ABSTRACT A field test program was carried out with the CCGS Terry Fox off the coast of Newfoundland in June 2001. An area in the port bow of the ship was instrumented with strain gauges to measure local ice pressures. The ship impacted bergy bits of various sizes at a range of ship speeds and ice impact pressures on the bow were measured. Of the 178 impacts during the test program, 116 impact events were suitable for analysis. The bergy bit sizes ranged from 30 t to 22,000 t, and ship speed from 0.2 to 6.5 m/s. The highest pressure recorded on an area of 0.33 m2 was 5.8 MPa. Average pressure decreased with "design" area, as found in other studies. Higher pressures tended to be associated with higher impact velocities. Pressure increased with bergy bit mass for masses up to ones equivalent to that of the Terry Fox.
INTRODUCTION Studies have been carried out to measure local ice pressures from ships transiting sea ice; for example USCGC Polar Sea (St. John and Daley, 1984 and the CCGS Louis S. St. Laurent (Ritch et al., 1999). Until the project described here, no programs had specifically addressed determining the local or global loads associated with impacting glacial ice. A test program to impact icebergs was considered too hazardous, but using a ship with a very strong and robust hull structure to impact bergy bits (ice mass up to 1500 t) and growlers (ice mass up to150 t) was seen as being feasible. A field test program using the CCGS Terry Fox was put together. It took several years to gather the necessary financial resources, secure permission to use the ship, design and build test instrumentation, and plan the test program itself.