VESSEL REVIEW | USV Bris – Hybrid unmanned craft for water profiling in Norway's remote areas

Norwegian unmanned systems operator Nordic USV and UK-based maritime robotics company HydroSurv Unmanned Survey have entered into a 60-month lease agreement for an unmanned surface vehicle (USV).

The craft, named USV Bris, is purpose-built for low-emission hydrographic, geophysical, and oceanographic survey tasks, particularly in complex or remote nearshore environments.

“The craft marks a significant step forward in our portfolio of electric and hybrid USVs, being the first to incorporate rim-driven propulsion, a feature that enhances both operational efficiency and resilience in challenging nearshore environments,” David Hull, HydroSurv's Founder and CEO, told Baird Maritime.

Hull said the platform embodies a proven design and its lightweight aluminium hull builds on those of its predecessors, while a 48V hybrid-electric propulsion architecture and integrated vessel control system deliver a balance of performance, endurance, and economy for multi-mission operations.

Built for harsh environments

“It is the first of her series to be commissioned by Nordic USV for delivery this year,” said Hull. “It represents the industrialisation of capabilities matured on earlier USV builds.”

Hull explained that Nordic USV required a platform that was capable of autonomous, multi-day endurance sampling and observation operations from Bergen and other remote bases in Norway and that was capable of acquiring high-quality environmental and geophysical datasets in harsh, often ice-prone conditions.

The vessel’s autonomy, endurance and system reliability are central to reducing the logistical overhead and manual intervention required for data acquisition missions.

The vessel also needed to maintain operability during the extreme winter months, prompting the integration of advanced winterisation features including a battery module heating system to safeguard charge performance in sub-zero environments.

“A key operational requirement was deep water conductivity-temperature-depth profiling. To meet this, HydroSurv integrated a 1,500-metre OSIL profiling winch into USV, complete with an updated proprietary winch control application developed in-house.

"This represents a significant capability leap from Nordic USV’s earlier craft, USV Nordy, which was fitted with a 500-metre micro-profiling system.”

The OSIL winch is housed within a purpose-designed hull compartment. The winch control software has been rewritten by HydroSurv, permitting a suite of advanced features enabled by the new larger-class system.

“The OSIL winch control interface sets the stage for future integrations where the winch provides both power and comms through a single tether system. This creates a path toward more sophisticated subsea sensor deployments using common hardware and shared software.”

Electric drive for long-endurance missions

The newer USV also boasts greater endurance, being able to operate for up to 72 hours, as well as improved seakeeping and deeper profiling capability. This allows Nordic USV to scale its offshore environmental monitoring services with reduced operational burden and expanded data capabilities.

The craft is powered by two rim-driven electric thrusters from Rim Drive Technologies, configured in a counter-rotating setup with independent steering. This arrangement provides excellent low-speed control and minimises thruster saturation at transit speeds.

“Rim-driven thrusters offer operational advantages in shallow or weedy environments by eliminating exposed propeller hubs, reducing the risk of entanglement,” Hull told Baird Maritime. “This is a key benefit in the vessel’s nearshore and coastal deployment zones, where entanglement could immobilise a USV and cause severe damage.”

The propulsion system is powered by a 48VDC architecture supported by Mastervolt MLI Ultra 6,000Wh lithium-ion batteries. The onboard energy system is hybridised via a 4kW diesel generator and further supported by a remote charging and mooring latch located at the home pontoon, enabling fully automated recharge cycles.

“For operators seeking zero-emission solutions, HydroSurv will offer an all-electric variant with a 24kWh battery pack, paired with the mooring latch. This option is ideal for regular short-duration tasks in ports and inland waterways. Extensive field trials in the UK and Norway are scheduled throughout the summer of 2025 ahead of commercial rollout.”

USV Bris also has an advanced navigation suite integrating Furuno hardware with TimeZero marine navigation software that can also display real-time video from both EO/IR and navigation cameras. This will enable enhanced situational awareness for coastal deployment in challenging Nordic conditions.

Also fitted are a solid-state radar, a satellite compass, as class B AIS, a weather station, and a depth/speed log.

“The utility of the platform extends much further,” said Hull. “For example, the subsequent build nearing completion is being delivered with hull-mounted 3D side-scan sonar, a parametric sub-bottom profiler, and an upgrade option for towed magnetometer capability, allowing the vessel to be adaptable across a broad spectrum of survey missions.”

Improving upon earlier craft designs while ensuring compact construction

Hull said designing the USV centred on optimising the delicate trade-off between payload capacity, endurance and platform cost. At less than half the price of a larger HydroSurv USV, USV Bris required an elegant simplification of onboard systems while maintaining core survey capabilities.

“A major structural evolution from earlier modular builds was the adoption of a one-piece hull and superstructure. This increased internal stiffness and usable space, reduced overall mass and preserved the vessel’s compatibility with a 20-foot container footprint.

“While modularity remains a common request among operators, we observed that in practice, these features were rarely utilised, allowing us to streamline the vessel without compromising functionality.”

Additional challenges included designing for minimal maintenance intervention, given the vessel's remote area of operation. Hull said the early service life of the USV will inform technical modifications aimed at achieving monthly or less frequent maintenance cycles.

“As a first-of-class build, USV Bris underwent a rigorous commissioning phase that revealed several power integration nuances stemming from the system-wide voltage shift from 24 V to 48 V. These were resolved through the integration of additional opto-isolators and revised DC architecture.”

Accommodating the larger OSIL profiling winch in a compartment originally designed for a smaller system posed a challenge, though one resolved through moderate retrofits. Future hulls will feature structural redesigns to better accommodate similar sized winch payloads.

“Overall, though, build complexity was reduced compared to earlier models due to better space utilisation and cable routing improvements made during design.

"Supply chain delays (rather than technical issues), were the primary source of frustration during the build cycle – an observation echoed in the rapid delivery of the second build just weeks following the handover of USV Bris."

For HydroSurv, the tight build timeline and concurrent construction of subsequent hulls led to a rapid feedback loop between construction and design. Minor changes, such as improved hatch ergonomics and repositioned harness routing, were immediately adopted.

“Our continuous improvement approach ensures ongoing enhancements across all builds,” Hull told Baird Maritime. “Structural revisions, better cable management through integrated securing features, and hardware adjustments are now embedded into the second and third USVs in the series.”

Customer feedback has prompted additional upgrades for future deliveries, including increased fuel capacity, improved vision systems, and passive acoustic devices. From build five onwards, UK-flagged vessels will also be structurally aligned with the MCA's MGN 705 guidelines, which were published in December 2024.