Gitana 17-100' Trimaran Foiler-Launch 7/17/17

Discussion in 'Multihulls' started by Doug Lord, Jul 13, 2017.

  1. Doug Lord
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    Doug Lord Flight Ready

    Great shot of the ama shape aft of max beam: Gitana 17 ama shape.jpg
     
  2. Doug Lord
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    Doug Lord Flight Ready

  3. Doug Lord
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

  4. Doug Lord
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    Doug Lord Flight Ready

  5. wet feet
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    wet feet Senior Member

    My memory is telling me that they added a fairing to the aft beam last year to improve the aerodynamic drag and I don't see it on the relaunching photograph.
     
  6. Dolfiman
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    Dolfiman Senior Member

  7. Doug Lord
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    Doug Lord Flight Ready

    Maybe they don't want it to be too easy to copy?
     

  8. Dolfiman
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    Dolfiman Senior Member

    Thanks to « Voiles et Voiliers » magazine , here below this interview of Guillaume Verdier dated december 2019, just after the vistory of Gitana 17 in the Brest Atlantiques :

    Architect Guillaume Verdier explains Gitana 17 and how to fly better in a foil boat. A good year for Guillaume Verdier, who designed Maxi Edmond de Rothschild victorious at Brest Atlantiques. Verdier also designed Apivia, winner of the Transat Jacques Vabre in Imoca, the Pogo3 winner of the Mini-Transat in series and he is working to ensure that Team New Zealand's flying AC75 retains the America's Cup. Voiles et Voiliers met him for an exclusive interview. Small explanations for better boat flying and on a major innovation of Gitana 17: the ray wing ...

    Voiles et Voiliers : Guillaume, it's been a busy year with successes for the boats you have designed in almost all categories!
    Guillaume Verdier : Ambrogio Beccaria performed superbly in the Mini-Transat… Unfortunately, I don't have many Class40s running anymore. But in the Transat Jacques Vabre it's really good, because with all my team, we fought hard to be on time: Apivia was launched in August and it won in Salvador de Bahia, even if there is still progress to be made on the foils.
    And here in Brest, it's good that there are so many people around the Ultim Gitana 17 trimaran: between the public, the technical team, the builders, the people who support me in architecture, the relatives… This trimaran , these are hours and hours of reflection and realization: 15,000 hours to design it and 130,000 hours to build it!

    Voiles et Voiliers : But the trimaran Gitana 17 broke during the Route du Rhum ...
    Guillaume Verdier : It hurt our morale! We have since reinforced it: maybe it was a resonance or buckling issue, but we'll never really know. In fact, the boat was under pilot and it left loose: it came across the sea at 40 knots in 4 meters waves ...

    Voiles et Voiliers: And today, on arrival in Brest, the boat seems almost in perfect condition after 17,000 miles on the water …
    Guillaume Verdier: We have added UD carbon to the sheer lines in the floats and the central hull and the trimaran is equipped with a multitude of optical fibers and sensors. But we only measure very few constraints....

    Voiles et Voiliers: And since leaving the yard last spring, there are two new skippers.
    Guillaume Verdier: I worked respectively with Charles Caudrelier on the Imoca Safran, and with Franck Cammas on the ClassC Groupama challenge. So I knew them both well before they took the Ultim. And they won the Fastnet Race and the Brest Atlantiques! Well done. It didn't take them long to find out how the boat was going ...

    Voiles et Voiliers: Gitana 17 is a very special flying multihull ...
    Guillaume Verdier: We wanted to make a platform that is very stiff in torsion: I decided to design high freeboard floats which take a large part of the torsion (important boxes therefore, editor's note) and which also gave us an important sea guard.
    The link arms (the « akas ») are thus less "crossed" with a very thin central hull without working in torsion: it is distributed over the three floats. The arms (akas) are also very "boxed": they are no longer "U" beams but rectangular section boxes to take less risk if there is damage to the fairings. The sum of these choices resulted in this vessel which is quite high in freeboard and which gives a feeling of security in the formed seas.

    Voiles et Voiliers: And this is the first trimaran to have a "ray wing" under its centerboard ...
    Guillaume Verdier: In fact, we designed the “ray wing” (horizontal plane at the bottom of the daggerboard, editor's note) for Gitana 15, now Giovanni Soldini's trimaran (Maserati): we saw that the instability in roll at which we expected, was frankly reduced with this appendage which acts as a supporting plane at the level of the center of gravity.

    Voiles et Voiliers: And this "ray wing" is under the daggerboard ? Behind the daggerboard? In one block?
    Guillaume Verdier: The idea is for the boat to fly without the risk of falling sharply or heeling in the wind: it is very hard to make fly the boat without a "ray wing"! We should have already done this on the Orma trimarans ... In short, having a "sheet" in the water reduces the effect of roll. On Maxi Edmond de Rothschild there is a fixed part and two "flaps" at the rear. It also allows violent « direction change to leeward » (my translation of « abattée »?) without risking capsizing.

    Voiles et Voiliers: Is it that famous ray wing that broke just before the doldrums?
    Guillaume Verdier: In fact, it was one of the flaps at the rear that went off, the "ray wing" itself was intact. I do not know whether it was a shock or not that caused this damage, it may be the hinges that jumped: we will take a closer look now.

    Voiles et Voiliers: So the Gitana Team changed the two flaps in Salvador de Bahia?
    Guillaume Verdier: No, the whole "ray wing" has been changed. In fact, it clips, it's interchangeable like a car tire! This is also why the manipulation did not take too long: it was enough to "sink" the centreboard and bring it up on the quay to change the whole "ray wing".

    Voiles et Voiliers: On the other hand, we can see that the performances on the Brest Atlantiques are not astounding! The best day (in the Bay of Biscay) is 741 miles against 908 miles for the 24-hour record …
    Guillaume Verdier: Normally, the boat could do better, but you have to see with the weather conditions it had! I imagine that Franck and Charles had the will to preserve their machine: no need to push if there is no pressure behind ...

    Voiles et Voiliers: On the drone images, we see that Maxi Edmond de Rothschild often sails counter-heeled …
    Guillaume Verdier: It's not bad to sail like this: Franck (Cammas, editor's note) finds it efficient. This raises the float with the foil and lowers the upwind one for aerodynamic reasons and for the rig that works better. I'm not for flying high! Because we can break a lot from higher up ... We just have to raze the waves.
    Of course, when there is sea state you have to go up more, but up to a point. By playing on the flaps of the "ray wing" exactly. The rudder stabilizers are more dedicated to pitch trim, for pitching up in the sea and for "nose down" in flat seas such as the America's Cup. By putting the trimaran on its nose and heeling it upwind, the aerodynamic drag is reduced and the foil is extended further outwards: the righting moment increases.

    Source : EXCLUSIF. L’architecte Guillaume Verdier explique Gitana 17 et comment mieux voler en bateau à foils https://voilesetvoiliers.ouest-france.fr/industrie-nautique/chantier/architecture-navale/exclusif-l-architecte-guillaume-verdier-explique-gitana-17-et-comment-mieux-voler-en-bateau-a-foils-aec96748-1699-11ea-a513-e79918f31c1d
     
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