Kiwis: step closer to walking on water?

Team New Zealand credits its 2-0 Cup lead, in part, to innovative boat design

February 25, 2000|By Gilbert A. Lewthwaite | Gilbert A. Lewthwaite,SUN FOREIGN STAFF

AUCKLAND, New Zealand -- The 30th America's Cup between New Zealand and Italy here is turning out to be a competition between innovation and grace, and at the moment, innovation is winning, 2-0.

The New Zealand boat, Black Magic, is turning out to be a real box of tricks -- above and below the water line.

The Italian boat, Luna Rossa, is a classic 75-foot Cup racer, the fine-lined product of the big-spending Prada syndicate.

It was so sleek and fast during the past four months as it sped past 10 other boats from six nations to win the challengers' series that it earned the nickname "Silver Bullet."

But it has yet to prove a match for the Kiwis' racer, untried in competition until this week. The Italians thought their best chance at victory was with the light air of yesterday, which is why they objected to the postponement of the third race for lack of wind. Race 3 will be at 7: 15 p.m. EST today (tomorrow in Auckland).

Both boats were built within the same design rules, a complex formula involving trade-offs between weight, sail area and length. Yet, they are radically different.

The design limits were introduced after the embarrassing 1988 mismatch between the 116-foot New Zealand, the country's first-ever entry into the America's Cup, and the 60-foot catamaran, Stars & Stripes, skippered by U.S. sailor Dennis Conner. Conner won, 2-0.

The rule has since pushed designers into a corner, with most using maximum displacement -- the weight of water a boat displaces -- as their starting point for calculations.

This leaves them only length and sails with which to juggle. Technically, the longer the boat in the water, the faster it can go. Equally, the larger its sails, the faster it should go.

At its simplest, the Kiwis have opted for a slightly longer boat, the Italians for marginally more sail area.

But beyond that bold assessment lies a series of compromises, with Team New Zealand using the most innovative approach to strike the bedeviling balance between a boat suited to light air and one able to exploit stronger winds.

Black Magic has a bow design, rig setup and keel bulb never seen before on an America's Cup course.

When the boat was displayed earlier this month, skeptics howled: Black Magic was ugly; it had too much wetted area; it would be slow in light winds; it was designed for heavy-weather sailing.

"I wasn't surprised at that sort of reaction," said Laurie Davidson, chief designer of Black Magic. "The norm in the yachting and sailing game is very conventional."

The Kiwi design team started planning for this competition immediately after winning the 1995 America's Cup in San Diego. The Kiwis' 5-0 defeat of Conner established that they had the fastest two boats of their class, with the best rigs, in the world.

They brought those boats back to New Zealand as the design bed for their Cup defense.

In San Diego, the boats had sailed through the rollers washing in from the Pacific. As they crashed through the waves, the long overhang of their classic bows, known as "meter" bows, were submerged in the sea, increasing their water length -- and speed.

But in the sheltered waters of Hauraki Gulf, the overhangs were rarely submerged, providing little speed advantage. Davidson decided to try what is known as the destroyer bow, an almost vertical front.

He sawed off the meter bow of a water-tank model and replaced it with the destroyer design. It worked well in smooth waters, but not in the sort of choppy conditions that can be encountered off the coast here.

He worked on a compromise: the "knuckle bow." It shortens the overall length of the boat above water, but deepens the bow.

This increases the water length while affording a shorter overhang. Tank tests confirmed Davidson's belief: His new design would increase boat speed in both calm and heavy seas.

"There was much shaking and scratching of heads," recalled Davidson at the Team New Zealand compound. "They were saying, `I think Laurie has fallen out of his tree,' before I was able to convince them even to try it."

The front of one of the San Diego racers was replaced by Davidson's knuckle design. It out-sailed its sister boat in all conditions, cutting as much as two minutes off its course performance in California.

The downside: The knuckle design enlarged the wetted area of the hull, thereby increasing the boat's frictional resistance through the water, which could slow it in light air.

But Davidson found that it actually created a better overall hull shape. This explains why, in the first race, Black Magic confounded the critics who thought Prada would be faster in winds below 12 knots. Black Magic won by 1 minute, 17 seconds.

Skeptics thought the deeper bow would impede the boat's maneuverability, but the way skipper Russell Coutts turned Black Magic in the start-box dial-up for Race 2 quickly put an end to that notion. Black Magic won by 2: 43 after the Italians were plagued by mishaps.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.