A UK interim report on Thursday said that winds exceeding 117 km/h probably caused the superyacht to sink off Sicily in 2013, killing British tech tycoon Mike Lynch, among others.

Marine Accident Investigations Branch in Britain said that the 56-metre (184-foot-long) Bayesian, which was moored near Porticello, a small port near Palermo last August, was probably hit by a strong downwind, killing Lynch and his daughter Hannah, as well as five other people.

Investigations revealed that wind speeds of more than 117km/h on the beam could knock Bayesian off balance when the retractable keel is in the raised position. The report said that the yacht could be equally vulnerable to wind speeds of lower speed.

The owner and crew of Bayesian were unaware that these vulnerabilities existed because they were not listed in the information booklet on stability.

Andrew Moll is the Chief Inspector for Marine Accidents. He said that the findings indicated that the extreme winds experienced by Bayesian were sufficient to knock over the yacht.

The situation was irrecoverable once the yacht reached an angle greater than 70 degrees.

A sudden increase in wind speed caused the yacht's keel to turn 90 degrees in under 15 seconds, according to the report.

It said that water entered the vessel through the stairwells within seconds after it entered over the starboard rails. The yacht sank in the deep sea after 18 minutes.

Perini Navi is an Italian luxury yacht builder. The 72 metre (236 foot) tallest mast in the world was featured on this yacht.

Giovanni Costantino said that the Perini yacht is "one of most safest in the world". It's also virtually unsinkable.

The company has not yet responded to the UK report.

(source: Reuters)