THE AMERICA’S CUP : For ‘Banana Boat,’ the Stars & Stripes Is Doing Just Fine

The first time Australian yacht designer Ben Lexcen saw Dennis Conner’s Stars & Stripes, he hooted.

“Bloody banana boat,” chuckled Lexcen, who designed the winged-keel Australia II, III and IV. He suggested Conner hire Harry Belafonte as bowman so he could sing “Day-O” when they sailed.

To anyone accustomed to traditional 12-meters and the America’s Cup, Stars & Stripes is indeed funny-looking, with a turned-up bow and stern that give it its distinctive banana profile.

But Conner is getting the last laugh. Recently, Stars & Stripes eliminated the more conventional-looking New Zealand from the challenger trials and, beginning Saturday, will go against Kookaburra III in the best-of-seven final series for yachting’s top prize.

So what is this curious-looking creature called Stars & Stripes, and what makes it so special?

“It’s a medium-sized boat that acts like a big boat,” said design coordinator John Marshall, who along with three yacht designers and a host of computer whizzes hatched the design with which Conner hopes to regain the Cup he lost to Australia II in 1983.

It took Marshall’s crew two years to come up with the design. They built three other boats, spent millions of dollars and thousands of man-hours on computer research and tank-testing. In the end, they settled on something so sufficiently different that it probably is the second-most radical design here, after Tom Blackaller’s USA, the boat with a rudder at each end.

As odd as Stars & Stripes looks from the waterline up, with its beaklike prow and sharply upturned transom, what’s under water is just as weird.

For the first four months here, Conner shielded the underbody from public view. But in the last few weeks, after time ran out for anyone to duplicate it, the shape of success has been revealed.

Once past the shock of the space-age strips of plastic “riblets” covering the underbody to reduce drag, you can see that, as Marshall said, Stars & Stripes is a big boat crammed into more moderate measurements.

The underwater body is bulbous at the ends, like a whale’s belly, in order to create the sailing characteristics of a bigger boat without paying a penalty.

Under the 12-meter rule, the basic design variable is size; the penalty is power. The bigger the boat, the less sail area permitted.

For Fremantle’s big seas, most successful boats have been on the large side, to punch through heavy conditions without losing boat speed.

To Marshall and his group, including defense contractors SAIC, Grumman and Boeing, as well as top yacht designers Britton Chance, Dave Pedrick and Bruce Nelson, the challenge was to get big-boat characteristics without paying the price in reduced sail area.

They came up with the bulbous shape, with unusually rounded and voluminous ends under the water that Marshall said “creates the wave of a big boat” but has the measurements of a more moderate one.

Is it the shape of the future? Seven races will tell.

The advantage of Stars & Stripes’ oddball shape is high upwind potential for speed in moderate to heavy breezes as the big underbody accepts the extra power and puts it to work, rather than bogging down.

The disadvantage is a dramatic drop in performance pushing the bulbous body around if the wind gets below 14 knots, which, luckily for Conner, doesn’t happen too often around here.

Also, because of the substantial wetted surface, designers shied away from super-efficient, wide-winged keels that proved successful on other boats, notably Kookaburra III. Too much extra drag under the water, the Stars & Stripes team figured.

Stars & Stripes’ keel, which has not yet been publicly exposed, is fairly conventional, Marshall said, with delta-shaped wings on the bottom that aren’t particularly wide.

With its bulbous hull to push around, Stars & Stripes is no world-beater on downwind legs, either, but usually more than makes up for that with superior upwind speed, getting the lead on the first windward leg and hanging on as long as the wind stays up.

Even the turned-up ends that so amused Lexcen have a purpose. The 12-meter rule calls for a certain average freeboard, or height of the deck above the waterline, with measurements taken at three points.

Stars & Stripes is high at the two ends and low in the middle, concentrating weight amidship, where it helps provide stability.

There are a number of other technical oddities in the design that all add up to a shock effect on first sight. Stars & Stripes looks a bit like one of those drag-racing “funny cars,” but its functional lines grow on you, especially when it thunders along in a big wind, fully powered, next to a less stable vessel getting banged around by the big seas.

The only question remaining is where they got the color--powder blue--which in the macho Cup environment has since been dubbed gunsmoke blue.

It was Conner’s idea, it turns out. He saw the blue Volvo of tactician Tom Whidden’s wife one day and was sold.

“He just said, ‘That’s it. I have to have that color,’ ” said Whidden’s wife, Betsy.