Analysis of data from bergy bit impacts using a novel hull-mounted external Impact Panel

A new Impact Panel has been used to measure forces and pressures during collisions of a ship (CCGS Terry Fox) with bergy bits and a small iceberg. Data were acquired from impacts on bergy bits of various sizes (100-22,000 tonnes) and over a range of ship speeds (5-12 kt). The data indicate that a typical zone of ice contact during a collision is comprised of a small irregular shaped area of relatively intact ice, where the pressure is high (8-20 MPa) and roughly uniform, that is usually surrounded by a larger area of pulverized ice, where the pressure is low (similar to 2.5 MPa). The maximum estimated force measured was around 2.4 MN. The relatively low force values were attributed to the slanted shape of the impacted hull resulting in a glancing/sliding type of impact with limited ice penetration. Duration of impacts was in the 0.2-0.6 s range. Pressure on the hard zones was observed to increase as the hard zone area increased. (c) 2007 Elsevier B.V. All rights reserved.