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.

22.02.2008

The Doldrums after the Doldrums.

par Gitana

This is called not counting your chickens before they’re hatched! Plain and simple. And yet yesterday morning at daybreak, after a night devoid of squalls, we really thought we’d got away. Ahead of our bows the horizon is furnished with cumulus, a real tradewind sky as they say. The E’ly wind is still light, 6 to 9 knots, but we’re calmly waiting for it to back to the NE, with a slight increase in strength thrown in. But here we have it, as the sun is gradually rising in the sky, the wind is dropping off… Deprived of a fan, we’re really frying on deck, the slightest area of shade worth its weight in gold. A temporary canopy has been rigged up to protect the helmsman a little bit. Meantime the wind still hasn’t kicked in and this blue water at 29°C are cruelly mocking us. However, despite this little air, we are still managing to make headway at 5 knots and it’s out of the question to brake Gitana 13’s progress and take an impromptu dip!

Under this blazing heat the day goes on, the hours tick by, the crew moving around according to the shade. Meantime, the Doldrums are sneakily moving up to the East of us, this time gripping us tightly in its clutches. Just before sunset, that is around 0100 UT this Friday morning, we were well and truly surrounded by the heavy black clouds, which are so characteristic of this zone of convergence. At 0200, we were subject to our first torrential rain, the very first since we left New York. The wind keeps changing its mind, one minute it serves up W’ly, the next E’ly. Whilst the solent comes and goes between port and starboard, sometimes inflated by 15 knots of wind, but more often, sadly, by a lot less. At the time of writing, that is 0315 UT, I can hear the rain beating down on deck. The repeater beside my screen is indicating pitiful numbers: 1.1 knots of boat speed, 2 knots. We’re not out of the woods yet then, far from it. Today, with less than 150 miles, has suddenly been the slowest of all then and we can but hope that this haemorrhage is about to be stemmed.

Until tomorrow
Nicolas Raynaud

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