Experts share why the Titan sub may have exploded – including a new theory about how it was dragged to the Titanic site behind its ‘mothership’.
Oceangate CEO Stockton Rush, who died along with four of his company’s passengers in the June 18 disaster, invented the Titan’s unique design, which he hoped would become a new industry standard.
But several moves designed to cut costs and make ocean exploration more profitable could also have disastrous consequences, engineering experts told The New York Times in an article published Friday.
Comparing the Titan to Alvin, a US government research submersible that has safely completed more than 4,500 deep-sea dives since 1973, experts cite several design and protocol changes that could have doomed the Titan.
Unlike Titan, Alvin was designed as a sphere with an all-titanium hull, which was moved to the dive site on the deck of a mothership, while Titan was towed over the rough waters of the North Atlantic on its small dive platform. , before the potentially damaging ship exploded and killed five people.
Polar Prince is seen towing the Titan submersible to its launch platform. Experts say many cost-cutting measures may have contributed to the sub’s catastrophic explosion
OceanGate CEO Stockton Rush, who died along with four of his company’s passengers in the June 18 disaster, invented the Titan’s unique design to cut costs.
Titan, owned and operated by OceanGate Expeditions, first began taking people aboard the Titanic in 2021, for up to $250,000 per passenger per trip.
It was noted for a roomier cylinder-shaped cabin made of carbon-fibre – a departure from the spherical-shaped titanium cabin used by most submarines.
The submarine Titan lost contact with its support ship on June 18 when it landed on the wreck of the Titanic, about 12,500 feet below the surface.
A few days later, its wreckage was recovered from the ocean floor, and investigators believe the sub was crushed by deep-sea pressure.
In addition to Rush, four others died: British adventurer Hamish Harding, 58; Pakistani tycoon Shahzada Dawood, 48, and his son Suleiman Dawood, 19, French Titanic expert Paul-Henri Nargiolet, 77.
Before Titan, submersibles including Alvin had a strong track record of safety. Submarines differ from submarines in that they must be launched into the ocean from a mothership.
Theories as to what caused the disaster include…
The Titan was towed across rough seas – the deck was not secured
The Alvin research sub is towed to dive sites on the deck of a dedicated mothership, outfitted with custom winches and a large crane that keeps it at sea.
In contrast, the Titan had no dedicated mothership, and to cut costs it was towed to sea by a small chartered vessel, the Polar Prince, via fatal dives.
The Polar Prince, a decommissioned Canadian Coast Guard icebreaker, was smaller and older than the ships Oceangate had used in previous years in Rush’s cost-cutting move.
Using a tow cable, the ship towed the Titan hundreds of miles across the open ocean to the launch platform used to recover the sunken and sub.
Asked if there was a risk of damage from the Titan being towed, a company spokesman told The Times: ‘Oceangate is unable to provide any additional information at this time.’
The Alvin research sub is towed to dive sites on the deck of a dedicated mothership, outfitted with custom winches and a large crane that keeps it at sea.
In contrast, the Titan (above) had no dedicated mothership and was towed to sea by a chartered vessel named the Polar Prince to cut costs.
The Titan is seen taking a dive into place. In May, the sub and platform met with a ‘near-miss’ and partially submerged in the open sea, an eyewitness recounted.
Travel Weekly editor-in-chief Ernie Weissman made an Oceangate voyage in May, using the same Polar Prince mothership that took her from St. John’s, Newfoundland, about 435 miles to the Titanic site.
‘I thought the sub and the platform were being thrown around fairly,’ Weissman told the Times.
Although he spent a week on the Polar Prince waiting for the weather to clear, the dive was eventually called off and Weissman never made it to Titan.
In a column for Travel Weekly, Weissman recounts a harrowing tale of ‘near-disasters for subs and platforms’ during high seas.
He wrote, ‘At the end of the rope connecting the stern of the ship to the platform, we found that the front of the platform and the sub were under water’.
It’s unclear what happened, but crew members theorized that a fishing buoy could be seen in the area entangling a line with the platform and pulling the air tanks down with water.
Attempts to raise the platform with a buoy on the tow line failed, and Rush had to send divers to clear water from the platform’s bouncy tanks, a process that took half a day.
No fishing line was discovered entangled in the platform, leaving the cause of the incident a mystery.
Asked if the incident had put the sub in danger, Weissman recalled, Rush joked: ‘So a sub is underwater. Why is this a problem?’
Pill-shape design rather than the tried-and-tested round shape that resists pressure better
Alvin, a famous research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution, has a spherical design.
In the deep sea, a sphere is the best shape to withstand crushing pressure that can reach three tons per square inch, because the pressure is distributed evenly across the hull.
Alvin’s downside is its limited capacity — the sub is only capable of carrying three people to the ocean floor.
Rush, who was charging $250,000 per passenger to dive on the Titanic wreck, would be able to take only two customers per trip with the same design, assuming an Oceangate pilot was on board.
Instead, his Titan design was spacious, with room for five people in a pill-shaped sub, with a carbon-fiber tube capped by titanium spheres at each end.
The Alvin, a famous research submersible owned by the United States Navy, has a spherical titanium hull for passengers, seen on the left in the plan above.
Alvin has safely completed more than 4,500 deep sea dives since 1973. Above, the crew sphere with room for three is seen housed inside other assistive devices
The Titan’s design was more spacious, with room for five people in a pill-shaped sub, with a carbon-fiber tube capped by a titanium sphere at each end.
Retired forensic metallurgist Tim Focke told The Times that changes in Titan’s hull geometry — from a tight sphere to a long tube — may have contributed to the sub’s catastrophic failure.
He noted that the larger a sub is, the stronger and thicker its hull should be to withstand the same pressure.
In two subs of the same hull thickness, the larger one would ‘collapse or buckle’ first, he said.
Carbon-fiber hulls that are more vulnerable to compression
One of Rush’s main innovations in the Titan was the use of carbon fiber for most of the hull, which is cheaper and lighter than titanium.
OceanGate promotes the Titan’s carbon fiber construction – with titanium endcaps – as ‘lighter in weight and more efficient to maneuver than other deep diving submersibles’ on its website.
The material reduced the Titan’s weight by 21,000 pounds compared to the Alvin’s 45,000 pounds.
But experts say carbon composites are much tougher against pulling forces than they are against crushing forces.
One of Rush’s main innovations in the Titan was the use of carbon fiber for most of the hull, which is cheaper and lighter than titanium.
OceanGate boss Stockton Rush is seen inside Titan’s carbon tube hull
The tube was five inches thick and was made by wrapping many layers of carbon fiber
“I was very surprised” by the Titan’s fiber construction, Folk told the Times, because compression was the main force the submarine faced on its deep-sea dives.
Jasper Graham-Jones, associate professor of mechanical and marine engineering at the University of Plymouth in the UK, says carbon composites also have limited life when subjected to excessive loads or poor design.
‘Yes, composites are very strong. Yes, composites are extremely durable. But we have a problem with composites and the fact that composites fail in slightly different ways than other materials,’ he told The Associated Press.
Additionally, the Titan’s 5-inch-thick hull had been repeatedly stressed during about two dozen previous dives, Graham-Jones said.
Each trip will cause small cracks in the structure. ‘It may be small and undetectable to begin with but soon it becomes critical and creates rapid and uncontrolled growth,’ he said.
The use of different materials increases the risk of premature closure of joints
The Titan’s design required its carbon-fiber tube to be attached to a titanium endcap, which was achieved with strong glue.
But experts say that because different materials change shape at different rates under pressure, maintaining a seal between them can be challenging.
Alfred S. McLaren, a retired Navy submariner and president emeritus of the Explorers Club of New York City, explained that the different components of the Titan’s hull ‘have different coefficients of expansion and contraction, and that works against keeping a watertight bond.’
In other words, if the carbon fiber tube is compressed in a slightly different way than the titanium end caps, it can compromise the seal between them, especially after repeated dives.
This image shows a titanium ring bonding to the Titan’s carbon tube hull. Because different materials change shape at different rates under pressure, maintaining a seal between them can be challenging
Wreck of the submersible Titan, recovered from the seabed near the wreck of the Titanic, is unloaded from the ship Horizon Arctic at a Canadian Coast Guard pier
The launch platform used for the Titan submersible is brought back ashore in the port of St. John’s, Newfoundland, Canada, after the sub was destroyed.
Experts have also questioned Oceangate’s refusal to seek outside testing and certification for Titan.
Graham-Jones says it is standard practice in engineering to seek outside expertise to ensure ships conform to the highest industry standards.
In a 2019 company blog post, OceanGate criticized the third-party certification process as time-consuming and stifling innovation.
“It is the bane of rapid innovation to bring an external entity up to speed before putting each innovation to real-world testing,” the post said.