The maker of Mike Lynch's yacht says it took 16 minutes to sink and the crew should have had time to rescue passengers

• Mike Lynch and at least five others are dead after his superyacht sank off Sicily.
• The Bayesian sank during a storm. The Italian Sea Group CEO said the yacht took 16 minutes to sink.
• Giovanni Costantino told the Financial Times the ship was "designed to be absolutely stable."

The maker of Mike Lynch's superyacht, which sank off the coast of Sicily, said it was "absolutely stable" and that it never should have gone down.

The 183-foot ship — named the Bayesian — sank during stormy weather near Palermo, Italy, in the early hours of Monday morning local time.

Fifteen people, including Lynch's wife, were rescued, while six others, including Lynch, have been confirmed dead.

Divers discovered the body of the final person missing from the superyacht on Friday, the Italian Coastguard said, according to reports, which would bring the total to seven.

Lynch's 18-year-old daughter Hannah was the only person still unaccounted for.

Giovanni Costantino, the chief executive of The Italian Sea Group, which owns Perini Navi, the Bayesian's builder, said the ship was "designed to be absolutely stable" as it had the second-tallest mast in the world.

"The torture lasted 16 minutes. It went down, not in one minute as some scientists have said. It went down in 16 minutes," Costantino told the Financial Times. "You can see it from the charts, from the [Automatic Identification System] tracking chart."

Business Insider could not independently verify his statement.

Costantino added that the yacht's skipper "should have locked everything up. He should have gathered all passengers in the safe point. This is protocol. No one should have been in their cabin."

An investigation into the exact cause of the sinking is ongoing.

Authorities previously confirmed a strong storm had been in the area, though search-and-rescue experts have suggested that multiple factors could have contributed to the disaster.

One theory is that soaring temperatures in the area caused passengers and crew to leave windows and doors open, which would have allowed water to fill the ship quickly during the storm.

"The boat sank because it took on water," Costantino said.

He added that a large opening just above the waterline on the stern could have been left open and become flooded.

Out of the 15 who escaped, nine were crew members. One of the crew, a chef named Recaldo Thomas, was confirmed dead on Monday.

Stephen Askins, a lawyer specializing in maritime cases, told MailOnline that the crew was likely already awake before the ship sunk, while the passengers may have been sleeping below deck.

"The water came in from [hatchways] left open," Costantino told FT. "There is no other possible explanation. If maneuvered properly, the boat would have comfortably handled the weather — comfortably."

Matthew Schanck, a maritime search-and-rescue consultant, previously told BI that the disaster was "shocking" because Lynch's vessel was a "modern, state-of-the-art superyacht" that would have been commercially certified with the appropriate safety regulations in place.

Witnesses told BBC News they saw a waterspout — an uncommon weather phenomenon consisting of tornadolike wind and water — before the ship went down.

"This tends to have been the accepted theory, that the vessel was hit by a waterspout and the crew didn't see it coming because it was nighttime and dark," Schanck said.

He added that this scenario made sense but questioned how witnesses would have noticed a waterspout if the crew hadn't seen it.