Rolls-Royce upgrades ‘Norwegian Epic’ propulsion

NCL is the first cruise customer for Rolls-Royce’s permanent magnet technology, which the supplier says offers a 25% increase in power output compared to the same propeller using traditional thrusters. Noise and vibration are also reduced.

The permanent magnet tunnel thruster comprises a permanent magnet motor in a rim, which drives the propeller. The motor consists of a stator carrying electrical coil windings and a rotor fitted with strong permanent magnets. The stator creates a rotating magnetic field which interacts with the fields of the permanent magnets on the rotor, generating force to drag the rotor around.

The thruster is also removable underwater, removing the need for dry docking. Other benefits include free space above the thruster where traditional tunnel thruster motors are located, and a symmetrical design that gives equal thrust to port or starboard. It is available in 1600mm and 2000mm diameter.

Jay McFadyen, senior vice president – marine services, Americas, Rolls-Royce said: “Passenger comfort is a top priority for cruise lines, and the reduction of both noise and vibration is of paramount importance to successful cruise operators like NCL.”

The company noted that the first operation of the permanent magnet tunnel thruster, on the Rolls-Royce designed offshore anchor handling vessel Olympic Octopus, showed that the thruster is capable of running for thousands of hours in intensive dynamic positioning mode.