COOPERATION Torsional vibrations are a constant problem in propulsion and auxiliary machineries on board ships. The system has to be carefully studied in order to prevent any failure that could lead to economic or even human disaster. The role of the classification societies is to ensure that all equipment has vibratory levels within the manufacturer’s and regulations’ limits. It is therefore necessary to keep pace with technical progress and to take new technological components and their characteristics precisely into account. A technical solution based on the requirements of Bureau Veritas has been developed by the German company ITI and integrated into SimulationX.