Oceanus12 USV achieves several firsts during REPMUS

The Oceanus12 uncrewed surface vessel (USV) has achieved several firsts during this year’s REPMUS exercises off the coast of Portugal, according to a September 22 press release. In particular, the Oceanus12 deployed and recovered a towed acoustic array autonomously, a world first, according to the press release. 

“Until now, arrays were typically pre-deployed and clipped on or required manual crew handling during launch and recovery,” it states. Additionally, Oceanus12, which is built by British company Zero USV, has deployed on a daily basis. During those deployments, it has distributed G-sized sonobuoys using a system from Zero USV called the Sonor Integrated Launch (SOIL) system. Sonobuoys are used to provide a persistent sensor capability in a given area. They are a key element of anti-submarine warfare (ASW), and often deployed from aircraft. 

The Oceanus12 has now deployed sonobuoys multiple times, with total deployments “now into the teens,” which also is a key milestone in autonomous sensor delivery, the press release states. Moreover, the USV has been at sea for 40 operational hours, with 100% uptime. 

This element of the USV’s performance should be expected. The technology behind the Oceanus12 is a direct evolution of the knowledge and experience gained from the Mayflower Autonomous Ship (MAS400) project. Zero USV was founded by collaborators from the MAS400 effort, including Marine AI and MSubs. The Mayflower’s successful transatlantic autonomous voyage in 2022 was a key milestone, proving the capabilities of the same inter-company collaborations and the core autonomy software, which was developed by Marine AI. The Mayflower was able to autonomously navigate the Atlantic Ocean, indicating that high reliability is a significant element of the Zero USV approach. 

The towed array is understood to be from Optics11 in the Netherlands. The company has developed a sensor system called the OptiArray, which uses fibreoptics to measure acoustic, temperature, and pressure signals. This, the company states, is a more effective approach than traditional towed arrays. Calibre Defence recently interviewed SEA about the company’s KraitSense, which is a sonar towed array designed to be deployed from small vessels including USVs. It seems likely that using multiple sensor types would be the preferred method to detect a submarine, so the two could be complementary. 

Tech profile: Oceanus12

The Oceanus12 USV was developed over an 18-month period, with the first vessel being launched in early 2025. Zero USV’s business model is to offer the vessel for charter, making it the “world’s first charter fleet” of fully autonomous USVs. This approach aims to provide customers with a turnkey solution, including the vessel, maintenance, and support from a remote observation centre. The Oceanus12 is described as a fully autonomous USV, not a remotely controlled one. Its autonomy is powered by Marine AI’s GuardianAI software stack. This system integrates multiple data streams from a suite of sensors, including a high-definition radar, to enable real-time processing and decision-making. A core feature of its autonomy is the ability to operate safely and in compliance with COLREGs (International Regulations for Preventing Collisions at Sea) even without continuous connectivity. This “edge computing” model means the vessel can continue its mission and avoid other ships during communication outages.

• • Length: 11.55 m
  • Displacement: 6 tonnes
  • Beam: 2.33 m
  • Draught: 1.76 m
  • Propulsion: Hybrid-electric twin drive system. It’s designed to be quiet and efficient, with a low environmental impact.
  • Range:
    • Standard: 2,500+ nautical miles
    • XLR (Extra Long Range) version: 7,500+ nautical miles (with an increased length of 13 m and larger fuel capacity)
  • Speed:
    • Cruising: 6 knots
    • Sprint: 10 knots (subject to payload)

Calibre comment

REPMUS (Robotic Experimentation and Prototyping using Maritime Uncrewed Systems) is NATO’s largest annual exercise for uncrewed naval systems, hosted by the Portuguese Navy off the Tróia Peninsula and Setúbal Bay. It has led the way in helping to develop different use cases for USVs and LUUVs in the ASW role amongst other things. However, the pace of development has arguably been quite slow. The Allied Underwater Battlespace Mission Network project (AUWB-MN), which is intended to connect autonomous vessels using a common framework, was launched in 2021. However, it was only in 2025 that Saab and a consortium was selected to develop and deliver the AUWB-MN. Russian submarines are already a challenge for NATO and there are many hurdles to overcome to make autonomous vessels ready for widespread use and deployment. Hopefully, successful demonstrations will help NATO forces move more confidently and quickly towards deploying these capabilities at scale. 

By Sam Cranny-Evans, published on September 23, 2025. Credit for the lead images is Zero USV.