Increasing requirements to modern vessels concerningperformance and ma-noeuvrability led to very complex drivetrain designs. Therefore azimuthing thrusters became very common in the area of offshore supply vessels, tug boats and specialized research vessels. In order to extend the already huge field of operation and to better understand dynamic effects in such azimuthing thrusters the research project "EraNetHyDynPro" was started. The projectfocuses on the design of a robust drive train which contains a bevel gear stage. Therefore loads caused by propeller-water-interactions as well as loads while operating under ice conditions will be analysed. Based on this interdisci-plinary project a contemporary way of gear calculation will be shown in this paper. For gear calculation it is necessary to acquire design loads. These can be measured at high costs or be simulated numerically. In the last few years the Multi-Body-System (MBS) Simulation got more and more popular to determine static and dynamic properties of large drive trains. This simulation can containmathematical models of the propeller behaviourin side the water and under ice conditions as well as models of the electric motor. Based on this a good prediction of gearing loads is possible. By the knowledge of the gearing load time series a complextooth contact analysis can be made fore verya rbitrary point in time using specialized gearinoftware. Gear tilting are considered in order to calculate the load distribution on the tooth flanks. By this knowledge a local comparison of the load and load capacity can be carried out. But how to handle the vast variety of load situations duringdifferent load cases and long time series? Thereforean appropriate classificati on of the different occurring states of gear deviations and gear loads will be presented. This way weare able to determine the risk ofcommon gearing failures likepitting and tooth root breakages in detail for individual drive trains under dferent operating conditions. The paper will present the procedure of this contemporary way of designing gears. By using a simple spur gear set the general idea of simulating the operating conditions of a drive train and the subsequent complex tooth cont actanalyss will be explained. Onbasis of this information a suitable approach to assess the risk of different gearing failuresiscarried out and the results will be illustrated.