Graphic shows how ferocious waterspout capsized doomed Mike Lynch's Bayesian superyacht before vessel sank beneath the waves in a matter of minutes

Experts reviewing the tragic sinking of the Bayesian off the coast of Sicily earlier this week have delivered theories on how the superyacht was forced beneath the waves. 

The luxury sailboat was anchored just a few hundred metres off the coast of Porticello on calm seas when it was suddenly struck by a violent waterspout just before 5am on Monday which the captain said no one had seen coming.  

Tornado-speed winds battered the vessel so ferociously that there was no time for those on board to raise the alarm or call for help before they were left swimming for their lives.

Those who made it off were stranded in the pitch-black water as the storm raged around them, while six people are believed to have been trapped inside the below-deck cabins when the boat sank beneath the murky surface.

It is believed the ship sank after its mast - one of tallest in the world at an enormous 246ft-high - snapped during the brutal incident and keeled over, taking the hull beyond the 'down-flooding angle', according to nautical experts. 

Former shipyard manager and maritime technical inspector Gino Ciriaci told Italian daily Corriere Della Sera said once the mast had fallen, the vessel was far more prone to pitching and rolling as it was battered by waves without the sails to steady it. 

In the case of the Bayesian, he said the waterspout was so violent that the boat, dragged down by its broken mast, tilted until the edge of the deck slipped under the surface.

The entire ordeal likely lasted only a few minutes, with the ship sinking rapidly as it took on seawater.

Inspector Marco Tilotta, leading the Palermo Fire Brigade's diving unit, likened the grim search operation to the Costa Concordia cruise ship disaster in 2012 which claimed the lives of 33 people.

Eerily, the specialist cave divers called in for the search and rescue operation found 'virtually everything intact' on board, with little sign of damage, and 'no rips in the side, no signs of impact,' he told MailOnline.

The boat is resting on the seabed on its starboard (right hand) side, 164ft below the waves, and the first efforts of the dive teams were unsuccessful in moving furniture impeding their access to the cabins below, said Insp. Tilotta.

The rescuers still hope that survivors might be found, against all odds, in trapped air pockets, but Insp Tilotta admitted 'it is a race against time and the quality of the oxygen will be bad'.

His choice of words however told the unpleasant truth: 'We will do everything to recover the bodies. The weather conditions are worsening but we hope to continue operations without problems'.

Sam Jefferson, editor of magazine Sailing Today, said hatches and doors left open overnight may have also contributed to the sinking of the Bayesian. 

The expert 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.

'The reason it got pinned over so hard was because the mast is huge. It acted almost like a sail. (It) pushed the boat hard over on its side.

'This is all speculation, but that's the only logical explanation.'

Jefferson added that such incidents are 'incredibly rare', describing the chances of a yacht being hit by a waterspout as 'minuscule'.

Salvo Cocina, of Sicily's civil protection agency, said of the Bayesian's crew: 'They were in the wrong place at the wrong time.'

In the next few hours and days, the accident investigators will have to work out exactly how it was possible for the vessel to capsize and sink so quickly while others were hardly affected.