First ship with Azimuth Rim Driven Thrusters enters commercial service

Caption: M/F Eiksund

Image credit: Sondre Kristoffer Mo

In Wärtsilä’s Yellow River scenarios for year 2030, a 1,312 ft (400 m) box carrier is shown powered by twin Rim Drive Thrusters (RDT). The Norwegian company Brunvoll has been developing just such a device since 2002 and following a successful development program, was chosen to pioneer a research and development project.

The M/F Eiksund, a RoRo car and passenger ferry of LOA 160 ft (49 m), beam 34.7 ft (10.6 m) and draft 10.2 ft (3.1 m) was built in 1970 and originally powered by a single Wichman 552 kW (750 hp) diesel engine with mechanical drive to two propellers.

She has been repowered with a new propulsion system consisting of two new diesel engines driving Permanent Magnet (PM) generators and two Brunvoll RDT1500 azimuth RDT which is the world’s first commercial application of this type of drive. Control and management of the generators and propulsion system is provided by Inpower, Norway.

The general benefits of the newer propulsion system are: reliability through redundancy from two independent propulsion systems, enhanced manoeuverability, more usable space due to better machinery locations, flexibility to meet different operating conditions in terms of load profile on the engines. The specific benefits of the RDT are system simplicity and associated reduction in investment and maintenance costs, optimal space utilization, improved propulsion efficiency with reduced exhaust emissions and lower  noise and vibration levels.

After completion of the refit, an extensive testing program verified the above benefits of the new propulsion system and in particular the lower power requirement and fuel consumption for comparable conditions with similar load distributions between the aft and forward propeller. Additionally, both course keeping stability and crash stop capability were described as being excellent.

Caption: One of the two Brunvoll RDT1500 azimuth rim driven thrusters installed at either end of the ferry.
Image credit: Brunvoll