Submarines

UK Unveils ‘Herne’, An Extra Large Autonomous Submarine — XLAUV

45 days duration at depths of up to 3,000 metres, this is a serious multi-mission boat

The development of Extra Large Autonomous Underwater Vehicles (XLAUVs) is a significant evolution in submarine technology. These uncrewed platforms are engineered to perform a range of complex tasks beneath the surface without human intervention, thereby extending the operational reach of navies.

And Herne is the UK’s new XLAUV.

A collaborative project between BAE Systems and Canadian company Cellula Robotics, Herne has been designed as a modular and adaptable platform to provide naval forces with an enhanced capability for extended missions. This vehicle’s development, physical characteristics, and strategic purpose position it as a key asset in modern naval operations, particularly in the domain of seabed warfare and surveillance.

The Herne project proceeded from concept to in-water demonstration with a rapid development timeline. Commencing engineering work in September 2023, the collaboration between BAE Systems and Cellula Robotics produced a functional demonstrator within eleven months.

This accelerated schedule was facilitated by the partnership, which combined Cellula Robotics’ commercial platform expertise with BAE Systems’ military knowledge and its Nautomate autonomous control system.

The schedule was also influenced, I’m sure, buy the emerging threat of Russian sabotage to underwater infrastructure around the UK and the Baltic Sea, including critical telecoms cables, power cables, oil and gas pipelines.

[embed]Spyship Yantar: A Curious Cruise Round European Undersea Infrastructure and a Russian Wreck Up to no good wherever it ismedium.com

Initial trials

The initial trials, which took place off the south coast of England, focused on intelligence, surveillance, and reconnaissance (ISR) missions. These trials demonstrated the vehicle’s capacity for covert sub-surface harbour entry and autonomous navigation, demonstrating its ability to operate independently and identify targets.

Three software plug-ins were demonstrated during the course of the ISR vignette: goal-based mission autonomy (enabling Herne to autonomously re-route to avoid a number of drag net hazards); machine vision (processing high definition camera imagery to classify ships by type); and track-and-follow (exploiting the camera feed to shadow a rigid inflatable boat ‘target’). — Naval News

Construction

Physically, Herne is a platform constructed around a lightweight aluminium frame, measuring 12 metres in length and displacing between eight to ten tonnes, contingent on its payload and power configuration. The vehicle’s modular design is a core feature, allowing for mission-specific reconfiguration. It fits inside a standard 2TEU — a 40 foot shipping container.

Engineering a submarine is far simpler when human life support is not required, and the pressure hull size can be minimised to protect the essentials of power, propulsion and control systems.

It includes two modular payload bays, each with a 2,500-litre capacity, which can be combined into a single 5,000-litre bay for larger equipment. This design enables a rapid payload swap-out, which can be completed in approximately ninety minutes. This payload can include mines and offensive materiel.

Power is currently provided by Lithium-ion batteries, which offer an endurance of several days at 3 knots. However, the design also accommodates future integration of hydrogen fuel cell technology, which is projected to extend its submerged range to approximately 5,000 kilometres and 45 days duration.

The propulsion system consists of two independent electric motors, achieving a sprint speed of eight knots and a cruising speed of three knots, while its depth rating extends to 5,000 metres — deep enough to survey almost all the lengths of transoceanic comms cables. The propellers are clearly visible in the picture.

I has two cargo holds totalling 5 cubic metres. They can be combined for larger format payloads.

Observations

If you look closely at the image you will see lateral and vertical thruster tubes at the stern and the bow for precise position holding. The X rudder design is interesting and suggests that the vessel can run inclined or even run upside-down — not generally a feature of manned submarines but useful when working under a structure or another vessel when the ‘sail’ and mast superstructure would normally be a hindrance.

Herne XLUAV on the blocks. Pic: BAESystems

The ‘sail’ appears to shield a grappling arm, probably hydraulic or possibly electrically driven (visible in headline photo).

It’s about the same length as the Royal Navy’s ‘Excalibur’ unmanned submarine announced some months ago, but designed for a different purpose.

Royal Navy ‘Excalibur’ unmanned submarine prototype. Photo: UK MoD.

Missions

Herne is intended to fulfil a range of strategic roles in the maritime environment. Its primary purpose is to provide a persistent presence in areas of interest, conducting tasks that would otherwise place crewed platforms or personnel at risk.

The vehicle’s ability to operate for extended periods without surfacing makes it a suitable platform for intelligence gathering, surveillance, and reconnaissance. It can also be configured for anti-submarine warfare, the protection of critical national infrastructure such as subsea cables, and mine countermeasures — let’s not forget its cargo-carrying capacity.

The system’s autonomy, managed by the Nautomate control system, allows it to execute complex missions and adapt its route autonomously. This reduces the reliance on human crews for routine or hazardous tasks, allowing skilled personnel to focus on higher-level operations. Herne’s design also incorporates a low acoustic signature, which supports its use in covert operations.

We don’t know how it communicates with its operators say for changes in mission profile or recovery instructions. This could be via an acoustic channel (short range) from a nearby mothership or perhaps using a dipped buoy from a helicopter, or radio via a surface float aerial raised at pre-programmed intervals. It is unlikely to use the low bandwidth VLF system that UK nuclear submarines utilise.

Conclusions

In conclusion, Herne is a forward-looking approach to underwater capability. The vehicle’s modular architecture, long-endurance potential, and capacity to host a variety of payloads provide a flexible asset for a range of defence and security roles.

Its rapid development timeline points up a successful partnership integration structure for bringing new technologies to market.

The ongoing trials and future integration of hydrogen fuel cell technology will further refine its operational parameters. The Herne XLAUV is a clear example of how autonomous systems are being integrated to enhance the effectiveness and efficiency of naval forces.

The Royal Navy’s Excalibur was designed as a testbed for new technologies in XLUUB operations, whereas Herne is designed to deliver, very soon.

https://www.baesystems.com/en/product/herne--xlauv

[embed]BAE Systems surfaces autonomous submarine for military use Battery powered now, fuel-cells tomorrow - all packed in a shipping boxwww.theregister.com

www.navalnews.com/naval-news/2024/11/more-details-on-uks-herne-xlauv-demonstrations/

[embed]UK's first autonomous submarine evolves BAE Systems and Canadian firm Cellula Robotics have extended their collaboration on Herne, signing a ten-year exclusive…ukdefencejournal.org.uk

[embed]VESSEL REVIEW | Herne - Unmanned submarine built for seabed warfare and surveillance missions A team of engineers based in Portsmouth in the UK has successfully demonstrated a new type of autonomous submarine…www.bairdmaritime.com

https://www.royalnavy.mod.uk/news/2025/may/15/20250515-uncrewed-submarine-naming-ceremony

https://www.baesystems.com/en/product/nautomate