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.

15.11.2002

Tough weather on the Route du Rhum.

The multihulls fleet has been badly hit by particularly difficult weather conditions... Router of the Gitana Team and in charge of safety maritime weather forecasts for the French Weather Bureau (Météo France), Sylvain Mondon explains how the phenomenon emerged. He has followed the system's evolution closely in order to plot skipper of Gitana X Lio…

par Gitana

The multihulls fleet has been badly hit by particularly difficult weather conditions… Router of the Gitana Team and in charge of safety maritime weather forecasts for the French Weather Bureau (Météo France), Sylvain Mondon explains how the phenomenon emerged. He has followed the system’s evolution closely in order to plot skipper of Gitana X Lionel Lemonchois’s route…

What just happened is not completely exceptional on a statistic level. The general situation was a disturbed north-westerly blow, one of the typical patterns of this area in winter. We have a low pressure zone centred on the British Isles, and a high pressure system over the Azores : the air flow is canalised in this corridor, and the winds are rather strong.

What the navigators encountered on Tuesday and caused so much damage is in fact the consequence of a smaller low that built up within the disturbed general flow, and which came to its maturity in the Cape Finisterre area (western most tip of Spain). This phase of development is called “cyclogenesis”, and that’s where very strong wind variations are observed (as Philippe Monnet, skipper of Sopra Group explained, “I never saw the wind become so strong so quickly”, editor’s note).

If you add to that the fact that the system is moving very fast, you get Force 8 to 10 winds (exceeding 45 knots/87 km/h), with very strong gusts. We had planned a southern route for Lionel at the exit of the Channel, then he was to tack to west in order to avoid the biggest part of the disturbance : he had just done so when Gitana’s X mast broke’, says Sylvain.

About the Route du Rhum (Classification, map, news)

www.routedurhum.org
www.france2.fr

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