A desperate search for the six people missing after a luxury £30million yacht was caught in a freak storm off the coast of Sicily was once again underway on Wednesday, as a new theory emerges as to why it sank so quickly.

British tech tycoon Mike Lynch, his daughter Hannah, 18, Hiscox chairman Jonathan Bloom, his wife Judy, Chris Morvillo, a lawyer part of the legal team that represented Mr Lynch, and his wife Neda are all still unaccounted for.

15 of the 22 people on board were pulled to safety after the 56-metre vessel was caught in what is believed to have been a powerful waterspout tornado as it was moored off the coast of Porticello, Sicily, around 5am local time on Monday.

One man, a chef named as Recaldo Thomas, has been confirmed dead.

Divers from Italy's fire brigade Vigili del Fuoco have been working from dawn until nearly midnight searching the Bayesian for any survivors as relatives hope there's a slim chance small pockets of air may still exist in the wreck 50 metres down on the seabed.

A new theory has emerged the ship, which had the world's tallest aluminium mast, may have gone down so quickly in the storm due to hatches, portholes or doors possibly being open.

Sailing expert Sam Jefferson, editor of magazine Sailing Today, said: "I would have said that the boat got hit very hard by the wind, it was pinned over on its side.

"I imagine all the doors were open because it was hot, so there were enough hatches and doors open that it filled with water very quickly and sank like that."

Andrea Ratti, a nautical design professor at Milan Polytechnic University, said that a boat the size of the Bayesian would only sink so quickly by taking in a huge amount of water. He also suggested that portholes, windows or other openings may have been left open, letting in water.

Follow this LIVE blog for more updates throughout the day...