Forced to sail mostly on guesswork after a technical glitch, Britain's INEOS Team UK broke the magical 50-knot barrier in beating Italy's Luna Rossa by 33 seconds on Saturday in the final round-robin race of the America's Cup challenger series at Auckland, New Zealand.
In doing so Team UK, which had been a lame duck due to equipment and systems issues in pre-Christmas racing, retained its unbeaten record after five races in the Prada Cup challenger series to qualify automatically for the final.
On Saturday the British yacht Britannia came from behind to lead by one second at the final mark and held on to win a race that contained nine lead changes and was the best of the regatta so far, gripping to the last gybe.
When the boats came together on opposing gybes near the bottom of the last leg -- Team UK on port and Luna Rossa with the right of way on starboard -- Britannia slid just across the bow of Luna Rossa; only meters separated the yachts. The Italian team immediately protested, but the umpires dismissed the protest and Britannia went on to a narrow win.
"What an amazing race," Team UK skipper Ben Ainslie said. "I think It's one of the most amazing races I've ever been involved in. That last cross at the finish was really, really close but I think it was just OK. Sometimes races come down to that, a matter of meters and that's the kind of racing we want to see."
Luna Rossa helmsman Francesco Bruni said his team accepted the umpire's decision.
"I think you have to just digest the decision. I think it was pretty close and from the boat it always feels a lot closer, probably it is," he said.
"We will review the video. The umpire has software that shows the boat. It's their decision in the end, there's nothing you can do."
Team UK now moves directly to the Prada Cup challenger final from Feb. 13. Luna Rossa will race the United States team American Magic in the semifinal, starting next weekend. American Magic is currently making repairs to its race yacht Patriot, which was severely damaged in a capsize a week ago.
The British team had a major problem in the lead-up to Saturday's race with the Cunningham, the hydraulic downhaul system which controls the shape of the sail. Its setting changes upwind and downwind and as the wind shifts but after a malfunction before Saturday's race, Team UK was forced to guess the right settings and rely on snap judgement during the race.
"We had a problem with our Cunningham ram so we had to lock it off," Ainslee said. "We had to guess before the start really which wind we thought we were going to have and where we should lock the Cunningham at.
"It was a real sailor's race today and I think both teams did a great job. Given the turmoil in our pre-start preparation I think the boys did a great job to keep things calm, as calm as we could."
As they rushed to make repairs before the race the British team was able to take advantage of a new rule that allows both teams one chance to call for a 15-minute postponement to the start. The race start had already been delayed on several occasions as the wind shifted from southwest to west, forcing the race committee to adjust the orientation of the course.
Britannia and Luna Rossa were side by side across the start line with the British yacht to windward. Ainslie pushed the Italian yacht to the left-hand boundary before tacking away.
When the boats first crossed, Luna Rossa was just in front of Team UK but the British boat was slightly faster. It approached the top mark just inside Luna Rossa and rounded two seconds in front.
Luna Rossa showed its speed advantage downwind and reached the second mark nine seconds ahead. It extended on the second upwind leg and led by 19 seconds at the top mark.
Team UK made some gains on the fourth leg of the leg of the six-leg race, cutting Luna Rossa's lead to 10 seconds. It continued that improvement on the penultimate leg, finding speed on the left of the course as the wind continued to shift.
The British yacht turned the final mark just one second ahead of Luna Rossa, choosing the right marker while the Italians chose the left. That allowed Luna Rossa to spend longer on the favored gybe but the British boat held its advantage. It gybed back to the left and then, almost laying mark came back on port and just squeezed across Luna Rossa's bow.
Team UK and Luna Rossa were due to race again Sunday, but the British team's win on Saturday made the second race unnecessary. The teams could still race by mutual consent.