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Carbon fiber, one of the Titan submersible's experimental materials, comes under scrutiny

Experts say carbon fiber is a relatively new material, especially for building submarine hulls, that has not been tested over time in such extreme depths.
The Titan submersible.
The Titan submersible.OceanGate Expeditions via AP

The one-of-a-kind Titan submersible that imploded on its descent to the site of the Titanic this week, killing all five passengers, was made with experimental materials, including carbon fiber, which experts say has not been pressure-tested over time in such extreme depths.

Since the fatal dive, the innovation behind the Titan and OceanGate Expeditions — the company that owned and operated the vessel for paid tours to the Titanic — has come under increased and intense scrutiny.

Days after the Titan was reported missing, sparking a frantic search, the U.S. Coast Guard said Thursday that the 22-foot craft imploded, though officials do not yet know when or why.

It killed OceanGate Expeditions CEO Stockton Rush, British billionaire Hamish Harding, French diver Paul-Henri Nargeolet, prominent Pakistani businessman Shahzada Dawood and his 19-year-old son, Suleman.

The tragedy comes years after many marine experts and former OceanGate employees had sounded the alarm on the technology.

“Innovation is a wonderful thing,” said Bart Kemper, a mechanical engineer who is part of the Marine Technology Society, an industry group of ocean engineers, technologists, policymakers and educators.

“But," Kemper added, "everything that is new and not tried introduces uncertainty, and uncertainty is risk.”

The 23,000-pound vessel was made of “titanium and filament wound carbon fiber” and had been “proven to be a safe and comfortable vessel" that could "withstand the enormous pressures of the deep ocean,” OceanGate said on its website. 

While carbon fiber has long been used within the aerospace industry, Kemper said it had not been proven to repeatedly withstand such deep-sea pressures. 

The wreckage of the Titanic lies at a depth of about 13,000 feet. That is significantly deeper than the roughly 2,000 or 3,000 feet that a typical U.S. Navy submarine descends to. 

At Titanic depths, the water pressure is nearly 400 times more than at the ocean’s surface, experts told NBC News. Some 6,000 pounds would have been pressing down on every square inch of Titan’s exterior.

“It’s a design that’s not been used in this way at this depth,” Kemper said, comparing a submersible to a balloon. “All it has to do is fail in one spot and game over.”

In contrast, U.S. Navy submarines are made with carbon steel, a “tried and true material” that is reliable and thoroughly understood, according to Captain David Marquet, a retired Navy submarine commander. 

“It’s not sexy. It’s not, some would say, innovative, but we understand how it reacts in these situations very clearly,” Marquet said. 

Carbon fiber, the former sub commander said, is a relatively new material, especially for building submarine hulls. He said multiple repeated dives, inspections, X-rays and ultrasounds are needed to fully understand how the material responds to stress and pressure over time. 

The Titan was diving 10 times deeper than the Navy takes its submarines, which meant it was undergoing 10 times more pressure, Marquet said. 

“We are super scared of the pressure,” he said.

The Titan was only on its third Titanic trip since OceanGate Expeditions began offering them in 2021, with prices of a spot on the submersible reaching as high as $250,000.

Since 2018, Kemper said he and more than three dozen members of the Marine Technology Society worried that the company’s “experimental approach” could result in “negative outcomes,” whether minor or catastrophic, that could have serious ripple effects in the industry. 

That year, they sought to send Rush a letter warning him of safety concerns related to the Titan. The group met with Rush and expressed their concerns in person instead.

But, Kemper said, Rush "would not budge” on using the industry’s standards and codes.

In a blog post in February 2019, OceanGate said the Titan wasn’t classed by an independent group that sets safety standards, as most chartered vessels are, because its technology was so new and the company's innovation “falls outside of the existing industry paradigm.”

It said there’d be a “multi-year approval cycle due to a lack of pre-existing standards.”

Classing usually checks if vessels meet standards in buoyancy, the number of life rafts and hull materials, the blog post said. OceanGate said that while classing has a safety value, it is “not sufficient to ensure safety.”

On Friday, experts in the industry continued criticizing the lack of testing, as they called for more oversight into experimental submersibles. 

“It was very clear that these people were operating a submersible that was unsafe,” said Katy Croff Bell, president and founder of the Ocean Discovery League, a nonprofit group that works to broaden access to deep-sea exploration and research. 

“They knew it. They had been warned on multiple occasions,” she added. “And I think that we can only hope that we ensure in the future that something like this does not happen, and people take this very, very seriously.”