New approach to determine equivalent ice thickness for ships in dynamic compressive ice

Dynamic compressive ice is one of the most severe ice conditions which can lead ships to be stuck in the ice. In these cases, icebreaker assistances are needed to release the ships which complicate the traffic and lower traffic efficiency, adding additional economic and environmental costs. This paper investigates these situations by first reviewing current best practices and approaches to assess the compressive conditions for ships. Based on potential gaps, this paper aims to utilize a new model developed for ships in dynamic compressive ice to simulate performances of different types of ships by considering both no compressive ice situation and different compressive situations. In this way, various data are obtained and h-v curves for ships in normal level ice and dynamic compressive ice can be obtained. By comparing the relationships between the normal level ice and dynamic compressive ice h-v curves, an equivalent ice thickness can be determined, which is practically useful for system level winter navigation simulation and decision making. In addition, new features of h-v curves for ships in dynamic compressive ice are investigated and discussed.