2015 IMOCA 60-Foil Assist

Discussion in 'Sailboats' started by Doug Lord, Jan 15, 2015.

  1. Doug Lord
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    Doug Lord Flight Ready

    IMOCA 60 Foil Assist

    Virbec foil:

    [​IMG]
     
  2. Doug Lord
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  3. rcnesneg
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    rcnesneg Senior Member

  4. ariel zerpa
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    ariel zerpa Junior Member

    These curved transition from high to low pressure may generate a big vortex
     
  5. Doug Lord
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    Doug Lord Flight Ready

    IMOCA 60 Foil Assist

    Safran has had to retire from the TJV due to problems with the hull around the foil trunk:

    On Monday night at 2020hrs (French time), Morgan Lagravière contacted the race management to inform them of damage to Safran and announce his decision to head back to the port of Brest, in Brittany. Joining by the official race radio this morning, Lagravière detailed the nature of the damage and the circumstances in which it occurred: "The foil area is damaged on the starboard side," Lagravière said. "The damage has spread around the area and water is seeping into the boat. We quickly tacked to get the damaged section of the hull out of the water. At the time of the incident, the conditions were intense but not extreme. There were 25-knots of wind and 3-4 metres of swell. The sea was not particularly rough and we didn't hear a particular sound."
     
  6. Doug Lord
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    Doug Lord Flight Ready

    IMOCA 60 Foil Assist

    From the Saffran sailing team and The Foiling Week:
    Why does Saffran have foils?

    "To go fast, a boat must balance lightness with power. These two concepts, often contradictory, can be combined thanks to the foils," Vincent Lauriot-Prévost, one of the architects, says. "The foils make it possible to create dynamic power and thus lighten the boat. Although lifted, an IMOCA equipped with foils does not literally fly, and is not more powerful, but it sails in a more aerial way, with less wetted surface and therefore less drag. Hence there is a significant gain in speed at certain angles." Due to the limit of five appendages on the IMOCA (two rudders, a keel, two dagger boards / foils)1, the challenge was to conceive of a geometric solution for achieving a single appendage that could both lift the boat on downwind angles and give control upwind. The research by the architects led to these "Dali moustaches". The arguments in favour of the now famous lifting appendages that Safran is equipped with, convinced the other teams who had started the construction of new generation IMOCA 60: Banque Populaire, Edmond de Rothschild, Hugo Boss, Vento di Sardegna and St Michel-Virbac. It is also possible that we will see at the beginning of 2016 2 skippers of older generation boats ask the question of replacing their straight dagger boards with foils. "All the competitive teams are interested in them but they are observing, and waiting for the first results before changing everything," Guillaume Verdier, the other of the boats chief architects, says.

    Boats designed for the Vendée Globe

    "It's on downwind angles, and especially when reaching (side-on to the wind), that the theoretical gain is most significant," Lauriot-Prévost explains. "Strong winds are also favourable: the faster the boat goes, the more the keel and the foils lift and the lighter it gets." Following a 24-hour sail on board Safran, Verdier agrees: "Downwind, I was also struck that the behaviour of the boat was healthier," he says. "Thanks to the effect of the lifting appendages, it slams less and the stresses on the structure are reduced."

    On the negative side, the foils do not offer the same surface control of a traditional straight dagger board, meaning there is a handicap upwind, especially in light weather, because they then generate a greater drag. But upwind sailing represents only about 10-15% of the conditions encountered during a Vendée Globe. Thus, the new generation boats are particularly designed for the southern seas where solo sailors normally sail downwind; in strong winds and big seas. "The choice of the foils constitutes risk-taking, but it's calculated risk taking because we did a lot of studies and routings of the Vendée Globe course." Quentin Lucet, an architect at VPLP, says reassuringly. On paper, the foils could take two days off the record of 78 days set by François Gabart in 2013. These promising simulations still need to be confirmed on the water.

    The Transat Jacques Vabre, a full-scale test

    As we see, the performance of the new IMOCA 60 is subject to weather conditions. That is why the architects and the sailors are careful not to draw too hasty conclusions. The races held so far (the Record SNSM, Artemis Challenge and Fastnet Race) were certainly to the advantage of the most optimised older generation boats (PRB, SMA, Quéguiner - Leucémie Espoir). But these events took place on short courses and generally in 10-15 knots of wind, conditions far from representative of a round-the-world race. "We're in the middle of understanding the foils," Lucet says. "The IMOCA rules forbid dynamic adjustment of the incidence of foil. We must find the best compromise to increase performance when reaching and reduce the deficit on upwind angles. These are very fine calibrations and adjustment that will, hopefully, increase the effectiveness of the foils, and thus make the boats more versatile. We've seen some really promising phases, and we have to continue sailing to refine their use." Safran will serve as a sort of "floating laboratory" on the Atlantic and at the end of the Transat Jacques Vabre we will know a lot more about the behaviour of foils and their effectiveness.

    1 The limitation imposed by IMOCA: http://www.imocaoceanmasters.com/pages/the-boat

    2 At the request of the teams that have built new IMOCA, VPLP and Guillaume Verdier signed an exclusive contract and are committed to not work on older generation boats in the development of foils. In January 2016, the architects will be released from this clause and will be able to collaborate with existing IMOCA skippers who choose, or not, to replace their straight daggerboards with foils.


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

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

    Doug Lord Flight Ready

    Alex Thomson Racing / Hugo Boss

    From ATR:
    Alex Thomson and his team are onboard HUGO BOSS which is now in a stable situation. Alex’s IMOCA 60 is undergoing the necessary checks in order to tow her back to A Coruna, Spain. Where additional team members are on hand to assist with the pending arrival. The rig has been removed and the water onboard pumped out, allowing the racing yacht to be towed. The weather conditions have enabled Alex Thomson Racing to complete a swift response to the emergency situation which occurred yesterday. The yacht is currently situated 100 miles offshore. The crew will remain onboard to make the necessary checks to ensure a safe tow through the night.
    Technical Director Ross Daniel says ‘I am proud of our team considering the potential severity of the situation. Of course it’s disappointing we have had to retire from the race. But this year’s Transat Jacques Vabre has provided the fleet with challenging conditions, forcing seven IMOCA’s to retire. As a team we now need to focus on getting HUGO BOSS safely through the night and then assess the situation once she is alongside tomorrow
    .’
     
  9. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 344, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready


  10. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 344, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

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