The dangers involved sailing the new America's Cup boats have been revealed by a picture showing Luna Rossa hurtling skywards.

And the team's coach Philippe Presti revealed the incident occurred in less than 15 knots, during a jibe turn, leaving the crew "shocked".

With lockdown restrictions being eased, the challengers have December's world series event in Auckland to aim for, before the America's Cup takes place early next year.

The foiling monohulls are expected to provide spectacular racing off Auckland, but the latest incident during testing in Sardinia also emphasises the dangers.

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Luna Rossa's AC75 leapt off the water but descended safely and remained upright, avoiding another accident for a team which has had a dismasting and suffered bow damage previously.

Jimmy Spithill, the Aussie America's Cup legend who is in the afterguard, reckoned the team was "easing back into it".

After Luna Rossa released the photo, Rossi was far more forthright saying that other teams including Team New Zealand had capsized in such situations.

"Fortunately, the best sailors in the world are in charge," he said of the AC75 boats.

Presti said Luna Rossa - the Italian challengers of record - had come out a jibe with their angle slightly wrong, putting the boat nearer the "power zone".

"The forces exerted on the rigging with this tight angle are more violent," he said.

"Again, this remains manageable at the helm, but leads to heeling over. The rear of the boat descends very quickly…(it propelled) the bow of the AC75 towards the stars because the stern of the boat is no longer supported by the rudder.

"This is exactly what the photo shows. The boat stopped dead before resting on the water. The shocked crew facing the wind with beating hearts…and took off again."

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He said the incident was more proof that the boats were pushing the limits which meant small errors could become major problems in an instant.