USS San Francisco was one of the first Los Angeles-class nuclear attack submarines of the United States, built in 1972 and commissioned on April 24, 1981. It is also the quietest submarine in the US Navy. The bow part of the ship was crushed after hitting a mountain. Photo: National Interest USS San Francisco has a displacement of 6,900 tons when submerged, 110 meters long and 10 meters wide. The train is equipped with a General Electric PWR S6G nuclear reactor with a capacity of 35,000 horsepower, helping it to move at a maximum speed of 61km / h. According to the National Interest, the accident occurred with the Los Angeles-class submarine USS San Francisco (SSN-711), on January 8, 2005. At the time of the collision, the ship was near Guam conducting training and preparing to sail to Australia. At that time, the ship was diving at a depth of 160m and moving at a great speed, more than 48km / h. The impact was very strong. The sailors present in the dining room were thrown into the air. In a 60-minute interview, Brian Barnes, a submariner, recalled: “I just saw people lying everywhere. Glass was broken, dishes were splattered, sailors groaned from their injuries, screamed.” The bow of the USS San Francisco was severely damaged, 30m of the front hull was flattened and exposed to the sea. Water flooded the submarine. The urgent task at that time was to urgently pump compressed air into the ballast tanks of the submarine to help the ship float to the surface. The USS San Francisco has a total of 127 crew members. The collision left 98 people injured and many of them were unable to continue operating the ship. Sailor Joseph Allen Ashley was wounded in the head and later died. Another sailor broke both arms but still managed to open the submarine’s air valve to fill the ballast tanks. Danny Hager, who monitors the submarine’s depth gauge, had a terrifying experience after the valves were opened. “I told everyone that the ship was at a depth of 160m. And I kept waiting, 5 seconds, 10 seconds passed and so on I don’t know how much longer, the ship was still at a depth of 160m. The atmosphere is very calm because everyone is waiting for me to announce that we are preparing to come up.” The problem was that the ballast tanks at the front were broken in the collision. The air escapes to the outside. 60 seconds passed and the ship remained unchanged in depth. Fortunately, the aft part of the submarine began to point upwards as the ballast tanks at the aft were filled with compressed air. Danny Hager now feels less worried: “It feels really relieved when I announce the ship has risen to a depth of more than 152m”. Finally, the USS San Francisco also surfaced, but the journey home is still quite far. Fortunately, the nuclear reactor was not damaged in the impact. The crew steered the ship back at a speed of 16km/h and so to return to Guam, it took the ship 52 hours. Unexpected causes Despite its immense firepower and nuclear propulsion, the USS San Francisco, like all submarines, relies on charts providing data on the topography of the seabed. After the investigation, the US Navy found that the submarine used old charts that did not mention the submarine mountain range in the area of ​​​​the ship’s operation. Meanwhile, other maps warn about this mountain range. The charts used by the crew of San Francisco were provided by the Defense Mapping Agency in 1989. By 2008, a study by the University of Massachusetts showed that images obtained from the Landsat satellite showed An underground mountain range more than 30m above the seabed in the area. However, the US Navy did not update this information to the chart. During the repair, the bow of the USS San Francisco was removed and replaced with the bow of the submarine USS Honolulu, which was about to be decommissioned. USS San Francisco rejoined the fleet in 2009 and served for another seven years. It was later converted into a training submarine. Ship commander Kevin Mooney was reprimanded for this unfortunate accident. Several sailors received medals for their brave actions when the ship was in distress. Only the sailor who died Ashley is inscribed at the Navy Memorial in Washington DC So how could the ship survive the high-speed crash into the underground mountains? In 1963, after the sinking of the submarine USS Thresher, the US Navy established the SUBSAFE program. The goal of this program is to ensure that the hull will remain pressurized in the event of an accident and that it can float. This program makes keeping nuclear reactors safe and making them recover from accidents a top priority. If the ship can surface and the nuclear reactor continues to operate, the crew will have a good chance of survival. USS San Francisco has ensured those conditions. Thus, the fact that the USS San Francisco can “survive the accident” is the result of the dedication and relentless research efforts of the US submarine force.

Fortunately, the second half of the 2,600-ton submarine, 73 meters long, displaced the water, remained undamaged after the fire. And in the difficult emergence of wisdom, French naval officials had the idea of ​​pairing the rest with its “sister” – the Saphir submarine. Perle nuclear submarine intact. Photo: Reddit Although decommissioned in 2019, and waiting to be dismantled, the Saphir front section remains relatively stable in construction. Therefore, French authorities determined that the ship could still be combined with the back of Perle to form a new attack submarine. Perle was subsequently relocated from Toulon to Cherbourg in December of last year. The workers cut it in half and the Saphir. According to French naval contractor Naval Group, earlier this month, the second half of the Perle and the front half of the Saphir were put on “conveyor” at the shipyard in Cherbourg, so that they can be carefully calibrated and welded. together. Perle submarines after being burned by fire nearly half. Photo: Marine Nationale A Naval Group spokesperson said assembly will continue to be completed in the coming months. The complete submarine, still named Perle, will be about 1.5 meters longer than its “predecessors” thanks to an additional “intersection zone”. The intersection zone on the new version of the Perle submarine will add a bit of living space for about 70 sailors operating inside the ship. Digital model According to Naval Group, all assemblies are simulated using 3D digital methods before being applied to a real ship. This is the effort spent more than 100,000 hours of technical research and 250,000 hours of manual work by more than 300 technicians and shipbuilders. Two pieces of the Perle submarine after being cut in half at the Cherbourg Shipyard, France. Photo: AP Franck Ferrer, Director of Naval Group Services, said in January the new version is expected to return to Toulon by the end of this year, for further engineering and upgrade of the combat system. . The ship will rejoin the French Navy fleet in early 2023. “The implementation of the project for these cases, namely the repairing and joining of parts of two sister ships together, was the first thing Naval Group did in modern history,” said Ferrer. said. Rare luck The Perle was not the first instance of two parts of two different ships being assembled together. According to Thomas Shugart, a retired commander of the American attack submarine, the US Navy did the same thing by replacing the damaged bow of the USS San Francisco with the bow of the soon-to-be retired USS Honolulu. The process of assembling two-part Perle submarines with Saphir. Video: Le Télégramme However, the Perle submarine can “revive” is still considered a rare luck compared to similar cases in the past. In 2012, a disgruntled worker caused a serious fire on the USS Miami submarine, while the ship was undergoing repairs at the port of Portsmouth, Maine (USA). The ship then became a waste product due to the high cost of restoration. By 2020, the amphibious assault ship USS Bonhomme Richard is also damaged by fire while being upgraded in San Diego port (USA). After determining it would take up to $ 3.2 billion and seven years to repair, the USS Bonhomme Richard was finally removed from service with the US Navy.