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.

05.09.2008

Dear Atlantic !.

par Gitana

Making an east to west rounding of the southern tip of Africa, you can better understand why the Cape of Good Hope, situated around fifty kilometres to the south of Cape Town, has become legendary. This is in contrast to the Agulhas Cape which, 150 kilometres further away, marks the real southern tip of the continent, such as Cape Horn does for South America.
This ‘anomaly’ in the scale of notoriety has a meteorological explanation.

The Antarctic lows which freely circulate in the deep south climb, especially in winter, until they rub up against the African mountain. The Cape of Good Hope, a sentry standing out from the landform turned towards the south west, acts like a real wedge dividing the flow into two very distinctive air currents. The largest section is forced to slip along under Africa, channelling the NW’ly wind as far as the Agulhas Cape. The W to SW’ly winds from the lows, take over along the south coast and render the navigation difficult for over 800 kilometres, offering no shelter prior to Port Elizabeth. A real ‘Way of the Cross’ for those who approach from the Indian Ocean.
Meantime the most N’ly part of the disturbances, scalped by the famous cape, is diverted towards the left, generating S’ly winds which run along the coast as far as Namibia. Indeed this didn’t facilitate the lot of Portuguese explorers who took tens of years to cover the little ground prior to reaching Cape Town.

The Cape of Good Hope and not the Agulhas Cape thus marks the real barrier between the NW’ly winds and those of the south. The border between the two flows is very tight and the rounding takes place within the space of just a few miles. The transition can be sudden.

That’s exactly what happened to us yesterday morning. At daybreak, whilst we were beginning to discover the magnificent contours of the whole peninsula, the wind suddenly shifted, transforming our laborious beat into a joyful session of slipping along. It was such a coveted present; the gateway to the Atlantic was finally wide open. Blue skies, loads of birds, seals, dolphins, a long, gentle swell, Table Mountain which overhangs Cape Town in the morning mist… We quickly took off our foulies to make the most of the spectacle. An orgy of delight!

Since leaving Hong Kong three weeks ago, we have always been heading southwards, the air getting colder day by day. We’re now beginning the climb towards summer and towards home, hoping that we’ll be able to take long strides.

Be gentle with us please Atlantic…

Dominic Vittet

Retourner aux articles

Heritage