Team New Zealand sailing coach Ray Davies believes there's a "high chance" there will be capsizes during racing in this year's America's Cup.

The lead-up to the regatta, which gets underway in Bermuda later this month, has seen a flurry of mishaps on the Great Sound as the teams push their boats to its limits in pursuit of performance gains.

The Cup defenders, Oracle Team USA, have been in the thick of a lot of the thrills and spills, suffering three major scares over the past few weeks. The most recent was a capsize in training yesterday, when a high-speed foiling gybe went wrong. It was Oracle's second capsize in the space of a month.

Davies doesn't think these mishaps will be confined to just training runs. He said given the skittish nature of the high-powered wing-sail catamarans, it is likely we will see boats capsize during racing.


"There's a high chance that we could [see a capsize during racing]. Those conditions when [Oracle] capsized yesterday was only about 18 knots, so put another 5 knots on top of that and another boat in the vicinity and there's some luffing going on and some close quarter action, and the boats can capsize very easily," he said.

"The key when the breeze is up over 20 knots is just to do less mistakes than the opposition. People will make mistakes on those windy days and that's what will win and lose races. If there's a lot of breeze I'm not sure the performance difference between the two boats will be key, it'll actually be who can get around the race track in one piece."

At this stage Oracle are the only team to have flipped their race boat. The fact they have now done so twice has led some to conclude there are problems with the stability of their boat - christened USA-17 - or the crew's technique during manoeuvres.

Davies said from his position on the Emirates Team New Zealand chase boat, Oracle appeared to have been experiencing problems with their rudders in yesterday's training session.

"There seemed to be a few issues with their rudders yesterday. I'm sure they've learned a lot from it, but it looked like they had a few control issues yesterday, which is why they capsized - they turned a bit too far in the gybe," said Davies.

"It's a fine line - these boats get pretty unwieldy quite quickly. You have the boat set-up for certain conditions and that particular day the wind increased very quickly and maybe they were not quite on the right setting and a wee crew handling error and over she goes."

If practice racing is anything to go by, Davies said we will see yachts sparring in much closer quarters in this America's Cup, compared to the series of drag races that developed at the last event in San Francisco.

He suggested the pressure of having another yacht bearing down on a team at speeds of up to 50 knots can lead to costly mistakes.

"We are definitely seeing boats engage with one another quite a lot [in the practice racing]. There were a lot more tacks than you'd see when the boats have a bit more separation between them. There was some match racing going on, keeping a close cover on the boat behind - that was pretty interesting to see," he said.

"That just doubles the workload all of a sudden for the crew to throw more manoeuvres at them, there's a lot more resource needed to handle that. It's interesting to see the teams are turning it into a match race rather than just tearing off from one side of the course to the other going for speed."

Team NZ will get another opportunity to test themselves under race-like conditions in next week's official practice racing window. Given the Kiwi syndicate missed all but one day of the four previous practice racing rounds, they team are looking to take full part in next week's racing.

"We'll definitely try do as much racing as we can, we haven't done much against another yacht. We do a lot against the chase boat, but that's not the same thing - it's a bit like dancing with your sister really," he joked.