[Source/Observer Network Mountain Cat]

According to reports by Japanese media last week, a public relations magazine issued in the first quarter of this year by the South Kanto Regional Defense Bureau (the regional defense bureaus of Japan can be somewhat understood as provincial military regions) revealed that the Japan Maritime Self-Defense Force's first batch of new patrol ships (referred to as "sentinel ships" in Japanese) had already begun construction this year.

The magazine mentioned that on February 14th this year, the Ishikosho Shipyard of "Japan Marine United Corporation" (JMU) located in Yokohama City, Kanagawa Prefecture, held a steel cutting ceremony for the first four patrol ships. The lead ship is expected to begin segmented assembly in the dock in June, followed by the second ship also entering the dock for construction; the two ships are expected to be launched as early as November this year. Subsequently, the third and fourth ships will enter the dock for final assembly, with plans to be launched in March 2026, and all four ships are expected to be completed and delivered before March 2027.

Steel cutting ceremony for the new maritime self-defense patrol ships

As mentioned in the article above, these patrol ships are a new type of vessel recently introduced into the Japan Maritime Self-Defense Force. They first appeared in the "Defense Guidelines for the Heisei 31st Year" released at the end of 2018 and the "Mid-Term Defense Force Development Plan (2018-2023)." In the original plan, a total of 12 "sentinel ships" were to be built, with the first batch of 4 ships constructed during the period from 2018 to 2023.

When the defense guidelines were released at the end of 2018, relevant Japanese sources revealed that the "sentinel ships" mentioned in the guidelines were precisely the next-generation base patrol forces of the Maritime Self-Defense Force. After the reform of surface warship formations in March 2008, only six Haya-class missile boats were assigned to each of the five major bases (Yokosuka, Sasebo, Kure, Ominato), with two boats assigned to each base. These missile boats were tasked with near-sea patrols and even the tracking and monitoring of foreign vessels around Japan. This was not entirely suitable for the original design purpose and operational conditions of the missile boats. As the frequency and intensity of countries around the region passing through the first island chain into the Pacific increased, the main force fleet of the Maritime Self-Defense Force struggled to cope, and the older second-line escort ships were increasingly unable to handle the heavy workload, especially with the small tonnage of the missile boats stationed at the bases.

Using small missile boats for near-sea patrols and long-distance tracking and surveillance is not ideal. Above is the Haya-class missile boat PG-827 "Bear Eagle" of the Maritime Self-Defense Force.

Therefore, Japan needs larger displacement, longer endurance, and better living conditions for lightly armed vessels to replace the current missile boats for patrol duties, and they must have high levels of automation to adapt to Japan's declining birthrate and difficulties in recruiting for the Self-Defense Forces. Thus, the "sentinel ships" were born. According to requirements, they will also have some redundancy space to mount modularized anti-submarine and anti-ship combat equipment when necessary. During this time, some shipbuilding companies in Japan also proposed several light patrol ship designs or models, which were generally considered as bids for the "sentinel ship" projects or their derivative export versions.

Several patrol ship designs unveiled by various companies in Japan during this period.

Later, this plan was delayed and re-released in late 2022, scheduled for implementation from 2023 to 2028, where the first batch of 4 ships would be built, with the total number still set at 12, requiring procurement within 10 years. Subsequently, in the defense budget for 2023, a total of 35.7 billion yen was allocated for the construction of these 4 ships, with an estimated cost of approximately 8.925 billion yen per ship (converted to RMB at the exchange rate at the time of the budget announcement, approximately 462 million yuan). The ship type was defined as OPV (offshore patrol vessel), or offshore patrol vessel. Since 2023 is the fifth year of the Reiwa era according to the Japanese calendar, these 4 ships are also called 05OPVs.

Schematic diagram of the new patrol ship construction proposal by JMU.

According to media reports, this type of patrol ship is approximately 95 meters long, with a displacement of 1920 tons, using "autonomous navigation technology" to save manpower on board, reducing the crew size to 30 people, which is one-third of the scale of the similarly automated Mogami-class multi-purpose frigates. The armament has been kept at a lower level to meet basic needs, and it is currently known that a 30mm caliber cannon (presumably the US-made 30mm Mk44 "Bushmaster" cannon, which is commonly equipped on large and medium patrol ships of the Maritime Security Agency) will be installed. Additionally, the Ministry of Defense allocated 4 billion yen in the 2025 budget to equip the new patrol ships with 6 V-BAT vertical take-off and landing fixed-wing drones purchased from the United States, further enhancing their sea surveillance and intelligence gathering capabilities.

The Self-Defense Force hopes to expand the sea surveillance capability of the new patrol ships through shipborne drones.

For now, the advancement and implementation of the Japan Maritime Self-Defense Force's new patrol ship project will completely replace the Haya-class missile boats with poor working conditions at sea. Although their direct combat capability is not strong, the doubling of their quantity may free up the larger and medium-sized main combat ships of the maritime self-defense force from routine tracking, surveillance, and near-sea patrol tasks, objectively improving the operational efficiency and flexibility of their main combat units. With the recent announcement of the naval surface force restructuring by the Maritime Self-Defense Force, Japan will have more favorable conditions for achieving the mechanization and field deployment of its main naval forces. These developments warrant continued attention.

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Original source: https://www.toutiao.com/article/7493482772774781476/

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