Following extensive trials of the first prototype tunnel thrusters, including installation on the anchor handling vessel Olympic Octopus, the first rim-drive azimuth thruster was introduced in 2015 onboard the Norwegian research vessel RV Gunnerus, representing a significant leap forward in marine propulsion.
Since then, the technology has evolved into a versatile offering available in both tunnel (RD-TT) and azimuth (RD-AZ) configurations, for a wide range of vessel types including offshore support vessels and cruise ships, and dynamic positioning platforms.
The rim-drive thrusters offer high-efficiency, low-noise operation, achieved through a direct electric drive with a permanent magnet motor integrated into the propeller rim. This design eliminates the need for a vertical drive shaft and gearbox, reducing mechanical complexity and underwater radiated noise, an increasingly critical factor in sustainable marine operations.
Per Håvard Siljan Hjukse, Executive Vice President Propulsion & Handling at Kongsberg Maritime, said: “This milestone reflects our commitment to delivering future-ready propulsion solutions that support the maritime industry’s transition to cleaner, quieter, and more environmentally conscious operations. Ten years on, the rim-drive thruster is a proven, high-end technology that continues to evolve in line with the requirements of our customers.”
The azimuth (RD-AZ) variant features hydrodynamically optimised supporting struts and a patented open-flow design that allows water to pass between the supports, reducing drag and enhancing manoeuvrability.
Gunnar Johnsen, Technology Manager at Kongsberg Maritime, adds: “In addition to the efficiency of the rim-drive technology, the thruster design eliminates the vertical drive shaft found in conventional designs. For the azimuth models, this allows for a unique strut configuration that improves water flow and reduces resistance. This patented feature gives less nozzle drag and improves operational performance.”