Italian prosecutors are to speak to the Bayesian superyacht's designers and analyse the vessel's keel as an unearthed clip from 2019 shows what should have happened when the ship was hit by a waterspout. 

Yesterday five bodies were discovered as divers continued an urgent search of the £30 million yacht for six missing people after it sank while anchored at around 5am on Monday.

While 15 of the 12 guests and ten crew members managed to escape and make it onto a life raft, owner Mike Lynch, his 18-year-old daughter Hannah, Morgan Stanley International chairman Jonathan Bloomer and his wife Judy and Clifford Chance lawyer Chris Morvillo and his wife Neda remained unaccounted for.

As search efforts get underway for the final missing person, whose identity has not been confirmed, prosecutors are set to investigate the ship's keel, which was partially elevated at the time of the storm.

The keel, which extends like a giant fin underneath the boat and acts as a counterweight to the tall mast, was not fully down despite poor weather being forecast hours ago. 

Experts told the Mail that it is fairly standard for the keel not to be fully lowered while a ship is at anchor, but with storms forecast and portholes reportedly left open, it raises questions over the cause of the tragedy.

And amid reports prosecutors are seeking to speak with the ships' designers - after captain James Catfield was questioned for two hours on Wednesday - the company which manufactured the boat has now claimed human error was to blame.

It comes as an unearthed video from Auckland, New Zealand, showed what should happen if a ship such as the Bayesian overturns in stormy weather. 

The CCTV footage shows a tornado pushing a large superyacht with a similar mast style to the Bayesian onto its side. 

But rather than capsizing, the mast quickly flips straight back up to its upright position. 

It has not been confirmed yet if the bodies recovered yesterday are that of Mr Lynch or his 18-year-old daughter Hannah, although reports in Italian media suggested the pair had been found in the same cabin trapped between two mattresses. 

The body of the yacht's chef Recaldo Thomas was found shortly after the tragedy. 

Amid increasing questions as to how such a robust ship, which had previously sailed in Antarctica and was described as 'bulletbroof', could have sank Giovanni Costantino, CEO of Italian Sea Group, has spoken out on the tragedy.

ISG bought the Bayesian's constructors Perini Navi two years ago. Mr Costantino said: 'This was human error, the yacht sank because it took on water. From where exactly the investigators will tell us. The dynamic of the sinking is seen and read from AIS (Automatic Identification System) data and lasted sixteen minutes.

'We have given this data to the prosecutors at Termini Immerse. From the images it looks as if the yacht had been taking on water for four minutes. 

'All it took was another gust of wind to turn her over, that meant more water coming in. She then straightened very briefly before going down.'

Earlier a spokesman for the company told MailOnline 'procedures were not followed' on the luxury vessel and the sinking was down to 'portholes being left open despite bad weather being forecast hours earlier'.

A spokesperson said: 'The Bayesian was built to a very high standards and it would not have sunk if proper procedures had been followed by the crew.

'A storm had been forecast earlier, no fishing boats went out and yet the portholes were not shut, the yacht sank because it was engulfed by a massive amount of water through open portholes.'

The spokesperson added: 'The Bayesian would have remained afloat in any weather, even if it was being swung from left to right in gale force winds but it could never have remained in the water with open port holes.

'The design made the yacht extremely sturdy, but it couldn't stay up because there had been a huge intake of water though open portholes.

'The yacht was built to withstand whatever the conditions were. The mast has nothing to do with what happened, it was built that way when it was launched and it had a refit in 2020 in Spain, the yacht sank because procedures in bad weather were not followed.'

The Bayesian was 56m long, had a 74m mast and was built in 2008 with David Hutchinson, captain of its sister ship Rosehearty, telling Boat International 'she was bulletproof'.

He told the specialist publication: 'We've been to Antarctica and Chile, and we've had her in 70knots of wind ' but they had never been put in a situation that he felt was unmanageable.

The Bayesian went down in a matter of minutes after being struck by the tornado while anchored off the coast at Porticello, near Palermo Sicily on Monday.

Bayesian's captain James Cutfield, 51, survived and is currently in hospital.

Prosecutors are looking into the theory that the yacht's portholes and hatches were not closed in time ahead of the storm, despite bad weather being forecast, and if any of the crew are liable.

Italian Sea Group completed the buyout of Perini Navi for 80 million Euros in 2022 and a press release at the time said they were 'extremely satisfied' with the purchase complementing its 'expertise in the sailing yacht sector'.