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.

22.07.2002

Assessment of damage….

After an uneventful return delivery in very changing breeze conditions between Boulogne-sur-Mer and Vannes - from the Channel to the Atlantic - Gitana X was back at her builders Multiplast early last week. Her mast was unstepped and she was lifted back into the shop for an in-depth assessment, following the damage to her forward beam.

par Gitana

After an uneventful return delivery in very changing breeze conditions between Boulogne-sur-Mer and Vannes – from the Channel to the Atlantic – Gitana X was back at her builders Multiplast early last week. Her mast was unstepped and she was lifted back into the shop for an in-depth assessment, following the damage to her forward beam.

Stopped just a short distance from the port of Zeebrugge (Belgium), Gitana X abandoned the idea of racing her 1st Grand Prix on July 12th, and this on the decision of the experts, despite the rapid repairs carried out by Multiplast.
Back in the yard, more precise analyses have been carried out by “electronic tapping”, exactly like the doctor tapping his patient’s back with the back of his hand, listening to the difference in resonance to detect possible problems.
This latest investigation did not reveal anything so it was decided to sand down to the carbon cloth to obtain a direct vision of the incriminated zone. Once again, everything proved to be homogenous, the carbon cloths are perfectly bonded to the honeycomb core. Verdict: the construction is apparently not to blame. So the Gitana Team have therefore pointed their research towards a possible weakness in the engineering of the beam.

Powerful foils

The new generation of 60 ft (18.28 m) trimarans to which Gitana X belongs, uses very efficient curved foils placed on the floats just abaft the forward beam, which permit, as soon as the boat accelerates, the catamaran to lift therefore increasing speed by reducing drag through the water.
These foils are precision parts in carbon, they are immensely strong and load up the beams enormously, while the old straight foils generated much lower loads with inferior lift. The use of these new foils have obliged the designers to precisely study the loads that they generate in order to calculate the right scantlings. This is an area where the strength to lightness compromise is very difficult to find on prototypes, despite the precision of the calculations.

Reinforce the beam stocks

The damage to Gitana X – a crack in the forward beam stock 15 cm above where it fits into the float – appears to stem from a lack of stability of the carbon fibers in compression (direction of the carbon fibers) at this point.
The Gitana Team engineers have already provided some elements of the reply as to what caused this damage and next week will be proposing some new approaches for strengthening and improving the reliability of the beam stocks.

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