Icebreaker Assistance Research Articles

Advanced Human Reliability Analysis Approach for Ship Convoy Operations via a Model of IDAC and DBN: A Case from Ice-Covered Waters

The melting of Arctic ice has facilitated the successful navigation of merchant ships through the Arctic route, often requiring icebreakers for assistance. To reduce the risk of accidents between merchant vessels and icebreakers stemming from human errors during operations, this paper introduces an enhanced human reliability assessment approach. This method utilizes the Dynamic Bayesian Network (DBN) model, integrated with the information, decision, and action in crew context (IDAC) framework. First, a qualitative analysis of crew maneuvering behavior in scenarios involving a collision with the preceding vessel during icebreaker assistance is conducted using the IDAC model. Second, the D–S evidence theory and cloud models are integrated to process multi-source subjective data. Finally, the human error probability of crew members is quantified using the DBN. The research results indicate that during convoy operations, the maximum probability that the officer on watch (OOW) chooses an incorrect deceleration strategy is 8.259×10−2 and the collision probability is 4.129×10−3. Furthermore, this study also found that the factors of Team Effectiveness and Knowledge/Abilities during convoy operations have the greatest impact on collision occurrence. This research provides important guidance and recommendations for the safe navigation of merchant ships in the Arctic waters. By reducing human errors and adopting appropriate preventive measures, the risk of collisions between merchant ships and icebreakers can be significantly decreased.

A kinematic model for collaborative icebreaker convoy operations in ice-covered waters

Icebreaker assistance is a common yet intricate operation in ice-covered waters, frequently leading to collisions between ships and icebreakers. This underscores the need for advanced kinematic models to improve safety and coordination in convoy operations. Consequently, this paper introduces a kinematic model for guiding intelligent ships under icebreaker assistance. The model, grounded in the Traffic Factor State Network (TFSN), evaluates the safety state of a fleet in various ice conditions, using data from actual convoy operations. An enhanced Proportional Integral Derivative (PID) algorithm is integrated to formulate a multi-ship following model, which accounts for the kinematic characteristics of ships in ice. The model also incorporates the transmission process of ship maneuvering commands. Its validity is confirmed through application to two ships under icebreaker assistance. The findings show that the model effectively simulates safe speeds and maintains proper inter-ship distances over time, and it generates safe kinematic instructions for the fleet. This model may contribute to navigational safety in ice-covered waters and demonstrates the potential for inclusion in ice navigation support systems.

On the data-driven investigation of factors affecting the need for icebreaker assistance in ice-covered waters

Merchant vessels often require icebreaker (IB) assistance to create safe pathways and improve efficiency when navigating in the Baltic Sea. Since IB resources are limited, an accurate estimation on the need for IB assistance is important. Whether IB assistance is needed depends on multiple factors. While practical experience from captains is naturally a source of valuable information for the decision on the need for IB assistance, systematic analysis of the reasoning is limited. The primary aim of this paper is to holistically investigate the influencing factors and their effect on estimating the need for IB assistance through data-driven techniques. Based on a comprehensive list of potential factors, different of data such as traffic history, environmental conditions, and ship specifications are gathered to present complex navigational scenarios. Each scenario is labeled by different navigation modes (independent navigation or IB assistance), laying the foundation for influencing factor identification and effect quantification. Logistic regression is applied to evaluate the effect of the factors on the need for IB assistance. The results show that the impact of the factors is diverse, and ridged ice concentration has the most significant impact. The effectiveness of identified factors is measured by comparing it to that of the factors that have been implemented by the existing studies (e.g., the combination of ice concentration, thickness, and ship ice class, or only ship speed). By considering the factors in this study, the classification performance can be improved by at least 5.6%. The findings in this paper can provide insights for predicting IB workloads and optimizing IB resources and have the potential to support the development of an intelligent decision-support system for winter navigation.

Decarbonizing shipping in ice by intelligent icebreaking assistance: A case study of the Finnish-Swedish winter navigation system

Ice often complicates shipping in extremely cold regions, leading to energy-consuming, expensive transportation. Ship performance can be significantly improved with icebreaking assistance that uses specialized ships called icebreakers to create navigable pathways in ice fields. Icebreakers are a critical and expensive resource with high energy consumption that must be judiciously utilized for efficient traffic flow. Optimizing icebreaker usage requires careful consideration of multiple factors related to weather, ships, and regulations. The existing decision support tools for icebreaker management primarily aim to minimize the total waiting time of ships, which may result in allocation of excess icebreakers. The paper presents a novel simulation-based approach for decarbonizing shipping in ice by intelligent icebreaking assistance. The proposed approach optimizes icebreaker assistance for both eco- and cost efficiency, allowing for more sustainable icebreaking policies. A case study representing a simplified configuration of the Finnish-Swedish Winter Navigation System demonstrates this approach to come up with alternate operating strategies that can significantly improve the emission and/or cost (e.g., up to 7 percent less greenhouse gas emission or up to 14.2% lower costs). Results show that the proposed approach is promising, for providing recommendations on environmental and economic policies to decarbonize the Finnish-Swedish icebreaking assistance.

Analytic representation of the propeller thrust for modelling ship manoeuvring within an ice channel behind an icebreaker

Navigation of cargo ships using icebreaker assistance is a common tactic in difficult icy conditions. The icebreaker makes the ice channel and the lone cargo ship, or the convoy, sail within the channel it has made. When the icebreaker or the vessel ahead stop before the insuperable ice obstacle, the danger of an emergency appears, namely, the collision with an icebreaker or the ship ahead, if the interval between them is not sufficient for effective braking and stopping, or for a way out in compact ice cover. To find the safe interval recommendation, it is necessary to carry out modelling of the ship manoeuvring: either braking or the leaving of the channel. In these modes of ship movement, the propeller operates in unusual modes: in reverse mode when braking, and in close to mooring mode when leaving the channel, which do not have analytical descriptions because of the detached flow of the blades. This paper describes a developed empirical method for the parameterization of the propeller thrust coefficient dependence upon the advance, based on diagrams for the design of the propellers, which were created from the test material of the serial propeller tests. Outcomes of the investigation will be applied for computer modelling of the ship's manoeuvring within the ice channel and the safe interval between the ship and an icebreaker evaluation in what follows.

A data mining method for automatic identification and analysis of icebreaker assistance operation in ice-covered waters

Icebreaker assistance is a common but complex operation in ice-infested regions. Currently, the operational decision-making and the decisions regarding the safety indicators are primarily based on expert knowledge, resulting in subjectivity and the ad hoc nature of icebreaker assistance. This can negatively impact both the navigational efficiency of icebreaker services and the productivity of port services. This paper proposes a data mining method to automatically identify icebreaker assistance cases from big data. The identified cases are then used to statistically analyze the safety indicators. The data used in the paper include navigational data obtained from the Automatic Identification System (AIS) and sea ice data in the Baltic Sea area. A multi-step clustering method is adopted to cluster similar trajectories of merchant vessels and icebreakers, identifying assistance events automatically. The results show that the proposed method can automatically identify icebreaker assistance cases with an accuracy of 99.6%, precision of 87%, and recall of 78.3%. The automatic identification along with the statistical analysis can assist in the development of an intelligent decision-making system for safe and efficient winter navigation.

Navigability of the Northern Sea Route for Arc7 ice-class vessels during winter and spring sea-ice conditions

Sea ice hinders the navigability of the Arctic, especially in winter and spring. However, three Arc7 ice-class Liquefied Natural Gas carrying vessels safely transited the Northern Sea Route (NSR) without icebreaker assistance in January 2021. More and more Arc7 ice-class vessels are putting into the transit services in the NSR. Therefore, it is necessary to analyze sea-ice conditions and their impact on navigation during wintertime, and the future navigability of Arc7 ice-class vessels along the NSR during winter and spring. Based on sea ice datasets from satellite observations and a model using data assimilation, we explored the sea-ice conditions and their impact during the first three successful commercial voyages through the NSR in winter. In addition, we analyzed the sea ice variation and estimated navigability for Arc7 ice-class vessels in the NSR from January to June of the years 2021–2050 using future projections of the sea-ice cover by the Coupled Model Inter-comparison Project Phase 6 (CMIP6) models under two emission scenarios (SSP2-4.5 and SSP5-8.5). The results reveal lower sea ice thickness and similar sea ice concentration during these three transits relative to the past 42 years (from 1979 to 2020). We found the thickness has a larger impact on the vessels’ speeds than sea ice concentration. Very likely sea ice thickness played a larger role than the sea ice concentration for the successful transit of the NSR in winter 2021. Future projections suggest sea ice thickness will decrease further in most regions of the NSR from January to June under all scenarios enabling increased navigability of the NSR for Arc7 ice-class vessels. Such vessels could transit through the NSR from January to June under all scenarios by 2050, while some areas near the coast of East Siberian Sea remain inaccessible for Arc7 ice-class vessels in spring (April and May). These findings can support the strategic planning of shipping along the NSR in winter and spring.

Автоматическая маршрутизация судов во льдах: постановка задачи и инструменты решения

Development of the applied solutions to optimize ship path in dynamic ice environment is one of the urgent problems due to the ongoing growth of Arctic shipping. Ice routing makes it possible to increase the efficiency of sea transportation, reduce the risks of ship operation in ice, and minimize the negative anthropogenic impact on the atmosphere. This article describes in a concentrated form the authors’ experience in this area and presents Boreas, the developed research software application for automatic ice routing. Mathematical formulation of ice routing task is based on a universal economic criterion that allows optimizing not only a trajectory, but also the amount of icebreaker assistance, ship operation modes (astern or bow forward), and some other aspects of ice navigation. Functionality and architecture of the Boreas software allow carrying out various studies in the field of ice routing. The application supports alternative ice data sources and various speed regimes of a ship. It allows using different search algorithms (grid, wave-based, and combined) and considers numerous navigation features (predefined fairways, navigation depths, and restricted areas). As an example of using the Boreas software, we compared the route of Norilskiy Nickel containership from Dudinka to Murmansk on March 19—22, 2018 with several automatically generated routes for various speed regimes. Based on our experience and the results of this study, we can state that the development of applied solutions for Arctic routing is significantly complicated by multiple sources of uncertainty and requires further research. The article formulates a list of scientific and technical problems that need to be solved for the comprehensive understanding and further implementation of ice routing technologies in the practice of ship navigation in the Arctic.

INTEGRATED ACCIDENT MODEL FOR MARINE CONVOY TRAFFIC IN ICE- COVERED WATERS

Independent safe navigation in ice-covered water is difficult. Icebreaker assistance is required for sailing through ice- covered waters. This poses an additional risk of collision. The study proposes a modified Human Factor Analysis and Classification (HFACS) framework to identify and classify contributing risk factors during a convoy. HFACS integration with Nagel-Schrekenberg (NaSch) model considers an operator’s behaviour and links it with the occurrence of various risk factors. The study finds significant influence in risk from small changes in two new factors, viz., crew reduction and crew overload. For example, based on the sensitivity analysis, it is determined that about a 17% contribution of crew reduction and about a 24% of contribution of crew overload increase the contribution of risk taking by an amount of approximately 93% in the overall risk of accidents. The accident probabilities obtained here will be helpful in decision making concerning safe operations during a convoy.

Icing of the Chukchi Sea in winter

The modern change trends for the navigation conditions in the Northern Sea Route, belonging to the Chukchi Sea in winter were investigated. In the context of ongoing climatic changes and reducing Arctic ice cover, shipowners are using this transport route. Trial voyages of merchant ships in the eastern part of the Northern Sea Route are being carried out in the winter-spring period; however, shipping has not yet become massive due to difficult ice conditions and insufficient knowledge of the navigation areas. This study was carried out on the basis of information on ice thickness obtained from the GLORYS12.v1 reanalysis databases, NASA ICESat, ICESat-2 and Ice Bridge missions and the Global Sea Ice Digital Data Bank for 1993–2018 for the period from November to March. The probabilities of solid ice posing a danger to navigation were assessed (using the example of “YamalMax” vessels). The distributions of these probabilities over the water area of the Chukchi Sea were presented in a map form. It was found that the navigation conditions improved in most areas of the Chukchi Sea; however, in the southern part of the sea they worsened. This effect was most pronounced in November; in the subsequent winter months, its intensity decreased. The revealed effect is presumably a consequence of the warming of the Arctic climate, leading to the melting of ice massifs of Greenland, the Canadian archipelago and Alaska. The latter causes an imbalance in the levels of the Chukchi and Bering Seas and a change in the directions of surface currents, capable of both delivering ice to the strait and carrying it to the north. The revealed trends suggest further complication of ice conditions in the southern part of the Chukchi Sea, as a result of which even vessels with a high ice class may require icebreaker assistance in November and December.

Development of an Augmented Reality Concept for Icebreaker Assistance and Convoy Operations

A vessel convoy is a complex and high-risk operation completed during icebreaking operations in the Arctic. Icebreaker navigators need to continuously communicate with their crew while monitoring information such as speed, heading, and distance between vessels in the convoy. This paper presents an augmented reality user interface concept, which aims to support navigators by improving oversight and safety during convoy operations. The concept demonstrates how augmented reality can help to realize a situated user interface that adapts to user’s physical and operational contexts. The concept was developed through a human-centered design process and tested through a virtual reality simulator in a usability study involving seven mariners. The results suggest that augmented reality has the potential to improve the safety of convoy operations by integrating distributed information with heads-up access to operation-critical information. However, the user interface concept is still novel, and further work is needed to develop the concept and safely integrate augmented reality into maritime operations.

A Holistic Multi-Objective Design Optimization Approach for Arctic Offshore Supply Vessels

This article presents a new holistic multi-objective design approach for the optimization of Arctic Offshore Supply Vessels (OSVs) for cost- and eco-efficiency. The approach is intended to be used in the conceptual design phase of an Arctic OSV. It includes (a) a parametric design model of an Arctic OSV, (b) performance assessment models for independently operating and icebreaker-assisted Arctic OSVs, and (c) a novel adaptation of the Artificial Bee Colony (ABC) algorithm for multi-objective optimization of Arctic OSVs. To demonstrate the feasibility and viability of the proposed optimization approach, a series of case studies covering a wide range of operating scenarios are carried out. The results of the case studies indicate that the consideration of icebreaker assistance significantly extends the feasible design space of Arctic OSVs, enabling solutions with improved energy- and cost-efficiency. The results further indicate that the optimal amount of icebreaking assistance and optimal vessel speed differs for different vessels, highlighting the motivation for holistic design optimization. The applied adaptation of the ABC algorithm proved to be well suited and efficient for the multi-objective optimization problem considered.

Problem statement on the vessel braking within ice channel

Abstract Sailing within the ice channel that assisting icebreaker tracks is usual for difficult ice conditions in the Northern freezing seas and the Arctic region. There is the danger of emergency, namely, the collision with an icebreaker or the ahead vessel, when ones stop before insuperable ice obstacle or because the engine trouble. The paper contents analysis of the vessel braking process and formulation of the equation that gives possibility modelling this process and evaluating the distance that is necessary for safe stopping of vessel in dependence on its characteristics and ice conditions. Outcomes of investigation will be applicable for the caravan of cargo vessels forming while the icebreaker assistance.

Simulation-Based Assessment of the Operational Performance of the Finnish–Swedish Winter Navigation System

This article presents a discrete event simulation-based approach for assessing the operating performance of the Finnish–Swedish Winter Navigation System (FSWNS) under different operating scenarios. Different operating scenarios are specified in terms of ice conditions, the volume of maritime traffic, number of icebreakers (IBs), and regulations such as the Energy Efficiency Design Index (EEDI). Considered performance indicators include transport capacity, number of instances of icebreaker (IB) assistance, and IB waiting times. The approach is validated against real-world data on maritime traffic in the Bothnian Bay. In terms of the number of ship arrivals per port, indicating the transport capacity of the FSWNS, the simulation agrees well with the data. In terms of the number of instances of IB assistance and IB waiting times per port, the standard deviations between the mean of 35 independent simulation runs and the data are 13% and 18%, respectively. A sensitivity analysis indicates that the simulated number of instances of IB assistance and IB waiting times is particularly sensitive to assumptions concerning the presence of brash ice channels. Case studies indicate that, unless the number of IBs is increased, the EEDI regulations may result in a significant increase in both the number of instances of IB assistance and the cumulated IB waiting times.

Analysis of the current state of the Northern Sea Route and the potential development of the icebreaker fleet

The article provides a general description of the current state of the Northern Sea Route (NSR), highlights existing problems and prospects of the Northern Sea Route development. There is a tendency to increase the volume of sea freight traffic on the Northern Sea Route, which is facilitated by the development of new oil and gas fields in the Arctic and increased safety of navigation in the NSR. It is noted that despite the revival of transport infrastructure in the western part of the NSR, its eastern part is characterized by a depressed state. The main drawback of the Northern Sea Route is the severe natural conditions that limit the navigation time. Special attention is paid to the Russian nuclear icebreaker fleet. Both its current state and promising nuclear icebreakers, which are currently under construction or in the design stage, are considered. The main requirements for the characteristics of nuclear icebreakers are identified, which are necessary for their effective use on the routes of the Northern Sea Route in the context of increasing volumes of cargo transportation. Thus, an important requirement for maintaining the growth in cargo traffic is to ensure year-round icebreaker assistance to cargo ships along the Northern Sea Route. There is a need for the construction of new nuclear-powered icebreakers due to the expiration of the lifetime of nuclear icebreakers of the Arctic and the Taimyr classes. In the future, in the next decade, the main core of the Arctic nuclear icebreaker fleet should be universal icebreakers capable to provide icebreaking assistance for ships both in coastal areas and estuaries and in the western part of the Arctic.

Integrated Accident Model for Marine Convoy Traffic in Ice-Covered Waters

Independent safe navigation in ice-covered water is difficult. Icebreaker assistance is required for sailing through ice- covered waters. This poses an additional risk of collision. The study proposes a modified Human Factor Analysis and Classification (HFACS) framework to identify and classify contributing risk factors during a convoy. HFACS integration with Nagel-Schrekenberg (NaSch) model considers an operator’s behaviour and links it with the occurrence of various risk factors. The study finds significant influence in risk from small changes in two new factors, viz., crew reduction and crew overload. For example, based on the sensitivity analysis, it is determined that about a 17% contribution of crew reduction and about a 24% of contribution of crew overload increase the contribution of risk taking by an amount of approximately 93% in the overall risk of accidents. The accident probabilities obtained here will be helpful in decision making concerning safe operations during a convoy.

A cellular automation model for convoy traffic in Arctic waters

Marine transportation in arctic waters involves risk due to the presence of ice, rapid weather changes, reduced visibility, and remoteness. Icebreaker assistance and ice-convoys are used to facilitate the safe navigation of commercial vessels transiting Arctic waters. Collision between individual ships, or a ship and an icebreaker, during a convoy is a potential danger. To study such risk, this paper presents an updated Nagel-Schrekenberg (NaSch) model of the marine convoy traffic integrated with a Bayesian Network (BN) based probabilistic approach. This approach has been used to predict the maximum waterway density for the safe flow of traffic, and the collision probability during a convoy. The approach is tested here on a convoy in the Vilkitskii strait. The BN model proposed here could assist in assessing the failure probabilities of the causal factors and their contribution to collision likelihood. It may also be useful in developing a collision monitoring system that provides a real-time estimate of collision probability. The estimated probability could be used as an early warning for potential collisions, thus enhancing safe navigation and safety at sea.

Optimal ice routing of a ship with icebreaker assistance

Offshore development and growing prospects of commercial shipping in the Arctic pose the challenge of optimal ship routing in ice. Route selection in spatially distributed ice conditions significantly affects the voyage time and determines the efficiency of shipping. Most of the applied methods of ice routing solve the problem of a single vessel route selection without considering icebreaker support. At the same time, the real practice of ice navigation is closely connected with icebreaker assistance. It allows reducing the voyage time and fuel consumption, while having additional costs for icebreaker services. Such opposite trends set an optimization task that has not been studied in detail before. In this article, we presented the formulation of a Single Vessel and Icebreaker Assisted Ice Routing optimization problem in non-stationary ice conditions. We considered the icebreaker assistance as an integral part of the overall route optimization problem, and used the economic criterion to optimize both ship route and amount of icebreaker involvement. The article contains the adapted mathematical formulations of classical graph-based and wave-based routing problems in order to consider icebreaker assistance. To prove the practical applicability of these formulations, we developed special subject-oriented research software and implemented there both graph-based (Dijkstra, A*) and the wave-based ice routing methods. Using this developments, we conducted several case studies and made the analysis of strengthens and weaknesses of the alternative routing methods in case of ice operation. The results of the study may serve an additional step to the practical implementation of ice routing technologies and planning of icebreaker resources.

Big maritime data for the Baltic Sea with a focus on the winter navigation system

The automatic identification system (AIS) has become a key element in maritime domains of inquiry and the number of related articles has increased rapidly. The systematic integration of AIS data with other datatypes has received less attention and has mostly resulted in application-specific datasets that are small relative to the available AIS data. This work presents an accumulating multi-purpose database for the northern Baltic Sea that combines nine years of AIS data with marine environmental data. The main application is winter navigation research, for which purpose the environmental data is from ice charts and ice drift models. The AIS data is from terrestrial stations and amounts to 6 billion messages. It has a full update rate which is also required for the analysis of ice navigation as this involves close encounters, icebreaker assistance, convoy operations, and rapid speed changes. To identify and study such traffic features, distances between ships that are close to each other are included in the database. Application examples are given for spatial traffic statistics, reduction of ship speed with increasing ice thickness, and for icebreaker assistance.

Use of HFACS and fault tree model for collision risk factors analysis of icebreaker assistance in ice-covered waters

Use of HFACS and fault tree model for collision risk factors analysis of icebreaker assistance in ice-covered waters