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 (∼ 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.