Japan commissions second Taigei-class diesel-electric attack submarine.

The second of Japan’s Taigei-class diesel-electric attack submarines (SSKs) has been commissioned into service with the Japan Maritime Self-Defense Force (JMSDF).

Christened JS Hakugei (pennant number SS 514), the new ship joined Escort Division 1 of Escort Flotilla 1, based at the Kure naval base in Hiroshima prefecture, shortly after to be handed over by shipbuilder Kawasaki Heavy Industries (KHI) at a ceremony held at its facility in the city of Kobe, in Japan’s western Hyogo prefecture, on March 20.

Hakugei translates to “white whale” in Japanese. Following the “Shio” (tide) and “Ryu” (dragon) series seen on prior JMSDF submarines, all Taigei-class submarines integrate “Gei” (whale) into their names. The very name “Taigei” translates to “huge whale.”

According to the JMSDF, the new submarine has a crew of about 70, a length overall of 84 meters, a beam of 9.1 m, a draft of 10.4 m, and a standard displacement of about 3,000 tons. It is slightly larger than the previous well-known Soryu-class SSKs, which are 84m long, 9.1m wide, 10.3m draft, and have a standard displacement of 2,950 tons.

The new submarine has a diesel-electric engine producing 6,000 hp and costs roughly 71.7 billion yen ($548 million) to build.

Japan’s security environment is becoming increasingly tense. Regarding submarines, China and Russia are increasing their nuclear submarine forces, and North Korea also aspires to possess nuclear submarines. 

Since it lacks nuclear submarines despite having exceptional cruising and diving capabilities, Japan must now focus on developing its conventional submarine fleet to meet this formidable threat.

As part of these efforts, the JMSDF began installing lithium-ion batteries instead of conventional lead-acid ones, starting with the Soryu 11 and 12-class submarines. The most recent submarines of the Taigei class were built from the ground up to use lithium-ion batteries.

Lithium-ion batteries have more than twice the energy density of lead-acid batteries. According to Ridzwan Rahmat, a senior defense analyst at military publisher Janes, this allows submarines to stay underwater longer than lead-acid ones. The increased resistance underwater makes the ships more difficult to detect and will expand the range of operations the JMSDF can carry out.

In addition to conventional submarine warfare, the vessels can be deployed closer to enemy shores to carry out reconnaissance missions or land special forces personnel.

These new submarines’ lithium-ion batteries were supplied by GS Yuasa, a Kyoto-based inventor and manufacturer of battery systems. Lithium-ion batteries have only been seen in SSK in Japan so far. Submarines of the KSS-III class are next on the list, and South Korea is slated to be the country to commission them (also known as Dosan Ahn Chang-ho).

The first Taigei-class submarine, named Taigei (with the flag number SS 513), entered service in March 2022. The third submarine of the Taigei-class, the Jingei (SS 515), was launched by Mitsubishi Heavy Industries (MHI) in October 2022 and is scheduled to enter service in March 2024. Jingei translates as “quick whale.”

The Japanese Ministry of Defense has allotted funds for the construction of four further submarines of this class, designated SS 516, SS 517, SS 518, and SS 519, with KHI constructing the first and third and MHI the second and fourth.

Most recently, on December 23, 2022, the Japanese Defense Ministry allotted 80,8 billion yen for the fiscal year beginning in April 2023 to construct the seventh ship of the class.

Japan’s Defense Strengthening Program, approved by the government in mid-December last year, states: “To achieve submarine supremacy, the MSDF will develop a submarine (SS) equipped with a Vertical Launch System (VLS) to acquire stand-off missile-carrying submarines.

To achieve this, new high-power diesel engines and related equipment are expected to be installed, starting with the fourth Taigei-class ship. It is becoming increasingly important to secure additional power supply capacity for the Taigei class to carry the VLS.

Furthermore, the hulls of the new Japanese submarines will inevitably be larger from now on as a result of mounting not only the VLS but also carrying state-of-the-art high-powered sonars and various unmanned underwater vehicles (UUVs).