ON THE TRANSIENT RESPONSE OF A FLOATING ICE COVER TO AN ADVANCING SHIP
P. Valanto, Hamburg Ship Model Basin HSVA, Germany
ABSTRACT
Model tests on the icebreaking process were carried out in three dimensions for verification and further development of the mathematical model on the transient response of a floating ice sheet to an advancing ship model, which is under development by the author. Two bow forms were tested: (1) a Simplified Waas-Bow; (2) a Simplified Round Bow. Icebreaking forces at the design waterline on the bows of the models were measured with one and two measuring segments, simultaneously with the measurement of the transient deflection of the ice sheet m space fixed coordinates in front of the advancing model. Detailed information on the icebreaking process in model ice was 0 acquired.
PRELIMINARY INVESTIGATIONS INTO MOORING FORCES ON A SEMISUBMERSIBLE AND A TURRET MOORED TANKER IN PACK ICE, CURRENT AND WAVES
J. J. Murray, Institute for Marine Dynamics, National Research Council Canada, St. John's, Newfoundland, Canada, Al B 3T5
D. Spencer, MaRE, Torbay, Newfoundland, Canada, A I K I E4
ABSTRACT
Physical model tests were carried out on a scale model of a semisubmersible and a monohull tanker in drifting pack ice. The tests covered a range of drift velocities, directions and ice concentrations. The models were tested in both a fully restrained and moored condition. Data from the experiments were used to develop a semi-empirical numerical model to predict maximum global loads on the mooring system. These results were compared with the maximum loads on the mooring system caused by hydrodynamic forces (waves and current) predicted from a linear numerical model for waves. Analysis results showed that the maximum mooring loads due to the pack ice on the semisubmersible were considerably higher than those caused by the hydrodynamic forces on the same vessel. Also, the maximum mooring loads due to pack ice on the tanker were close to the maximum mooring loads caused by the hydrodynamic forces. Maximum mooring loads related to pack ice forces were realized in ice concentrations of 10/10 coverage while for concentrations less than 6/10 coverage loads attributed to pack ice were negligible in comparison to the hydrodynamic forces. The paper also presents a number of recommendations, based on these findings, to improve the performance of both vessel types and to advance the general state-of-the-art for analysis procedures related to offshore vessel moored in pack ice.
