Like Two Ships Not-Quite-Passing In the Night

The Atlantic Ocean is big — very big. It has an area of more than 40 million square miles (100 million square kilometers), which is more than twice the land area of Asia. And, given that it’s ocean, very few people live there. Sure, there are a lot of ships cruising throughout the seas, and there are people on board those ships, but even if we were to treat those people as permanent residents of the Atlantic (which I originally typoed as “reseadent,” which kind of works!) you’d need more than 50 million of them to have a population density equal to Alaska, which is easily the least-dense state of the 50 American states.

All of that is to say that you’re cruising around the Atlantic, chances are, you’re not going to run into anything. That’s particularly true if you’re not in a port, where there are lots of ships moving in a small area, or if it’s during peacetime, when ramming into another ship may be intentional. And it’s supremely true if you’re in a submarine — not only are there far fewer subs than there are ships on the water’s surface, but you also add a y-axis to the equation.

So it must have been really strange when, on the evening of February 3rd to 4th, 2009, the HMS Vanguard — a British submarine — crashed into something.

Oh, and potentially very dangerous, too, because the Vanguard was a nuclear sub carrying a payload of atomic weapons.

Submarines are typically designed to be hard to detect. They travel underwater (obviously) and are, therefore, already difficult at best to detect from the surface or the sky. The easiest way to find a submarine is using sonar (which, originally, was an acronym meaning “Sound Navigation and Ranging”) — basically, you use listening devices to “look” for any sounds that don’t match the normal noises you’d expect to find in the ocean. As submarines have motors and people — things you typically don’t find in the depths of the ocean — if you know what you’re listening for, you can often detect an oncoming sub.

But over the decades, submariners have become better and better at hiding from enemy sonar. The National Museum of the U.S. Navy’s website explains:

To increase stealth, submariners take advantage of how sound waves act in ocean water. The speed of sound in seawater is greatly determined by temperature, pressure, and salinity. These three factors vary in different locations and bend the sound waves accordingly. Because SONAR depends on receiving sounds signals, the way sound waves bend determines what can be picked up by SONAR. Submariners can find places between the bending sound waves of active enemy SONAR called shadow zones. There, subs can hide and watch the enemy without being detected.

And on that day, the Vanguard was likely taking efforts to hide itself — the British military, understandably, has been mum on the details. Unfortunately for them, so was the Le Triomphant, a French nuclear submarine. Le Triomphant happened to be in the same area, “conducting routine national patrols in the Atlantic Ocean” according to the British Ministry of Defense (via the Guardian), and because the two submarines were doing their best to hide, they didn’t detect one another. And, despite the vastness of the ocean, they collided.

The collision happened at a very low speed and no one aboard was injured, and thankfully for the rest of us, none of the nuclear stuff on either ship went boom. The damage to the French ship was so minimal that they claimed to have not realized they hit another ship; per the Guardian, “On 6 February, France’s defense ministry had said that the boat “collided with an immersed object (probably a container)” when coming back from patrolling and that its sonar dome was damaged.” (It wasn’t a container, unless you’re being very, very literal.) The French ship needed repairs to its active sonar dome while the British ship suffered damage to the casing that held its missiles on its right side, which is to say, the damage was pretty minor. That said, the repair bills, according to the Telegraph, were “expected to cost up to £50 million in repairs,” or about $65 million for the two combined. (That’s a lot, but the sub cost more than £3 billion to build, so it’s not outlandish.)

There were some calls after the event for the UK and France to better coordinate their efforts to patrol under the Atlantic, but neither nation acknowledged if any efforts were being made to do so. The good news is that such an event is unlikely to happen again, if for no other reason than it was incredibly unlikely to have happened in the first place.

Bonus fact: The 1995 movie “Crimson Tide” takes place upon a fictional American submarine and involves a mutiny (sorry for the minor spoiler), and the United States Navy wasn’t a fan of the script. As a result, the Navy didn’t help filmmakers with the movie, which is a problem — it’s not so easy to get footage of a submarine without the Navy’s assistance. (Again, subs are supposed to be stealthy.) The filmmakers wanted a shot of a sub descending into the ocean, but without the Navy’s help, that was going to be difficult. So the filmmakers decided to go to Pearl Harbor and wait until they saw it happening in real life. According to the Honolulu Star-Bulletin, on January 31, 1995, “as the USS Alabama sailed out of Pearl Harbor [ . . . ], suddenly two boats loomed off to one side of the Trident submarine and a helicopter buzzed overhead. The sub’s officers tried to make contact with the other vessels — but got no response.” The sub wasn’t under attack — the ships and the copter were part of the film crew, and the only shooting being done was the shooting of film. Per a Navy official, this was perfectly legal, and no action was taken against the movie makers.

From the Archives: How Potatoes Changed the Outcome of a World War II Naval Battle: Potatoes on a sub? (That’s a bad, and admittedly lazy, sandwich pun.)