Researchers in motion link with China

Western Australian based researchers are collaborating with the Marine Design & Research Institute of China (MARIC) to examine ship motion behaviour in volatile weather conditions. Curtin University?s Centre for Marine Science and Technology is employing computer modelling to develop more advanced theories to predict heave, pitch and roll motions in rough seas. Chief investigator Dr Jinzhu Xia says he aims to complete a computer program by June 2002 to provide an accurate and efficient tool for motion calculation and control in ship design, installation of onboard systems and operation in the marine and offshore industries. “Specific emphasis will be placed on prediction of ship motions in rough seas, where excessive sea loads may lead to structural damage and severe motion stability problems as there is still a great need to better understand the mechanics of ship capsizes and to limit maritime disasters,” Xia says. Xia says unlike previous linear theories, the new research will place particular emphasis on modelling of the coupled heave, pitch and roll motions. Quite often roll motion is treated as a single degree of freedom (DOF) dynamic problem, whereas heave and pitch are solved in a coupled two DOF system, Xia says. The coupling effects between roll, heave and pitch are very important when a ship is oscillating in large-amplitude oblique waves, particularly when the lateral symmetry of the underwater part of the hull is lost, he adds. “Excessive roll motion increases the probability of seasickness of the crew, reduces the operability of the onboard systems and in the worst case, causes capsize of the vessel,” Xia concludes. Dr Sheming Fan of MARIC has joined the research programme to bring the benefits of technology transfer and wider exposure to the international market.