The ''Sōryū''-class submarines (''16SS'') are diesel-electric

attack submarine An attack submarine or hunter-killer submarine is a submarine specifically designed for the purpose of attacking and sinking other submarines, surface combatants, and merchant vessels. In the Soviet Navy, Soviet and Russian Navy, Russian navies ...

s. The first boat in the class entered service with the

Japan Maritime Self-Defense Force The , abbreviated , also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy ( ...

in 2009. The design is an evolution of the , from which it can most easily be distinguished by its X-shaped stern combination

diving plane Diving planes, also known as hydroplanes, are control surfaces found on a submarine which allow the vessel to Pitch (flight), pitch its bow and stern up or down to assist in the process of submerging or surfacing the boat, as well as controlling ...

s and

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw ...

s. At the time of launching, the ''Sōryūs'' had the largest

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of any submarine used by post-war Japan. The Sōryū-class is Japan's first

air-independent propulsion Air-independent propulsion (AIP), or air-independent power, is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen (by surfacing or using a snorkel). AIP can augment or replace th ...

submarine class. From ''Sōryū'' to ''Shōryū'' are fitted with Kockums Naval Solutions

Stirling engine A Stirling engine is a heat engine that is operated by the cyclic expansion and contraction of air or other gas (the ''working fluid'') by exposing it to different temperatures, resulting in a net conversion of heat energy to mechanical Work (ph ...

s license-built by

Kawasaki Heavy Industries is a Japanese Public company, public multinational corporation manufacturer of motorcycles, engines, Heavy equipment (construction), heavy equipment, aerospace and Military, defense equipment, rolling stock and ships, headquartered in Minato, To ...

, allowing them to stay submerged for longer periods of time. The 11th submarine of the class, ''Ōryū'', is the world's first

lithium-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. Li-ion batteries are characterized by higher specific energy, energ ...

submarine. The cost of the sixth submarine (''Kokuryū'') was estimated at US$540 million. In 2023, the first of the replacements for the ''Sōryū''s, the , entered service.

Naming convention

Japanese submarines since World War II were named after

ocean currents An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours ...

. The JMSDF changed its

naming convention A naming convention is a convention (generally agreed scheme) for naming things. Conventions differ in their intents, which may include to: * Allow useful information to be deduced from the names based on regularities. For instance, in Manhatta ...

with the ''Sōryū'', and submarines will now be named after mythological creatures. ''Sōryū'' (そうりゅう) means blue dragon in Japanese and shares its name with the World War II aircraft carrier , sunk during the

Battle of Midway The Battle of Midway was a major naval battle in the Pacific Ocean theater of World War II, Pacific Theater of World War II that took place on 4–7 June 1942, six months after Japan's attack on Pearl Harbor and one month after the Battle of t ...

Variants

The eleventh ''Sōryū''-class submarine (''Ōryū'') is the first Japanese submarine in the fleet to mount

lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. Li-ion batteries are characterized by higher specific energy, energy ...

. The JS ''Ōryū'' was given a budget of under the 2015 Japanese Defense Budget. Lithium-ion batteries have almost twice the electric storage capacity of traditional lead-acid batteries. Updated ''Sōryū''-class boats also added more batteries by placing them within hull spaces previously occupied by AIP system machinery. These upgraded boats benefited by increasing both the size and energy density of their battery storage. The change to lithium-ion improved the underwater endurance significantly and will be an advantage over the slow recharge capability of the AIP system. In any event, JMSDF believes that lithium-ion is the way forward and intends to 'trial' this new system and compare it to the previous AIP system for operational effectiveness.

Exports

Japan offered ''Sōryū''-class submarines to Australia as replacements for the

Royal Australian Navy The Royal Australian Navy (RAN) is the navy, naval branch of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (Australia), Chief of Navy (CN) Vice admiral (Australia), Vice Admiral Mark Hammond (admiral), Ma ...

's s, as part of the . On 9 April 2014, then-Australian Minister for Defence, David Johnston, described the ''Sōryū'' class as "extremely impressive" while discussing Australia's future submarine options. On 26 April 2016, Australian

Prime Minister A prime minister or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. A prime minister is not the head of state, but r ...

Malcolm Turnbull Malcolm Bligh Turnbull (born 24 October 1954) is an Australian former politician and businessman who served as the 29th prime minister of Australia from 2015 to 2018. He held office as Liberal Party of Australia, leader of the Liberal Party an ...

announced that the Australian contract had been awarded to the French-designed Shortfin Barracuda, though this deal was eventually rescinded.

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Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

, and

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

have also approached Japan, and expressed an interest in buying ''Sōryū''-class submarines. During a visit to Japan, India's then- Union Minister of Defence,

Manohar Parrikar Manohar Gopalkrishna Prabhu Parrikar (13 December 1955 – 17 March 2019) was an Indian politician and a member of the Bharatiya Janata Party who was the Chief Minister of Goa for three terms. He also served as the Union Minister of Defence ...

, invited the Japanese government to participate in their US$8.1 billion Project 75I-class submarine procurement program. File:JS zuiryu（SS-505）.JPG, ''Zuiryū'' (SS-505) under construction File:Hakuryu-130412-N-LS794-166.jpg, ''Hakuryū'' (SS-503) visiting Guam in 2013

Boats

References

External links