Police divers searching a British superyacht that sank off the coast of Sicily are taking 12-minute underwater shifts to try to locate those missing.

The rotating search teams, clad in wetsuits and equipped with oxygen tanks, can only stay below for that length of time because the Bayesian vessel is resting at a depth of 50m.

British tech tycoon Mike Lynch, 59, and his 18-year-old daughter Hannah are still missing after the 56m luxury yacht sank near Palermo after being struck by a heavy storm in the early hours of Monday.

Morgan Stanley International Bank chairman Jonathan Bloomer and his wife Judy are also among the missing.

A body, believed to be that of the vessel’s cook, has been discovered.

Four of the missing passengers are British and two are American, Italian news website la Repubblica reported.

What happened to the Bayesian?

The British-flagged vessel was carrying 22 people – 12 passengers and 10 crew – when it was hit by a heavy storm that created waterspouts over the water on Monday morning.

It was reportedly anchored to the sea bed near the harbour of the small fishing village of Porticello, to the east of Palermo, when the storm struck.

Witnesses say the ship’s 72m-long mast was broken in half and the ship lost balance and sank, disappearing under the water at about 5am local time.

Who was on board?

Those still missing

Mike Lynch

Once described as “Britain’s Bill Gates”, the 59-year-old technology tycoon, born in Ilford, Essex, to Irish parents, founded software giant Autonomy in 1996, later selling it to US company Hewlett Packard for £8.6bn in 2011.

He went on trial in San Francisco over a fraud charges related to the sale, but was found not guilty on all counts. A spokesperson for Lynch has said there was no comment.

Hannah Lynch

Sicily’s civil protection agency told the BBC that Lynch’s 18-year-old daughter was also among those missing.

Jonathan Bloomer

The BBC reported that Sicily’s Civil Protection department had identified that Bloomer, 70, the chairman of Morgan Stanley Bank International and insurance company Hiscox was missing. The Mail Online reported that Italian authorities said Bloomer’s wife is also missing.

Later, Hiscox group chief executive Aki Hussain confirmed the couple were missing.

“We are deeply shocked and saddened by this tragic event,” he said.

“Our thoughts are with all those affected, in particular our chair, Jonathan Bloomer, and his wife Judy, who are among the missing, and with their family as they await further news from this terrible situation.”

Chris Morvillo

A US partner at law firm Clifford Chance, Morvillo worked on the case that saw Lynch cleared of fraud. It is thought the yacht trip was a celebration of Lynch’s acquittal. The BBC reported that Morvillo had been identified as one of the missing, while the Mail Online said his wife Nada was also on board and has not been found.

Ricardo Thomas

Sicily’s civil protection agency told the BBC that Thomas, the yacht’s chef, was among those still missing. Two other British nationals and one American are still thought to be missing.

One unnamed body

The Palermo Coastguard confirmed a body had been found and recovered. A Canadian foreign ministry spokesperson told the BBC they were “aware of reports that a Canadian citizen has died”.

The Survivors

Angela Bacares

The 57-year-old wife of Lynch is reportedly recovering in a wheelchair after injuries she sustained while escaping the yacht.

She told La Repubblica that the couple woke up at 4am when the vessel made a “slight tilt”. She reportedly sustained injuries to her feet after walking through broken glass to get off the boat.

Charlotte Golunski

Briton Charlotte Golunski, a partner at Invoke Capital, founded by Lynch, was rescued from the water with her husband James Emsley and their one-year-old daughter, Sofia, whose live she saved.

Golunski said they survived because they were on deck when the yacht started to sink.

She told La Repubblica: “For two seconds I lost my daughter in the sea then quickly hugged her amid the fury of the waves.

“I held her afloat with all my strength, my arms stretched upwards to keep her from drowning.

“It was all dark. In the water I couldn’t keep my eyes open. I screamed for help but all I could hear around me was the screams of others.”

All three family members were treated in hospital.

Ayla Ronald

A senior associate at law firm Clifford Chance, New Zealand lawyer Ronald, 36, worked on Lynch’s acquittal.

Her father, Lin Ronald, told The Telegraph she had been invited on to the yacht to celebrate the court case win.

He said she had texted him to say that she and her partner, Matthew Fletcher, had survived the sinking.

Other survivors

A number of people thought to have been rescued have been named by various local media, including Sasha Murray, 29, from Ireland; Myin Htun Kyaw, 39, who has a Burmese passport; Matthew Griffith, the yacht’s captain and a French citizen and James Caulfield, 51, from New Zealand. A Dutch foreign ministry spokesperson said a man from the Netherlands had been rescued and was not in a life-threatening condition. A total of 15 people have been rescued.

Bayesian search latest

Operations were continuing on Tuesday morning off the coast of the village of Porticello, with a number of rescue boats pictured in the waters.

The Italian fire brigade have said the yacht had sunk 50m.

The fire department, Vigili del Fuoco, said that early inspections of the wreck were “unsuccessful” due to limited access to the bridge and furniture obstructing passages.

Divers are tag-teaming in 12-minute underwater shifts to search the vessel, with the teams made up of two specialist cave divers.

Divers have said that no casualties have been found on the bridge, the room in which the captain controls the boat. They are not yet able to see inside the vessel, the Italian news agency Ansa reported.

The UK’s Marine Accident Investigation Branch said four of its inspectors were being deployed to Palermo.

A basic assessment of the scene will be made by the team, with no investigation launched at this stage.

What we don’t know

While it is thought the yacht encountered bad weather, the exact nature of the incident hasn’t been confirmed.

One witness told the Ansa news agency that the “boat was all lit up”, adding, “At about 4.30am, it was gone. It was a beautiful boat where there had been a party. A normal day of vacation spent happily at sea turned into a tragedy.”

The witness said the boat was not far from the port, and “took a little to raise the anchor” and head into the port.

“They were evidently surprised by the storm that suddenly fell and failed to avoid the sinking,” the witness added.

It is thought the storm would have broken the vessel’s sail tree, which would have caused an imbalance of the boat, Ansa reported, but this has not been confirmed by authorities.

Co-defendant in fraud trial killed in separate tragedy

Lynch’s co-defendant in his US fraud trial, Stephen Chamberlain, has died after he was hit by a car on Saturday.

Chamberlain, the former vice-president of Autonomy, was struck by the vehicle while out running in Cambridgeshire on Saturday morning, his lawyer said.

He and Lynch were acquitted of all 15 fraud and conspiracy charges against them over the sale of Autonomy to Hewlett Packard.

Chamberlain’s lawyer, Gary Lincenberg, said: “Our dear client and friend Steve Chamberlain was fatally struck by a car on Saturday while out running.

“He was a courageous man with unparalleled integrity. We deeply miss him.

“Steve fought successfully to clear his good name at trial earlier this year, and his good name now lives on through his wonderful family.”