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.

05.04.2008

Half-time.

par Gitana

At 0951 UT, but 2151 local time, we crossed the international date line under gennaker and full mainsail. There are smooth seas and starry skies and we’ve just finished rounding the volcanic arc of Hawaii. On crossing this symbolic line where you switch over from west to east, we have to reset our watches. We’re going straight from the evening of Friday 4th to the evening of Saturday 5th, so as to stay firmly in touch with the reality of our world. The difference with the Greenwich meridian, which was increasing all the time, is that it will now begin to decrease. ‘Losing’ 24 hours has naturally given rise to the odd joke, of varying degrees of quality, such as “it was exactly at that point that we were going to beat the 24 hour distance record”…

With just 2,000 miles to go to reach Yokohama, yesterday and today have felt like half-time. Currently being blown by around fifteen knots of breeze, sailing conditions are perfect. There’s not a drop of water on deck and the platform is not shuddering in the slightest. Instead the hull is hissing gently through the water like the safest of cradles, giving us around twenty knots of boat speed. This isn’t set to last however. The wind will fill in to 35/40 knots, or more. The end of the course promises to be bracing and physical but quick. Solely the latter adjective will be of any importance of course. Thanks to this, we’ll be able to fully reap the rewards of this truce in the weather conditions and then there’s no doubt we’ll take up our Pacific sprint again in around thirty hours time.

Until tomorrow

Nicolas Raynaud

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