Vo70

Discussion in 'Sailboats' started by D'ARTOIS, Nov 13, 2005.

  1. RHough
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    RHough Retro Dude

    Here is a cross section of the wetbox on the Farr design. The fairing bits on the sides are supposed to keep high pressure water out of the box. When the fairings get ripped off the box is exposed to high pressure water flow. Pirate's reports that the bellows were swollen and the lid was leaking on Leg 1. I've lost count on how many times Movistar's fairings have failed. IIRC The box itself cracked and started leaking on Pirate's on Leg 2.

    Of course Farr just designed the system, they did not build the boats.
     

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  2. usa2
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    usa2 Senior Member

    but its a stupid design.
     
  3. tamkvaitis
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    tamkvaitis sailor/amateur designer

    Quite clear drawings had been published in the SA
     
  4. vinceUK
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    vinceUK Junior Member

    Sorry I'm a french student in England and I don't know what th SA is... Sorry for this silly question!
     
  5. frankofile
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    frankofile Junior Member

    Post a link?
     
  6. Vega
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    Vega Senior Member

  7. frankofile
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    frankofile Junior Member

    How about a link to the drawings?
     
  8. guit
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    guit Junior Member

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  9. Vega
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    Vega Senior Member

  10. frankofile
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    frankofile Junior Member

  11. RHough
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    RHough Retro Dude

    ABM AMRO One wins the Rio in-port race.

    I think that means that ABM AMRO One has been first at every finish and every scoring gate except the first in-port race and leg 3 to Wellington.

    Even though ABM AMRO has been dominating, the race series is still interesting and the in-port racing has been very good.

    Paul Cayard must be having fits about the performance of Pirates.
     
  12. RHough
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    RHough Retro Dude

    It turns out that one of the guys I used to work with knows some of the top guys at Farr.

    I asked what the Farr office had to say about the VO70's, the failures and the seeming lack of performance.

    They feel the failures although keel related are not the same on each boat. Similar results from different failures.

    They feel the race so far has been sailed in heavier air than predicted putting their light air boats at a disadvantage. With more than half the points still up for grabs and the lighter air legs ahead they hope to see the Farr designs place better.

    Abm Amro's win in light to moderate conditions in Rio did not sit well.
     
  13. guit
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    guit Junior Member

    And Sanderson commenting on their own design: The coming legs are what our boat is designed for.

    Ps. They have won the in-port whilst the keel-fin was damaged causing lots of extra drag and vibrations through the steering...
     
  14. RHough
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    RHough Retro Dude

    It has long been understood that the skippers of the Farr-designed Volvo Open 70s have been working on improving the performance of their boats in heaver winds relative to the Juan Kouyoumdjian-designed ABN AMRO twins. They have also been suffering from problems with the keel doors which not only fair the bottom in the way of the keel, but also keep the water out when sailing at speed.

    The Farr office has been working long and hard, providing solutions to both problems and to try to give their design team a head start with generation two of the Volvo Open 70, ready for the next race and any other events for which the boats might be suited, they were testing solutions during the stop over in Brazil.

    Initial research showed that appendage drag was increasing at an exponential rate thanks to the speed of the boats and the drag on the angled strut and fin. Different fin and bulb shapes were tried in the wind tunnel to attempt to overcome the difficulties, but the structural requirements always overrode the purely hydrodynamic ones. If the fin was strong enough to take the likely loads put through it, then the drag was no better; if the drag was acceptable, then the keel fell off.

    Working with the keel doors it was quickly found that any increases in speed negated any advances in water tightness. Water pressure increased so much when keel drag was reduced, and therefore boat speed increased, that there was still a danger of the boat taking on water when least needed.

    It looked as though a breakthrough was needed that would solve both problems.

    As usual with all things of this nature, it took some blue-sky thinking to come up with the answer.

    To start with, water is six times more dense than air, so any way to allow the keel to work in a less dense medium would immediately reduce the drag on the fin and bulb. So, while we were canting the keel, why not cant it all the way out of the water? The Volvo Open 70 rule says that the keel can only cant to 40 degrees, but the definition of keel is, according to all dictionaries, something that sticks down into the water – the new system does not meet the water so therefore can’t be a keel and can cant as far as it likes.

    In fact, the initial pictures taken of the prototype version fitted to Paul Cayard’s Pirates of the Caribbean, The Black Pearl, show that the keel extends to windward from just below the gunwale of the boat. Overheard conversations indicate that it retracts to change righting moment and on tacking is swung aft and across the transom to the other side. It appears to operate in a slot formed through the topsides just below gunwale level. The slot is closed by doors, but as only the leeward doors are likely to be deeply immersed and subject to large hydrodynamic pressure, these doors are able to seal properly and make the topsides of the boat flush as well as watertight.

    In one fell swoop, the Farr office has solved the problem of the leaking doors, and also taken a quantum leap on towards a whole new generation of ultra-fast monohulls.

    Our photographs, provided by the Brazilian military who were flying a surveillance mission and who happened across the boat during testing, show the breakthrough in design. The photograph is not quite clear enough to reveal the sealing doors, or the articulation system for the keel, but they do clearly show the keel in fully extended position.

    Security has been such that our reporters in Rio, Kate Laven and Riath Al-Samarrai, have not been able to gain any more insight into the system and, more importantly, when it might be used in the race. Realistic expectations seem to indicate that it might be used during the transatlantic leg, when the fastest crossing record is up for grabs as well Volvo Ocean Race points.
     

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  15. solrac
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    solrac 100% sudaca

    excuse me for my lack of knowledge on the subject, but seriously with this modification, as it's not anymore considered a keel, (it's really not a keel system, it's function is a kind of ammas yeah?) , won't it be considered a kind of multihull? it won't be fair to compete with the rest of the fllet on the same category...
    what a coincidence just post on april fool's day...
     
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