Team New Zealand boss Grant Dalton says the new AC75 America's Cup monohulls could roll right over if someone on board makes a mistake.
Speaking to the Herald from Italy, Dalton said the 75-foot foiling AC75 was unlikely to do a dramatic pitch-pole like the world saw two years ago but it could turn upside down. The boats were designed to be self-righting, depending on wind conditions, he said.
"I don't think you'll see a face plant like we did in Bermuda because monohulls don't do that. But you're more likely to see, and it's quite possible, that you'd see a boat, if it's manoeuvred incorrectly, roll over."
Team New Zealand know all too well about how easy it is to make a mistake when sailing a highly-technical boat under extreme conditions.
Two years ago spectators watched in horror as ETNZ's AC50 catamaran plunged bow-first into the Great Sound off Bermuda before a race, hurling some of the crew into the water and allowing Sir Ben Ainslie's British syndicate to win by default.
The team's shore crew, crew and volunteers worked overnight to repair the severely damaged wing-sail and Peter Burling and his crew went on to win the Cup.
The new boats are expected to reach speeds as high as 40 to 50 knots and by all accounts will be difficult to sail. Luna Rossa team principal Patrizio Bertelli this week labelled the AC75 design "too difficult, too extreme" in an interview with Italian publication La Stampa.
Helmsman Francesco Bruni said the AC75 would be more difficult to sail than the AC50 catamarans in Bermuda. The multi-hulls balanced on four points whereas the monohulls rested on three, the two rudders and the arm-foil. "It's a question of balance. You have to come up with a new way to navigate and it's not easy."
Team NZ team principal Matteo de Nora said Bertelli was right in saying the AC75 design was extreme.
"It was a very specific choice we made. It's supposed to be challenging to sail."
The America's Cup could not be just another of the hundreds of regattas that occurred around the world.
"It has to be, in our opinion, the Formula One of sailing from a technical point of view. It is a way to show the innovation that is part of the New Zealand culture."
Dalton said work done in the simulator indicated the AC75 was unlikely to be more difficult to sail than the AC50 catamarans.
"That'll be proved on the water one way or the other. But if it is, I'm not sure that's a bad thing."
Referring to what he described as the "impressive bunch of guys" announced today as crew for the 36th America's Cup in 2021, Dalton said if the AC75 was harder to sail "that's possibly a good thing for us".
Aucklanders will get a chance to see the AC75 in action from about August when Team New Zealand will begin practising on the Auckland harbour.