What You Need to Know: In a 2005 wargame, the Swedish Gotland-class submarine shockingly “sank” the U.S. supercarrier USS Ronald Reagan, exposing the vulnerability of carriers to low-cost yet highly stealthy threats. The Gotland class sub only cost a little over $100 million to build, while the Navy's aircraft carrier cost, according to many estimates, around $4.5 billion. 

-The Gotland’s air-independent Stirling engine allowed it to move with ultra-quiet precision, avoiding detection by the Carrier Strike Group's advanced systems.

-Its design—featuring a hydrodynamic hull, radar-absorbent materials, and rubber dampeners—further minimized acoustic and electromagnetic signatures, rendering it nearly undetectable.

-This exercise highlighted the Navy’s need for enhanced anti-submarine tactics against stealthy, non-nuclear threats, a lesson that remains relevant amid evolving asymmetric warfare tactics globally.

How a Swedish Sub Sunk a U.S. Aircraft Carrier in Wargames: The Gotland’s Silent Victory

The American supercarrier is the largest and most expensive example of warship ever built. Costing several billions of dollars and housing many thousands of men, the supercarrier is a floating city, the lynchpin of the U.S. Navy force structure, and a vital feature of U.S. grand strategy. But in 2005, during a wargame exercise with a humble adversary, the Swedish Navy’s Gotland submarine, an American supercarrier, the USS Ronald Reagan, was felled.

The Gotland’s victory left the American war planners scratching their heads, wondering how their mighty vessel, and their mighty Carrier Strike Group, had lost to such a modest foe.

Tactical Oversight

The Gotland’s ability to land a torpedo and “sink” the Reagan offered the U.S. Navy a valuable lesson, albeit with a humiliating realization: the modern supercarrier was vulnerable to relatively simple machines that cost a mere fraction of the Reagan’s seven-billion-dollar-price-tag. 

A similar dynamic is on display today, in the Middle East, where Houthi rebels are successfully disrupting U.S. carrier operations with low-tech drones and missiles. The Gotland however offered a shock to the Navy’s system, some twenty years ago.

So, how did the Gotland sneak past an entire Carrier Strike Group and land a blow against the Reagan? Several features permitted the Gotland to operate with such stealth. One advantageous feature was, technically, a lesser system, which ironically, allowed the Gotland to move almost silently: the non-nuclear Stirling engine.

The Gotland features Stirling engine with an air-independent propulsion system. The system allows the Gotland to stay underwater for weeks at a time, relying upon two 4-cylinder external combustion engines that mix diesel fuel and liquid oxygen. The main benefit of the Stirling, at least in the context of wargames with the Americans, is the ultra-low acoustic signature. 

Quieter than traditional diesel submarines, and quieter than the nuclear-powered submarines, which are the default of today’s advanced navies, the Stirling allowed the Gotland to operate so quietly as to avoid acoustic detection.   

Of course, the U.S. Navy has other methods of detection. But the Gotland avoided those, too.

Aside from the Stirling engine, the Gotland features a hydrodynamic hull, which reduces the noise, infrared signature, and active sonar response of the submarine. The Gotland’s tower and mast were constructed from radar absorbent materials, much like a modern fighter jet such as the F-35. 

As the name suggests, radar absorbent materials absorb radar and reduce the likelihood of radar detection. The Gotland was also equipped with twenty-seven electromagnets, which served to reduce the submarine’s electromagnetic signature. That’s not all. 

The Gotland’s various equipment was all covered with rubber. Why? To reduce the likelihood of sonar detecting the equipment. Similarly, the Gotland’s machinery was isolated and mounted on rubber dampeners for the sake of vibration and noise reduction.

The end result, of course, was a submarine so quiet and so stealthy as to evade an American Carrier Strike Group and land a blow on an American supercarrier.

About the Author: Harrison Kass 

Harrison Kass is a defense and national security writer with over 1,000 total pieces on issues involving global affairs. An attorney, pilot, guitarist, and minor pro hockey player, Harrison joined the US Air Force as a Pilot Trainee but was medically discharged. Harrison holds a BA from Lake Forest College, a JD from the University of Oregon, and an MA from New York University. Harrison listens to Dokken.

Image Credit: Creative Commons and/or Shutterstock. Main image is from a USS Enterprise fire back in the 1960s.