An investigation of shaft line torsional vibration during ice impacts on PSRV's

In order to estimate the forces exerted on ship propellers during ice navigation, the rotational dynamics of the propulsion system need to be accurately modelled. The direct measurements of propeller loads of ships during ice navigation is challenged by the harsh operating environment. Indirect measurements are therefore performed on the shaft line of such ships to estimate propeller loads through an inverse problem. Three case studies are presented, namely open water, cavitation and ice navigation. The maximum torque loading on the shaft occurred during ice navigation and the maximum thrust case during cavitation. Ice-induced moments on the SAA II propeller were determined from shaft line measurements using inverse methods, whereby the maximum ice load was found to be 941 kNm. Estimated load profiles for navigation in the Arctic and Antarctica are presented using rainflow counting techniques. The aim of the present research was to perform data-driven modelling of the rotational dynamics of the shaft line to aid future design of ice going vessels.National Research Foundatio