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.

11.05.2008

Gliding along in the Yellow Sea.

par Gitana

Gliding along in the Yellow Sea

A complete turnabout. After yesterday’s storm, the night was dedicated to traversing a ridge of high pressure as best we could. It wasn’t until the early hours, downwind of a little South Korean island, that the ridge deigned to push us towards the goal as it should. The large gennaker in position, this kind SSW‘ly breeze is enabling us to glide across the Yellow Sea, which is as smooth as a millpond. A real joy.

This Sunday was therefore dedicated to drying out as the sun and blue skies were part of the proceedings, as well as some much needed recuperation; everyone’s sleep ration being largely in the red. The wake-up calls were difficult as a result because, for the first time since the start, we were in a ‘real deep sleep’, and no longer between ‘two worlds’, as you don’t have the worry of getting ejected from your bunks anymore.

This sail in the Yellow Sea is a big first for the eight of us and we’ve observed that it requires as much, if not more attention, than navigating along the Breton coast. We have spent our day passing fishing boats displaying Chinese flags, where you could clearly hear the sound of a diesel engine of a certain age whose age is far from certain! It was also necessary to slalom between the lines of fishing nets measuring several hundred metres in length, barely visible on the surface of the water, and marked out in what appeared to us to be a rather random manner. The result of that is that we passed over one of them, as easy as pie, which was fortunate for both ourselves and the net.

Whilst Qingdao, our next stopover after Dalian, is 140 miles abeam of us, we look set to reach the 4th largest city in China in the early hours of Monday morning. The objective we’d set ourselves for this Yokohama/Dalian record, namely to pass under the four day barrier, is therefore on the point of being reached. As usual Gitana 13 is preparing to reach the finish without the slightest damage, just like the crew itself it has to be said!

See you soon,

Nicolas Raynaud

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