Sir Ben Ainslie’s cutting edge catamaran bears little resemblance to the serene yachts that competed in the first America’s Cup 165 years ago. The 45ft twin hull is a 21st century flying machine – crafted from carbon fibre and loaded with as much technology as an F1 racing car.

‘Rita’, as Sir Ben affectionately calls his boat, carries a sail as large as the wings on a 747 jet. It carves through the water at 50mph – riding five feet above the surface on a brace of boomerang-shaped hydrofoils. And today I’m hanging on the back – a unique opportunity to watch Britain’s most successful sailor as he prepares to win the America’s Cup.

I can barely keep my eyes open as salt water from the Solent lashes off my face. The catamaran bucks and pitches as we flash past a race marker with only inches to spare, but there’s nowhere to shelter from the cascade of spray pouring from the hulls. There’s no chance to adjust my glasses either before another wave catches me head on. It’s so intense that I’m struggling to focus on anything through the briny haze. Instead, I cling to the netting that’s strung between the hulls with a vice-like grip.

The sound of the hydrofoils slicing through the sea is a continuous, whale-like moan. We’re soaring five foot above the water – held aloft by the power of the wind and those incredible blades. They’re shaped to cut through the waves with minimal resistance and lift the 2,400kg boat clear of the sea. It’s a magical sensation, even for the most experienced sailor. The boat pitches and yaws as Sir Ben battles for control. There’s a sense that the slightest gust could send us catapulting into watery oblivion at any point.

Sir Ben has put British sailing on the map in recent years. With four consecutive Olympic titles, multiple world championships and a knighthood in 2013, he was even given the honour of carrying the flag for the British team at the 2012 Olympic closing ceremony.

It would have been understandable if he never stepped foot on a boat again. However, the 39-year-old isn’t finished quite yet and has embroiled himself in his toughest challenge to date – bringing the America’s Cup to Britain for the very first time.

“I had two ambitions as a child: to have an Olympic gold medal and win the America’s Cup. Many Brits have tried for the latter but it hasn’t happened since the event started in 1851,” says Sir Ben, when we get back to shore.

“Immediately after I won my last gold medal at Weymouth in 2012, I said I probably wouldn’t compete at Rio. It was quite an emotional moment but my campaign to win the next America’s Cup in 2017 has already proved a massive effort.”

Winning the America's Cup is the last great sporting hurdle we have to cross

Sir Ben actually won the America’s Cup in 2013 with Oracle Team USA. At the time, the victory was described as the ‘greatest comeback ever’, with the Americans trailing Team New Zealand 8-1 in San Francisco Bay before Sir Ben was asked to take charge of the yacht as tactician. In a truly remarkable turnaround, he used all of his sailing know-how to bring Oracle back from the brink, winning the 17-race series 8-9.

“It was amazing to win in 2013 but now I want to bring the cup home to England. This is probably the only major trophy we haven’t won. Only the Tour de France eluded us for such a long time – then Bradley Wiggins cycled into the history books in 2012.”

The America’s Cup is the oldest trophy in international sport. Originally awarded by the Royal Yacht Squadron for a race around the Isle of Wight, the first event in 1851 featured 15 British boats and just one team from the USA. However, the schooner America proved to be more than a match for the British yachtsmen and it finished a full eight minutes ahead of its closest rival. Later, the trophy was renamed America’s Cup after it was donated to the New York Yacht Club.

“Despite numerous attempts to win it back, every one has ended in glorious failure. It’s part of our British maritime history – the last great sporting hurdle we have to cross. My team is aiming to right that wrong.

“Had I been involved in that first race in 1851, I would have been really furious. The British were absolutely trounced. It would certainly have been very embarrassing for everyone who took part. It’s that 165 years of hurt that needs to end in 2017.”

Before he takes on holders Oracle USA in Bermuda this June, Sir Ben has already enjoyed another special moment last summer. He and his wife, Georgie Thompson, a former Sky News presenter, had their first child, a baby daughter called Bellatrix.

His single-minded determination to win the America’s Cup for Britain saw Sir Ben set up Ben Ainslie Racing (BAR) in 2014, at a purpose-built base in Portsmouth. He then had to raise £85m in commercial sponsorship to get his boat in the water.

“The challenge of raising the money was a totally new experience – way beyond anything I had ever done before. Thankfully, we had the support of many individuals and companies like Land Rover, BT, JCB and Siemens.”

Sir Ben reveals he was interested in sailing from a young age. “When I was eight, I woke up on Christmas Day to find a dinghy in my bedroom. It was a fantastic present and I remember dashing to pull on my duffle coat and wellies to head straight out onto the water.

“My father, Rod, sailed in the first Whitbread Round the World Race in 1973 and has had a big influence on my career. I caught the sailing bug because of him. I was also bullied at school, which was uncomfortable but probably toughened me up as well.”

He calls his latest catamaran a “fighter jet on water”, and enthuses that “it’s the most amazing ride. And because you aren’t protected from the elements, the noise and sensation of movement is amplified to the point where it feels like you are taking off.”

Martin Whitmarsh, chief executive of Sir Ben’s team, Land Rover BAR, used to head up McLaren F1. “Technology will be key to success. This boat has much more in common with an F1 car than a traditional sailing yacht.

“We have had to develop all of the systems to enable the boat to fly quicker and move dynamically faster than the opposition. The sail and hydrofoils borrow much from motor sport – we even use sensors fitted around the boat to measure performance, just like in F1.”

At least Sir Ben himself didn’t have to worry about his diet so much this summer. In the larger boats used for the America’s Cup campaign, crew weight isn’t such an issue. “Before every Olympics I had to bulk up from 85kg to 93kg, eating whatever I liked and drinking those awful protein drinks.

“I used to burn up to 5,000 calories a day dinghy racing. Now I’ve retired from that, I don’t have to worry about maintaining my weight so much. As the helmsman, it’s more important that I’m light, so that any extra weight allowance on the boat can be spread around the big guys who work the winches.”

There’s still a strict exercise regime, though, and the total weight of the six crew cannot exceed 525kg. Previous America’s Cup sailors were power-sprint athletes, bristling with muscle to work the winches and grinders that trim the sails. Now they’re more likely to be a 10km runner or a rower, so they are producing a constant power output without going into the red for 40 minutes to recover.

The team’s strength and conditioning coach, Ben Williams, explained: “They have become endurance athletes. We did a lot of development work and then went and talked to the design team about how much power we thought we could give them to race in the America’s Cup. They will use that number – so the amount of power the sailors can deliver is central to the design of the boat.”

Each member of the crew is expected to burn up 36,000 calories a week – 20,000 on sailing. They undergo blood tests three times a year so a hematologist can assess what vitamins and minerals should be added to their already strict diet. Williams is also keen on preventing injuries before they happen.

“The more often I can deliver those guys to the boat uninjured with maximum energy and power, fully hydrated, the better they’ll become tactically, emotionally, physically and mentally.

“So we have created an environment where the most important thing is training to prevent injuries, as well as to develop mobility, flexibility, and the ability to get into different positions under load and not get injured. That forms the foundation of our training. Then we have the crew weight restrictions to consider, and we have to be able to create that defined amount of power. It’s a vital part of our mission to bring the cup home.”

For more info: benainslie.com; americascup.com