Ice Resistance Assessment for a Large Size Vessel Running in a Narrow Ice Channel Behind an Icebreaker

Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers. This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions. Currently, new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers. At the same time, no mathematical description exists for the breaking mechanism of ice channel edges, when such vessels move under icebreaker escort. This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel; the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice. The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges. The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel. In general, proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system. The paper also discusses the ways for further refinement of the assessment procedure suggested.