Electric Ferry Wins Ship of the Year

Ferry owner Norled and Fjellstrand Yard have won the prestigious "Ship of the Year" industry award presented in Hamburg last week for the world's first battery driven car ferry – ZeroCat 120.

Rolls-Royce contributes to the innovative ZeroCat 120 ferry with optimized Azipull thrusters and hull design and hydrodynamics, based on advanced analysis.

An important factor in the development of the ferry was to provide a propulsion system with the lowest possible energy consumption during fjord crossings, and at the same time ensure safe and efficient low speed maneuvering when operating near piers. The propulsion system is a key element in lowering energy requirements, enabling a reasonably sized battery pack to be installed onboard. To achieve high energy efficiency, the system from Rolls-Royce has a low propeller rotation rate, propeller blades with high aspect ratio and a low blade area, as well as a slender thruster body. The battery technology and electrical systems are provided by Siemens.

The vessel has one thuster at each end of the catamaran's hulls. The Azipull 085 thrusters are the first to have a propeller that can be adjusted to a fully feathering position. This means that the four propeller blades on the front Azipull thruster (which are not in use during the crossing) are adjusted to an angle that minimises resistance from the water flow. Hydraulic steering of thrusters has been replaced by electric steering to further reduce energy consumption.

Leif Vartdal, Rolls-Royce, section head for hydrodynamics, said: "An efficient propeller has a large diameter that rotates at a low speed to turn engine power into thrust in an effective way. In this case we have achieved this because the Azipull units have a high torque transmitting capacity for the given power of the propulsion motors. The hull design also allows for a larger propeller diameter than usually found in a double ended ferry. The result is better propulsion efficiency and less power drained from the batteries."

Norled's new ferry is expected to enter operation on a fjord crossing on the Norwegian West Coast in 2015, and will produce no local emissions. ZeroCat 120 has space for 120 cars and up to 360 passengers.