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.

14.08.2015

Fit for service!.

par Gitana

After an eleven-month build at the Multiplast yard in Vannes, the Mono60 Edmond de Rothschild hit the water for the first time last Friday 7 August. However, this initial contact with the liquid element was in no way synonymous with the start of sea trials. Indeed, launched without a keel or a mast, the 60-footer fitted out by Baron Benjamin de Rothschild quickly made for nearby Lorient to have these precious elements stepped and undergo a series of tests that are compulsory for any new IMOCA monohull, with the emphasis on checking compliance with the class measurement. Suffice to say that the members of Gitana have had a hectic week.

For the past week, Sébastien Josse and the members of Gitana Team have spared no effort. Immediately after her launch last Friday, the Mono60 Edmond de Rothschild was delivered to her port of registry in Lorient so as to have her keel stepped over the weekend. With the imposing 4.5-metre appendage securely in position, the most recent of the Gitana fleet once again sampled the delights of the ocean at noon last Monday. On the programme for the start of the week: 180° righting tests and mast stepping prior to the static tests and the 90° test. Such operations are always tricky (see video above) but they were carried out to perfection by the five-arrow team.

180° and 90° tests

These tests, which are a welcome sight for those strolling around the Keroman submarine base, the majority of whom are both amazed and amused by the freestyling moves that the carbon monster is subjected to, are primarily geared towards safety. As shown by the images taken aboard the Mono60 Edmond de Rothschild on Monday, the 180° righting test is by far the most spectacular of the tests required by the IMOCA measurement. Sébastien Josse gives us the low-down on the principle behind this operation: “With the help of strops, the crane pulls on the bulb to gently rotate the boat through 90 then 180°. Once she is upside down, the boat is relatively stable with her keel vertical. As such, you need to activate the keel from inside the boat and without external assistance to heel her to the left or the right so as the bulb weight acts as a pendulum and enables the boat to right again. This test is compulsory to check that the skipper and the boat are able to right themselves without assistance in the event of a capsize.”

Meantime, the so-called 90° test enables the boat’s true centre of gravity to be determined so as to adjust her power.

Static tests

Less telegenic than those involving self-righting, the static tests are just as important, as the skipper of Edmond de Rothschild explains: “Alongside, we test all the elements where there is the most stress and check how much strain they can withstand. We exert pressure on the boat to see if all the composite parts can take the load. From the runners which can withstand up to 3 tonnes, to the mainsheet tackle to the hooks…. you have to increase the strain to the theoretical working load and check that the integrity of the structure is intact.”

“As ever, the team has done an outstanding job in the space of a week, which means we can go for our first sail in the next few days,” says Sébastien Josse, who makes no secret of how keen he is to finally familiarise his new steed with the open ocean.

Tech spec

LOA: 20.1m
Waterline length: 18.28m
Beam: 5.70m
Air draught: 29m
Water draught: 4.50m
Displacement (weight): 7.6 tonnes
Weight of keel bulb: 3 tonnes
Maximum upwind and downwind sail area: 290m2 / 490m2
M² of living space: 10m2
Number and type of daggerboards: 2 foils
Source of energy production on-board: generators coupled to the diesel engine + hydrogenerators

Naval architects: Verdier / VPLP
Yard: Multiplast (Vannes)

Retourner aux articles

Heritage