OREANDA-NEWS. June 05, 2015. Rolls-Royce today unveiled the latest addition to its range of marine thrusters, with the launch of a new azimuth thruster powered by permanent magnet (PM) technology.

Launched at the Nor-Shipping maritime exhibition in Oslo, the new thruster is the Group’s latest development of PM technology, which already includes tunnel thrusters and a newly developed winch.

The launch follows a programme of sea trials in which a pair of thrusters demonstrated efficiency savings of 7-13% depending on ship speed, and in comparison to azimuth thrusters powered by a conventional diesel-electric system. The trials took place on board the RV Gunnerus, the Norwegian University of Science and Technology’s (NTNU) research ship, based in Trondheim.

Helge Gjerde, Rolls-Royce, Senior Vice President for Propulsion - Commercial Marine said: “Following a programme of successful sea trials, which exceed our expectations in terms of efficiency, we are delighted to broaden our range of permanent magnet technology with the launch of a new azimuth thruster.

“The sea trials are continuing but initial findings have significant implications for future ship sustainability in both the marine and offshore sectors, as PM thrusters become a valuable supplement to traditional thruster technology.”

Besides improved fuel economy, other benefits include more power through a propeller of the same diameter, reduced noise and vibration, and scope to remove and maintain PM thrusters without the need for a dry-docking.

The Gunnerus trials follow operation of Rolls-Royce’s first commercial permanent magnet tunnel thruster by Olympic Shipping, a Norwegian offshore vessel operator. The tunnel thruster, now in operation on board the Olympic Octopus, a multifunctional anchor-handling vessel (AHTS) of Rolls-Royce UT 712 L design, has clocked up more than 4,000 trouble-free running hours.

Each PM azimuth thruster comprises three main assemblies – the PM motor/propeller/nozzle underwater unit, the hull mounting system which includes the azimuth bearing and duplicate frequency controlled electric steering gear, and the inboard power unit which feeds electric power to the thruster.

The permanent magnet motor consists of two main parts – a stator that carries a number of electrical coil windings, and a rotor fitted with a number of very strong permanent magnets.

A rotating magnetic field is created by the stator which interacts with the fields of the permanent magnets on the rotor, which generates force to drag the rotor around, providing the mechanical power.