VESSEL REVIEW | Long-endurance USV to enhance US Navy’s surveillance capabilities

US Naval Forces Central Command (NAVCENT), the US Navy command whose area of responsibility also encompasses the Middle East, has begun operating a new unmanned surface vessel (USV) as part of an initiative to integrate modern unmanned systems and artificial intelligence (AI) into the activities of the US Fifth Fleet.

NAVCENT began operating the USV, which was developed by California-based unmanned systems manufacturer Saildrone. The craft has a length of 23 feet (seven metres), a height of 16 feet (4.8 metres), a draught of six feet (two metres), a wind-driven propulsion system, and an array of onboard sensors all powered by solar energy. As with the other USVs in the Saildrone product range, the NAVCENT USV can travel at an average speed of between two and six knots under wind power and can reach most ocean locations within 30 days from the closest shore and cover large survey areas.

The unmanned craft's patented propulsion system consists of a tall, hard wing, a longitudinal spar, and a vertical tail. A trim tab on the tail adjusts the wing angle to the wind, similar to the way an elevator trim tab controls the pitch of an aircraft. The wing technology will enable mission durations of up to 12 months without the need to return to land for maintenance or refueling, making the USV ideal for extended surveillance missions in international waters.

The reliance on wind and solar energy also mean the USV will generate significantly reduced noise and vibrations compared to traditionally manned surveillance craft. Besides ensuring the accuracy of the data gathered by the many onboard sensors, the quieter operation minimises any adverse impact that the craft's activities may have on the surrounding marine environment.

For safety purposes, the USV operates under the constant supervision of a human pilot via a satellite link. The craft will navigate autonomously from one prescribed waypoint to another, accounting for wind and currents, while staying within a user-defined safety corridor. The vessel can also operate under extreme weather conditions such as hurricanes, guaranteeing adequate data collection is done without putting human crews at risk.

To further ensure safe operations, the USV is equipped with an AIS transceiver, navigation lights, a radar reflector, and four onboard cameras to provide the human operators with clear, real-time views of the vessel itself and its surroundings. Also installed is an advanced acoustic and camera system. When combined with Saildrone's proprietary onboard machine learning algorithm, the system fuses sensor data to deliver significantly expanded information to combatant commanders requiring fresh intelligence on areas of interest in the open sea.

Task Force 59, NAVCENT's dedicated staff for new unmanned systems and AI discovery, initiated operational testing of the Saildrone USV off the coast of Bahrain one month after trials in the Gulf of Aqaba off Jordan. During the earlier trials in December 2021, the USV successfully operated at sea continuously for more than 30 days, demonstrating what navy officials claimed is persistence in a dynamic maritime environment.