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.

28.10.2010

Gitana 11’s second youth.

After achieving the reference time between Saint Malo and Pointe-à-Pitre in 7 days 17 hours 19 minutes, the reigning champion Gitana 11 was radically modified when the organisers of the Route du Rhum - La Banque Postale opened the event to yachts of all sizes. However, the technical constraints were considerable in the process of retaining the same…

par Gitana

After achieving the reference time between Saint Malo and Pointe-à-Pitre in 7 days 17 hours 19 minutes, the reigning champion Gitana 11 was radically modified when the organisers of the Route du Rhum – La Banque Postale opened the event to yachts of all sizes. However, the technical constraints were considerable in the process of retaining the same structures without affecting the potential of the trimaran fitted out by Baron Benjamin de Rothschild.

In the history of naval architecture, the modifications and optimisations are numerous, but to extend the length by over 25% overall, there was a giant technological step to make in order not to change the nature of the overall configuration of Gitana 11. In the hands of Lionel Lemonchois in 2006, the trimaran proved that she was the most well suited to this course blending headwinds, light airs and a final push through the tradewinds. In 2010 the problems are somewhat different as the boat length is one of the key factors of speed in relation to its sail surface, its weight and the power that is linked to its beam.

The equation to be resolved…

As the size is no longer limited, deciding on the different length in relation to Gitana 11’s original platform (ex-Belgacom built in 2001) was restricted by the designers’ desire not to modify the beams or the distance between them. “77 foot was retained because it was important not to make the structure too heavy so as to ensure the trimaran remained highly responsive. As there is an overhang limit, the new floats were lengthened by four metres up forward and by one metre aft, whilst the central hull essentially upped its length by grafting onto it a bow measuring four metres longer. Even though the sail plan hasn’t changed, the power has increased, which meant that the forward beams needed reinforcing” explains William Fabulet, the multihull’s boat captain.

The problem with this type of surgical operation was that we couldn’t touch the central structure. Though the floats were built in New Zealand and the grafting of the central hull was done in Arcachon in South-West France, all the other modifications were able to be performed by the composite specialists within the Gitana Team (Rolland Allanic, Hubert Corfmat, Marie Dixneuf, Daniel Le Digabel, Patrice Richardot), which amounted to a ten month refit in 2009. The cockpit was also transformed in Saint-Philibert, SW Brittany, to adapt Gitana 11 to this new Route du Rhum format.

“As such the boat has the same general configuration with some additional length. In terms of weight, Gitana 11 is just 600 kg heavier with the same sail area. The results are very positive as the trimaran borders on 21-22 knots upwind (compared with 17-19 knots beforehand) and easily reaches 30 knots downwind. The handling at sea has improved considerably, especially as regards her passage through the waves. In fact, the boat goes faster in every sector, whilst being safer… She still remains very responsive, so she is more flighty than her rivals in Saint Malo: she is formidable in the light airs and still performs very well downwind!” concludes the technical manager of the Gitana Team.

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