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.

24.08.2008

Relativities.

par Gitana

Beyond shortening the course time and breaking records, speed enables you to play with the elements and not have to endure them. Rounding a zone of high pressure, avoiding a zone of calm or escaping a low are notions reserved for the few giants of the seas of which Gitana 13 is part. In its northern sector, the Indian Ocean is providing us with a well established ESE’ly tradewind, which is enabling us to maintain high average speeds under pleasant conditions. With 1,300 miles (around 2,400 km) covered in 48 hours, and a capability of doing at least 1,500 over the next three days, the contours of the playing field are a little closer in one sense. Mauritius is nearby, the African coast isn’t far off and the Cape of Good Hope is already in our line of fire.

As the ocean gradually reveals its gameplan and the hypotheses take shape, we’re refining our course. The white page laid before us at the entrance to the Indian is being written up, day after day, with details of the strategy in progress and some probable routes. We therefore hazard a programme outline: another three days where we can slip along the contours of the zone of high pressure in the Indian, followed by a period of transition towards the African coast with a SW’ly breeze veering North. And to end, a good W’ly storm with which to round the Cape of Good Hope. Perhaps we’ll be sailing in the Atlantic by 31st August, which is an ocean we left at the end of January 2008 as we rounded Cape Horn.

The rapid shifting of our ‘home’ is having a direct affect on the life of the crew. Making 2,500 km westwards means we’ve experienced nearly two hours’ time difference in the space of two days! In fact we’re going to change the onboard time tomorrow by passing from UT +8, which was the time in Hong Kong, to UT + 5. The miles we’ve covered towards the south have shortened the length of the days (we are in winter time here) and have reduced the temperature of the water from 12° C in Hong Kong to 7° C since Java. The spray is less pleasant and the showers more startling.
In the gangways, sleeping is no longer torture and we willingly envelope ourselves in our sheets. The guys have got out their technical underwear, and the first thin layer fleeces are being pulled on at night under our foulies. With the change of watch come some funny exchanges: “what are you wearing?” or even “it’s still alright in shorts, but only just”: you have to adapt and be quick at it. This is a particular characteristic of north-south or south-north voyages; you’re constantly changing season and sometimes this happens in the space of 24 hours. Anticipating and adapting remain the two golden rules for a sailor.

Dominic Vittet, in the middle of the Indian Ocean

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