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.

17.08.2008

Beating in the monsoon.

par Gitana

In order to escape the scorching China Sea, and make our way out into the Indian Ocean in favourable winds in a few days time, we’re going to have to battle against the headwinds, which are characteristic of this region at this time of year. In reality, the SE’ly tradewinds which blow this side in the southern hemisphere, are crossing the equator and spilling over into those on the north side as they bend to the south-west: it’s the monsoon phenomenon. There is nothing violent for the time being; 13 to 20 knots maximum, and with all the sail aloft Gitana 13 is able to relieve its windward float by thrusting its fine bows into the short little chop at an average speed of 15 knots. It mustn’t get any fresher than this! In truth, our proud 33 metre catamaran, loathes this point of sail… As soon as the wind exceeds 20 knots and the seas get bigger, it begins to slam, shake and lash out, and all that makes life on board a real ordeal.

We’re closing on the coast of Vietnam. Léo got out some very light foulie tops yesterday which may well prove useful to us very soon as some huge stormy masses are heading up from the equator and are likely to punctuate the next watches with squalls and gusts. There are doubtless a few manœuvres in view.
The local gannets, which have orange feet here, swallow the flying fish as they take off in a bid to escape Gitana 13’s hulls.

Dominic Vittet, 200 km to the east of the Vietnamese coast

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