Netherlands Advances Uncrewed Sonar Vessel for New Anti-Submarine Warfare Frigates.

Thales announced on August 3, 2026, that Dutch Naval Design has entered the design phase for a 12-meter uncrewed surface vessel that will operate from the Royal Netherlands Navy’s future Anti-Submarine Warfare frigates, expanding their ability to detect and track submarines far beyond the reach of the ships’ organic sonar. The new platform will provide each frigate with a persistent off-board active sonar capability, extending underwater surveillance while reducing reliance on NH90 helicopters for prolonged anti-submarine missions.

The program builds on a 2024 agreement between the Dutch Materiel and IT Command (COMMIT) and Dutch Naval Design, a consortium led by Damen Naval with MARIN and DEMCON. Once fielded, the uncrewed vessel will strengthen the Netherlands’ shift toward autonomous naval operations, enhancing fleet survivability and anti-submarine warfare effectiveness as part of a broader maritime modernization effort.

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The Royal Netherlands Navy's future anti-submarine warfare frigates will deploy a 12-metre uncrewed surface vessel equipped with active sonar, extending submarine detection beyond the ship and its NH90 helicopter (Picture source: Dutch MoD).

The most detailed public engineering baseline predates the latest design phase but establishes the parameters Dutch planners are working from. COMMIT’s initial concept measured 11.2 metres long and 2.5 metres wide, displaced 9.2 tonnes and was capped at 10 tonnes including fuel and payload. Requirements called for at least 96 hours of endurance, with half the operating cycle allocated to transit and half to stationary sonar work, a sprint speed of 20 knots in Sea State 5, and launch and recovery in the same conditions. The active dipping sonar was positioned in a central moonpool to reduce the effect of pitch and roll and protect the transducer during transit. Redundant propulsion was also required so that a single engine failure would not leave the craft unrecoverable. No torpedo, missile, or gun has been announced for the vessel; on the available evidence, it is a sensor carrier rather than an armed combat craft.

The proposed “sprint-and-dip” method has a specific tactical purpose. At 20 knots, the vessel could reposition 10 nautical miles in 30 minutes, stop, lower its sonar below a local temperature layer and search from a new acoustic location. A 96-hour sortie theoretically provides about 48 hours of stationary sonar operation, although actual output will be reduced by weather, maintenance checks, obstacle avoidance and transit back to the frigate. Separating the transmitter from the frigate also permits bistatic or multistatic operations: the uncrewed vessel can transmit while receivers aboard the frigate, helicopter or allied ships listen for echoes from different bearings. This complicates submarine evasion, but it does not make detection automatic. Performance will still depend on water depth, salinity, seabed composition, ambient shipping noise and the submarine’s speed and acoustic signature. Active transmissions will reveal the sonar vessel’s approximate position, while interrupted data links could delay classification or force it to operate under pre-programmed rules.

The vessel is intended to work as one element of a larger underwater-warfare chain. Each frigate will carry a hull-mounted sonar, a Low-Frequency Active Passive Sonar with variable depth, and equipment for receiving sonobuoy data. Its embarked NH90 can deploy sonobuoys, use the HELRAS dipping sonar, and attack with the Mk 54 lightweight torpedo. The Mk 54 has a diameter of 324 millimetres, weighs approximately 275 kilograms, and carries a 45-kilogram high-explosive warhead. The Netherlands has not announced a vertical-launch anti-submarine missile for the frigates, so a contact detected at substantial distance would normally require the NH90 to deliver the torpedo or the frigate to close within ship-launched torpedo range. This is an important limitation: the uncrewed vessel expands the detection area, but the helicopter remains the principal means of converting a distant contact into an attack.

The frigates themselves are 145 metres long, 18 metres wide and draw 5.5 metres, with a displacement of about 6,400 tonnes and a core crew of 117. Hybrid diesel-electric propulsion is intended to reduce radiated machinery noise during submarine searches; electric motors can support low-noise operation, while diesel engines provide power for transit without the gas turbines used in many high-speed frigates. The hull size also accommodates the uncrewed vessel, an NH90 hangar, underwater decoys and future equipment margins. Damen will build parts of the hulls in Romania before completion and combat-system installation in Vlissingen. The schedule change to 2033 indicates that accommodating these systems has required more redesign than expected, particularly to restore growth allowance for later weapons and sensors.

Above water, the armament is structured primarily for self-defence while the frigate conducts submarine searches. ESSM Block 2 missiles will be launched from Mk 41 vertical cells and controlled through Thales APAR Block 2 and SM400 Block 2 radars. The RIM-162K missile is 3.83 metres long, weighs 306 kilograms, carries a 37-kilogram warhead, reaches approximately 4,500 kilometres per hour and has a stated range of up to 45 kilometres; its active and semi-active radar seeker reduces dependence on continuous shipboard illumination. Short-range defence will include Rolling Airframe Missiles and a Leonardo 76/62 Sovraponte gun capable of 120 rounds per minute, with 80 ready rounds and a 16-kilometre maximum range using standard ammunition. DART guided projectiles add a radio-frequency-commanded option against manoeuvring missiles, aircraft and small surface craft. Kongsberg Naval Strike Missiles provide engagement of ships and selected land targets at more than 300 kilometres, while Mk 54 torpedoes provide the frigate’s direct anti-submarine weapon. The uncrewed vessel therefore changes the sensor geometry and contact-persistence problem, not the frigate’s weapon inventory; its military value will be determined by sonar performance, communications resilience and whether a 10-tonne craft can be launched and recovered reliably in North Atlantic conditions.

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