Although much of the story about the 33rd annual America's Cup race starting today has focused on the endless court battles, when the boats actually face off it will be a display of science and nautical technology unlike any ever seen.

The boats – both multihulls – can sail up to three times faster than the wind that powers them. The designs elements that facilitate this performance can only be described as exotic, a long list that includes canting masts, wing sails, composite hulls, carbon fiber rigging, unique keel shapes and mysterious electronics.

The result is two sailboats capable of speeds north of 40 knots. That's fast enough to give most powerboats a run, to cause difficulties for broadcasters who cover the event and to challenge the race committee that judges it.

Whatever the outcome of the match in Valencia, Spain – and the ongoing legal action – the boats themselves present a show of their own.

ED BAIRD-ALINGHIDefender Alinghi 5 shows off her sail plan and twin hulls in the sun off Valencia."This will be quite possibly the most spectacular America's Cup ever," said Paul Cayard, an veteran of the America's Cup, the Olympics and several round-the-world races who will broadcast the races for Eurosport. "The boats are technologically the most advanced sailboats ever built." 

THE DEFENDER

It is not a stretch to say that Alinghi 5 is the ultimate high-tech sailing catamaran. Every component and system aboard represents the leading edge – maybe the bleeding edge – of technology, from the miles of carbon fiber in the structure to the 3-D composite sails to the computerized monitoring and control systems. Alinghi 5 shares the basic design elements of all sailing catamarans, with her twin hulls and single mast. But to create her, team leader Ernesto Bertarelli and his designers pushed every element to its extreme. The result is a 90-foot long by 90-foot wide monster that will make previous America's Cup racers look like a herd of turtles.

The sloop rig utilizes a swept-back, canting main mast made of carbon composite that is as tall as an 18 story building. The sails are made of stiff composite materials and molded to the optimum airfoil shape, a so-called 3-D sail. The mainsail is approximately 6,000 square feet, while the standard headsail is 4,000 square feet. Alinghi also carries a huge gennaker of almost 12,000 square feet – the third largest ever made, according to the team.

The outsized dimensions and massive sail area of Alinghi require tremendous structural strength combined with light weight. That dictated the use of expoxy-infused carbon fiber throughout the boat. A specially designed Y-shaped tube transfers forces from the rigging to the central spine structure. Even the rigging is carbon fiber – 1,762 feet of it. Some 150 fiber-optic sensors monitor the health of the structure in real time and will warn the crew of potential overloads.

Alinghi uses an engine to power hydraulic winches, reducing the manpower requirements for sail handling – no more grinders. The engine also powers pumps that move water ballast from one hull to the other. With no central hull, the bowsprit is anchored at the base of the mast and is actually substantially longer than the main boom. The yacht also uses specially designed foil shapes as sophisticated dagger boards in both hulls. The foils are S-shaped to develop lift as well and resist the side forces imposed by the sails. By raising or lowering them, the crew can carefully control the amount of lift generated.

THE CHALLENGER

Recently rechristened USA, the BMW Oracle boat is an even more extreme form of sailing multihull than Alinghi's cat. Built to roughly the same 90-foot by 90-foot dimensions, USA is a significantly different boat. BMW Oracle chose a trimaran hull configuration, with wave-piercing bows in the two outer hulls, which are quite a bit longer than the central hull.

After initial tests in the United States last fall, the team removed the soft mainsail and replaced it with a solid wing – the “ultimate sail.” Because the function of a main sail is to generate lift by manipulating the flow of air over its curved surface, a solid wing like those on airplanes can theoretically master that task. Although Dennis Connor's Stars and Stripes, which won the 1988 America's Cup race, had a wing sail, the one aboard USA is significantly larger. In fact, it dwarfs those on jumbo jets, towering nearly 223 feet above the deck.

According to Joseph Ozanne, an aeronautical specialist with the BMW Oracle design team, the ability to trim the wing sail easily is one of its big advantages over a soft sail. “You need massive tension to trim the soft sail," he says. "With a wing sail, you can get the shape you want much more easily."

GILES MARTIN-RAGETBMW Oracle’s USA helmsman is a long way above the water in this shot of recent training off Valencia.The wing aboard USA has an area of 7,000 square feet, while the standard headsail is 6,700 square feet and the gennaker is 8,400 square feet. The wing and sails generate an immense amount of speed. The team says the boat is easily capable of 40 knots and may even approach 50 knots.

Where these multihulls really excel is in light-air sailing. There is a video of USA sailing at an estimated 29 knots in approximately 7 knots of wind. In fact, the race will be called if wind speeds exceed 15 knots or is seas grow greater than three feet.

This kind of performance is a direct result of the design of the high-tech wing design. For example, the mast itself is the leading edge of the wing, and it can be rotated to present the least amount of wind resistance and to properly direct the airflow over the sail. The two separate sections of the wing are adjusted to further optimize that airflow, much like the flaps on the trailing edge of an airliner's wing can be raised or lowered to adjust performance.

The hulls of USA are joined by two wing-like connectors, with the twin helms on either side of the aft section. In photos of USA sailing in a stiff breeze, both the windward outer hull and the center hull are lifted clear of the water and the helmsman looks to be 15 to 20 feet above the surface of the water. USA also utilizes specially curved dagger boards to control lifting and side-forces. And, like Alinghi, she uses hydraulic winches for raising, lowering and trimming sails, with the notable exception that the wing cannot be lowered, only de-powered by deliberately reducing its effectiveness.

SAFETY QUESTIONS

Neither boat has been in its final configuration for more than about a month at the race site in Valencia, and the unique designs employed by both teams has raised questions.

For example, one element that remains to be seen is how well these two behemoths can be maneuvered. With most of the hull surface out of the water, and only one board and a single rudder submerged, there may not be a great deal of control authority. Many observers also worry about the structural loads on these boats. USA suffered a dramatic mast failure in early testing on the west coast of the United States last fall, before the wing was fitted.

Another concern is for the stability of the boats and safety of the crews. Extreme-powered multihulls are not the most stable of platforms, and capsizing is not unheard of. At the same time, both boats are being driven by the most experienced – and most extreme – sailors in the world. Whatever happens, race fans are likely to see an America's Cup match unlike any in history.

GEORGE JOHNS-ALINGHIDefender Alinghi 5 is seen here practicing in the days before the race.