Banque Populaire: Worlds Largest Foil Assist Multihull

Discussion in 'Multihulls' started by Doug Lord, Aug 27, 2008.

  1. Doug Lord

    Doug Lord Guest

    This boat is a 40 meter tri-the ocean racing sailing trimaran yet launched. And one of the most significant aspects of this boat(like the huge AC tri) is that it uses lifting hydrofoils to support approx. 70% of the boats weight when flying the main hull. Heres more:
    http://www.bymnews.com/news/newsDetails.php?id=41626
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    Here are the foils for Banque Populaire from a story on the SA front page.
     

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  2. Chris Ostlind

    Chris Ostlind Previous Member

    Yep, that's the standard release article on BYM when a new, big boat goes wet. Still, not one word about the lifting foils in the copy and nowhere on the page does anyone state that the foils will lift up to 70% of the boat weight when sailing.

    I know you just go googly over anything that foils, but why do you make these kinds of statements without one bit of supportable evidence to back it up? Perhaps you are simply extrapolating from another design and assuming that the same will hold true for this boat? There sure isn't any evidence within the link you provided. Kinda anxious there, Doug?

    Get some supportable quotes from the designers or the owners of the boat and let's work from that position. Then everyone's happy and you don't come off like a goofball.

    When I'm in France next week, I'll see if I can squeeze a side trip over to the new homeport of BP and get a look at the big girl. Maybe....
     
  3. Doug Lord

    Doug Lord Guest

    Sorry, forgot the foil pix; just added them to my previous post. As to the "approx. 70% of the boats weight" that I used: that was based on a figure from an ORMA 60 footer. These will be close because the foils only pay of themselves if they lift enough to reduce wetted surface significantly.
    From http://www.wired.com/wired/archive/14.05/sail_pr.html

    " Most radical of all has been the introduction of curved foils below the hulls that act like wings, producing vertical lift and reducing drag by raising even the leeward hull out of the water. Lift equals speed; speed begets more speed. "Sometimes you are even 100 percent on the foil - the whole boat on one single point," says Vincent Lauriot Prévost, the Brittany-based designer behind seven of the multihulls that competed in the Jacques Vabre. "Six years ago, foils took 30 percent of the displacement, and the boats were sailing at 28 or 29 knots," he says. "This year it's 70 percent, with speeds of up to 39 knots, which means you are sailing on the very sharp edge of a knife. We are pushing the limits of the machines."
     
  4. Doug Lord

    Doug Lord Guest

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  5. Doug Lord

    Doug Lord Guest

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  6. Munter
    Joined: Jul 2007
    Posts: 285
    Likes: 11, Points: 18, Legacy Rep: 125
    Location: Australia

    Munter Amateur

    Doug - I'm sure that anyone with a subscription would have read the article if they were interested. To the rest of us your post is useless. Please stop posting links to restricted websites.
    [​IMG]
     
  7. Doug Lord

    Doug Lord Guest

    It wouldn't be useless if you were very interested in these kinds of boats and didn't know the Daily Sail existed! Or that it had just posted this article. I'll continue to post new info about this boat -and a link to that info-as I find out about it-you can count on it.
     
  8. RHP
    Joined: Nov 2005
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    Location: Singapore

    RHP Senior Member

    Wouldnt want to have to go-about at speed in that bugger!
     
    Last edited: Dec 1, 2008
  9. Doug Lord

    Doug Lord Guest

    Worlds Fastest Offshore Sailboat?

    Heres an excerpt from the Daily Sail articles referenced above:
    The million dollar question is - is the Banque Populaire maxi the ultimate G-Class maxi-multihull? Clearly on paper a bigger boat would be faster, but the 120-125ft size seems to be at the present limit of technology for a boat where humans must grind the winches and where any degree of reliability is to be maintained.

    “If we built a new one, bigger might not be faster,” says Gautier. “Smaller and lighter, maybe wider might be faster. We will discover with this one - if the boat is not about to pitchpole all the time, we will be able to say the boat is too long for the sail area, so we might be able to reduce the length [and therefore displacement].”

    Vincent Lauriot Prevost is more cautious: “At this stage for sure we don’t have enough feedback to think about a bigger boat. Up until now in early sea trials it looks like the boat is easier to sail than expected. You get used to the size quite quickly. Pascal and the crew I think they have that same feeling about it. The boat is not as monstrous as you could have imagined.”

    One avenue Lauriot Prevost thinks might be the next step on would be a boat that works more on its foils. He states that Banque Populaire is ‘foil assisted’ and not a ‘foiler’. So could you for example add another set of curved retracting foils in the floats? “No. There would be too much extra drag and it would affect the balance of the boat too much. If we had two foils I don’t think we would be able to use them independently. If we wanted to push the foiler option we would have a smaller boat to be able to work on the efficiency of the foils. At the moment we are stuck with the compromise between efficiency and structural problems.”
     
  10. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Thanks Dough,

    I find the way they construct these monsters quite interesting. There must be huge cost and plenty of cadwork involved in building those eh.

    Damn, it must be a kick under the butt to sail.
     
  11. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Btw, the one in the article that capsized... if they had a clutch release on the sail line(s) it may not have capsized. In full race the clutch can be omitted.
     

  12. Doug Lord

    Doug Lord Guest

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