The Japan Maritime Self-Defense Force (JMSDF) has commissioned the third of its Taigei-class diesel-electric attack submarines (SSK), which feature better underwater endurance than its older boats, Naval News reports.
Named JS Jingei (with pennant number SS 515), the new Taigei-class boat was inducted into the Submarine Division 4 of Submarine Flotilla 2, which is homeported at the Yokosuka naval base in Kanagawa Prefecture, shortly after being handed over by shipbuilder Mitsubishi Heavy Industries (MHI) at its facility in Kobe City on March 8.
The first submarine of this class, Taigei, was converted to a test submarine on the same day, meaning Japan continues to maintain a total fleet of 22 submarines.
According to the JMSDF, the new submarine has a crew complement of about 70, an overall length of 84 m, a beam of 9.1 m, a draught of 10.4 m, and a standard displacement of about 3,000 tonnes, meaning that it is slightly larger than the well-known previous Soryu-class SSKs, which are 84 m long, 9.1 m wide, 10.3 m depth, and have a standard displacement of 2,950 tonnes.
The Taigei-class for the first time has female-only compartments such as a living space for up to six women, according to the JMSDF.
Jingei means “speedy whale” in Japanese and was the name borne by an ocean-going imperial yacht and a submarine tender during the Imperial Japanese Navy. The Taigei class submarines all incorporate “Gei” (whale) into their names, following the “Shio” (tide) and “Ryu” (dragon) series seen in previous JMSDF submarines. “Taigei” itself means “big whale.”
The new submarine, which cost about 69.9 billion yen ($473 million) to build, is powered by a diesel-electric engine generating 6,000 hp. It has a maximum speed underwater of 20 knots.
The JMSDF said that the Taigei-class boat is all equipped with lithium-ion batteries in place of lead-acid ones, just like the final two Soryu-class boats for the JMSDF: Oryu (SS 511) and Toryu(SS 512).
GS Yuasa, a Kyoto-based developer and manufacturer of battery systems, provided the lithium-ion batteries for those new submarines. So far Japan is the only country known to have fitted lithium-ion batteries into SSKs, with South Korea expected to be the next country to do so with the second batch of KSS-III (also known as Dosan Ahn Chang-ho)-class submarines sometime in the late 2020s.
The new Taigei class employs a “compact” and “highly efficient” electricity storage and supply system that extends the submarine’s endurance under water without the need to increase the size of the boats, according to the Japanese Ministry of Defense (MoD).
The class also employs a new combat management system (CMS) combining advanced integrated sensors, command-and-control, and weapon engagement systems, the MoD said.
In addition, it adopts an enhanced snorkel system to reduce signatures, and a new-generation sonar system based on fiber-optic array technology to enhance detection capability.
The Taigei class employs the same torpedo counter-measures system that has been incorporated into the last four Soryu-class boats. It uses Japan’s newest torpedo, which is called the Type 18, succeeding the previous Type 89. Initially referred to as “G-RX6,” the new torpedo will feature improvements in a number of areas, including propulsion, target detection, and processing.
The class is also capable of deploying the UGM-84L Harpoon Block II anti-ship missile against surface targets. This missile range is 248 km – enough for Japan to acquire a “counterattack capability,” which has been still under hot debate in Tokyo.
In May 2015, the U.S. Department of State approved the possible sale of those submarine-launched missiles to Japan. The deal was estimated to be worth $199 million at the time. The Japanese government had requested 48 UGM-84L Block II missiles to supplement the JMSDF’s existing capability of UGM-84C and RGM-84C Harpoon missiles, the U.S. Defense Security Cooperation Agency said.
The lead submarine of the Taigei class, named Taigei (SS 513), was commissioned in March 2022. The second of the class, named Hakugei (SS 514), was commissioned in March 2023. The fourth of the class, named Raigei, was launched by Kawasaki Heavy Industries (KHI) in October 2023 and is expected to enter service in March 2025. Hakugei means “white whale” while Raigei means “thunder whale.”
The MoD has allocated funds for the construction of four more submarines of the class – SS 517, SS 518, SS 519 and SS 520 – with MHI building the first and third submarine, and KHI the second and the fourth.
The JMSDF has not officially decided on how many submarines of the Taigei class will be built. But considering that the fact that the JMSDF had built approximately 10 submarines of every class so far, it is likely that the total number of Taigei-class submarines will be around the same level. In other words, the MoD and the JMSDF will likely stick to the current pace of replacement for the aging Oyashio-class submarines.
Under the nation’s current Defense Buildup Program (FY2023 to FY2027), approved by the government in December 2022, the 11th Taigei-class submarine will likely be built as the last of the class during FY2027.
Most recently, on December 22, 2023, the Ministry of Defense in Tokyo secured 95 billion yen for fiscal year (FY) 2024 starting April to build the eighth SSK, or SS 520, of the class.
The construction of the next class of submarine will likely start based on the following FY2028 budget. That means the Defense Ministry and the JMSDF must begin serious consideration of the next generation submarine now.
Taigei-class and the new security environment
Looking at the security environment surrounding Japan, China and Russia are increasing their nuclear submarine forces. North Korea is also aiming to acquire nuclear submarines equipped with cruise missiles with a range of more than 1,500 km that can reach the Japanese archipelago. As the possibility of a Taiwan Strait emergency becomes increasingly real, the operational missions and sea areas that the JMSDF’s submarines can take on are expanding.
In such a stern security situation, the development of the new class submarine must be in line with Defense Buildup Program, which calls for acquiring counterstrike capabilities, entailing the possibility of attacking enemy territory.
The Defense Buildup Program specifically states, “To gain underwater supremacy, MSDF will develop a submarine (SS) equipped with Vertical Launching System (VLS) with the aim of acquiring stand-off missiles carrying submarines.”
More than a few military experts in Tokyo have pointed out that it is difficult for the Taigei-class to carry the VLS because of its relatively small hull size and limited power supply compared to nuclear submarines, although new high-powered diesel engines and related equipment are being installed from the fourth Taigei-class ship.
To build a new submarine with a vertical launcher capable of launching long-range missiles from underwater, it is essential that Japan’s new submarine hulls will be larger than now and secure additional power supply capacity.
In addition, it is also inevitable that Japan’s new submarine will need to carry next-generation high-powered sonar and various underwater unmanned vehicles (UUVs), all of which will require a larger amount of power than now.
When asked about the requirements for the next submarine by Naval News, Admiral Sakai Ryo, chief of staff of the JMSDF, answered as follows at a press conference on March 6:
“That’s definitely something we have to consider in the future. There will be submarines equipped with the vertical launching system (VLS) that can launch Tomahawk missiles. We recognize that future consideration has to be given to how to differentiate between conventional submarines and submarines that have the ability to launch counterattacks by launching missiles. I cannot provide any further details.”
Admiral Sakai Ryo
