NTSB engineer says Titan submersible’s carbon fiber hull has ‘anomalies’

A piece of the Titan’s carbon fiber hull recovered after the submersible’s catastrophic and deadly implosion had “anomalies,” a National Transportation Safety Board engineer said Wednesday during a weeklong hearing into the incident.

Don Kramer, acting chief of the NTSB’s Materials Laboratory, testified at the U.S. Coast Guard hearing into the June 2023 implosion of the OceanGate submersible during a deep-sea dive to the wreck of the Titanic.

Kramer said his team examined materials from the hull’s manufacturing and discovered “several anomalies in the composite and adhesive joints, including ripples, wrinkles, porosity and voids.”

They also examined a piece of hull recovered from the ocean floor and found similar anomalies, including “ripples and wrinkles in the layers of the hull” and voids in the adhesive that held the layers together, he added. The recovered hull also had “features consistent with friction damage at one of these adhesive joints.”

MORE: OceanGate co-founder says company didn’t originally plan to build its own submarine

Kramer said the Titan’s debris on the ocean floor showed that the hull “encountered a significant amount of delamination” – or separation into layers – much of which was within or near co-bonded adhesive interfaces.

Asked by OceanGate’s attorney whether delaminations, voids or friction damage could have been present before the implosion, rather than being caused by the implosion, Kramer said he did not offer an analysis as to when they occurred.

Asked again by OceanGate’s attorney whether any of the problems he observed could have caused the implosion, Kramer said that “is still the subject of our own internal analysis at this point.”

MORE: ‘All is well here’: Final messages revealed by Titan submersible before implosion: Coast Guard

Stress response after a loud noise during a dive to 80

Kramer also discussed the deafening noise passengers heard as the Titan was being raised during a dive that occurred a year before the implosion on July 15, 2022 — known as Dive 80 — and that was discussed throughout the two-week hearing. The noise was also detected by the Titan’s real-time monitoring system, which had sensors to detect acoustic events, as well as multiple strain gauges to monitor mechanical stress, he said.

Kramer said his team determined that the hull’s stress response changed after that loud bang incident during subsequent dives in 2022. He said strain gauge data showed a change in hull stress for four of the eight gauges.

“These changes persisted from dive to dive,” he said.

According to Kramer, no differences were observed when comparing the stress response with a dive prior to Dive 80.

According to Kramer, no stress data is available for dives conducted in 2023.

Phil Brooks, OceanGate’s former chief technical officer, testified Monday that after the loud noise on Dive 80, the strain gauge data showed a minor “change,” though they did not see “any other changes in the strain data” on subsequent dives in 2022. Nothing “really seemed out of the ordinary,” and OceanGate co-founder and CEO Stockton Rush made the decision to continue the dives, Brooks said.

Asked how his team arrived at its determination of the change in stress response based on graphs of the available data, Kramer said, “I guess it’s a matter of opinion as to whether you can discern changes in stress output.”

Brooks said Rush speculated that the loud bang was due to the frame “readjusting to its original shape” as it returned to the surface.

Kramer noted that the NTSB’s investigation is still ongoing, so the scope of his presentation is limited.

Draft letter from the Marine Technology Society to Rush

William Kohnen, CEO and founder of submarine maker Hydrospace Group, said in testimony Wednesday that he would not have made a carbon fiber hull. He added that it would be “too expensive” and that it is “really, really difficult.”

Investigators questioned Kohnen about a draft letter from the Marine Technology Society he wrote in March 2018 to Rush based on public safety concerns raised at a conference.

“It was seen as an issue that we, as professionals in this industry, had significant concerns about – not about any particular point, but about the overall approach of neglecting the years of experience, tradition and diligence that we have applied,” he said.

Kohnen said the letter was signed by about 40 members and was submitted for further drafts, though the Marine Technology Society’s board never approved it being sent to Rush on behalf of the society. Rush did manage to obtain a copy of the original draft letter, which Kohnen said they discussed over the phone.

In the call, Kohnen said he told Rush that he found the language on OceanGate’s website confusing to the general public unfamiliar with submersibles and that they “strongly inferred” that the experimental sub was classified, when it was not. He said the website was subsequently updated.

Kohnen stressed the importance of classification and regulations in building safe submersibles.

“We have a 50-year record without a single death until Titan,” he said. “That shows the power of our regulations.”

OceanGate suspended all exploration and commercial operations following the deadly implosion, which killed five people, including Rush.

The hearing into the incident is scheduled to continue until Friday.

The primary purpose of the hearing is to uncover facts related to the implosion and make recommendations, the Coast Guard said.

NTSB engineer says Titan submersible’s carbon fiber hull had ‘anomalies’