Crouched low in the belly of the boat, you do not notice the other vessel until it is upon you. Suddenly, a flash of sail appears out of the corner of your eye and whizzes past. Your boat responds, jockeying for position, fighting for the same advantageous piece of water. It is fast and aggressive — and the race has not even started yet.

This week, The Times was allowed to sail with Ben Ainslie and his British America’s Cup entry, TeamOrigin, in the Louis Vuitton Trophy in Nice, where they are racing other future contenders for the oldest trophy in sport. We were just along for the ride — “Don’t touch anything, especially those ropes there if you want to keep your fingers,” one sailor warned — but it was a fascinating experience.

The first thing you notice is the lack of room on board. Seventeen sailors are packed in like sardines, yet are so well drilled that when the time comes for action they slide in beside each other to yank on ropes, whirr the grinding wheels and spin the boat.

The next thing is the sheer silence for much of the time. As they take their course, most of the crew crouch below the gunwales. Those standing — Ainslie, the skipper; Iain Percy, his tactician; and Ian Moore, the navigator — stay close together to reduce drag. The only sounds are the creak of ropes under tension, the moaning of the wind against the sails and the steady Irish purr of Moore, with a laptop in one hand and a yellow compass held to his eye with the other.

“Three, three and a half, a little higher,” he murmurs in a voice that has the same soothing repetition of the Shipping Forecast, calling the times to the next mark and the position of their opponent.

Rob Greenhalgh shins up and down the 100ft mast like a monkey. Perched at the top he scans the seas for the dark areas that indicate greater wind. He communicates this by radio to Andrew Simpson, the strategist on deck, who talks to Percy, who mutters suggestions into Ainslie’s ear.

Then, at a blink, the crew spring into action. Even Moore puts down his computer to heave on a rope and help to unfurl the spinnaker. “Big gains to us, Ben,” Simpson shouts. Ainslie, his shoulders hunched, looks grimly ahead, planning the next manoeuvre. It’s cat and mouse.

“We spend our whole time trying to make it look easy,” Mike Sanderson, the team director, said after the win that put them into today’s semi-finals as second seeds.

“Everyone is very professional,” Percy said as he, Ainslie and Simpson reflected on the race, recreating the moves with sugar cubes. “Staying calm and not screaming and shouting helps.”

The three have known each other for 20 years. Ainslie was at school with Percy — “I used to beat him up,” Percy said — and Simpson has been competing with the others since he was 9. “We’ve been friends a very long time, which helps because this is all about relationships,” Percy said.

“We are like a married couple, or a threesome; at times there will be stressful situations but we have such strong bonds that we can deal with that and get on with the race.”

Between them, Ainslie, Percy and Simpson have won six Olympic gold medals but to win the America’s Cup for Britain for the first time is what drives them now. “Winning with a team is far more rewarding than doing it on your own,” Ainslie said.

The team is more than just the sailors. “We have 24 people in our design office and they consider themselves to be as important as Ben Ainslie and Iain Percy and all the great sailors,” Sir Keith Mills, the team principal, said. “And frankly they are, because if they do a lousy design job it doesn’t matter how great sailors they are, we won’t win.”

They won’t challenge for the Cup until at least 2011, after Alinghi, the Swiss holders, and BMW Oracle, from the United States, have conducted a court-ordered duel for the trophy in February. Three things make a winning America’s Cup team, Mills said: “a great design team, a great sailing team and competent management”.

TeamOrigin arguably have all three as well as the ethical high ground through a new partnership with the Carbon Trust to minimise the team’s effect on the environment. Mean, keen and green: Oracle, with only four wins out of 11 in Nice, should beware.