The operating modes for the tug or the workboat decide the fuel and emmission reductions which can be expected. A harbor tug is used for a large variety of tasks with various speed and bollard pull. Depending on the vessels operating pattern, considerable fuel savings can be achieved. In some cases fuel savings up to a level of 40-50% may be obtained with marine hybrid gear drives.
The classic operating modes for a harbor tug is; stop-harbor, idle/standby, transit, with loads from low, medium and up to full load. A study of operations over time will indicate the vessels operating profile.