Late at night on Feb. 3, 2009 the crew of the French nuclear submarine Triomphant, experienced something of a shock. The 138-meter-long submarine, the lead boat of four serving today as a key part of France’s nuclear strike force, was returning to port submerged under the heavy seas of the East Atlantic when something impacted violently upon her bow and sail.
On Feb. 6 the French Ministry of Defense reported that the submarine had suffered a collision with an “an immersed object (probably a container).” The same day the Triomphant returned to her base in Ile Longue escorted by a frigate.
Curiously, HMS Vanguard, a British Royal Navy nuclear submarine also experienced a collision that evening. The first of her class, Vanguard measures 150 meters long and displaces 16,900 tons when submerged.
At some point, the two navies compared notes. On Feb. 16 they announced the two submarines “briefly came into contact at a very low speed while submerged.” Fortunately, no crew members were harmed in the accident, though repairs were estimated to cost a minimum of 50 million pounds.
When the Vanguard returned to her base in Faslane, Scotland, she was visibly badly mangled around her missile compartment and starboard side.
More:
https://warisboring.com/the-alarming-story-of-how-french-and-british-nuclear-submarines-collided/