What You Need to Know: China’s newest nuclear-powered submarine, the Zhou-class, reportedly sank near a Wuhan shipyard during construction, likely due to operator error, according to reports. 

-Satellite images revealed large cranes attempting salvage efforts in June, indicating a major setback for the People’s Liberation Army Navy (PLAN). Similar accidents have occurred elsewhere: India’s INS Arihant was damaged by flooding in 2017, and Britain’s HMS Thetis sank in 1939 due to design and operational issues.

-These incidents underscore the complexities and risks associated with new submarine classes. Lessons learned from these tragedies have previously led to design improvements, highlighting the need for rigorous testing in future builds.

In late May or early June, China's newest – and likely most capable – nuclear-powered submarines sank near a shipyard in Wuhan while under construction, and officials in Beijing sought to cover up, The Wall Street Journal first reported in September. The Zhou-class submarine was part of the People Liberation Army Navy (PLAN) massive expansion effort, and instead could be a significant setback.

According to the report from the paper of record, the nuclear-powered submarine is believed to be the lead boat of the Zhou-class, which was notable for featuring "a distinctive X-shape stern, which was designed to make the vessel more maneuverable." The submarine was under construction at the state-owned China State Shipbuilding Corp.'s facilities on the Yangtze River and was being fitted out before beginning sea trials.

"It's not surprising that the PLA Navy would try to conceal the fact that their new first-in-class nuclear-powered attack submarine sank pierside," senior U.S. defense official, as previously reported by Stavros Atlamazoglou for The National Interest.

The incident might not have even been noted, but satellite photos from June showed "large floating cranes," which "arrived in early June to salvage the sub from the river bed," WSJ explained.

Details Are Coming Into Focus

Since the reports that the PLAN submarine sank, a few details have come into focus – and it has been suggested that it wasn't a mechanical failure, but is more likely the result of human error.

According to a report from The Washington Times, U.S. defense officials have suggested that the mishap occurred due to "operator error" – perhaps the "result of leaving open a hatch that flooded the vessel."

An official was quoted as stating, "They goofed," which would be a considerable understatement to say the least but not really that uncommon when it comes to submarines that have been recently floated out and are still to conduct sea trials.

Past Submarine Accidents

In 2017, the recently completed $2.9 billion Indian Navy submarine INS Arihant was left inoperative for nearly a year after a hatch was left open, allowing seawater to flood the propulsion compartments and damage critical systems.

Not only did the propulsion compartments fill with seawater, but there was substantial damage to the pipes that ran through the submarine. Given how corrosive seawater can be to the various pipes, including those that carry pressurized water coolant to and from the ship's eighty-three-megawatt nuclear reactor, all had to be cut out and replaced. New Delhi also attempted to conceal the incident from the public, without success.

In June 1939, the Royal Navy's HMS Thetis (N25) sank before officially being handed over to the Royal Navy during a dive trial in Liverpool Bay. That incident occurred after the inner hatch on a torpedo tube was opened while the outer hatch to the sea was also open, flooding the submarine in the process. Apparently, some enamel paint had blocked the flow of water to the valve on the Number 5 tube, though the outer door (bow cap) was open. It remains unclear why that bow cap was open, but it was likely a malfunction.

There was also confusion among the crew due to the fact that the "Shut" position for tube 5 on the dial was the mirror image of Number 6. This was simply a counter-intuitive design that proved to be a recipe for disaster. Lieutenant Frederick Woods, the boat's torpedo officer, opened the hatch to confirm the tube was empty, and in doing so water rushed in. The crew reportedly didn't initially panic, as the T-class was designed with six compartments.

However, it proved more difficult than expected to close the watertight doors that separated the torpedo room from the stowage compartment. The Royal Navy's submarine at the time didn't feature the quick-locking door with a wheel, instead, each door had some eighteen butterfly bolts around the edge that needed to be closed in an emergency. That was another design flaw that prevented the doors from being closed.

 Matters were made worse by the fact that the torpedo stowage compartment was set up for a special lunch for the visiting dignitaries and was full of extra furniture and loose equipment that impeded the crew's escape. Just four sailors managed to make it to the escape hatch, while the boat became a tomb for the remaining 99 men on board.

The tragic sinking eventually led to the redesign of all torpedo tubes on British and Australian submarines. The boat was raised, renamed HMS Thunderbolt, and saw service during World War II. Tragically in 1943, the boat was struck by multiple Italian Navy depth charges, and HMS Thunderbolt sank in 4,430 feet (1,350 meters) of water, with the loss of all hands.

Author Experience and Expertise: Peter Suciu

Peter Suciu is a Michigan-based writer. He has contributed to more than four dozen magazines, newspapers, and websites with over 3,200 published pieces over a twenty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. You can follow him on Twitter: @PeterSuciu. You can email the author: [email protected].

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