How a $100,000,000 Swedish Submarine ‘Sank’ a $6,000,000,000 Navy Aircraft Carrier

Summary and key points: During a 2005 naval exercise, the Swedish diesel submarine HSMS Gotland stunned the maritime world by “sinking” the USS Ronald Reagan, a nuclear-powered American aircraft carrier.

-Despite the presence of a formidable aircraft carrier group, Gotland managed to break through the US Navy’s anti-submarine defenses and carry out several simulated torpedo runs.

-This feat highlighted the capabilities of Gotland’s modernized Stirling engine, which allowed it to operate silently and evade detection.

-While a real-world scenario may differ, the exercise exposed vulnerabilities in U.S. naval defenses, highlighting the need for robust anti-submarine strategies against advanced diesel submarines.

How a Swedish submarine ‘sank’ a US aircraft carrier

A few years ago, during a major naval exercise off the coast of California, a small Swedish diesel submarine sent shockwaves through the maritime world by “sinking” in a war game one of the world’s most advanced warships: a nuclear-powered American aircraft carrier.

Let’s sink an aircraft carrier

It was 2005 and the small diesel submarine HSMS Gotland was taking part in an anti-submarine warfare exercise against the US Navy.

The Swedish submarine and its crew were loaned to the US Navy for the purpose of testing anti-submarine technology, tactics and doctrine against a formidable enemy.

Despite having a full carrier strike group, including destroyers, helicopters and aircraft in pursuit, HSMS Gotland managed to slip through the formidable anti-submarine defensive net surrounding USS Ronald Reagan and score several simulated torpedo “hits”.

To top it all off, the Swedish submarine managed to repeat its feat several times over two years, alarming officials in Washington and encouraging rivals in Moscow, Beijing and elsewhere.

If a small diesel-powered submarine costing about $100 million—roughly the price of two of the dozens of F-18 Super Hornets aboard a U.S. aircraft carrier—could sink a $6 billion supercarrier, then the U.S. Navy would be at a serious disadvantage in a conflict with China or Russia.

Of course, the exercise was only a simulation and, in all likelihood, the outcome could have been different if it had been a real scenario.

For example, despite its size and weight, the USS Ronald Reagan has a top speed of over 30 knots, or about 35 miles per hour, which is very impressive for a ship weighing over 100,000 tons. If the HSMS Gotland had been a real enemy, the American aircraft carrier would have detected the torpedoes and initiated evasive maneuvers to avoid them.

Additionally, as a supercarrier, the USS Ronald Reagan is well-armored and could probably withstand a number of hits from the small Swedish submarine. But while the HSMS Gotland might not have sunk the American carrier, it most likely would have caused significant damage and forced it to withdraw for repairs.

But how did the small Swedish submarine manage to repeatedly “sink” US Navy ships?

Gotland Class – Old technologies with a modern twist

Most countries use diesel submarines rather than nuclear ones because of the cost and technological barriers that the latter entail. But diesel submarines are noisy, slower, and can only stay underwater for a few days or weeks without resurfacing, unlike nuclear submarines which can stay underwater for months if necessary.

Aware of the limitations of diesel submarines, Swedish engineers looked back in history and chose the Stirling engine, invented in the early 19th century, to power the HSMS Gotland.

The modern version of Stirling engines allowed the submarine to become almost completely undetectable by sonar, the main means ships use to hunt submarines. Several other layers of technology, such as a sonar-resistant coating and electromagnets to limit its magnetic signature, also helped make the Swedish submarine nearly undetectable.

About the Author

Stavros Atlamazoglou is a veteran defense journalist specializing in special operations and a veteran of the Hellenic Army (national service with the 575th Marine Battalion and Army Headquarters). He holds a bachelor’s degree from Johns Hopkins University and a master’s degree from the Johns Hopkins School of Advanced International Studies (SAIS). His work has been featured in Business Insider, Sandboxx, and SOFREP.

All images are Creative Commons.