USS Seawolf: The U.S. Navy's 'Secret Projects' Nuclear Submarine

USS Seawolf (SSN-575)
June 2, 2024 Topic: Security Region: Americas Blog Brand: The Buzz Tags: SSN-575U.S. NavyNavyMilitaryDefenseSubmarinesSeawolf-Class

USS Seawolf: The U.S. Navy's 'Secret Projects' Nuclear Submarine

The USS Seawolf (SSN-575) was the only submarine ever built to be equipped with a liquid metal (sodium) nuclear reactor.


Summary: The USS Seawolf (SSN-21) is one of the most advanced submarines in the U.S. Navy, boasting superior undersea warfare capabilities. Brandon J. Weichert of The National Interest highlighted its strategic importance, particularly against Russian and Chinese naval forces. However, Weichert overlooked an earlier namesake, the USS Seawolf (SSN-575), an experimental platform and the second nuclear-powered submarine after USS Nautilus.

USS Seawolf


-SSN-575, commissioned in 1957, featured an innovative but problematic liquid metal reactor, later replaced.

-Despite its challenges, SSN-575 demonstrated crucial advancements in nuclear submarine operations.

USS Seawolf (SSN-575): The Pioneering Submarine That Shaped Naval Warfare

Writing for The National Interest, Brandon J. Weichert reported on the United States Navy's Seawolf-class nuclear-powered submarines, describing them as the "most advanced undersea warfare technology ever developed, boasting capabilities that remain a concern for Russian and Chinese military strategists."

Seawolf-Class Submarine

What Weichert went on to say about the Seawolf-class is absolutely true, and it could be argued that despite the cost, the program shouldn't have been cut short. However, he missed one important point about the submarine – it was actually the second time the U.S. Navy operated a truly advanced undersea marvel dubbed Seawolf.

It gets a bit confusing, however, because the current USS Seawolf is designated SSN-21 – part of a decision by the U.S. Navy to make that new class part of the submarines of the 21st century. As only three were produced, the sea service reverted to the numbering system with its Virginia-class boats.

This brings us to the USS Seawolf (SSN-575), which wasn't the first nuclear-powered submarine – as that distinction belongs to the USS Nautilus (SSN-571). However, SSN-575 was very much a new vessel for a new era; an experimental platform that was employed to determine the future of U.S. Navy submarines going forward. Laid down in September 1953, and finally commissioned in March 1957, she initially operated largely in secret.

This included intensive training programs of the crew, while she took part in NATO exercises. The first major public announcement of the boat occurred after the USS Seawolf had completed a voyage of 13,780 nautical miles – which began on August 7, 1958, and concluded on October 6 – submerged the entire time. Though many ballistic missile submarines will spend months at a time deployed under the sea, this was quite a notable accomplishment at the time.

As the Naval History and Heritage Command reported, that voyage demonstrated to the world that a nuclear-powered boat could "remain independent of the earth's atmosphere for the period of a normal war patrol."

The boat continued to be employed in both independent and fleet operations, including a period of service where CVN-575 was part of the world's first nuclear task force, which consisted of surface ships and submarines equipped with nuclear-armed guided missiles.

During one cruise in September 1957, then President Dwight D. Eisenhower embarked on the boat and was taken for a short cruise! Ike reportedly had a special liking for submarines.

"I suppose you know this is the first time I've been aboard an atomic reactor submarine," the president remarked at the time. "Everything was of interest to me­all of the gadgets and the machines. But more interesting to me was to see the United States Navy at work."

Unique Nuclear Reactor for USS Seawolf 

One of the other notable facts about the USS Seawolf was that she was the only submarine ever built to be equipped with a liquid metal (sodium) nuclear reactor.

It provided a more efficient powerplant but presented numerous hazards for the ship and crew – notably the potential for a deadly fire and highly corrosive effects. After just two years of operation, the reactor on SSN-575 was converted to a pressurized water reactor.

During the boat's 30-year service life, the submarine performed as a "special projects platform." USS Seawolf was decommissioned in 1987, and while stored for a decade, she was dismantled in the U.S. Navy's Nuclear-Powered Surface Ship and Submarine Recycling Program.

USS Seawolf Specs

Displacement: 3,209 tonnes/3,260.5 tons (surfaced); 4,045 tonnes/4,109.9 tones (submerged)

Length: 103 meters (337 feet, 11 inches)

Beam: 8.5 meters (27 feet, 11 inches)

Armament: 6x533mm/21 inch tubes, 8 x torpedoes

Propulsion: SG2 liquid metal nuclear reactor (later converted)

Speed: 23 knots (surfaced); 19 knots (dived)

Complement: 101 men

Author Experience and Expertise: Peter Suciu

Peter Suciu is a Michigan-based writer. He has contributed to more than four dozen magazines, newspapers, and websites with over 3,200 published pieces over a twenty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. You can follow him on Twitter: @PeterSuciu. You can email the author: [email protected].