VESSEL REFIT | Sentinel – Royal Australian Navy patrol boat converted into autonomous systems demonstrator

The Royal Australian Navy (RAN) has taken delivery of an autonomous surface vessel (ASV) as part of a broader project that seeks to expand the service's autonomous systems capability. PBAT Sentinel is the former Armidale-class patrol boat ex-HMAS Maitland, which was retired from RAN service in 2022 and was rebuilt under the Patrol Boat Autonomy Trial (PBAT) program.

Austal Australia, which was responsible for the conversion work on Sentinel as well as the earlier construction of the vessel itself, is also one of the collaborators in PBAT. The aim of the program is to establish robotic, automated, and autonomous elements on a patrol boat, providing a proof-of-concept demonstrator for optionally crewed or autonomous operations for the RAN into the future. The trial will also explore the legal, regulatory pathways and requirements of operating an autonomous vessel at sea.

Building upon a proven platform

Specifically, PBAT's objectives included significantly progressing the concept of remote operations and the autonomous certification approach; increasing the understanding of fuel management, communication, and navigation systems to be made autonomous; investigating and understanding the sustained operation of shipboard mechanical systems without crew intervention, including systems of redundancy and reliability to support operations at sea for extended periods; providing input to long-term risk reduction for future naval projects, considering remote or autonomous vessels; and transferring lessons learned on the application of remote or autonomous systems to the RAN's current fleet to potentially optimise crew workload.

Sentinel underwent its conversion at Austal's shipyard in Henderson, Western Australia. The modifications included the fitting of a variety of monitoring and control systems and technologies that enable autonomous and remote operations. There were also modifications incorporated to the bilges, CCTV, and electrical systems. Sensors and computer units were also added by Greenroom Robotics to inform and host an autonomous control system.

The vessel was then registered under the jurisdiction of the Australian Maritime Safety Authority (AMSA) as a domestic commercial vessel, thus allowing sea trials to commence. Austal said that, with an LOA of 57 metres (190 feet), Sentinel is the largest vessel in Australia to be operated remotely and autonomously.

Performance validated in recent trials

The rebuilt vessel's sea acceptance trials (SATs) were conducted off the coast of Western Australia in March and April of this year. The vessel undertook multiple remote controlled and autonomous (pre-programmed) navigation events, including various manoeuvres, station keeping, go/no-go operation testing, advanced collision avoidance, contact detection and radar tuning and vessel dynamics testing. With the vessel safely and successfully completing all of the objectives of the SATs, the PBAT team progressed to the next stage of the project, which was an endurance trial that tested the remote and autonomous capability of the vessel and systems in an extended voyage journey over several days.

The other collaborators in PBAT are the Trusted Autonomous Systems Defence Cooperative Research Centre, Greenroom Robotics, and the RAN's Warfare Innovation Navy (WIN) Branch. The project is co-funded by the Australian Government.