The presence of sea ice significantly complicates shipping in the Northern part of the Baltic Sea. Moreover, the temporal and spatial variation of ice parameters makes it less predictable, hindering transportation reliability and sustainability.
Finland has more than 150 years’ experience of winter navigation. Winter navigation principles are defined as part of the Finnish-Swedish Winter Navigation System (FSWNS), maintaining safe and efficient year-round navigation. The system consists of three elements: ice-strengthened ships, icebreaker assistance, and traffic restrictions. The traffic restrictions ensure that only ships with some minimum size and ice class will get icebreaker assistance on the winter period and the harder the ice conditions the stricter will be the traffic restrictions. This is to guarantee that the icebreaker fleet is capable of offering the service required with minimum waiting time for the merchant vessels. Specifically, to make sure that ships have enough ice-going capability for safe and efficient operations, they must be built and operated following the Finnish–Swedish Ice Class Rules.
Climate change will affect future ice conditions, so the maximum ice extent and average ice thickness is decreasing. At the same time, climate change can result in more stormy winds and waves, increasing ice movements. This makes the ice more dynamic, results in a higher possibility of forming ridged ice, and makes the ice conditions more spatially heterogeneous and less predictable. Furthermore, the active development of offshore wind farms in the Baltic Sea will affect the system behavior and operational ice conditions of ships. Moreover, offshore wind farms require assistance from specialized vessels, which produce additional non-typical ship traffic affecting the winter navigation system.
The size of a typical ship is growing in the future, and the new strict environmental regulations will decrease the engine power installed on ships. The International Maritime Organization (IMO) together with EU have adopted a number of new regulations to increase the energy efficiency of ships and to decrease dramatically the amount of greenhouse gases (GHGs) emitted by ships. Although their goal is to target GHG emissions, they also limit the maximum installed propulsion power of conventional oil-powered ships and favor open-water optimized hull forms due to their technical content. This will decrease the ice-going capabilities of these ships dramatically and can result in higher demand for icebreaker assistance.
Therefore, developing system-level simulation tools that study such factors is essential to understand and reliably predict future trends. Considering the importance of supporting the interannual maritime transportation of goods and passengers, we need decision-support tools to improve the performance of winter navigation and icebreaking assistance in the Baltic Sea. Such tools analyze the performance of winter navigation systems under potential operating scenarios, e.g., different ship traffic, icebreaking assistance, ice conditions, and regulations.
The results of the analysis can identify the bottlenecks of the winter navigation system regarding different key performance indicators (KPIs, e.g., the total waiting time, emissions, cost, and safety) and propose potential solutions contributing to efficient decision-making. Thus, the expertise of a decision-maker complemented by the capabilities of the winter navigation simulation tools may result in more efficient and sustainable maritime transport systems.
Over the last decades, a number of studies have contributed to the topic at hand by modeling the system-level performance of winter navigation. The latest development include a system level digital twin to simulate the system level performance of the winter navigation, developed by Aalto University together with Taltech, Estonian Maritime Academy. Specifically, novel algorithms have been developed to model the dynamics of the icebreaker resource availability, optimize icebreaker allocation, and study how changing the dirways affects FSWNS efficiency. Icebreaker scheduling involves determining the number of icebreakers available each day, their initial positions, and their designated operational areas. Additionally, mathematical modeling is employed at the ship level to capture individual vessel interactions with ice conditions and their impact on overall traffic flow. Vessel speeds under different ice conditions, such as convoys and towing, are calculated using closed-form expressions.
The tool can be used in future to predict the need for icebreakers and to plan their operation policies when ice conditions, maritime traffic, and characteristics of ice-strengthened ships will be under dynamic change and stricter environmental regulations will also affect both ice-breakers and ice-going ships.
Pentti Kujala
Professor (emeritus)
Aalto University
Finland
Professor
Taltech
Estonian Maritime Academy
Estonia
pentti.kujala@taltech.ee
