Modeling of Brash Ice Channel and Tests with Model CCGS Terry Fox

Abstract

When an ice-going vessel navigates in the Baltic Sea, it normally follows a channel that has been made by previous ships or icebreakers. The channel is filled with broken ice pieces and repeated traffic makes the size of the ice pieces smaller. The typical size of the broken ice pieces is less than 2 m (Mellor, 1980), and the upper part of the channel can be frozen forming a consolidated layer. This is called a brash ice channel. In the Baltic Sea, a large demand for ice-going vessels is expected because of the transport of oil and gas from Russia to Europe. In order to design or assess the overall performance of a vessel transiting brash ice, model tests are essential, and appropriate brash ice modeling techniques play an important role in the success of the model tests. This paper proposes a methodology for producing a brash ice channel in an ice tank for model tests. The targeted ice class was the Finnish-Swedish Ice Class Rules (FSICR, 2005) class 1B, with 46-mm-thick brash ice at model scale (1 m at full scale). The basic concept behind producing the brash ice channel was the dumping of pre-broken ice pieces along the tank. The effects of the size of the broken ice pieces and the number of layers were taken into account. The test results suggest that an appropriate modeling of brash ice resistance requires at least 2 layers of ice pieces.