Sōryū class submarine

Hakuryū (SS-503) visits Pearl Harbor, Feb 2013
Class overview
Name:	Sōryū
Builders:	Mitsubishi Heavy Industries Kawasaki Shipbuilding Corporation
Operators:	Japan Maritime Self-Defense Force
Preceded by:	Oyashio-class submarine
Built:	2005–Present
In commission:	2009–Present
Building:	3
Planned:	12
Completed:	9
Active:	8 (1 launched)
General characteristics
Type:	Attack submarine
Displacement:	Surfaced: 2,900 tonnes (2,854 long tons) Submerged: 4,200 t (4,134 long tons)
Length:	84.0 m (275 ft 7 in)
Beam:	9.1 m (29 ft 10 in)
Draught:	8.5 m (27 ft 11 in)
Depth:	900 m
Propulsion:	1-shaft 2× Kawasaki 12Ｖ 25/25 SB-type diesel engines diesel-electric 4× Kawasaki Kockums V4-275R Stirling engines 3,900 hp (2,900 kW) surfaced 8,000 hp (6,000 kW) submerged
Speed:	Surfaced: 13 kn (24 km/h; 15 mph) Submerged: 20 kn (37 km/h; 23 mph)
Range:	AIP endurance (est.): 6100 nautical miles (11297.2 km; 7060.75 miles) at 6.5 knots (12 km/h; 7.48 mp/h)
Complement:	65 (9 officers, 56 enlisted)
Sensors and processing systems:	ZPS-6F surface/low-level air search radar Hughes/Oki ZQQ-7 Sonar suite: 1× bow-array, 4× LF flank arrays and 1× Towed array sonar
Electronic warfare & decoys:	ZLR-3-6 ESM equipment 2× 3-inch underwater countermeasure launcher tubes for launching of Acoustic Device Countermeasures (ADCs)
Armament:	6 × HU-606 21 in (533 mm) torpedo tubes with 30 reloads for: 1.) Type 89 torpedo 2.) Harpoon (missile) Mines

The Sōryū-class submarines (16SS) are diesel-electric attack submarines. The first boat in the class entered service with the Japan Maritime Self-Defense Force in 2009. The design is an evolution of the Oyashio-class submarine, from which it can most easily be distinguished by its X-shaped stern combination diving planes and rudders. The Sōryūs have the largest displacement of any submarine used by post-war Japan.

It is Japan's first air-independent propulsion submarine. The boats in the class are fitted with Kockums Stirling engines license-built by Kawasaki Heavy Industries, allowing them to stay submerged for longer periods of time. Some recent information suggests that the last units in the series will have their air independent propulsion systems replaced with banks of Li-Ion batteries.

The cost of the sixth submarine (Kokuryū) was estimated at 540 million USD. The eleventh Soryu-class submarine, with improved underwater endurance by mounting lithium-ion batteries, was given a budget of ¥64.3 billion/US$536.7 million under the 2015 Japanese Defense Budget.

Japanese submarines since World War II were named after ocean currents. The JMSDF changed its naming convention with the Sōryū, and submarines will now be named after mythological creatures. Sōryū (そうりゅう) means blue dragon in Japanese and is named after the World War II aircraft carrier Sōryū, which was sunk during the Battle of Midway.

Japan offered Sōryū-class submarines to Australia to replace the Royal Australian Navy's Collins-class submarines as part of the Collins-class submarine replacement project. On 9 April 2014, then-Australian Defence Minister David Johnston, while discussing Australia's future submarine options, described the Sōryū class as "extremely impressive". On April 26, 2016, Australian Prime Minister Malcolm Turnbull announced that the Australian contract had been awarded to the French-designed Shortfin Barracuda.