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.

29.01.2008

Expertise.

par Gitana

Yesterday, Monday, was our first day in the southern hemisphere during which we clocked more than 600 miles—616 miles in 24 hours, to be exact. Will there be more days like this? A concrete answer is of course impossible, but one thing is already certain: we won’t reach this goal during the day that will end today at 16:38 UT. Still, the wind is up, and we’re flying the small gennaker and genoa staysail, with one reef in the main. We’re still on port tack as we surf along the edge of the high-pressure system. But to top the 600-mile mark, it would need to blow really hard, with the needle rarely dropping below 23 or 24 knots. Yesterday afternoon the winds were weaker and further aft, a direction that is not ideal for speed. For a long time we considered putting up the big gennaker, but Lionel, the skipper, preferred to play it safe due to the rough seas, which have been bouncing us around for 24 hours already. And then Lionel must surely have the gift of sensing the wind. This slow spell, during which we were still able to move along at around 23 knots on average, only lasted a few hours. Then the wind came back, as powerful as before, and the sail of choice was the small gennaker. We were thus spared two time-consuming sail changes. Nice work Lionel. Tomorrow we should get close to 600 miles, and if I’m wrong, which is very possible, that would be even better.

Goodnight

Nicolas Raynaud

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