During a visit on board the Titan off the coast of the Bahamas in April 2019, Karl Stanley, an knowledgeable in submersibles, knew instantly that one thing was off: He heard a cracking noise that received solely louder over the 2 hours it took for the submersible to plunge greater than 12,000 toes.

The subsequent day, Mr. Stanley wrote an e mail by which he detailed his considerations to Stockton Rush, the chief government of OceanGate Expeditions, who was additionally on board the Titan for the dive, urging Mr. Rush to cancel the expeditions to the wreck of the Titanic that have been deliberate for that summer season.

“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, based on a duplicate of the e-mail 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 stated on Thursday {that a} remote-controlled car found debris from the Titan close to the wreckage of the Titanic, ending a four-day, multinational seek for the 22-foot watercraft that had captivated individuals worldwide. Mr. Rush was piloting the Titan and was among the many 5 individuals on board who have been killed. The Titan’s ultimate voyage would have been its 14th expedition to the Titanic’s wreckage.

Mr. Stanley has operated a vacationer submersible in Honduras for 25 years, though his vessel descends solely to about 2,000 toes, far lower than the greater than 13,000 toes that Titan was designed to succeed in. Accompanying Mr. Stanley on his dive on the Titan in 2019 with Mr. Rush was OceanGate’s program supervisor, Joel Perry, who Mr. Stanley stated in his e mail to Mr. Rush shared his considerations in regards to the Titan. Mr. Perry, who left OceanGate in 2019, months after the dive, didn’t instantly reply to a request for remark.

Mr. Rush had closely promoted his plans for the Titan earlier than its first deep-sea dive in 2019. The 12 months earlier than, at a convention of crewed underwater car specialists in New Orleans, a number of consultants confronted Mr. Rush straight about their considerations with the Titan in a tense alternate, Mr. Stanley stated. Shortly after the convention, greater than three dozen trade consultants despatched Mr. Rush a letter urging him to put the Titan through a certification process.

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

Mr. Rush was decided to construct a submersible with a bigger capability than different such craft, that are steel spheres that may carry three individuals at most, Mr. Stanley stated, recalling conversations he had with Mr. Rush in particular person and over the cellphone.

In the April 2019 e mail to Mr. Rush, Mr. Stanley stated the loud cracking sounds that that they had heard throughout 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 by no means replied on to that e mail, Mr. Stanley stated. But he made some modifications to the Titan, together with constructing a brand new hull, and referred to as off the deliberate dives for that 12 months.

Experts stated that one clarification for what may need triggered the Titan to implode was that water seeped in the place a titanium piece was glued into the top 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,” stated Capt. Alfred McLaren, a retired Navy captain and good friend of Paul-Henri Nargeolet, one of many individuals 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,” stated Captain McLaren, a nuclear assault 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 within the first dive of the season might have been related. Saltwater that had been trapped in between completely different supplies within the vessel from dives in 2021 and 2022 labored its approach by way of fibers and softened it up, making it extra prone to a leak, consultants stated.