case every night...
     

  8. tspeer
    Joined: Feb 2002
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    tspeer Senior Member

    They did moor the AC45s in Auckland and Cascais. I don't recall seeing them being moored in Plymouth in the TV coverage I watched.

    In Auckland, Paul Bieker came up with a neat mooring buoy. It consisted of an inflatable tetrahedral mark, filled with fresh water. This would float with the apex above the water. The boats were moored with the king post close to the buoy, so they couldn't sail around at the buoy as they were restrained by the mass of the fresh water. But because the buoy was floating, it would react slowly to wind and tide like a normal mooring buoy. The rudders on the AC45 can also be removed or turned 90 deg so they don't inhibit the boat from swinging at the mooring.

    The dollies the boats sit on while ashore (also designed by Paul Bieker) can also allow the boats to be "moored" on land. The wheels can caster and be pinned in position. If the forward wheels are pinned facing forward and the rear wheels are pinned at near-90 deg (such that their axles point at the midpoint between the two forward dollies), the boat will pivot freely about the virtual center of the axles - just like it's on a mooring. I don't think they have actually exercised this with the AC45s, but it is standard practice for rigid winged landyachts. No other restraint is needed - the boats don't have to be tied down because the athwartship orientation of the rear wheels keeps the yacht from sliding backwards. Many times I've seen tracks in the dirt from landyacht dollies that show they've rotated through 360 deg during the night, and I've never heard of one capsizing or having a problem when so moored.

    The other piece of kit that makes a big difference in handling the wings is the ballast box that is attached to the leading edge when the wings are stepped or struck. This box is filled with ~80 kg of water. It moves the c.g. of the wing forward so it has less tendency to flutter as it is hanging from the crane. Once the wing has been stepped on the yacht, the water is drained and the box removed.

    The methods for handling the larger wings of the AC72s are still being designed.
     
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