# Simulation Tool for Winter Navigation Decision Support in the Baltic Sea
###### Abstract  
This article presents a novel simulation tool for the analysis of winter navigation operations in the Baltic Sea in the context of the Finnish-Swedish Winter Navigation System (FSWNS). The aim of the tool is to simulate the performance of the FSWNS under various potential future operating scenarios and thereby support decision making in matters affecting the operation and development of the FSWNS, for instance, in terms of icebreaking resources and ice class regulations. To this end, the tool considers key performance factors and characteristics of the FSWNS, such as the prevailing ice conditions, the ice-going capability and other technical characteristics of the relevant merchant vessels, the availability of icebreaking resources, and the features of specific icebreaking operations (e.g., convoys). The tool would allow testing of several \"what-if\" scenarios, answering questions related to optimal engine power for safe, efficient, and environmentally friendly navigation and the optimal scheduling of icebreakers for effective and cost-efficient assistance missions. winter navigation; ice-class ships; icebreakers; maritime transport; discrete-event simulation; agent-based simulation; Baltic Sea +
Footnote †: journal: Applied  
0000-0001-5000-0001-5000]Cited: [PERSON]  
[PERSON]  
In areas with frequent ship traffic, such as the Baltic Sea, icebreakers typically create and maintain a network of ice channels, often referred to as dirways ('directed ways'). Dirways are routes defined by the icebreaking authority in the form of waypoints along which ships are advised to operate. Due to variations in prevailing wind and ice conditions, dirways are updated frequently, often at 2-14-day intervals [8]. To reduce the amount of Green House Gasses (GHGs) emitted by ships, in 2011 the IMO adopted its Energy Efficiency Design Index (EEDI) regulations [9]. These regulations aim to reduce the amount of GHGs from ships by promoting the use of highly energy-efficient solutions. Although the regulations target GHG emissions only, due to their technical content, they in effect limit the maximum installed propulsion power of conventional oil-powered ships and favor open water optimized hull forms Other upcoming maritime emissions limiting IMO and EU regulations have similar effect on merchant vessels. As a result, the average ice-going capability and attainable speed in ice conditions of ice-class ships may decrease. This in turn may result in an increased demand for icebreaker assistance, resulting in prolonged waiting times for icebreaker assistance. Prolonged icebreaker waiting times may have an adverse impact on the overall cost and energy efficiency of the FSWNS. The aim of this study was to develop and validate a simulation tool that would make it possible to simulate the performance of the FSWNS under various potential future operating scenarios and thereby support decision making in matters affecting the operation and development of the FSWNS, for instance, in terms of icebreaking resources and ice class regulations. To this end, a simulation tool is outlined that mimics winter traffic flows in varying operating conditions, incorporating factors such as icebreaker scheduling and airway changes. Icebreaker scheduling involves deciding on the number of icebreakers to be made available on any given day, their starting positions, and the assignment of operating regions for each of them. Along with simulation modelling at transport system level, mathematical modelling is used at ship level, to capture the effect of individual vessels' interactions with the prevailing ice conditions and the resulting impact on the overall traffic flows. Through closed form expressions, vessel speed has been calculated for various ice conditions and situations, such as convoys and towing. The proposed tool will allow users to test and analyze how the FSWNS performs in any number of hypothetical (what-if) scenarios, providing an enhanced understanding of the behavior of the system.