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.

07.04.2008

The tale of a col.

par Gitana

We thought we’d avoided it, we were delighted to have come out of it relatively unscathed, and then it landed right on top of us when we really weren’t expecting it. I’m talking about the flat calm and the windlessness, one of our worst enemies, if not the worst. It was at the end of last night, at the point where others in France were savouring the last light of what would doubtless have been a great Sunday. Here the darkness was even darker than usual and the lightning, which was illuminating the sky without a sound all around us, blinded us for long periods. The electrical discharges were incredible and certainly on a par with the power of this immense ocean. A stormy mass slyly buried us in its snare and what was supposed to come, came: not a breath of air, the sails hanging lifeless for the first time since our departure. At the first light of day, we were manoevring every which way to try and escape this sticky situation as quickly as possible.

We needed a good 5 hours to definitively escape this situation in the end, which is symbolic of a ‘col’ separating two zones of high pressure. We went from one side to the other and now that’s done, the stampede has free rein again. On chaotic, messy seas, we’re bouncing from wave to wave, lots of manœuvres punctuating the scene once more in order to adapt to the capricious wind, both in strength and direction. We play with the staysail or the solent, with a reef or without, it’s a generous partition. This downwind ride will enable us to link up with a tropical low, which we’re expecting from tomorrow onwards. It’s this system which will bridge the gap and it should enable us to arrive in Japan with a burst of speed. By rounding it in the right direction to the north, we’re going to continue to sail downwind. The seas should build, the wind possibly filling to as much as 60 knots. This feisty finish suits us down to the ground. Anything is good except for the flat calm and our other worst enemy, namely close-hauled conditions, with headwinds !

Until tomorrow

Nicolas Raynaud

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