According to Naval News, named Niyodo, the Mogami-class vessel (pennant number FFM-7) entered the water during a ceremony held on September 26 at the company’s Nagasaki Shipyard & Machinery Works in Nagasaki Prefecture. It is expected to enter Japan Maritime Self-Defense Force (JMSDF) service sometime in fiscal year 2024 after the fitting out stage of the frigate and a variety of performance tests.
The vessel is named after the Niyodo River, a river in the Shikoku region of southwestern Japan. All ships of the class are named after famous rivers in Japan. There was another JMSDF ship with the same name, which is JDS Niyodo (DE-221), or the seventh Chikugo-class ship. JDS Niyodo (DE-221) was launched in August 1973 and decommissioned in June 1999.
JS Niyodo (FFM-7) is being built for about 47.4 billion yen ($318 million) under a contract awarded in March 2022, according to info obtained from the JMSDF and Mitsubishi Heavy Industries (MHI).
Mogami-class specifications and systems
As with the other ships of the class, Niyodo has a full load displacement of about 5,500 tons (a standard displacement of 3,900 tons), with a length of 132.5 meters/434.7 feet, a beam of 16.3 meters/53.5 feet, a hull draught of 9 meters/29.5 feet, according to MHI. This compact hull makes it fast and maneuverable, with a top speed of more than 30 knots/34.5 mph/55.5 kph.
The Mogami-class frigate has a low crew complement of about 90 sailors (out of whom 10 are female), indicating a high level of automation on board.
The JMSDF has repeatedly emphasized that the Mogami-class is the first JMSDF vessels aimed at saving manpower and reducing ship construction costs, taking into consideration the JMSDF’s manpower shortage and Japan’s tight finances being caused by the declining birthrate and aging population.
For reference, the JMSDF’s Asahi-class destroyer JS Shiranui (DD-120), built at the same shipyard in Nagasaki, has a standard displacement of 5,100 tons, a length of 151 meters/495.4 feet, and a beam of 18.3 meters/60 feet, all of which clearly show how compact the FFM hull is. In addition, the Asahi-class has a crew complement of about 230, meaning the Mogami-class requires less than half the manpower to operate. On top of this, the construction cost of the Mogami-class is only about two-thirds of that of the Asahi-class, which costs more than 70 billion yen per ship ($470 million).
The Mogami-class is powered by a COMbined Diesel And Gas (CODAG) propulsion system featuring two MAN 12V28/33D STC diesel engines and one Rolls-Royce MT30 gas turbine, which provide a total of 70,000 horsepower/51.5 MW. The Mogami class marks the first installment of a CODAG system on any JMSDF ship.
Armaments on the frigates include a BAE Systems 5-inch (127-mm)/62-caliber naval gun on the foredeck of the ship, two launchers for a total of eight MHI Type 17 anti-ship missiles, also known as the SSM-2, and a Raytheon 11-cell SeaRAM Close-In Weapon System (CIWS) that can deploy RIM-116C Block 2 Rolling Airframe Missiles (RAMs).
The frigates are also equipped with the OQQ-25 variable depth sonar and towed array sonar systems for Anti-Submarine Warfare (ASW) operations. The ships will also be equipped with a MK41 Vertical Launch System (VLS).
Mogami-class as a Mothership
Besides anti-air, anti-surface and ASW capabilities, the Mogami-class has also been designed to undertake operations as a «mother ship» for an Unmanned Underwater Vehicle (UUV) and an Unmanned Surface Vehicle (USV), both of which will see the first installment on any Japanese frigate ever. This aims to enhance the UUV’s Mine CounterMeasure (MCM) functions.
ATLA has said that the Mogami-class will be equipped with MHI’s OZZ-5 used for MCM operations as a UUV.
The system serves an automatic detection and classification function to alleviate operator workload in processing collected data.
The OZZ-5 UUV, which measures 4 meters/13.1 feet long and 0.5 meter/1.64 foot wide with a displacement of 950 kg/1094 lbs., is equipped with Japan’s NEC-made low-frequency Synthetic Aperture Sonar (SAS) and France’s Thales-made high-frequency SAS combinedly, which is designed to ensure a robust MCM capability for the detection and classification of different mine threats in a range of environments.
The UUV is powered by a lithium-ion rechargeable battery.
According to the JMSDF, the Mogami-class is intended for surveillance missions in waters surrounding the Japanese archipelago, including the East China Sea. It will be equipped with enhanced multirole capabilities, including the ability to conduct anti-mine warfare operations, which until recently had been mainly performed by the JMSDF’s ocean-going minesweepers.
As neighboring China expands the size and capabilities of its naval forces, the Mogami-class is intended for surveillance missions in waters surrounding the Japanese archipelago. In particular, the JMSDF plans to enhance maritime security to defend the southwestern Nansei Islands, including the Senkaku/Diaoyu Islands in the East China Sea, by boosting its patrol activities using compact FFM multi-mission frigates. The Senkaku/Diaoyu Islands are controlled by Japan but also claimed by China and Taiwan.
FFM program: What’s next?
The JMSDF had originally planned to build a total of 22 Mogami-class frigates as Tokyo ramps up efforts to strengthen the country’s naval forces under its Mid-Term Defense Program (MTDP) for fiscal years 2019-23, which was approved in December 2018.
However, in late August 2023, the defense ministry for the first time explained at its budget request for the next fiscal year 2024 that it has decided to now procure a total of only 12 such frigates until 2023, with plans to construct a new class of 12 FFMs from fiscal year 2024. The new frigates will be virtually improved Mogami-class ships.
The new-class FFM will be fitted with longer-range missiles, enhanced anti-submarine capabilities, and improved capabilities for various maritime operations.
Specifically, the ship-launched, improved version of the Type 12 SSM and the new Ship-to-Air guided Missile (or simply A-SAM) will be equipped with the new-class FFM, defense officials said.
The MoD documents, released by the Ministry of Defence (MoD) on August 31, said the new-class FFM has a standard displacement of 4,500 tons. Meanwhile, according to MHI’s proposal of the new-class FFM, which was officially released by the ATLA on August 25, the new warship class will feature a heavier standard displacement of about 4,880 tons, a greater overall length of about 142 meters/465.9 feet, and a wider overall beam of about 17 meters/55.8 feet. The new vessels have a top speed of more than 30 knots/34.5 mph/55.5 kph, according to MHI’s proposal. Despite the fact the new class will be bigger than Mogami-class, defense officials said the new class’s crew complement will be only 90, the same as that of the Mogami-class. To achieve this, Japanese naval planners have likely incorporated the new class with a higher level of automation and deployed extensive lean-manning concepts throughout the vessel.