Tuesday, 2 February 2010

America's Cup: Alinghi 5 - From Concept to Valencia

Beam was a major factor in the design of Alinghi 5. The mast also stands 17 storeys tall. Image copyright George Johns/Alinghi.

by Alinghi media

A boffin’s favourite day is the one when they’re given a blank sheet of paper and told to create. Such was the brief given to Alinghi’s 23-member design team – led by co-ordinator Grant Simmer, chief designer Rolf Vrolijk and chief engineer Dirk Kramers. The result of their work is the carbon-fibre technical and engineering wonder called Alinghi 5.

“This really has been a designer-driven programme, basically because not many of the sailing team have a lot of experience in a multihull this big,” says bow team member Rodney Ardern, who has minimal previous experience aboard multihulls.

One of the strengths of Alinghi during its two America’s Cup victories was the interaction between the design team and sailing team. The two teams worked closely together to develop a boat that had good VMG speeds and was manoeuvrable. But because of the stop-start nature of this Cup cycle and the short lead time the designers have shouldered heavy responsibility in creating Alinghi 5.

“Nothing is straightforward with Alinghi 5. Nothing,” said Simmer. “I think everything is bigger and higher loaded than anything any of us have ever done before.”

The conceptualisation phase began early in 2008. That’s when the design team began exploring the areas of length, beam, hull shape and sail plan. At that time Alinghi faced the possibility of a match in October 2008. So the design team also had in mind that it needed a boat that could be built quickly so that it could be sailed for two months before the match. Construction of Alinghi 5 began in May 2008.

“The brief for the boat was for something that could be constructed very quickly,” says Kramers. “We needed something very simple, because with a tight time frame we were way behind on the learning curve.”

While Simmer, Vrolijk, Kramers and their fellow design team members have proven their expertise with two Cup victories, they needed multihull expertise in the team. Kramers is a multihull sailor and was part of Dennis Conner’s design team during the 1988 Match, and engineer Kurt Jordan had prior multihull experience with the offshore catamaran PlayStation. But beyond those two, the team was thin. So they turned to Frenchman Nigel Irens and his design partner Benoit Cabaret for help conceiving the boat.

“All credit to Dirk and Kurt and the other engineers because they have built something none of us had ever had experience with,” Simmer said. “Nigel was good to have around, particularly at the beginning to make sure we didn’t make a mistake conceptually.”

The design team worked on the assumption that the challenger would be 90ft long by 90ft wide. That type of beam is easier to achieve in a trimaran than a catamaran, and beam was one of the key parameters that underwent a lot of research because righting moment is in direct relation to beam and rig height.

“We had to make early decisions on what we thought was the maximum righting moment we could live with structurally,” said Simmers. “The greater the righting moment the faster you will be. But every time we added righting moment, our VPP kept telling us more sail area. So we had to choose a reasonable limit, and that also involved mast height.”

Construction of Alinghi 5 resumed in April 2009 when the New York Court of Appeals re-imposed GGYC / BMW Oracle Racing as the challenger of record, thus mandating a Deed of Gift match. Some three months later, on 8 July 2009, Alinghi 5 emerged from its build shed in Villeneuve, Switzerland, a completed cat. Two and a half weeks later, on 20 July 2009, Alinghi 5 made its maiden sail on Lake Geneva.

“The very first day we went sailing we had these grand plans of being very conservative,” said Simmer, “not allowing the boat to fly, just take it easy. We got a little gust and the thing started to fly, and we just sailed off. It seemed perfectly natural.”

Since that day Alinghi 5 has been developed through a detailed plan. A taller rig was stepped last November during testing in Ras Al Khaimah. And the interaction between the design team and sailing team has resumed. The sailing team has become so used to the yacht that the sensitivity of the alarms has been decreased as the sailors’ intuition regarding safety limits has increased. But there have still been moments of trepidation.

“We’ve had the boat in up to 19kts true wind speed,” Simmer said. “It’s scary. It is scary at that sort of wind speed.”


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