Toward a hybrid model of ship performance in ice suitable for route planning purpose

Abstract

Practical knowledge about the performance of a ship while navigating in ice is crucial for the selection of safe and efficient route for a ship. Existing route finding tools estimate ship performance in ice adopting numerous approaches, ranging from model tests and engineering models to experts-based guidelines. Therein ship performance is usually understood as attainable ship speed or the average speed in given ice conditions; rarely the probability of besetting in ice is taken into account. Those models despite being fairly accurate in the theory share the same shortcoming in practice. The latter encompasses three main issues: (1) inaccurate information about prevailing ice conditions, (2) presence of ice conditions that goes beyond the scope of the models, and (3) the effect of operational patterns and traffic organization on the performance of an individual ship. To approach those issues, we propose a hybrid model of ship performance in ice-covered waters. The hybrid model combines two other sub-models: engineering and data-driven. The former determines ship speed and besetting probability in ridged ice field with ice concentration close to 100%. The latter sub-model provides information on ship's speed in the actual ice conditions, where the speed is affected also by operational restrictions and icebreaker assistance. It is based on an extensive dataset combining ship data from automatic identification system and ice data from ice charts and ice forecast models. The presented hybrid model is valid for a specific ship type, which is ice going bulk carrier (IA Super ice class), operating within the Northern Baltic Sea winter navigation system. The obtained results reveal that the hybrid model in principle is capable of providing reliable information about the performance of a ship in a wide range of conditions accounting for environmental variability and existing operational conditions. The model is suitable for the purpose of safe route planning in ice for a single ship or group of similar ships, accounting for the economy and safety of a voyage.

Estimating the Speed of Ice-Going Ships by Integrating SAR Imagery and Ship Data from an Automatic Identification System

“…The presence of ice modifies both the traffic patterns and risks, but also introduces traffic system features that are not present in open water conditions-especially icebreaker assistance and speed reduction and besetting due to ice conditions. AIS data have been used to assess the winter navigation system [16], navigation risks [21], icebreakers and convoy operations [22], ship ice performance [23,24], ice resistance modeling [25] and route selection [26].…”

Hybrid Causal Logic Model for Estimating the Probability of an Icebreaker–Ship Collision in an Ice Channel During an Escort Operation Along the Northeast Passage

“…In the Arctic, icebreakers and ships frequently encounter thick firstyear and/or multiyear ice and ice ridges (Montewka et al, 2018). A harsh ice environment results in the icebreaker decreasing its speed substantially or stopping.…”

Multi-ship following operation in ice-covered waters with consideration of inter-ship communication

“…First, the regression analysis of big data set comprising ice thickness and resultant navigation speed is performed ( Montewka et al, 2019;Montewka et al, 2015). The former is obtained from numerical sea ice model called HELMI (Haapala et al, 2005;Lehtiranta et al, 2012), while the latter is a dataset recorded through the Automatic Identification System (AIS) for a period from 1 st to 12 th of March 2011 in the Northern Baltic Sea transportation system.…”