Jimmy Spithill, the Oracle Team USA skipper, lost his cool over umpiring decisions that have gone against his team in this America’s Cup.

The Australian decided enough was enough after his team incurred a penalty for failing to stay clear of challengers Emirates Team New Zealand during a dial-down on the first beat in race five yesterday.

It was a costly call that Spithill heatedly disputed.

“We had them altering the whole time, we were doing everything we can,” Spithill argued. “We had them altering and we’re frustrated with the penalty.

“We just feel these guys have been given a few soft penalties. We had one in the first race of the Qualifiers against us; they should have got one at the top mark and the umpires admitted that.

“We saw what happened in the Artemis race, they gave them one there. It’s just seems they are getting a few soft ones from the umpires.”

On a much more positive note, Spithill was delighted to see his team chalk up their first point after winning an exciting sixth race, which featured multiple lead changes and more breathtaking dial-downs.

“It was a well-earned win and was exactly what the boys needed,” said Spithill, the youngest skipper to win the “Auld Mug”. “That’s a big step for the team, getting a race win — and the boat is faster. “

Oracle started the day trailing 3-0 in the best-of-13 series and in desperate need of turning their flagging fortunes around to get their title defence back on track.

“It reminds me of San Francisco when, once the guys get behind and they can see the boat is faster, then you start building some momentum,” Spithill said. “So that was important to get that win today.”

Oracle made changes to their AC50 foiling catamaran during a five-day layoff period to try to make it faster in the light air and the result is a boat more evenly matched with the Kiwis in these conditions. Perhaps the most noticeable changes were the removal of the hybrid pedal grinder and foil design.

“We made a commitment inside the team that we would use every single one of them and we wanted to make the boat faster, and we all saw today that the boat is a lot faster,” Spithill said.

“It was five very long days, 24-hour shifts for the guys on the shore, and the good thing is we are now able to reward them with a win. And for the sailors they’ve now got confidence and that’s the most important thing.

“We are just happy with the performance of the boat today, but there is more speed left in the tank.”

While encouraged with his team’s morale-boosting triumph, Spithill said there is still room for improvements on boat handling — particularly on the starts after picking up a penalty in race five for going over the line early.

“We’re obviously frustrated with the first one,” he said. “On board the boat, all of our gear had us behind the line and it was wrong, so we know we got to make some improvements there.

“Obviously, we’re not sailing as well as we should be; that’s pretty apparent. We know we can do a better job, technique — wise, and clearly we didn’t do that in the first [race].

“We had a few issues in the first race and even in the second race we had a pretty good lead and lost it again. It’s good to be able to come back from a race like that.

“But the important point is the boat clearly is faster because of the changes, and it showed in the second race if the athletes on board the boat can do a good job, then the boat is even another step faster.”