Ben Ainslie and Ineos Britannia crew plot dramatic America’s Cup comeback

Twenty-four hours can be a long time on the water. When the sea state off Barcelona changed on Tuesday, the balance of the 37th America’s Cup shifted with it. All of a sudden, Ineos Britannia, who were trailing Emirates Team New Zealand 4-0 in the best-of-13 series, were swept back into contention. The America’s Cup is a competition for sailboat builders as well as sailors, and the subtle design differences between the two AC75 yachts gave the British team an advantage in the heavier weather. Soon enough, they had pulled the score back to 4-2 .

Related: ‘The comeback is on’: Ainslie’s Britannia crew earn first America’s Cup points

One of the key reasons New Zealand had the edge in the calm seas during the opening days of the regatta was because their design team chose to optimise the boat’s performance in flat water. Their boat, Tahoro, has “dry bulbs” on its foil arm, to ensure their foils meet the stipulated weight while also minimising the amount of surface area in the water. It works when the waves are flat, but when the seas are up, the design puts them at a disadvantage.

“That’s part of the difference in performance, for sure,” Ben Ainslie said, “but it’s not just that.” He and his crew still had to get themselves into position to make the difference in performance pay. In the sixth race, which they won by seven seconds, they outwitted New Zealand during the pre-start when they caught them by surprise with a manoeuvre they had been working on in practice the day before. The Kiwis spent that reserve day on shore, because they felt the sea was too choppy.

That was a mistake. Not just because it meant the British were more familiar with the new conditions, but because it meant they felt sure that they were working harder than the opposition. Which is exactly the kind of mindset Ainslie wants.

Seven days ago, Ainslie was asked which America’s Cup skipper he most admired. Rival skipper Peter Burling had picked one of his countrymen, Russell Coutts, who won the Cup for New Zealand for the first time back in 1995. Ainslie, though, chose the Australian John Bertrand. It was Bertrand who skippered Australia II to victory in 1983. Australia II came back from 3-1 down in that series to win 4-3 and break the USA’s 132-year winning streak in the competition. It went down as the ‘Race of the Century’.

“It still makes the hairs stand up on the back of my neck,” Ainslie said. For a man who’s won so much, he loves to play the underdog. It’s why he’s spent this entire regatta talking up the opposition.

If Bertrand’s victory in ‘83 was the race of the last century, Ainslie himself has already had a star turn in the race of this one. He joined Oracle Team USA midway through the 34th America’s Cup in San Francisco in 2013. They were 4-0 down just before he took over as their tactician, and 8-1 down not long after, but, with his help, they came back to win it 9-8 . He is a man who knows, from intimate experience, how to work against the odds. Before the seventh and eighth races on Friday afternoon, the next question is whether he can do as well when they’re evening up, too.