The presentation illustrates a case study what is helpful for turbine designers to get more component understanding during work out and comparison of different turbine concepts. Derived from existing wind turbines and upcoming tidal turbine, it indicates suitable rotor bearing concepts for a new geared turbine in the 1MW range. Basic engineering working steps from first load analysis to the selection of shaft, bearing, seal, coupling, gearbox, generator and lubricant are pictured. Explanation of specific rotor bearing selection criteria’s according different standards and further application specific needs are part of the presentation. Different turbine layouts are compared in different technical and commercial aspects. The aim of the presentation is to inform and share existing drive train knowledge, re-use and further improve it. The content of this presentation is derived from practical experience from various advanced tidal stream turbine projects in Europe, North America and Asia. SKF who is one of the global leaders in the bearing industry is engaged with most advanced tidal stream turbine manufacturers from the early prototype phase. This involves drive train design, engineering, manufacturing, as well as validation and testing.