Kiwi Ayla Ronald, 36, was among the 22 people on board, one of whom has died and six are still missing, when a tornado struck the area where the Bayesian was anchored about 3pm (NZT).
One person died and six people are missing. The missing include UK tech entrepreneur Mike Lynch and his daughter.
Lin Ronald told RNZ his daughter was alive and well, but shaken.
His daughter has been working in London at one of the UK's top law firms, Clifford Chance.
He confirmed Wall Street Journal reports she had worked on Lynch's long-running fraud case in the US over the sale of his company to Hewlett Packard.
The yacht trip was to celebrate Lynch's legal win in the wake of serious charges, including fraud.
Regarding the yacht sinking, Lin Ronald said it was "a very unusual very rapid incident which is very sad for all involved".
The luxury yacht was struck by an unexpectedly violent storm and sank off Sicily early on Monday (local time).
The British-flagged Bayesian, a 56-metre-long sailboat, was carrying 22 people and was anchored just off shore near the port of Porticello when it was hit by ferocious weather, the Italian coast guard said in a statement.
Eyewitnesses said the yacht vanished quickly beneath the waves shortly before dawn. Fifteen people escaped before it went down, including Lynch's wife, Angela Bacares, who owned the boat, and a one-year-old girl.
The names of the dead and missing were not immediately released, but a person familiar with the rescue operation confirmed that Lynch and his 18-year-old daughter, Hannah, were not accounted for.
Italian media said the dead man was the yacht's onboard chef.
The Italian coast guard said the missing had British, American and Canadian nationalities. Survivors said the trip had been organised by Lynch for his work colleagues.
"The wind was very strong. Bad weather was expected, but not of this magnitude," a coast guard official in the Sicilian capital Palermo told Reuters.
The captain of a nearby boat told Reuters that when the winds surged, he had turned on the engine to keep control of his vessel and avoid a collision with the Bayesian, which had been anchored alongside him.
"We managed to keep the ship in position and after the storm was over, we noticed that the ship behind us was gone," Karsten Borner told journalists. The other boat "went flat on the water, and then down," he added.
He said his crew then found some of the survivors on a life raft - including a baby girl and her mother - and took them on board before the coast guard picked them up.
Italian Carabinieri patrol the port of Porticello in Sicily. Photo: Getty Images
Lynch defeated US fraud charges
Lynch spent more than a decade building Britain's biggest software company and then almost as long again fighting fraud charges related to its multi-billion pound sale.
Lynch founded Autonomy from his ground-breaking research at Cambridge University in 1996, and was lauded by shareholders, scientists and politicians when he sold it to Hewlett-Packard for $US11 billion ($NZ18b) 15 years later.
But in late 2012, HP stunned Wall Street and the City of London by alleging a massive accounting scandal at the business, and writing off $8.8b of its value.
Lynch, known for an abrasive intellectual charm, said HP did not know what it was doing with Autonomy, which searched and organised data using patented algorithms based on a mathematics developed in the 18th century by Reverend Thomas Bayes.
He spent the next 12 years in courts trying to clear his name, locked in some of the biggest legal battles in corporate history.
HP pursued Lynch in London's High Court for $5b. It won most of its case in 2022 and is still awaiting the award of damages.
The judge found that Lynch and another colleague had fraudulently concealed a "fire sale" of hardware and engaged in convoluted reselling schemes to mask a shortfall in sales of Autonomy's software, the business HP coveted.
US authorities filed criminal charges including wire fraud and conspiracy against Lynch and sought his extradition.
The British government came under pressure from Lynch's supporters to block the application. If found guilty, Lynch could have faced decades in jail.
But the appeals failed, and Lynch took the stand in San Francisco in his own defence, where he denied wrongdoing and told jurors that HP had botched the integration of Autonomy.
He was acquitted on all charges and freed after a year under house arrest. Lynch said he was "elated".
"I am looking forward to returning to the UK and getting back to what I love most: my family and innovating in my field," he said.
A person familiar with the rescue effort said Lynch and his wife, Angela Bacares, were on the 56-metre long British-registered Bayesian sailboat when it was struck by an unexpectedly violent storm and sank off the Sicilian capital Palermo early on Monday.
The yacht was owned by Lynch's family and had 22 people on board when it sank just before sunrise.
Lynch was born in 1965 and was raised in Chelmsford near London where his mother was a nurse and his father a fireman. He said his parents instilled in him an appreciation of the value of education.
At Cambridge University, he studied physics, mathematics and biochemistry, and went on to research signal processing for his doctorate. His thesis is still one of the most widely consulted in the university's library, reports have said.
In 1996, Lynch founded Autonomy which searched and organised complex data such as emails, phones calls and video.
Lynch, who has a herd of rare breed cattle on his estate in Suffolk, East England, used some of the proceeds of the sale of Autonomy to set up venture capital firm Invoke.
It was a major backer of Darktrace, a British cyber security company that US firm Thoma Bravo agreed to buy for $5.32 billion in cash in April.
Reuters / RNZ / Star News
