The late tech tycoon Mike Lynch’s superyacht, Bayesian, sank after it was hit by winds of around 117km/h that drove the vessel past its point of stability and caused downflooding over the starboard rail, according to a preliminary safety report by the Marine Accident Investigation Branch (MAIB).

The investigators said Bayesian may have been vulnerable to high winds when running on its engine and that these “vulnerabilities” were “unknown to either the owner or the crew” as they were not included in the stability information book carried on board.

The luxury vessel, with a 75-metre (246ft) mast, was anchored just off shore near the port of Porticello, in the province of Palermo, on 19 August 2024 when it was struck shortly before dawn by a violent storm, killing seven people, including Lynch and his 18-year-old daughter, Hannah.

Fifteen people, including Lynch’s wife, Angela Bacares, were rescued

MAIB, which has reviewed the yacht’s stability, the likely local weather conditions at the time and its effect on the yacht, commissioned a stability study for Bayesian undertaken by the University of Southampton’s Wolfson Unit for Marine Technology and Industrial Aerodynamics.

The researchers built a stability model for Bayesian “that replicated the information contained in the approved stability information booklet,” the report said, and was subsequently adjusted to replicate its conditions on the night it sank, running in its motorised condition and with its centreboard up.

The report said a rapidly passing mesocyclonic thunderstorm generated transient hurricane-force gusts, which drove Bayesian over 90 degrees in under 15 seconds, leading to capsize. “Once the yacht had heeled beyond an angle of 70 degrees the situation was irrecoverable,” the report concluded.

Simon Graves, an MAIB investigator, told the Press Association: “You have the wind pushing the vessel over and then you have the stability of the vessel trying to push the vessel back up right again. And what our studies found was that they show that the Bayesian may have been vulnerable to high winds and that these winds were likely to have been evident at the time of the accident.”

Investigators said “there was no indication of flooding inside Bayesian until water came in over the starboard rails and, within seconds, entered the internal spaces down the stairwells”.

MAIB said its report was based on “a limited amount of verified evidence” as a criminal investigation by Italian authorities has restricted its access to the wreck and other pieces of evidence.

Further details such as “escape routes” will be included in the final report, once MAIB get access to the vessel.

The full investigation report will not be published within 12 months.

The wreck currently sits at a depth of 50 metres in the bay of Porticello.

Recovery operations to raise the Bayesian, which began early in May, have been suspended after a diver died during underwater work.

Preparatory work onsite to resume the recovery is due to begin on Thursday.