America's Cup: The key design that won Team New Zealand the America's Cup

Team New Zealand celebrate winning the America's Cup. Photo / AP.

The key design philosophy that won Team New Zealand the 35th America's Cup is also what very nearly ended the Kiwi campaign.

The decision to pitch the Emirates Team New Zealand boat more towards the lighter air and to push for speed over stability, is what made the sleek catamaran so unwieldy in heavier breeze, leading to the team's dramatic capsize during the challenger semifinals.

The shore crew somehow managed to piece the mangled wreckage back together again in time for Team NZ to get back on the water 48 hours later - a feat five-time America's Cup winner Dennis Conner referred to as the eighth wonder of the world - and close out the semifinals against Ben Ainslie Racing.

The capsize was the most extreme of a number of incidents where Team NZ experienced control issues, with helmsman Peter Burling and crew sailed on the edge for much of the challenger series. Some of the opening rounds of racing were punctuated by spectacular splashdowns and bucking hulls, as the New Zealand boat clearly lacked the same stability of some of their rivals.

Team NZ's technical director Dan Bernasconi said the design of the boat put the crew under serious pressure.

"In the appendage design it was clear even in the last America's Cup there was a tradeoff between a foil that was stable and one that is fast," he said.

"We decided right at the beginning we'd aim for the really high performance, but difficult to sail, and then work out how to sail it. Glenn [Ashby] was totally on the same page with that.

"That's the philosophy we've had all the way along, just push, push, push for performance and then work out how to get it around the track later on."

Adding to the difficulty early on for Team NZ, were the constant upgrades and changes to the boat, as part of the team's desire to keep developing and seeking performance gains right through the regatta.

"The boat was developing all through boat one - the test boat - and since we launched this race boat, so the guys never really had a stable platform to work out how to get the most out of until the last couple of weeks," said Bernasconi."

"That's how the boat has evolved and how we've ended up in the position we're in now."