RKB bearings for advanced yacht propulsion systems

Bearing applications in gearbox assemblies and shaftline couplings

In the luxury yacht segment, RKB has supported propulsion system installations involving articulated couplings between gearboxes and twin propulsion shafts. In one installation, RKB provided technical assistance for the mounting of GEP 500 spherical joints between gearboxes and twin propulsion shafts. The installation process involved dry ice cooling, temporarily reducing the joint diameter to achieve the interference fit required for assembly. Each gearbox in the system also incorporated a large-dimension 618/1000 bearing.

RKB has also supplied bearings for several large sailing yachts equipped with three-shaft propulsion configurations. These installations use tapered roller bearings and large-size rolling bearings integrated into gearbox assemblies designed for demanding marine applications.

Examples of bearings used in these propulsion systems include:

• 32028
• LL 788349/310
• LL 687949/9

These bearings are used in marine gearbox systems operating under high propulsion loads. Some large sailing yachts equipped with these propulsion systems also employ an advanced rotating mast sail configuration known as the DynaRig sailing system. This system uses freestanding rotating masts with rigid curved yards, allowing the sails to form a continuous aerodynamic surface when deployed. By rotating the entire mast structure, the sail angle can be optimized relative to the wind, improving propulsion efficiency while simplifying sail handling.

The system enables efficient sail management, reduces the need for large crews, and contributes to reduced fuel consumption. Modern implementations often incorporate large carbon-fibre masts and are used on some of the largest sailing yachts in operation today.