New from Rolls-Royce: Permanent Magnet Azimuth Thruster
The most recent addition to Rolls-Royce’s marine thrusters range was unveiled at Nor-Shipping in Oslo earlier in June.
Powered by permanent magnet (PM) technology, the new azimuth thruster is Rolls-Royces’ latest development in PM technology, adding to a portfolio that already includes tunnel thrusters and a newly developed winch.
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 PM motor, meanwhile, consists of two main parts: a stator that carries a number of electrical coil windings, and a rotor fitted with a number of 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.
A sea trials program aboard Norwegian University of Science and Technology’s (NTNU) research ship RV Gunnerus in saw a pair of thrusters demonstrate efficiency savings of 7-13 percent, depending on ship speed, and in comparison to azimuth thrusters powered by a conventional diesel-electric system.
Helge Gjerde, Rolls-Royce, Senior Vice President for Propulsion - Commercial Marine, said sea trials results have exceeded expectations in terms of efficiency. “The sea trials are continuing,” Gjerde said, “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.”
According to Rolls-Royce, the new thruster offers more than improved fuel economy, with added benefits including reduced noise and vibration, more power through a propeller of the same diameter and scope to remove and maintain PM thrusters without the need for dry docking.
Rolls-Royce’s first commercial PM tunnel thruster is being operated by Norwegian offshore vessel operator Olympic Shipping. The tunnel thruster, now in use aboard 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, Rolls-Royce said.