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Rolls-Royce has revealed plans for an autonomous, single-role naval vessel with a range of 3,500 nautical miles.

The vessel concept is said to be capable of operating for over 100 days and reach speeds above 25 knots. The 60-metre-long vessel is designed to perform a range of single-role missions, such as patrol and surveillance, mine detection or fleet screening.

At the heart of the vessel is a robust power-dense propulsion system, which combines Rolls-Royce's expertise in both gas turbines and diesels with its track record in electric propulsion, energy storage and propulsors.

The initial design features a full electric propulsion system which requires fewer auxiliary systems (lubrication, cooling system etc.) and is said to offer better reliability levels than mechanical counterparts. It features two Rolls-Royce MTU 4000 Series gensets, providing around 4 megawatts (MW) of electrical power to a 1.5 MW propulsion drive.

An alternative to diesel engines could be small gas turbines, further improving the system's reliability and reducing onboard maintenance.

Permanent magnet (PM) Azipull thrusters together with a bow mounted tunnel thruster have been incorporated to make the vessel highly manoeuvrable. To reduce fuel consumption and extend operational range, an additional 3,000 kilowatt hours (kWh) of energy storage will facilitate efficient low-speed loiter operations and the vessel will also be fitted with photovoltaic solar panels to generate power when the vessel is on standby.

Rolls-Royce points out that the absence of crew increases the need for very reliable power and propulsion systems. The company's approach is to blend advanced intelligent asset management and system redundancy in a cost effective manner that avoids sacrificing the cost and volume savings achieved by removing the crew. A suite of autonomous support tools, developed by Rolls-Royce, such as Energy Management, Equipment Health Monitoring and predictive and remote maintenance, are designed to ensure the availability of unmanned vessels.

Many of the technologies needed to make autonomous ships a reality already exist. Rolls-Royce has created what it believes to be the world's first intelligent awareness system, combining multiple sensors with artificial intelligence to help commercial vessels operate more safely and efficiently.

Benjamin Thorp, Rolls-Royce, General Manager Naval Electrics, Automation and Control, said: "Rolls-Royce is seeing interest from major navies in autonomous, rather than remote-controlled, ships. Such ships offer a way to deliver increased operational capability, reduce the risk to crew and cut both operating and build costs.

"Over the next 10 years or so, Rolls-Royce expects to see the introduction of medium-sized unmanned platforms, particularly in leading navies, as the concept of mixed manned and unmanned fleets develops. With our experience and capabilities we expect to lead the field."

Image: Rolls-Royce autonomous vessel concept deploying drones.