Submersible Expert Raised Safety Concerns After 2019 Trip on Titan Sub

During a trip on board the Titan off the coast of the Bahamas in April 2019, Karl Stanley, an expert in submersibles, knew immediately that something was off: He heard a cracking noise that got only louder over the two hours it took for the submersible to plunge more than 12,000 feet.

The next day, Mr. Stanley wrote an email in which he detailed his concerns to Stockton Rush, the chief executive of OceanGate Expeditions, who was also on board the Titan for the dive, urging Mr. Rush to cancel the expeditions to the wreck of the Titanic that were planned for that summer.

“A useful thought exercise here would be to imagine the removal of the variables of the investors, the eager mission scientists, your team hungry for success, the press releases already announcing this summer’s dive schedule,” wrote Mr. Stanley, according to a copy of the email seen by The New York Times. “Imagine this project was self funded and on your own schedule. Would you consider taking dozens of other people to the Titanic before you truly knew the source of those sounds??”

The U.S. Coast Guard said on Thursday that a remote-controlled vehicle found debris from the Titan near the wreckage of the Titanic, ending a four-day, multinational search for the 22-foot watercraft that had captivated people worldwide. Mr. Rush was piloting the Titan and was among the five people on board who were killed. The Titan’s final voyage would have been its 14th expedition to the Titanic’s wreckage.

Mr. Stanley has operated a tourist submersible in Honduras for 25 years, although his vessel descends only to about 2,000 feet, far less than the more than 13,000 feet that Titan was designed to reach. Accompanying Mr. Stanley on his dive on the Titan in 2019 with Mr. Rush was OceanGate’s program manager, Joel Perry, who Mr. Stanley said in his email to Mr. Rush shared his concerns about the Titan. Mr. Perry, who left OceanGate in 2019, months after the dive, did not immediately respond to a request for comment.

Mr. Rush had heavily promoted his plans for the Titan before its first deep-sea dive in 2019. The year before, at a conference of crewed underwater vehicle specialists in New Orleans, several experts confronted Mr. Rush directly about their concerns with the Titan in a tense exchange, Mr. Stanley said. Shortly after the conference, more than three dozen industry experts sent Mr. Rush a letter urging him to put the Titan through a certification process.

“People were basically ganging up on him in that room,” said Mr. Stanley.

Mr. Rush was determined to build a submersible with a larger capacity than other such craft, which are metal spheres that can carry three people at most, Mr. Stanley said, recalling conversations he had with Mr. Rush in person and over the phone.

In the April 2019 email to Mr. Rush, Mr. Stanley said the loud cracking sounds that they had heard during their dive “sounded like a flaw/defect in one area being acted on by the tremendous pressures and being crushed/damaged.” He wrote that the loud, cracking noise signaled there was “an area of the hull that is breaking down.”

Mr. Rush never replied directly to that email, Mr. Stanley said. But he made some changes to the Titan, including building a new hull, and called off the planned dives for that year.

Experts said that one explanation for what might have caused the Titan to implode was that water seeped in where a titanium piece was glued into the end of the vessel’s cylinder. “It could’ve been anywhere wherever you seal the carbon fiber to the titanium, or it could’ve been around that porthole,” said Capt. Alfred McLaren, a retired Navy captain and friend of Paul-Henri Nargeolet, one of the people who was on board the Titan when it imploded this week.

“At that depth, you could have a leak that’s not much bigger than a diameter of one of your hairs and you would be dead within a fraction of a second,” said Captain McLaren, a nuclear attack submarine commander. “They really wouldn’t have even known they would have died, they would have been dead before they knew it.”

That the vessel imploded in the first dive of the season may have been relevant. Saltwater that had been trapped in between different materials in the vessel from dives in 2021 and 2022 worked its way through fibers and softened it up, making it more susceptible to a leak, experts said.