Why the US Navy $3 billion nuclear submarine unable to detect seamounts?

The USS Seawolf class nuclear submarine “Connecticut” was damaged when it hit an unknown object in the South China Sea in October. This luxury sports car of the submarine version cost 3 billion U.S. dollars. It sails fast and is equipped with the most advanced electronic equipment. Why can’t it dodge the submarine mountains?


CNN reported that although the USS Connecticut (SSN-22) was expensive and equipped with sophisticated technology, it crashed into the Pacific Ocean Sea Mountains on October 2.

“Connecticut” is one of the three Seawolf-class submarines in the U.S. Navy fleet, each costing about 3 billion U.S. dollars. This submarine has a displacement of 9,300 tons and a total length of 353 feet. It entered service in 1998 and can carry 140 crew memeber and is powered by a nuclear reactor.

“Connecticut” is currently docked at the U.S. Naval Base Guam for maintenance. The U.S. Navy stated that Connecticut used its own power to sail 2,900 kilometers eastward from the South China Sea to Guam. Although 11 crew members on the ship were injured in the collision, thankfully the nuclear reactor was not damaged.

After being assessed for damage in Guam, the “Connecticut” will return to the Bremerton submarine base in Washington State for repairs.

US Department of Defense officials did not disclose details of the damage to the submarine. However, the US military has many questions to be answered in the coming weeks, even months. Most importantly, how did the accident happen?

Attack submarine USS San Francisco sits in dry dock, on January 27, 2005, in Apra Harbor, Guam to assess damage sustained after running aground
Attack submarine USS San Francisco sits in dry dock, on January 27, 2005, in Apra Harbor, Guam to assess damage sustained after running aground

The US Navy’s dismissal of the ship’s command level on the 4th due to a loss of trust may have given some hints. After the naval investigation, the commanding officer Cmdr. Cameron Aljilani and two other high-level cadres were dismissed.

According to the dismissal statement, the 7th Fleet Commander and U.S. Navy Vice Adm. Karl Thomas, commander of US 7th Fleet, determined that “sound judgment, prudent decision-making and adherence to required procedures in navigation planning, watch team execution and risk management could have prevented the incident,” according to a statement about the decision.

The submarine environment is very changing, and a small mistake can cause serious consequences.

Thomas Shugart, who has commanded attack submarines in the U.S. submarine service for more than 11 years, said, “Submarining is hard, it’s really hard. Not everything goes right all the time.”

Xu Carter currently serves as a part-time senior researcher at the Center for a New American Security. He said that surface ships or submarines navigating deep in the periscope can rely on the Global Positioning System (GPS) to provide accurate positions. But when diving into the deep sea, the GPS system cannot be used. Submarines can only use compasses and charts to locate.

Accurate seafloor maps (with a resolution of up to 100 meters) are drawn using multi-beam sonar technology, but this process is expensive and time-consuming, so up to 80% of the world’s seafloor topography has not been mapped.

David Sandwell, a geophysicist at the Scripps Institution of Oceanography at the University of California, told CNN that the South China Sea is one of the busiest sea areas in the world, and one-third of the world’s shipping trade passes through this place. China has also reclaimed the sea to build islands and build military fortresses here, and the seabed landforms it has drawn are still less than 50%. He said: “It’s not surprising that you could run into something.”

The U.S. Navy has not yet revealed where the Connecticut hit the sea mountain range. The official statement is in the Indo-Pacific waters, but officials from the US Department of Defense previously told CNN that the accident occurred in the South China Sea.

Sandwell tried to narrow the range a bit, using the method of measuring the vertical gradient of gravity to measure the earth’s gravity field through satellite altimetry, and coincide with the seabed topography of the South China Sea. He managed to identify 27 possibilities that were not on the US military chart. Location of the accident.

He said, “The depth of these locations is less than 400 meters. This depth submarine is likely to hit (undersea mountains).”

US Navy officials claim that the maximum operating depth of Seawolf-class submarines is 800 feet (243 meters), but some experts believe that the actual depth should be about twice.

The submarine itself is also equipped with sonar, but the use of sonar must pay a price: loss of concealment effect. While the sonar emits sound waves, it also exposes the position of the submarine.

Xu carter said, “Sonar is the only way to detect the seabed, but you don’t want to emit too many unnecessary sound waves.” If you want to get accurate images, “sound waves have to be emitted about every 20 seconds. That makes too much noise.”

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