Technology always has a major role to play role to play in the America’s Cup, and sometimes a specific advance will leave the tournament awash with intrigue. In 1983, it was the revolutionary winged keel built by winners Australia II. In 1987, it was the trail-blazing fibreglass hull built by Team New Zealand.

This year, when the yachts were unveiled in Valencia, all eyes turned to the defenders, Alinghi of Switzerland. It was rumoured that they had found a way to tilt their keel laterally, to prevent it from bending as the yacht heeled under sail and thereby reduce drag. Even a single degree of tilt could give them a significant advantage.

Yet the most eagle-eyed of yachting experts could not confirm the rumour, and the Swiss were saying nothing. In the end, Alinghi’s challengers decided it was a red herring. “Any system that was actually workable would be illegal,” commented Andy Cloughton, head of design for Emirates Team New Zealand. “The bulb weighs 19 tonnes on the end of a four-metre lever. You’d have to work pretty hard to shift that.”

To the inexperienced eye, all the yachts in the America’s Cup look identical. However, innovations in this sport can be both small and significant. The BMW Oracle team, for example, recently took advantage of BMW’s experience in Formula One motor racing to reduce friction on its sail winches, using a ceramic material developed for wheel hubs. Similarly, innovations in hydrodynamics and aerodynamics can be subtle in appearance but have a massive impact on performance.

The design of the hull begins with paper and pencil and then moves to computer-aided design and numerical analysis. Dirk Kramers, chief engineer of Alinghi, explains: “We use numerical tools and simulations. If the design passes that test, we might go to a wind tunnel. And if it passes that test and it’s still a good idea, we might build the full-scale part. Then we’ll test it on the water and if it’s still a good idea, we’ll race with it.”

Many of this year’s America’s Cup teams used a piece of software called CATIA (Computer Aided Three-dimensional Interactive Application) to design their yachts. According to the software’s developer, Dassault Systemes (one of the corporate partners of French team Areva Challenge), the software is popular because the America’s Cup design rules can be built in.

To manufacture a competitive yacht, the hull is fabricated from honeycomb-patterned carbon fibre, to save weight. It is then coated with a mandatory type of polyurethane paint (compounds designed to help the yacht slide more easily through the water have been banned).

Under America’s Cup rules, only two components are allowed to move underwater: the rudder and the keel trim (which is why the idea of a tilting keel is being discounted). The bulb of the keel – responsible for keeping the boat upright and counteracting wind pressure on the sails – represents 80 per cent of the yacht’s total weight. So the keel itself must be incredibly stiff. At the same time, it must be as thin as possible to reduce drag.

The mast is designed in conjunction with the sails. Together, they exert 60 tonnes of pressure, as if the mast were an arrow about to be fired through the bottom of the yacht. There are 15 tonnes of tension in the forestay alone.

Most of the sails used in the America’s Cup are manufactured by a single company, North Sails, based in Florida. At its high-tech factory in Minden, Nevada, the company casts the giant sails in huge moulds – to the teams’ exact specifications – from Kevlar, Mylar and carbon fibre.

There are basically three types of sail on an America’s Cup yacht: the mainsail; the headsails, of which the largest is the genoa; and the spinnaker. The mainsail is “squared” in profile at the top to reduce drag. It is also given tautness by carbon fibre battens set in pockets across its surface. The design and positioning of the battens is something the teams keep a closely guarded secret.

The sails have four or five horizontal bands of colour called “canvas stripes,” which can be photographed and analysed to understand how the sails behave under different conditions. Emirates Team New Zealand is one of the few yachts racing with masthead video cameras in place. Andy Cloughton says: “We have a system that automatically analyses data from the canvas stripes and presents it as information for the sail trimmers [who work the ropes that control the mainsail and genoa].”

Every ocean-racing yacht is now also dependent on its electronics, which are carefully sealed away to keep out seawater. These are especially important during the dog-fight before a race begins, as the yachts circle each other, seeking an advantageous position at the starting gun.

The US satellite-based global positioning system (GPS) is used in conjunction with weather data and information about the yacht’s dynamic characteristics. In pre-race testing, hulls are festooned with sensors and strain gauges and data is transmitted in coded form back to base for analysis. For the race, all the measuring gear is stripped off to reduce weight.

GPS plays a big part in another technological aspect of the America’s Cup: the spectator experience. Yachting is not an ideal spectator sport because the yachts are distant, the playing “field” is hard to visualise and it is often difficult to understand who is winning or losing. This is why every competitor is now obliged to carry equipment from the New Zealand company Animation Research (AR). This equipment uses GPS and other information to determine the precise position of each yacht during each race, and relay this information to shore. There, the company creates a virtual video model of the race for distribution to broadcasters and sponsors worldwide.

AR is not the only New Zealand company at the leading edge of nautical electronics. Ivistra Technology of Auckland will be piloting what is thought to be the world’s first broadband desktop television for the Cup. Emirates Team New Zealand, meanwhile, has chosen to use another Kiwi company, Tate Radios, for secure communication. The company has developed a robust version of a US professional service radio standard with powerful encryption technologies.

When mere seconds can separate the victor from the vanquished, it is clear that technology can provide the winning margin. But sailing is still about the wind, the waves and the weather, and these are hard to model, no matter how powerful your software. As Dirk Kramers of Alinghi puts it: “The most valuable asset in terms of technology is still the people.”

Alan Cane is the FT’s senior technology correspondent