Monday, 8 February 2010

America's Cup: Around the Course with Alinghi 5

by Alinghi media

For a crew as experienced as Alinghi’s there have been plenty of moments of trepidation during the six months of training and trialling Alinghi 5. They all stem from a combination of loads and boatspeed.

“I’m pretty sure we won’t get another chance to build a boat like this, with such high loads, such a huge, powerful machine,” says Alinghi design team co-ordinator Grant Simmer. “Its’ one of the highlights of this Cup; that these two boats are so extreme. In all our careers we’ll probably never have another opportunity to build a boat this extreme. That’s a really exciting and cool thing about this Cup.”

Exciting and cool for the designers and engineers, but an alarming experience for the sailors. There are moments when parts of the 90ft cat are experiencing loads five times in excess of the all-up weight of a Version 5 America’s Cup Class sloop. And the speeds are anywhere from two to four times as fast, depending on the angle of sail. For sailors largely versed in monohulls it’s an experience that makes their eyes pop out, especially when the alarm starts going off.

“The alarm is deafening, I hate that thing,” said team skipper and tactician Brad Butterworth, referring to the alarm rigged to the 150 fibre-optic sensors on the boat that goes off maybe five times a day. “The problem is bearing away. Everything quadruples. And that’s where you run the risk of flipping them.”

The timing is also familiar. The competitors will be given an attention signal at 10 minutes, a warning signal at 6 minutes, preparatory at 5 minutes, followed by the start. After the 5-minute preparatory signal the two crews have 2 minutes to enter the start box. If one or both boats fail to enter into the start area within the 2-minute period they’ll be assessed a penalty by the on-water umpires.

That’s all standard stuff. What isn’t standard is the pre-start entry line.

In an attempt to keep the two multihulls from going bow-to-bow at incredible speeds – for argument’s sake we’ll say a closing speed of 50 knots – a second port-end vessel will be placed downwind of the pin end yacht, creating a diagonal entry line (see diagram above). The distance the entry pin end is placed to leeward will be determined by the race committee.

“The idea is that neither team would like to see the boats aiming at each other at 30-plus knots,” says Ed Baird of the Alinghi afterguard.

Once both boats have entered the start box the temporary port-end boat will be removed and the start line will be live. If one or both boats are on the course side before the start gun they’ll have to re-round one end of the start line.

In a wind square to the actual start line, the skewed entry line should nullify the starboard-tack advantage. If the port-tack boat enters the start box at the 5-minute gun it should be able to get into the lower right corner of the start box without incident. But then the fireworks could start.

“This means that the boats can get into the starting area in a safe pattern and the first time they get next to each other is more likely to be on same tack,” Baird says. “So the speeds could be closer and they should be able to manoeuvre around each other in a much easier way.

“This is an intelligent way to avoid a high speed multihull dial up that could end in large tears,” Baird says.


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