Oki Electric Industry has signed a supply contract with Mitsubishi Heavy Industries (MHI) to deliver towed passive sonar systems and related equipment for the Australian Government’s new fleet of general-purpose frigates.
The contract covers the first three vessels in a planned total of eleven ships. The electronic surveillance technology will be installed on the 06FFM, an improved Mogami-class frigate, which was selected by Australia as part of its General Purpose Frigate programme in August 2025.
Towed passive sonar technology is used to detect submarines and other underwater targets by capturing acoustic information from sensors towed behind a vessel.
The system, which features on existing Mogami-class frigates, was selected for Australia’s new ships based on its operational record. The contract marks OKI’s first overseas transfer of defence equipment.
OKI claims to have a history of more than 90 years in underwater acoustic research and product development.
The Japanese company has supplied sonar systems and related technologies for defence applications, including supplying the Japan Maritime Self-Defense Force. In these projects, OKI supports its sonar products across their full lifecycle, from initial design through to maintenance.
For the Australian contract, OKI will provide the same type of towed passive sonar and associated equipment as it currently supplies within Japan, leveraging its technological expertise and experience.
Following Australia’s decision to proceed with the upgraded Mogami-class design for its new frigate fleet, MHI began contract negotiations. In April 2026, MHI finalised an agreement with the Australian Government for the construction of the first three vessels.
The ships, built at MHI’s Nagasaki Shipyard & Machinery Works, are scheduled for delivery with the initial frigate expected to be handed over by December 2029. The construction project involves cooperation between the Australian and Japanese governments, as well as participating companies.
The 06FFM frigate, a 4,800-tonne variant of the original Mogami class, offers a range of up to 10,000 nautical miles. It will be equipped with a 32-cell Vertical Launch System and fitted with surface-to-air and anti-ship missiles.
The vessels will be crewed by 92 members of the Royal Australian Navy and are designed to operate the MH-60R Seahawk maritime combat helicopter.
In May 2026, Raytheon was awarded a contract by MHI to supply SeaRAM missile-based ship defence systems for the Australian general purpose frigate programme.
