Emirates Team New Zealand design overview

“These are big boats. They weigh close to 27 tonnes in racing
trim and they’re an absolute handful for the crew – not so much
in a straight line but actually turning the corner.
That’s quite a game.”
ANDY CLAUGHTON, design co-ordinator of Emirates Team New Zealand, explains some of the principles behind the team’s America’s Cup Class yachts

“Of our total weight in measurement trim, 19.5 tonnes is in the ballast bulb and nearly two tonnes in the keel fin and rig. We are left with 2.5 tonnes to built the hull and all the winches and other paraphernalia. We’re fully powered up in 8 knots of breeze.”

“Upwind, we’ve got 15 tonnes of load on the headstay, corresponding to 15 tonnes of load in the runners, and 28 tonnes of shroud tension. The mast has 56 tonnes of compression; a lot for something that you can get your arms round. On any given day the sailors can break it. If they wind too hard on the winches, something will go.”

“So we are sailing within a load limit all the time. One thing we use to monitor that is a fibre optic system etched with Bragg gratings. You fire a laser up the cable, the grating reflects it back and you get a shifting wavelength that a computer can analyse. We laid a single cable starting at the starboard quarter with gratings at various sites.”

“When we’re sailing at 10 knots, the driving force from the sails is about 450kg. As a byproduct we’ve got 2.5 tonnes of heeling force and 450kg of drag. People often draw analogies between America’s Cup racing and Formula 1, but our power output is the equivalent of a 1957 VW Beetle.”

“The dark blue is laminar flow - smooth with low drag. When the bulb gets to maximum thickness the flow breaks down and goes turbulent. Another tool we use is a probe the size of a postage stamp with a sensing element that is heated up or cooled depending on how fast the water is flowing.”
“ As we don’t have much power, we have to make sure the drag of the hull is as small as it can be. We use computational flow dynamics to look at the flow over the keel fin and bulb. The dark blue is laminar flow - smooth.

“We have a green stripe on our sails. Masthead cameras are looking down at the sails and at the shape of them. Red would have been a more appropriate colour but it would have been harder to pick out so we plumped for green.”

“This is the view the cameras are seeing. Every second they’re doing a fit of the position of the hull, the shape of the sail, the twist of the sail. We’re trying to determine how much depth to put in the sail.”

“We’ve got the processing down to such a fine art that there are displays for the trimmers see what the camber and twist are and see the blueprint setting. That’s very important coming up to the start line.”

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Emirates Team New Zealand design overview

by YachtingWorld on Jun 20, 2007

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Emirates Team New Zealand design overview — Presentation Transcript