A voyage-level ship performance modelling approach for the simulation of the Finnish-Swedish winter navigation system

The Finnish-Swedish winter navigation system plays an essential role in logistics to the ports surrounded by frozen sea in winter. Coordination of icebreakers is crucial to guarantee sufficient transit speed of merchant ships and minimize the waiting time. Simulation of the winter navigation system provides the opportunity to optimize the system performance and help the planning of future icebreaker fleets. For simulation, estimation of ship performance, such as the actual speed in ice, is essential. Calculation methods to estimate ship performance in such contexts are typically required to be of simple form without the need for heavy computation. Existing ship performance models embedded in route optimization algorithms and winter navigation simulations in the literature are often oversimplified. This paper proposes a systematic ship performance modelling approach which accounts for a wide range of parameters, such as ice condition and parameters, power variation and icebreaker assistance. The approach is validated against real ship voyages. The proposed approach is implemented into a simulation model which simulates the operation of merchant ships and icebreakers on the Baltic Sea. Analyses are conducted on the system level in terms of the waiting time of merchant ships needed for icebreakers as well as the energy consumption.