OKI, Japan’s 90 year old underwater acoustic technology specialist, is exporting its passive sonar system for the first time. The system detects submarines using towed sensor arrays. The contract with Mitsubishi Heavy Industries covers sonar equipment for Australia’s new general purpose frigates.
OKI announced on 28 July 2026 that it has signed a formal supply contract with MHI for the delivery of towed passive sonar and associated equipment. The systems will be installed on the first three ships of Australia’s 11 vessel New General Purpose Frigate Programme.
06FFM Design and Sonar Integration
The Australian Government selected Japan’s FY2024 improved Mogami class frigate, the 06FFM, for its New General Purpose Frigate Programme in August 2025. The 06FFM will be equipped with OKI’s towed passive sonar and associated gear. The contract was signed based on the proven performance of these systems on Mogami class frigates. This agreement marks OKI’s first ever transfer of defence equipment overseas.
How the Sonar System Works
Towed passive sonar is a system that detects submarines and other underwater targets by receiving acoustic information through sensors towed behind a ship. OKI will supply towed passive sonar and associated equipment to Australia under the contract with MHI, drawing on its accumulated technology, expertise and proven track record.
90 Years of Underwater Acoustic Experience
OKI has been developing underwater acoustic technologies for over 90 years, primarily designing and producing underwater acoustic sensors and associated gear for defence applications. For sonar systems used by the Japan Maritime Self Defence Force, OKI provides comprehensive support throughout the product life cycle, from design to maintenance.
Under its Management Plan 2031, OKI has committed to focusing on and strengthening its business operations in the defence and ocean sectors, which the Japanese government has identified as priority areas in its growth strategy. To meet growing demand in the defence sector, OKI plans to expand production capacity, strengthen overhaul capabilities and contribute to maritime security both in Japan and internationally through this project.
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Source: C4Defence–OKI
