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.

26.02.2008

Upwind tales.

par Gitana

When you spend your time struggling along, feeling Gitana 13 suffer in its battle against the elements, you can’t claim to have had a good day. One piece of good news though is the 360 miles we have made on course towards San Francisco. The other is that it was a great sight once again. After a daybreak which was a touch gloomy, the skies were of an incredible pureness once again, powerfully highlighting the dark blue seas dotted with white horses. With a long, powerful W’ly swell, from the other side of the Pacific perhaps, this stirred-up race zone was particularly captivating to look at. As regards the very cold, N’ly wind, varying between 13 and 20 knots, this is forcing us to sport hats or balaclavas, whilst our fleeces have been a must for a good two days already.

It remains that this second section of the record has been totally different from the first. Though we hardly strayed from the direct route on the way down to the Horn, which provided us with some fine stretches with eased sheets or close reaches enabling us to rack up some great speeds, this climb up the Pacific has been quite the reverse. With the all too odd exception, we have never been able to adopt the shortest course, instead spending our time tacking upwind or on a reach. The upshot of this is not a single day of over 500 miles to get our teeth into, and indeed this will continue to be the case between now and the finish. Though we’ve been on a favourable tack towards San Francisco for the past four days, little by little we’re distancing ourselves from the direct course. Tonight we’ll have to reposition ourselves slightly towards the coast for the first time. In a straight line the finish is very close, now less than 600 miles (at 0900 UT), but in reality it is more likely to be a good 800 miles. This shouldn’t prevent us from retaining the same ETA though, which is set to be during the day on Thursday 28th.

Until tomorrow
Nicolas Raynaud

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