Recent trends in the marine industry toward smaller crew size, heightened public concern about marine safety, and changes in navigation have made Marine simulators a complete, realistic, and risk free-training environment suited for full-scale operational situations. Transas Tug Operator Trainer allows mariners to develop and demonstrate the skills needed to obtain or upgrade their mate/master towing license. From familiarization, standard operation, and watch-keeping to advanced operation, troubleshooting, and vessel resource management, this simulator is capable of training mariners for a full range of functions. Simulator training can be formalized into scenarios that are used for training and performance evaluations. Simulator-based training and assessment permit hands-on maneuvering in a realistic marine environment without interfering with the vessel's operation or exposing it to risk while underway. The integration of marine simulation into mariner training and assessment programs offers advantages and opportunities to improve human performance in real operating conditions.