The ITTC78 method was originally designed for conventional single screw ships, but has later been modified to adapt twin screw ships and podded propulsors. Nowadays even more unconvensional propulsors are introduced, and the need for a new powering performance method is increasing. This thesis covers the load varying self propulsion method, and looks into how this corresponds to the standard ITTC78 method. The load varying method uses data from a self propusion test only, and uses a predefined increment value to change the revolutions during each run. In this way there are no need for an open water test or a resistance test, and time can be saved. In addition the vessel is tested as a unit, and not broken down into separate pieces like with the ITTC78 method.