Retractable Y-shaped foils, adjustable in three dimensions

Inspired by the appendages of the America's Cup foiling monohulls, these Y-shaped foils have a wingspan of over 5 metres. They are designed to generate powerful lift, increase power and offer a wide range of adjustments to optimise flight at every point of sail and in all conditions. Beyond their impressive size, these foils feature many unique innovations.

Revolutionary U-shaped rudders

These are probably the most visually striking innovations on the new Maxi Edmond de Rothschild. To fly high above rough seas while maintaining control, the team wanted very long rudders that would remain in contact with the water. The challenge is that longer rudders tend to flex under load, severely affecting steering and the efficiency of their lifting surfaces. A new geometry was needed to give these appendages maximum stiffness, resist cavitation and ultimately improve control of the boat and make better use of its power. The result is a set of U-shaped rudders over 4 metres long, a metre longer than those on Gitana 17. Their shape, reminiscent of a tripod or an inverted π, is only the visible part of what makes them so distinctive.

A daggerboard optimised to stabilise the boat and limit cavitation

With its wide span, the daggerboard resembles an aircraft tail assembly, with two adjustable flaps: one on the vertical section and the other on the horizontal section, the distinctive “manta-ray wing”. On Gitana 18, the innovation is to position this wing behind the vertical part of the appendage, rather than directly beneath it, to minimise flow disturbance and cavitation.

Rig: adjustable spreaders to control mainsail power while sailing

Gitana 18’s mast is 1.50 metres taller than its predecessor’s. The boom is also shorter, creating a more slender sail plan. The major innovation is a set of spreaders that can be adjusted while sailing to bend the mast fore and aft. Actuated by hydraulic rams, these spreaders can pivot through 35 degrees to adjust the bend in the middle of the mast. This unprecedented system allows the sailor to control mainsail power: adding depth in light winds to take off sooner, or flattening the sail to reduce power at high speed or in strong winds. Adjusting the depth, and therefore the power, of the mainsail can also save a solo sailor time and energy by reducing the need for risky manoeuvres or headsail changes.

Central hull:
an integrated, structural coachroof

The naval architects and Gitana design team wanted an exceptionally stiff, structurally robust platform. This applies both to the floats, which must withstand heavy loads from the foils and rudders, and to the central hull, which is subject to torsion. The enclosed coachroof is integrated into the hull and contributes to its structural strength. Inside, the cockpit brings all sail-handling controls together, with ergonomics shaped by many hours of design and development. The coachroof also stands out for the number and size of its windows. This configuration meets the visibility requirements of the Ultim class rules and gives sailors the best possible view to keep a visual watch.

19.11.2002

The art of choosing the right route.

As hours go by, the Route du Rhum final podium is getting clearer, and it looks as though no one will steal Steve Ravussin's first place (if no technical incident occurs). Lalou Roucayrol, aboard Banque Populaire, is becalmed in the north of the Azores high pressure zone since Saturday, while Michel Desjoyeaux, sailing south of the leader, is still…

par Gitana

As hours go by, the Route du Rhum final podium is getting clearer, and it looks as though no one will steal Steve Ravussin’s first place (if no technical incident occurs). Lalou Roucayrol, aboard Banque Populaire, is becalmed in the north of the Azores high pressure zone since Saturday, while Michel Desjoyeaux, sailing south of the leader, is still doing 20 knots and takes a serious option on the second place in the final rankings. Three boats, three different route choices : a situation that Marc Guessard, co-router* and responsible for strategy for the Gitana Team, analyses for us.

Frustrated, disappointed and aware of the fact that he had presumably lost his second place, Lalou Roucayrol said yesterday during the daily audio session : “it’s a drag, I can’t seem to get out of this”. Banque Populiare is having trouble exceeding 5 knots of speed, while down below, Michel Desjoyeaux is on the southern expressway. What separates the two skippers ? The Azores high and related light airs, which each of the two men have chosen to avoid in different ways. “I still do not understand why Lalou Roucayrol went up north, wonders Marc Guessard, and most of all why he kept on persisting in that option. Maybe he wanted to try something different from the leader’s route, in order to avoid being on the same trajectory. If he had gone right behind Ravussin, he would have encountered the same conditions, obtained the same boat speed, which would not have allowed him to close the gap. Maybe he tried to pull a trick ? We must not forget that Lalou might have some technical problems we’re not informed of, and which may have forced him to chose this option”.

Anticipation and reactivity

“As far as Ravussin is concerned (the Swiss skipper was leading by more than 500 miles this morning, and should cross the finish line late Thursday night – editor’s note), he has always had wind. It’s a situation we had seen evolving since the start of the race : it was clear that the trade winds would be settled in the south of the Azores high, and that this situation would be steady. Michel Desjoyeaux played it safe by choosing to stop in Madera and not in the Azores archipelago, which has allowed him to keep some wind all the way, to fight back as soon as possible : as a result, he’s about to take the second place from Lalou Roucayrol thanks to his southern route… It’s the same option we had decided upon for Lionel Lemonchois, and it’s all the more frustrating to have broken the mast… Especially since our strategy was destined to spare the gear ! Because a route is plotted according to what we know of the boat’s settings and strong or weak points, and according to the skipper as well. Our task is also to anticipate. Then, of course, Lionel remains the ship’s master, and he decides if he has to tack or not… Anyway, he’s not the kind of guy who accepts to be remote-controlled”.

*with Sylvain Mondon, from the French Weather Bureau (Météo France)

About the Route du Rhum

www.routedurhum.org
www.france2.fr

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