Search crews have carried out further inspections of a luxury yacht that sank in a storm off the coast of Sicily as the hunt for six people feared trapped in the vessel continues.

The Italian Coastguard has not ruled out the possibility that those missing, including technology tycoon Mike Lynch and his 18-year-old daughter Hannah, may still be alive, with experts speculating air pockets could have formed as the yacht sank.

Among those also missing are Morgan Stanley International bank chairman Jonathan Bloomer; his wife, Judy Bloomer; Clifford Chance lawyer Chris Morvillo; and his wife, Neda Morvillo.

Inspections of the yacht’s internal hull took place on Wednesday morning.

A team of four British inspectors from the Marine Accident Investigation Branch (MAIB) have arrived in Porticello, where they are expected to look at the site of the sinking.

The MAIB is looking into what happened because the yacht Bayesian was flying a British flag, it is understood.

The Italian Coastguard said the MAIB is not involved in the search for the missing people and that it has not been requested to assist.

A helicopter had been drafted in to help the search effort, as divers from the local fire service were seen entering the water with torches attached to their headgear.

A police boat and divers were also seen entering the water on Wednesday afternoon.

Fire crews from the Vigili del Fuoco said they have been accessing the vessel through natural entrances, without making openings.

Remotely controlled underwater vehicles are being used, with naval units and cave divers also taking part in the search, the Italian Coastguard has said.

Mr Bloomer’s twin brother, Jeremy Bloomer, told the BBC: “It’s a slow process and it will take time. So there might be air pockets, but we don’t know. It’s still wait and see, so fingers crossed.”

The body recovered at the scene of the sinking on Monday was that of Canadian-Antiguan national Recaldo Thomas, who was working on the Bayesian superyacht, the Italian Coastguard told Sky News.

Gareth Williams, a friend of the chef, told the BBC: “I can talk for everyone that knew him when I say he was a well-loved, kind human being with a calm spirit.”

Another friend, Eli Fuller, told the broadcaster Mr Thomas was “friends with everybody”, “always positive” and “sought-after” in his profession.

Bayesian was moored around half a mile off the coast of Porticello when it sank at around 5am local time on Monday as the area was hit by a storm.

Vincenzo Zagarola, of the Italian Coastguard, said the six missing tourists are feared dead.

Asked about the likelihood of them being alive, he said: “Never say never, but reasonably the answer should be not.”

He told the PA news agency: “We think they are still inside the boat, that is our very hard idea.

“Of course, we do not exclude that they are not inside the boat, but we know the boat sank quickly.

“We suppose that the six people missing may not have had time to get out of the boat.”

The wreckage of Bayesian is resting on the seabed off the coast at a depth of 50m (164ft).

Fire crews described the operation as “complex”, with divers limited to 12-minute underwater shifts.

Dr Jean-Baptiste Souppez, a senior lecturer in mechanical, biomedical and design engineering at Aston University, said the next 24 hours are “crucial” to find survivors trapped inside the wreck.

He said: “The speed at which the vessel sank (a few minutes, according to survivor and witness accounts) and the fact that it remains intact and on its side could favour the formation of small air pockets inside.

“But whether air pockets formed on the Bayesian is simply impossible to predict.”

Of the 22 passengers and crew on board, 15 – including Mr Lynch’s wife, Angela Bacares – were rescued after escaping on to a lifeboat.

The Mirror reported that Ms Bacares is in a “state of shock and sadness” as she awaits news of her husband. She has reportedly been joined by the couple’s elder daughter who was not on board the yacht.

More of the vessel’s rescued crew members were named by the Italian Coastguard on Tuesday, with Leo Eppel and South African nationals Leah Randall and Katja Chicken all confirmed as having been on board.

Survivors are recuperating at a hotel complex in Porticello, where authorities are gathering witness statements.

The Telegraph reported that authorities are investigating whether hatches left open by crew members contributed to the sinking, as well as what onboard measures were taken in preparation for the storm.

The ship’s captain, James Calfield, 51, told Italian media: “We didn’t see it coming.”

The boat trip was a celebration of Mr Lynch’s acquittal in a fraud case in the US.

The businessman, who founded software giant Autonomy in 1996, was cleared in June of carrying out a massive fraud relating to its 11 billion US dollar (£8.64 billion) sale to US company Hewlett Packard.

The Financial Times reported that Mr Bloomer appeared at trial as a defence witness for Mr Lynch, while media reports suggest the pair are close friends.

A spokesman for Morgan Stanley said the bank is “shocked and saddened”, while Clifford Chance said it was a “tragic incident”.

David Tabizel, Mr Lynch’s Autonomy co-founder, told Sky News: “I’m just heartbroken for him and his family and I hope there’s a miracle about to occur.

“If anyone has the resilience to survive this, he does. And I hope he’s found an air pocket.”

The former school of Mr Lynch’s daughter, Latymer Upper School in Hammersmith, west London, said its “thoughts are with their family and everyone involved”.

One of the survivors, British tourist Charlotte Emsley, told Italian newspaper la Repubblica she held her one-year-old daughter, Sofia, to stop her from drowning.

The pair were treated in hospital, as was Ms Emsley’s father, James Emsley.

In a separate incident, Mr Lynch’s co-defendant in his US fraud trial, Stephen Chamberlain, died after being hit by a car while out running in Cambridgeshire on Saturday.