How High Do You Fly ?
Posted April 22, 2015
“Everybody” wants to foil these days, including racing sailors headed offshore, some of them. Gitana has been talking for a while, and plotting and developing, and Baron de Rothschild’s team is on the cusp of going sailing to find the answers to questions that lab work just doesn’t yield.
Because you can’t really CAD-design to waves.
Offshore, should it be C-foils or L-foils? Howzabout one of each, for testing purposes?
The ride will be different from what we see above. KL
Here’s the word from the Gitana Team:
In refit since her return from the West Indies back in December, the Multi70 Edmond de Rothschild left the cosy atmosphere of her technical base in Lorient this Wednesday morning to return to the liquid element. Benefiting from the first tide of the day and the summery weather, it didn’t take long for the members of Gitana Team to release the carbon machine, which is now safely tied to the dock at the Keroman submarine base. This launch is synonymous with the start of phase two of a project initiated in early 2014 by the team created by Baron Benjamin de Rothschild: namely the mission to make the Multi70 the first flying trimaran on the offshore racing circuit.
An adventure in two chapters
Back in 2014, true to its philosophy, the team created in 2000 by Baron Benjamin de Rothschild paved the way by opting to kit out its 70-foot trimaran with lifting surfaces on the float rudders. The aim at that time was to participate in the 10th edition of the famous Route du Rhum and hence cross the Atlantic singlehanded. It was a bold challenge! Indeed, besides the technical development required by such a project, on the water the human commitment was significant since Sébastien Josse would have to compete against the giants of the Ultime class; the largest of which measured twice the size of the Multi70…
However, the team managed by Cyril Dardashti loves this type of ambitious challenge and the outstanding 3rd place posted by Sébastien in Pointe-à-Pitre proved them right: “From the outset our idea has been to try to get an oceanic trimaran flying offshore. The refit period we had last year prior to the Rhum wasn’t long enough to carry out all the necessary work. As such, it was decided that the process would be completed in two stages. Sébastien’s performance in the Rhum enabled us to consolidate our choices. Phase 2 is underway and we’re eager to see the boat put in her first tacks in her 2015 configuration,” admitted the General Manager of the five-arrow racing stable.
A 70-foot test laboratory
The forms below the waterline, the size of the floats… at first glance, the Multi70 Edmond de Rothschild is the same boat as that which set sail from Saint Malo last November in the Route du Rhum! Indeed, true to its initial plan, the team opted to adapt the original platform, even though the latter has undergone some structural reinforcement. However, the 2015 version has a host of new features if we look more closely at the appendages.
The first of these relates to the aft section of the floats where the T-foil rudders, the principle of which was tested and validated in the Rhum, have been scaled up: “The rudders have been extended both along the vertical section and the lower section. We’ve had new rudder elevators made so as to increase the surface area of the foils. The latter elevators are twice the size they were last year, which is essentially to balance out the platform following the added foil volumes,” explains Pierre Tissier, Technical Director of the five-arrow stable.
What immediately draws the eye are the new appendages adorning the trimaran in the middle of the floats. Fully in line with its research and development ethos, the Gitana Team has opted for asymmetric foils. Indeed, whilst the starboard float is kitted out with a C-shaped foil, the port float reveals an L-shaped foil. These shapes and architectural choices are explained to us by Antoine Koch, head of the Gitana Team’s design office: “With Gitana XV we’re in the process of carrying out research and performing trials so we’re using the platform as a laboratory for the Gitana Team’s future projects. To date the theoretical studies reveal two types of foils, which we’re hoping to trial. The C-shaped foil is a very efficient appendage in terms of hydrodynamics as it generates very little drag. Its ability to generate vertical lift is well established. Although we’re interested in flight, this form does lack stability. In contrast, the L-shaped foiled generates significant drag but it provides great stability and hence a sizeable saving in relation to the drag created by the platform itself. The boat’s handling at sea with such appendages remains a great unknown, but that is what is the interesting element to gauge in real conditions,” Antoine stresses. “These two types of foils are linked to two philosophies of flight. However, it all depends on what you call flight in offshore racing in big seas. Today, during inshore races, the boats in the last America’s Cup showed that one L-shaped foil, despite the drag it causes, is a more high performance compromise. However, the AC72s didn’t have the sea and swell parameters to take into account. That makes all the difference and it’s the primary difficulty that we’re currently trying to get our heads around.”
As with the first T-foil rudders, this second phase of modifications is the fruit of a close collaboration between Antoine Koch and Gitana Team’s design office, naval architect Guillaume Verdier and New Zealander Jamie France, American Bobby Kleinschmit as well as the Pure Design company, the latter being members of Team New Zealand.
For the Gitana Team, the completion of the refit and launch of the Multi70 Edmond de Rothschild is synonymous with the start of a test phase in real conditions on what is a demanding prototype. Experts in their field, the various members of the technical team will mould the machine piece by piece, one sea trial at a time. To pull this off, the communication between the sailing team and the refit team will be constant. Naturally this extensive session of fine-tuning will be orchestrated by Sébastien Josse at sea. Boasting such a test platform is a huge advantage given that the information gleaned on this 21-metre trimaran will be incredibly precious for the future and for the team’s subsequent projects. According to the conclusions of the initial sea trials, the team is not ruling anything out, including a potential participation for the Multi70 Edmond de Rothschild in a famous transatlantic race, due to set sail from Le Havre in late October, which recently opened its doors to multihulls from the Ultime category. In the meantime though… she will have to prove herself offshore.
The Gitana Team seeing double in the Tour de Belle-Ile
Though tomorrow will see the first of a series of training sessions for Sébastien Josse and his men off Lorient, south-west Brittany, the 70-foot trimaran will have to wait until 9 May and the Tour de Belle-Ile for her official return to the racing circuit. This 42-mile sprint around the Morbihan-based island, amateurs and professionals combined on the same start line, is the biggest sailing gathering in France with over 400 yachts expected to compete, so it is no surprise that it has become a classic meet for the Gitana Team. This year, the team with five arrows has even chosen to enter two of the craft fitted out by Baron Benjamin de Rothschild; two platforms whose common denominator is flight! Indeed, weather permitting, the GC32 Edmond de Rothschild – the stable’s latest arrival – will take the start alongside her big 70-foot sister. The helm of the flying catamaran will be entrusted to one Gurvan Bontemps, a 2015 recruit for Gitana Team, with a wealth of experience in ‘small’ boats, that notably includes several Formula 18 titles (double French champion, world No.2…), not to mention several years as the appointed sailor and performer on the Flying Phantom.