The most urgent task in tapping of the Arctic resources today is organization of year-round navigation through the Northern Sea Route. The efficiency of any transport system strongly depends on the deadweight and speed of cargo carriers. In this connection it is required to thoroughly examine the issues related to propulsion of large-size cargo ships in ice, while developing the tactical planning and operation control technologies for icebreakers and ice-going ships. It is found that large-size cargo ships are not able to navigate independently in ice at economically efficient speeds even if their hullform is optimized for these operating conditions. Thus, it is required to ensure their effective operation in ice channels made by icebreakers. For appraising the efficiency of a marine transportation system it is necessary to have data on ship resistance versus a range of factors including physical and mechanical properties of ice, ice concentrations, ship speed, etc. This paper presents the results of studies undertaken to examine various methods of icebreaker-assisted shipping operations and to develop a method for calculation of ship resistance in ice channel based on model test data. The research was supported by RSF (project No.17-79-20162).

In this study, we used multi-body dynamic (MBD) technique to numerically calculate the ice load of the icebreaker in pack ice conditions. Because MBD is a useful method for analyzing the dynamic behavior of a rigid body using the contact mechanism, MBD analyzes the interaction between each ice and icebreaker. Each ice and icebreaker also interact with the fluid. Simultaneously analyzing the interaction between fluids and float is difficult and complex, so Computational Fluid Dynamics (CFD) is used to simulate fluid-ice interaction and apply it to ice modeling. The simulation was performed in the time domain and compared to the average ice impact load obtained from experiments in an ice traction tank.

Ice management (IM) is often required to support offshore production of oil and gas in freezing seas. It helps to mitigate ice impact on marine structures and thus minimize risks of accidents as well as to increase weather windows for marine operations. One of the IM tactics is to use an icebreaker for producing a zone of managed ice for ensuring safe and efficient operation of marine facilities: platforms, offloading terminals, tankers, etc. The choice of the right icebreaker which is best capable to cope with the IM jobs is quite a challenging task. This paper suggests an approach to objectively compare operational efficiency of different icebreakers in performance of some typical IM tasks. This approach made it possible to work out universal criteria for assessing the efficiency of these ships. The criteria of icebreaker efficiency and operational performance have been derived from actual ice breaking and maneuvering data including safety aspects of required icebreaker maneuvers. The paper contains case studies with estimation of the said criteria for a number of IM icebreakers expected to be used for ice management in the south-eastern part of the Barents Sea.

Propulsion performance of icebreakers cannot be calculated as per the classic system of propeller-hull interaction coefficients due to high negative values of wake fractions. To overcome this difficulty, this paper applies an alternative system of propeller-hull interaction coefficients. This system consists of thrust deduction fraction, coefficient of hull effect upon thrust and coefficient of hull effect upon torque. The method suggested in this paper was used to analysis the data of ice trials for Vladivostok and Novorossiysk icebreakers. The input data in this analysis are speed in the ice field and required power. The sought values are propeller rotations per minute (RPM) and ice resistance. Propeller RPM values are compared versus the results of full-scale ice trials. Ice resistance values are compared versus the predictions based on the model test data obtained in ice basin of Krylov State Research Centre (KSRC). It is shown that at low speeds in the ice field (0.5–5.0 knots), calculated propeller RPMs have good correlation with the full-scale measurement data. This paper also gives propulsion performance calculation for Vladivostok icebreaker in 1.5-m thick ice field.

Recently, the research activities by domestic and overseas researchers using the Korean ice-breaking research vessel, ARAON have been actively conducted. The ARAON regularly operates for research activities in the Antarctic and the Arctic Ocean every year. She conducts many scientific and engineering tasks including ice load measurement, investigation of the properties of material strength for sea ice, and icebreaking performance test during her voyages. Such tests provide important data for studying icebreaker. Ice-breaking mode is determined by conditions of sea ice and ice field, and it is divided into ramming and continuous icebreaking. When the icebreaker meets thick ice or icebergs, the ramming is conducted. At that time, the ship speed is generally slower than that of the continuous icebreaking. The ARAON conducted icebreaking performance tests at the Amundsen Sea in Antarctica in 2012. Many strain data were measured in the ramming and the continuous icebreaking. This study was based on the strain gauge signals measured by the ARAON during the research voyage in 2012 in the Antarctic and 2010 in the Arctic. The signals measured from repetitive ramming under the heavy ice condition in 2012 in the Antarctic Ocean were classified into the five profiles. And the classified ice load signals were analyzed with a focus on raising time, half-decaying time and total time duration. Also, the signals measured from continuous icebreaking in 2010 in the Arctic Ocean were analyzed in the same way as the ramming data. Finally, the time histories of ice load signals were summarized from the viewpoint of speed change at the time of ice load, and two data sets were compared.

The interaction between sea ice and sea water is a complicated fluid-solid coupling dynamic process during the operation of polar ships. Using the finite element numerical simulation software LS-DYNA to simulate the continuous ice breaking of icebreaker, the ice load numerical calculation method considering the ice water coupling is presented. The effect of ice water coupling on ice load is studied. Based on the ice pool test data and the calculated results of this paper, the accuracy and rationality of the algorithm are verified. On this basis, the multiple factors affecting the coupling between sea ice and sea water are further studied, including the thickness of sea ice and the collision velocity of ship and ice which are affected by the environment of different polar sea areas. By simulating the numerical results obtained from the collision ice breaking of the targeted ship, the influence of various factors on the coupling effect between sea ice and sea water is summarized, and the local strength of the hull head structure is checked and evaluated. Furthermore, the impact-type icebreaking ability of the hull is put forward, which has certain guiding significance for the development of ship ice collision numerical simulation.

The Arctic plays a key role in the economic development of Russia. This region is fabulously rich with hydrocarbons and biological resources. One of the strategic goals in commercialization of the Arctic region is setting up of efficient transportation systems for year round navigation via the Northern Sea Route (NSR) to support shipment of various cargoes [1]. According to the latest studies, cargo vessels should be able to travel through NSR at speeds reaching 12 knots to make it a commercially competitively route. Highspeed moving can allow NSR to become competitive route as compared to the southbound route via Suez. It should be noted that ice conditions on this route are quite severe. Navigation in NSR of even ice-capable cargo carriers with icebreaker assistance will enable to increase the effectiveness of this shortcut shipping itinerary between Europe and the Pacific coast. For this purpose a novel nuclear Leader icebreaker has been designed, which, according to model tests in the Krylov Centre ice basin, will be able to sail in 2-meter continuous ice at 12 knots. The investigations of ship performance in ice at fast speeds are quite new and should be conducted very carefully. This paper focuses on some specific features of dynamic behaviour predicted for an icebreaker and a large-size vessel led by this icebreaker during speedy sailing in ice. It also discusses other important issues related to minimum power level requirement for vessels operating under these conditions as well as due account of the hydrodynamic resistance component in ice performance predictions.

The ice breaking capacity of the icebreaker depends on the geometric characteristics of the bow. Selecting reasonable bow configuration and characteristic parameters is helpful to improve the ice breaking capacity. In the ship parameters, the bow rake angle directly influences the ice breaking ability and the dipping efficiency. The ship collision with ice is simulated by using nonlinear dynamic analysis software LS-DYNA. By changing the bow rake angle, the collision force curves are obtained, and the ice breaking ability and efficiency of the polar ship with three bow configurations are calculated and compared with the ice resistance calculated by Riska formula. Through the analysis of the average longitudinal collision force and the ice breaking distance, the optimum bow configuration is selected. Combined with the calculation of the open water resistance, the scheme with the bow rake angle of 13 degrees is the best in the resistance performance.

Diminishing ice presence in the Arctic provides the potential for extended operable period for oil and gas exploration in the Arctic. Floaters are a flexible solution for such scenario whereas they can fully take advantage of the extended drilling season as well as operate in other harsh environment regions during the off-season. Such floaters can disconnect and reconnect to avoid large ice features such as icebergs and multi-year ice ridges. However, they still need to encounter relatively large level ice. Accompanying icebreakers will ideally assist in breaking the level ice into manageable pieces. The interaction of such level ice floes with floater has a significant influence on the dynamic ice load on the floater and resulting mooring load. There is significant uncertainty in the simulation of level ice-floater interaction numerically. Most of the current research focuses on the influence of ice breaking and subsequent flow of the broken ice around the floater. However, the hydrodynamic load due to the incoming level ice will also affect the response of the floater, which is usually not simulated. A recent study simulated the multibody hydrodynamics of level ice and floater Such multibody hydrodynamic analysis is computationally expensive, and complexity in the modelling is a hindrance to its implementation in the design phase. The present study, therefore, employs a conservative estimation to include the effect of wave load on the floater in addition to the ice load. Parametric studies are performed to estimate this effect by varying the incoming wave amplitude and wave period, ice sheet thickness, ice drift velocity, floater’s hull angle, mooring stiffness and the distance of large ice-sheet from the floater. Significant impacts of waves on the floater in terms of total force are observed which clearly reflects the importance of this study. The effect of mooring stiffness on total load is also investigated at the end of this study which can be considered as a foundation for further research on optimizing the mooring stiffness for such kind of arctic floater.

This paper presents a ship-mounted multi-lens camera system for sea-ice monitoring and algorithms to automatically evaluate the sea-ice concentration and to indicate the floe-sizes in a radius of 100 meter around the vessel. During the SWEDARCTIC Arctic Ocean 2016 expedition, 11 camera lenses recorded the sea-ice conditions around the Swedish icebreaker Oden. As an example of the possible use of this image system, the images of six lenses are combined into one 360° panoramic image. To distinguish between water and sea-ice in the images, and thus to evaluate the sea-ice concentration around the vessel, a direct thresholding, the k-means, and a novel adaptive thresholding method are applied. Moreover, an edge detector gives the number of pixels that either form the boundary between sea-ice and water or are part of a visible ice fracture. The ratio between these edge pixels and the total number of pixels containing sea-ice gives an indication of the floe size distribution (FSD) in the image.

Basic principles of the multidisciplinary approach to arctic marine transport systems (MTS) design and analysis are described in the article. The main idea of the approach is to synthesize geographic information system (GIS) technologies, different shipbuilding disciplines, fleet planning instruments and agent-based dynamic simulation models in an integrated software framework on the basis of object-oriented programming. Vessel operation is described as the movement and interaction of independent ships in GIS environment within the framework of the simulation model. MTS operation combines vessel operation itself (routing, determination of speed and fuel consumption, icebreaker escort, etc.) with plenty of external entities (port infrastructure, ice channel freezing process, offshore platform operation, etc.) that could be described as systems with comprehensive logic and physical behavior. Such integration provides a new quality of MTS simulation that allows considering complex interconnection of various subsystems and all the important details of each MTS project. The outline of the program framework to realize such an approach is given, and two case studies are described to demonstrate its capabilities and feasibility.

This paper presents a review of the state of the art of model-scale ice with a focus on mechanical behavior, mechanical testing and scaling. The goal of the model-scale ice production is the generation of a material that can represent sea ice in as many aspects as possible. The question therefore is, to what extent model-scale ice complies with this high level requirement and what possible limitations of model-scale ice are encountered. A part of the answer lies in the history of model-scale testing in ice as model ice was originally designed to test ships in ice. The interaction of ships with ice, when breaking level ice, differs from other interaction scenarios in terms of triggered failure processes and consequently in the relevant mechanical properties of the ice. The significance of the forces in particular interaction scenarios is reflected in the applied scaling laws. The standard scaling laws are presented together with published alternatives and their limitation and practicality is evaluated. The relevant interaction forces and ice properties are compiled for level ice breaking, ships in brash ice and offshore structures in slow ice drift. In the production of model-scale ice, the mechanical properties and their measurements play a significant role, as they determine how well the full-scale scenario is scaled. However, latest research in context with earlier published findings indicates that state of the art measurement procedures may not be able to capture the actual ice properties, as the mechanical behavior of model-scale ice might be different than generally presumed. Consequently, this paper presents alternative measurement procedures and highlights existing knowledge gaps which are worthwhile to be addressed in future.

As one kind of special ship, polar Ice-breaking ships are used to break the ice for other ships or for researchers going deeper to the polar region. The safety of Ice-breaking ships should be emphasized not only because of it special shape but also because of its unique load case and complex marine environment. Structure Health Monitoring (SHM) should be installed in them owing to reasons mentioned above, even if there are rules that had been used while designing the ships. How to choose appropriate monitoring points is one of the most important things in this whole project. For providing more rational approach to selecting measure points in Structure Health Monitoring by FEM analysis, two methods were proposed and compared in order to determine a better one which can reduce the workload. One of these two methods is design wave approach which can show ultimate strength but just in the case of hogging, sagging and other typical cases, which ignore a large number of cases the ship may meet. The other one is composed of 240 structural responses from 20 kinds of frequencies in 12 directions (Data of spectral analysis), and weighted mean value based on ocean wave spectrum would be seen as an assessment of the damage caused by natural environment. For huge data in the finite element analysis, there must be a set of feasible algorithms to automatically process the results to get monitoring points. After that the monitoring point can be and stress measured by fiber-optic sensor at that point will be monitored in real time.

Today, there is a strong emphasis on navigation safety in polar waters. IMO Subcommittee on Ship Design and Equipment has issued the Polar Code encompassing the matters of design, structure, equipment and operation of ships intended for polar waters. One of the main objectives of this Code is to work out the rules for man-made pollution management in the Arctic. Modern marine logistics systems developed to transport hydrocarbons and natural gas produced at the Arctic offshore include the ships with high ice class capable of operating both autonomously and with ice-breaker pilotage. This work explains how to assess, as per IMO formulas, the CO2 emissions from large ice-going ships in different scenarios of their ice-breaker pilotage. Obtained results served to assess power efficiency of large ships allowing evaluation of the pilotage techiques, both existing and those suggested by the authors of this paper, in terms of environmental safety.

When ships operate in the Arctic, sea-ice induce an additional environmental load on the vessel. The ice load can vary significantly depending on the dominating ice-breaking failure mode. In this work a sensor system for measuring ice induced accelerations on the Canadian icebreaker CCGS Amundsen and a Swedish Atle-class icebreaker is presented. The sensor system consists of low-cost inertial measurement units. Ship-ice interaction data has been collected during expeditions along the coast of Labrador in Canada and in the Greenland Sea north of the Norwegian Svalbard archipelago. Depending on the failure mechanism of the interacting ice, vibrations at different frequencies are induced into the icebreaker ship. A time-frequency decomposition based on the Wigner-Ville distribution has been modified such that it is applicable to analysis of ice-load induced acceleration signals. Based on the frequency pattern of the induced vibrations, this novel method allows for evaluation of the intensity of the ice-loads and identification of the dominating ice failure mechanism, which is demonstrated for several ship-ice interaction events. The presented novel time-frequency decomposition for ice induced accelerations is a powerful tool for the identification of the threat imposed by sea-ice to a structure. In further work the time-frequency decomposition will be used as feedback in ice-capable control and monitoring systems for Arctic offshore operations.

The interdependence exists between ship response and ice load during the ship-ice interaction process. According to the ice properties and the velocity between a ship and ice can make influences on ice load, taking a Russian icebreaker as model, a series of numerical simulations were performed to research the ice load variation tendency rules in 3 axial directions and the total force direction. On the basis of regarding ice elements as elastic materials, the theory of a semi-infinite elastic plate resting on an elastic foundation was used to simulate ice sheet. By means of finite element model, stress and strain contours of typical moment and ice load history curve in four directions were obtained. Furthermore, the effect of important parameters such as elasticity modulus of ice, ice thickness and ship speed on the impact force were also analyzed. The results indicate that ice sheet will crack in the form of a circle centered on the collision point which accord with actual circumstance, and there are some certain variation relationships between each calculation parameters and ice load values. At the same time, the study can also provide technological support for ice load research.

Arctic remains the final frontier in the oil and gas exploration regime. The diminishing presence of ice opens up the region for longer and wider exploration. However, even with the assistance of ice management, the threat of broken first-year level ice stays ubiquitous. Calculation of ice load for such ice features bases on the established formulation developed by observation from full-scale measurements and model test data over the years. However, the formulation mostly relies on the data derived from fixed structures or icebreakers. Such estimations of ice load do not account for the stiffness compliance afforded by mooring system of a floater, such as a semi-submersible or a spar. A floating oil and gas exploration system offers a number of advantages over the fixed platforms, such as the option to deploy elsewhere during the off-season in the Arctic as well as connecting and disconnecting during severe ice events such as an approaching iceberg or multi-year ice ridge. However, the current practice of employing dynamic ice load time-history available in ISO19906 or similar codes fails to account for the presence of the mooring system on these floating platforms, directly resulting in a lack of confidence in the derived response of the floater. This study aims to address this issue by developing a dynamic ice-load time-history algorithm, which, can readily couple with commercially available hydrodynamics and mooring system analysis software. This investigation puts forward the hypothesis that the evolution of ice load vs. ice feature displacement with respect to the structure remains same for both fixed and floating structures. However, the underlying assumption is that the size of the ice features remains comparable. This hypothesis accounts for the prominent influence of the size effect on the breaking strength of ice. The difference between the behavior of a fixed and a floating structure under ice load is due to the relative motion between the floater and the ice feature. The developed coupled ice-load-function accounts for this by including the relative displacement between the floater and the ice feature in the formulation. This study uses the semi-empirical formulation originally derived by Croasdale to calculate the main ice load components for a fixed structure with downward breaking slope. Subsequently, this study uses this coupled ice load subroutine to compare against the full-scale measurement data found in the literature for a floater with downward-sloped hull specifically designed to assist in ice breaking. A comparison against the peak load observed during full-scale measurements on a floater in the Arctic waters validates the proposed approach. Next, this study utilizes the coupled analysis to derive the displacement, velocity, and acceleration response of the studied floater for a range of ice parameters, such as the drift speed and thickness. Additionally, this study performs a parametric study by varying the downward breaking slope angle of the floater, the mooring configuration, and the water depth. Finally, this study summarizes the observed behavior of the floater under different ice parameters as well as floater shape and mooring systems parameters.

There are a variety of model ices and test techniques adopted by model test facilities. Most often, the clients would ask: “How well can you predict the full scale performance from your model test results?” Model-scale/full-scale correlation becomes an important litmus test to validate a model test technique and its results. This paper summarizes the model-scale/full-scale correlation performed on model test data generated at the National Research Council - Ocean, Coastal, and River Engineering’s (NRC-OCRE) test facility in St. John’s. This correlation includes ship performance predictions, i.e., resistance, propulsion and maneuvering. Selected works from NRC-OCRE on the USCGC icebreaker Healy , the CCGS icebreaker Terry-Fox , the CCGS R-Class icebreakers Pierre Radisson and Sir John Franklin and the CCGS icebreaker Louis S. St. Laurent were reviewed and summarized. The model tests were conducted at NRC-OCRE’s ice tank with the correct density (CD) EGADS model ice. This correlation is based on the concept that a “correlation friction coefficient” (CFC) can be used to predict full-scale ship icebreaking resistance from model test data. The CFCs have been compared for correlation studies using good-quality full-scale information for the five icebreaker models in the NRC-OCRE’s model test database. The review has shown a good agreement between NRCOCRE’s model test predictions and full-scale measurements. The resistance and power correlation were performed for five sets of full-scale data. Although there is substantial uncertainty on ice thickness and ice strength within the full scale data sets that contributes to data scattering, the data suggest a conservative estimate can be obtained to address reasonably this uncertainty by increasing the model prediction by 15% that envelopes most data points. Limited correlation for maneuvering in ice was performed for the USCGC icebreaker Healy . Selected test conditions from the sea trials were duplicated for the maneuvering tests and turning diameters were measured from the arcs of partial circles made in the ice tank. Performance predictions were then compared to the full-scale data previously collected. Despite some discrepancy in ice strength and power level between the model tests and sea trial, the model data agree well with the sea trial data except for three outliers. Otherwise, the maneuvering data show a good correlation between the model test and sea trial results.

One of the challenges related to the design of arctic cargo ships is that their transport capacity is dependent on a number of arctic specific design parameters (e.g., ice conditions and the availability of icebreaker support) in which there typically is a significant level of uncertainty and stochasticity. This paper addresses that challenge by presenting a design method that deals with the parameter uncertainty by integrating method of risk assessment in to the design process, i.e., by utilising the principles of Risk-Based Design (RBD). In order to obtain a holistic approach, the design method treats a ship as an arctic sea transport system that might include multiple ships, icebreakers, and port-based facilities such as cargo storages. Using the method it is possible to design an arctic sea transport system that provides a desired level of operational reliability. This provides the means to minimise costs and financial losses due to over- or undercapacity, and thereby to improve the resource-efficiency of the system as a whole.

The exploration and production of polar oil and gas fields, which are technologically challenging due to extreme weather conditions, are also constrained by strong environmental issues. Safe and economical activities in such hostile and fragile regions require very insightful engineering. The presence of sea ice is representing a triple challenge: economical, technological and environmental. This makes the Arctic exploration and production activities complex. Ice Management (IM) is one of the tools that could efficiently assist to develop Arctic reserves. However, for each project that uses IM operations, a preliminary study is required to evaluate the efficiency of these support operations and to estimate the possible extension in the season of operation of a field. Efficiency of an IM philosophy can be estimated in a global view based on the extension in the operability window. In a more detailed view, it can be assessed taking into account the optimal number of icebreakers, the IM patterns, the available time for eventual disconnection, and the floe size reduction (leading to ice load reduction). For this study, we will focus on the ice floe size and loads reduction. The most common approach for physical management of sea ice is the one where icebreakers reduce floe size of the drifting ice upstream the floating platform (ref. Moran et al. [1], Coche et al. [2]). This paper describes this philosophy and demonstrates based on real-time simulation that its benefit is limited to mild ice scenarios such as unidirectional ice drift. A more efficient way to manage sea ice is (1) to identify the most hazardous events (e.g. big ridges); (2) prioritize these events; and (3) deal with them starting by the most hazardous one.