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Kiwis: step closer to walking on water?; Team New Zealand credits its 2-0 Cup lead, in part, to innovative boat design

THE BALTIMORE SUN

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.

Black Magic's bulb keel is also longer and flatter than usual. The length again increases the wetted area, but also gives the bulb a smaller frontal area, which lessens resistance.

The flatter bulb lowers the boat's center of gravity and makes the racer more stable when it is heeled over, improving its heavy-weather performance. Davidson also experimented with the bulb's wings, putting them in the center of the bulb rather than the normal rear position.

In wind tunnel tests, he could find no difference, but when the positions were tested at sea, the crew felt the boat handled better with the wings in the bulb's midsection.

"It was not scientific," Davidson said.

The third major innovation was the "millennium rig." It gives Black Magic three horizontal mast spreaders instead of Prada's four. The stays go diagonally from the tip of one spreader to the tip of the next, crisscrossing the mast. This gives Black Magic's mast eight points of lateral support against Prada's four.

The idea came from the rig designers, and Davidson likes that with one less spreader and less wire both weight and windage are reduced.

In another novel move to reduce wind resistance by the merest faction, the Kiwis race without the masthead backstay attached to the stern on upwind legs, using it only for downwind runs.

"It's a pretty clever thing they have done," said John Bertrand, professional sailor and racing consultant in Annapolis. "They are playing at such a high level that other teams are not even thinking about things like that. That's what makes them so good."

Said Davidson: "We are not saying we have produced the best boat for every condition, but we think we have got a very good boat for every condition and the best boat in some conditions, which are probably the heavier ones.

"If the wind comes in at 20 knots or more, we will be smiling."

Although the forecast is for continuing light air, a smiling Davidson predicted: "Not a 5-0, but we will win."

America's Cup finals

New Zealand vs. Prada (Best of nine; New Zealand leads 2-0)

Race 1 -- New Zealand won by 1 min., 17 sec.

Race 2 -- New Zealand won by 2 min., 43 sec.

Today (tomorrow in New Zealand) -- Race 3

Tomorrow (Sunday in New Zealand) -- Race 4

Monday (Tuesday in New Zealand) -- Race 5

Wednesday (Thursday in New Zealand) -- Race 6*

March 3 (March 4 in New Zealand) -- Race 7*

March 4 (March 5 in New Zealand) -- Race 8*

March 6 (March 7 in New Zealand) -- Race 9*

*-If necessary

Pub Date: 2/25/00

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