Summary and Key Points: Japan’s Taigei-class “Big Whale” submarines are portrayed as a generational step beyond the Soryu-class—heavier, quieter, and built around years of research to reduce noise, improve survivability, and support higher onboard electrical demands.
-The design emphasis is on stealth: refined propeller and hull shaping, vibration-damping internal floorboards, and a quieter snorkel-based power generation concept intended to streamline energy production for modern sensors and electronics.
Taigei-Class Submarine from Japan. Image Credit: Creative Commons.
-With lithium-ion batteries extending submerged endurance, the Taigei fleet is framed as a major boost to Japan’s undersea posture.
-In a Taiwan contingency, the argument is that allied undersea superiority could threaten Chinese surface forces in ways surface ships cannot.
Japan’s “Big Whale” Submarines: Why the Taigei-Class Is a Quiet Game-Changer
Japan’s new Taigei-class submarine is called the “Big Whale” for a specific reason: the boat is 100 tons heavier, quieter, and more lethal than the preceding Soryu-class.
The Japanese Maritime Defence Force has launched as many as six new Taigei-class submarines, and three have been commissioned since 2022.
The boats are a generational leap forward in undersea technology, intended to improve quieting, stealthiness, survivability, higher power output, and emitted “vibrations.”
Interestingly, while the new submarines have been launched only in the last three years, the boats’ technological components are the result of more than a decade of cutting-edge research.
Taigei-Class Submarine from Japan. Image Credit: Creative Commons.
Stealthy Taigei-Class Submarine
A key focus of the research was to uncover and integrate new propeller and hull-shape designs that reduce noise generation and improve impact resistance.
Similarly, Japanese research also incorporated new “floorboards” attached to the inner shell through a buffer mechanism intended to minimize “vibrations” inside the submarine and prevent a more detectable signal from being emitted into the water. The floorboards are also designed to improve survivability by reducing “shock” impact from outside the boat.
The Taigei-class also incorporates a new “snorkel” power generation system designed to be quieter and generate higher power output, improving functionality and survivability.
Slides published by the Japanese Defense Ministry show that the Snorkel system streamlines power generation and provides the critical added benefit of enabling cutting-edge on-board power for electronic systems.
Taigei & Virginia-class Submarines
Technologically advanced submarines, such as the United States Navy’s Virginia-class, require new levels of electrical power to support next-generation on-board systems.
Finally, the new JMSDF submarines operate with lithium-ion batteries, which extend undersea mission time more than diesel/electric submarines do.
Taigei-Class Submarine from Japan. Image Credit: Creative Commons.
The arrival of these Japanese submarines is highly significant in terms of a US-Japanese allied deterrence effort in the Pacific, given that China is quickly progressing with its Jin-class submarines and already operates a larger Navy than the United States.
Therefore, a Japanese buildup advancing new generations of technology could immeasurably strengthen US-Japanese undersea superiority and deterrence.
This is of vital significance to any US-Japanese ability to defend Taiwan, as there is a credible argument suggesting that submarines could in fact “save” the island.
Japan vs China: Submarine Faceoff
While the US and Japan would, at least at the moment, enjoy air superiority in the region due to their combined number of available F-35s, China’s surface fleet poses a serious and formidable challenge to any US-Japanese surface defenses and Taiwanese ground-based weapons.
However, should the US and Japan operate with undersea superiority, a Chinese amphibious attack on the surface would be highly vulnerable to destruction from undersea.
While the US Navy still operates with an attack submarine deficit, which may grow more pronounced in the coming years, Virginia-class Block III and beyond boats have been integrated into the fleet with a new generation of quieting and stealth-enhancing technologies.
Japan AIP Soryu-Class Submarine. Image Credit: Creative Commons.
When combined with Japan’s growing fleet of advanced Taigei-Class submarines, it’s conceivable that US and Japanese subs could track and destroy both PRC submarines and surface ships in ways surface ships cannot. Surface ships are detectable by air, satellite, and surface surveillance technologies.
Yet, undersea submarines conducting clandestine reconnaissance and attack missions could destroy a Chinese Navy attack before it is detected fast enough.
About the Author: Kris Osborn
Kris Osborn is the President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.
