The World's Deepest Submarine Rescue

Jun 23, 2023 0 comments

More than eighty hours after the Titan submersible lost contact with its surface ship while on a dive to explore the wreck of the Titanic at 12,500 feet, reports have emerged that the submersible experienced a catastrophic implosion killing everyone on board. A remotely operated underwater vehicle has discovered debris from the Titan on the ocean bead, not far from where the wreck of the Titanic lay. Now as the world mourns the tragic loss of five lives and debates the sea-worthiness of the vehicle and all the wrongs the company OceanGate did, let us recall the story about a dramatic rescue that happened fifty years ago when another submersible sank to the ocean floor sparking a 76-hour international rescue operation.

The rescue of Roger Chapman and Roger Mallinson.

In the early hours of 29 August 1973, pilot Roger Chapman and senior pilot Roger Mallinson were laying transatlantic telephone cable on the seabed about 240 km southwest of Cork in southern Ireland. The job involved going down on a small submersible called Pisces III to a depth of 1,600 feet, then using water jets to liquefy the mud and lay the cable. Then the cable was covered with more mud.

The job was exhausting because of the cramped space, the long shifts (eight hour), and poor visibility.

“It was like driving down the motorway in thick fog and trying to follow a white line - you had to concentrate beyond belief. One pilot would have the controls for the sub in one hand and the manipulator - a mechanical hand, which would lift, twist, extend and move sideways - in the other, then we'd swap,” Mallinson said. “It was also uncomfortable. We had to kneel, with our heads by our knees.”

That day was additionally tiring for Mallinson because he had just spent 26 sleepless hours repairing a broken manipulator on the submarine. By a stroke of luck, the engineer also decided to change the oxygen tank for a full one, even though the one in the submersible had enough oxygen to last the eight hour dive. That decision would later prove to be a life-saving one.

Shortly after 9 AM, the submersible had returned from the trip to the ocean floor and was on the surface waiting for it to be lifted out of the water and back into the ship, when the towline got ensnarled with the aft sphere hatch and wrenched it open. Pisces III became inverted and fell back into the ocean with an opened hatch, through which water began to pour in. Fortunately, the aft sphere, which became flooded, was a watertight sphere where the machinery was located and was separate from the cabin which housed Chapman and Mallinson.

Divers assist the pilots of Pisces III to disembark from the submersible.

Weighted down by sea water, the submersible began to sink. At 175 feet, it jolted to a stop, held at the maximum length of the nylon towline, but only momentarily, before the towline snapped. The pilots immediately closed down all the electrical systems which left the sub in total blackness. They also managed to release a 400 pound lead ballast weight to make it lighter as they descended.

“It was about 30 seconds until we hit. We turned the depth gauge off at 500ft (152m) as it could have burst and got cushions and curled ourselves up to try and prevent injuries. We managed to find some white cloth to put in our mouths so we didn't bite our tongues off too,” Mallinson said.

Twelve minutes after they first sank, the submersible hit the ocean floor at 1,575 feet. Despite the violent impact, at an estimated 65 km/h, there were no injuries.

The sub was pitch black, but using a flashlight they reviewed their surrounding and made contact with the surface. The full tank of oxygen that Mallinson had added the previous day had a capacity to last approximately 72 hours, but eight hours had already been used on the dive, leaving them 64 hours worth of oxygen.

The pilots spent the first few hours sorting out the submersible which was almost upside down. They checked all the watertight doors for leaks and prepared for rescue to come. Understanding the importance of conserving oxygen, they consciously minimized physical exertion, refraining from even speaking. Seeking refuge from the noxious air that descended, they positioned themselves as elevated as possible, striving for comfort. Given the cramped confines of the crew sphere—a mere 6-foot internal diameter —the men had limited space at their disposal.

At the surface, preparations for rescue began. The support ship Vickers Venturer, then in the North Sea, was ordered to return to the nearest port with the submersible Pisces II aboard. Another submersible, Pisces V, was flown in. The Royal Navy survey vessel HMS Hecate arrived to offer assistance with special ropes, and the United States Navy offered another submersible belonging to the U.S. Salvage Department, called a Controlled Underwater Recovery Vehicle (CURV-III).

Pisces V. Credit: Wikimedia

More than forty hours after the submersible sank, the Vickers Voyager reached the scene of the accident and immediately proceeded to launch Pisces II with a tether attached. However, the lifting rope broke free of the manipulator arm and the submersible had to return to the surface for repairs. Then Pisces V was launched but it failed to locate Pisces III and returned to the surface after it ran out of power. Pisces V was launched again, this time successfully locating the stricken sub. However, an attempt to attach a rope failed.

Pisces V was ordered to stay with Pisces III, and an attempt was made to send Pisces II down again, but had to be called off when it suffered a leak. Even the CURV III had an electrical fault so was unable to launch. Just after midnight Pisces V was ordered to the surface, leaving the men on Pisces III once again alone. Chapman and Mallinson were now low on oxygen and lithium hydroxide to scrub the carbon dioxide from the deteriorating atmosphere in the submersible. They had only one cheese and chutney sandwich and one can of lemonade with them, but neither had the desire to eat.

On September 1, Pisces II was launched again with a purpose-built toggle and a new polypropylene tow rope. This time, the rescue sub had successfully attached the toggle to the distressed Pisces III. A few hours later, CURV III also came down and fixed another line. Only after Chapman and Mallinson were informed that the lines were attached to the sub, that their appetites returned. Both broke open the sandwich and the can of lemonade.

The lifting of Pisces III was very rough with a lot of jolting.

"We were thrashing and rocking about so they needed to get more ropes, so they could all be heaved together," says Mallinson.

The lift was stopped twice during ascent. Once at 350 feet to disentangle the CURV III, and a second time at 100 feet, so that divers could attach heavier lifting cables to the submersible. It took nearly two and half hours before the submersible broke through the surface. Divers tried to open the hatch to allow fresh air into the submersible, but found the hatch had jammed. After nearly 30 minutes of struggling, the hatch was opened and out stepped the two pilots, weary and struggling to stand, but alive. They had been trapped inside the craft for a total of 84 hours and 30 minutes. The sub carried oxygen for only 72 hours, but they managed to eke out another 12.5 hours. Subsequent evaluations revealed that only 12 more minutes of oxygen supply had remained.

Roger Mallinson, center left, and Roger Chapman watch as a bottle of champagne is opened after their rescue.

Inspired by his experience, Chapman founded the submarine company Rumic, which designed and built the LR5 submersible for submarine rescue. In 2000, LR5 was mobilised to rescue the Russian submarine Kursk, but for political reasons was never deployed. Another Rumic submersible, Scorpio-45, was used to rescue the Russian deep submergence rescue vehicle AS-28 in 2005.

In 2006, Chapman sold Rumic to James Fisher and Sons. He died from cancer in 2020, aged 74.

Mallinson continued to work with submersibles until 1978. Later, he became heavily involved in restoring steam engines, receiving a Lifetime Achievement award from Prince Michael of Kent for his involvement with The Shamrock Trust, in Windermere, in 2013. He still lives in the Lake District.

# Pisces III submersible: A dramatic underwater rescue, BBC


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