UK launches mass production of SG-1 Fathom naval drones to enhance British Navy undersea surveillance.

UK-based Helsing Resilience Factory has started mass production of the SG-1 Fathom autonomous underwater drone, according to information shared by the UK Ministry of Defence on 18 November, 025. The effort strengthens the British Royal Navy’s long-duration undersea surveillance network while advancing the UK’s sovereign defence manufacturing model.

UK-based Helsing Resilience Factory has started producing the SG-1 Fathom naval drone at scale, a move the UK Ministry of Defence says will expand the British Navy's ability to conduct persistent undersea surveillance in high-interest regions. Officials noted that the transition into steady output reflects confidence in the system’s endurance, low signature profile, and modular sensor suite.
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Engineers assemble SG-1 Fathom autonomous underwater gliders at a Helsing Resilience Factory in the UK, showcasing sovereign manufacturing of next-generation maritime surveillance systems for the British Royal Navy.  (Picture source: UK MoD)

At the heart of the SG-1 Fathom is a buoyancy-driven propulsion system that allows it to move silently through the water without conventional propellers. This unique mode of movement makes the platform exceptionally energy efficient and virtually undetectable by passive sonar, enabling it to remain submerged for up to 90 days. Its endurance and stealth characteristics make it ideally suited for intelligence gathering, subsea infrastructure monitoring, and maritime domain awareness operations across contested or sensitive waters.

For the British Royal Navy, the SG-1 introduces a new operational dimension. It provides the capability to quietly patrol deep underwater or remain stationary on the seabed, acting as a long-term sentinel without exposing valuable manned platforms. The glider’s compact form factor and modular architecture also allow for deployment and recovery by small crews from either naval vessels or commercial support ships. This flexibility enhances rapid launch options, reduces logistical demands, and supports wider mission scalability.

Beyond solo operations, the SG-1 Fathom was designed to operate in coordinated swarms. When deployed in groups, the gliders form an intelligent underwater network capable of sharing data, adapting routes, and collectively monitoring vast areas. This networked behaviour is powered by artificial intelligence developed by Helsing UK, enabling real-time onboard analysis and autonomous mission adjustment without constant communication with command units.

As adversarial submarine activity increases across the North Atlantic and concerns grow about the vulnerability of subsea energy and data infrastructure, the SG-1 provides the British Royal Navy with a discreet but powerful surveillance tool. It offers an asymmetric advantage by delivering persistent undersea awareness at relatively low cost, without escalating tensions or revealing high-value assets.

The decision to produce the SG-1 entirely within UK borders also reflects a deliberate move by the British MoD (Ministry of Defense) to insulate key defense capabilities from geopolitical disruption. The Helsing Resilience Factories, built to enable modular and distributed manufacturing, use additive production technologies, hardened digital engineering, and secure supply chains to guarantee continuity in times of crisis. The SG-1 is the first underwater platform to be scaled under this model and is expected to serve as a template for future unmanned systems.

In terms of configuration, the glider’s payload bay is highly adaptable. Depending on mission requirements, it can carry synthetic aperture sonar, environmental sensors, or passive acoustic arrays. Future upgrades may include underwater communication relays or electronic surveillance modules. The British Royal Navy has already initiated test deployments in the Hebridean Sea, evaluating both single-unit and swarm applications under operational conditions. Full operational capability is anticipated by the end of 2026.

Although no export agreements have been announced, defense sources indicate that other NATO partners have expressed interest in adopting or co-developing similar glider technologies. This interest stems from growing alliance-wide concern over subsea threats, particularly in the Arctic, Baltic, and Mediterranean theatres.

The SG-1 Fathom is more than a tactical asset. It reflects a broader strategic evolution in British maritime doctrine. As the British Royal Navy shifts toward a distributed, sensor-driven underwater force posture, unmanned platforms like the SG-1 will form the backbone of persistent surveillance, strategic deterrence, and infrastructure protection. In future high-stakes scenarios, these systems will ensure that the United Kingdom can see and respond beneath the waves without needing to be seen itself.


Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.