Ice Class Research Articles

An automated procedure to map breaking river ice with C-band HH SAR data

The development of effective strategies to manage the river ice breakup process or the associated risks is hindered by a lack of understanding and information. Radar earth observation satellites offer excellent potential for collecting up-to-date information on the conditions of and changes in river ice cover during the breakup period. This text describes the development, performance and limitations of an automated procedure to map breaking river ice by means of C-band, HH-polarized Synthetic Aperture Radar (SAR) images. An original two-step supervised classification model (IceBC), which uses backscatter intensities, lies at the core of the procedure. First, IceBC identifies three primary classes: water, sheet ice and rubble ice. Next, each primary ice class is divided in three secondary classes that denote top surface roughness scale differences. Input images must have incidence angles from ~27° to ~60°. Below ~36°, IceBC may assign a class labelled “unclassified” to water or sheet ice pixels. The primary classification model yields overall accuracies of ~86% and ~93% for independent test pixels with incidence angles ≤ ~49° and ≥ ~29° or ≥ ~36°, respectively. The associated class accuracies for water, sheet ice and rubble ice are ~97% & 96%, ~69% & 85% and ~97% & 99%. Given its connection to ice jam flood events, the classification accuracy achieved for rubble ice is particularly important. Maps produced by means of IceBC comprise detailed spatial information regarding ice cover conditions and the development of the breakup process. Their quality may be affected by: freezing conditions, wet snow cover, meltwater pools, infrastructure, rapids or high winds. Monitoring is the key to managing the impacts of most of these challenges. An IceBC prototype has been used operationally since 2015.

Local pressures for ships in ice: Probabilistic analysis of full-scale line-load data

Ships operating in ice might be exposed to significant ice loading. Using a probabilistic semi-empirical method known as the event-maximum method, the long-term maximum level of ice loading on a ship can be estimated based on parent distributions of short-term full-scale ice load measurements. The event-maximum method is used to model the relationship between extreme local ice pressures and impact area by estimating parameters corresponding to the inverse slope (α) and intercept (x0) for the line of best fit for the tail of ranked peak pressure data versus the natural logarithm of the Weibull plotting position. These best-fit lines are assumed to follow an exponential distribution and associated α and x0 values are produced for different local design areas. This allows for the determination of α-area curves, which reflects the relationship between ice pressure and the local design area. Previous studies have determined α-area curves for different geographical areas such as the Beaufort Sea and South Bering Sea, representing different ice types including both first-year and multi-year ice. In this study, two separate sets of full-scale ice load measurements having been considered, namely measurements from the Kara Sea and the Barents Sea, as well as measurements from the Antarctic Ocean. Using these two datasets, two new α-area curves have been generated that represent among other operating areas (the Kara Sea and the Barents Sea), operating modes (icebreaker assisted operation) and impact areas (aft shoulder) not covered by other curves. Earlier formulations of the event-maximum method are based on local design areas in which the width and height of areas are defined by the size of instrumented rectangular panel areas (or combinations of those areas) on the bow of the vessel from which the data were collected. In that approach, ice thickness is not directly considered since the height of individual panels is based on the dimensions of instrumented areas and moreover, detailed ice thickness records were not available for those data sets. In the present study, an alternative approach has been developed to extend the event maximum method for use with ship line-load data. In this approach ice pressures are calculated by dividing the ice force measured on frames by the corresponding line-load area (ALL), which is the product of the width (W) that is based on frame spacing and an assumed line-load height (H) corresponding to 30% of the maximum prevailing ice thickness, as per best design practice, along the lines of the Finnish-Swedish ice class rules. Data already presented as line-loads (in units of force per unit width), are converted to pressures by dividing line-loads by height H. The event definition used in the present approach is defined as the maximum pressure corresponding to 10- or 20-min intervals, as opposed to the impact event definition used in earlier works. In applying this extended method to develop new α-area curves, valuable insights into the relationship between local peak ice pressure and prevailing ice thickness have been gained for the above-mentioned full-scale measurements. The determined curves indicate a negative correlation between prevailing ice thickness and maximum local nominal ice pressure. Finally, it has been demonstrated that it is feasible to apply such curves in combination with the principle of the event-maximum method to estimate the maximum nominal ice pressure expected for a ship given a specified transit distance in sea ice with different prevailing thicknesses.

Prediction Method of Ice Resistance and Propulsion Power for Polar Ships

Polar ships need to meet stringent safety and environmental requirements. Usually those ships are classified by different ice classes based on ice operation capability. However, the polar ships are also trapped by severe ice condition due to low propulsion power. Therefore, it is a realistic question to design the appropriate minimum propulsion power for ice operation. This paper focuses on the ice resistance and its related propulsion power for the ships with polar code (PC) classes. In consideration of seven typical polar ice conditions related to the PC rule of International Association of Classification Societies (IACS), a prediction method of ice resistance is developed by Lindqvist’s model. The results are compared with those of Lindqvist’s model and Riska’s model by using two real ship lines. The comparison among propulsion requirements of representative classification societies is made, and a formula of minimum propulsion power is presented on the basis of ice resistance by revised Finnish-Swedish Ice Class Rules (FSICR) method. The results are verified by the actual values from seven ice class ships. A relatively good agreement is achieved. As a conclusion, the presented prediction method of ice resistance and minimum propulsion power is recommended for evaluation of ice resistance and its related propulsion power during the process of developing polar ships.

Modelling of maneuvering of the ship equipped with two azipods

Wide development of the Northern Sea Route is one of the main national projects of the Russian Federation. Solution of this large-scale problem is impossible without new types of ships, which are capable of working all year round among ice of polar latitude. These vessels are designed for different purposes, so that they are characterized by stronger hulls of ice class and new types of propulsion device – azipods, in other words – screw-steering columns. Rotating of azipods along vertical axis allows to direct propulsive force in arbitrary direction, which makes it possible to stop using rudder and move more efficiently. For example, proceed forward with stern of the ship. Ships with two azipods are of special effectiveness. With wide operation of new types of propulsion devices, it becomes necessary to include their particular mathematical models in general model of the vessel. This as well applies to azimuthal propulsion devices, known as screw-steering columns. Model becomes more complicated when the ship is equipped with two azipods, which influence each other during application in a particular way. The practicable way of research of such ships’ work is their mathematical modelling, which includes modelling of the hull of the ship, as well as the azipods the ship equipped with. Exactly this model is described in this research. The vessel with displacement of about 36000 tons is equipped with two azipods. Hull is described by the model in shifts, work of every azipod – by Hoffmann algorithm. Basic value of propulsion force of every screw of azipod before its turn is calculated with Lammeren curve of screw force.

A Framework for Integrating Life-Safety and Environmental Consequences into Conventional Arctic Shipping Risk Models

The International Code for Ships Operating in Polar Waters (Polar Code) was adopted by the International Maritime Organization (IMO) and entered into force on 1 January 2017. It provides a comprehensive treatment of topics relevant to ships operating in Polar regions. From a design perspective, in scenarios where ice exposure and the consequences of ice-induced damage are the same, it is rational to require the same ice class and structural performance for such vessels. Design requirements for different ice class vessels are provided in the Polar Code. The Polar Operational Limit Assessment Risk Indexing System (POLARIS) methodology provided in the Polar Code offers valuable guidance regarding operational limits for ice class vessels in different ice conditions. POLARIS has been shown to well reflect structural risk, and serves as a valuable decision support tool for operations and route planning. At the same time, the current POLARIS methodology does not directly account for the potential consequences resulting from a vessel incurring ice-induced damage. While two vessels of the same ice class operating in the same ice conditions would have similar structural risk profiles, the overall risk profile of each vessel will depend on the magnitude of consequences, should an incident or accident occur. In this paper, a new framework is presented that augments the current POLARIS methodology to model consequences. It has been developed on the premise that vessels of a given class with higher potential life-safety, environmental, or socio-economic consequences should be operated more conservatively. The framework supports voyage planning and real-time operational decision making through assignment of operational criteria based on the likelihood of ice-induced damage and the potential consequences. The objective of this framework is to enhance the safety of passengers and crews and the protection of the Arctic environment and its stakeholders. The challenges associated with establishing risk perspectives and evaluating consequences for Arctic ship operations are discussed. This methodology proposes a pragmatic pathway to link ongoing scientific research with risk-based methods to help inform recommended practices and decision support tools. Example scenarios are considered to illustrate the flexibility of the methodology in accounting for varied risk profiles for different vessel types, as well as incorporating input from local communities and risk and environmental impact assessments.

Investigations on the ship-ice impact: Part 1. Experimental methodologies

In the structural design of the Polar Class ships, glancing impact with ice has been considered as the governing load scenario for dimensioning the bow structure. At present, non-linear transient dynamic analysis has been reckoned as a fundamental requirement in the assessment of the structural strength of ships with higher ice classes. Under such requirement, understanding of the dynamic characteristics of the ship-ice impact load appears significant importance. The present study aims to investigate the spatial and temporal variations of the impact loads by simulating the glancing impact events between a polar research vessel and giant ice floes in ice tank. The ship-ice impact loads were recorded by a grid-based tactile sensor attached on the bow area of the model ship. To achieve a reasonable simulation on the design scenario described by the IACS Unified Requirements for Polar Class Ships (UR I), a series of methodological calibration tests were preliminarily carried out to determine the key parameters that should be carefully monitored and controlled, accompanying with thorough discussions on the ship-ice impact process. This paper provides detailed information on the preliminary methodological calibrations and the tactile data processing techniques, including the identification of the ship-ice contact area, the depiction of the ice loading trail and the outline of the spatial distributions of local ice pressures. A companion paper provides detailed analyses and discussions regarding the spatial and temporal variation of the ice impact loads from the formal tests based on the proposed testing procedures obtained by the methodological calibrations.

Analysis of the impact of arctic-related factors on offshore support vessels design and fleet composition performance

In this paper, we investigated issues of arctic supply vessel design and fleet composition. Analysis of factors of various nature that influence the performance of the Arctic supply system, as well as exploration the possible ways to improve its efficiency are presented. For addressing this we developed a research approach that joins the holistic parametric design model of arctic supply vessel and the fleet planning algorithm. The last one solves the fleet sizing problem and simulates the dynamics of vessel operation, ice state and logistics features of platform operation.We presented the results of system performance analysis for the case of supply fleet operation in the Kara Sea. Factors under investigation were ice class, deadweight, ship type, the structure of cargo-flow and distribution of useful hull capacity by cargo type. The article provides the recommendations on the formation of the offshore supply system based on the studied case. This confirms the usefulness of the proposed approach for handling the considered problem.

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The algorithm and program for the model of operation of the hydrocarbon loading complex, which consists of an ice class shuttle tanker and offshore platform equipped with an oil shipping system, are considered in the paper. The model allows you to analyze the process of carrying out cargo operations, taking into account the time the vessels stood at loading, waiting for the start of cargo operations, the downtime of the platform equipment in anticipation of the tankers arrival. By means of modeling, a statistical analysis of the system operation at specified time intervals is carried out, simulation modeling is carried out with arbitrary distributions of the intervals between the arrival times of ships and their service time, with various disciplines and service parameters. It is noted that solving the practical problem of ensuring the smooth operation of ships on the line, estimating the time intervals of oil loading on the platform under conditions of unsteady traffic flow can be successfully performed by simulating the problems of planning ice pilotage of vessels in the Arctic regions. The operability of the model based on the use of tools of computing environments and digital technologies is determined by the high level of adequacy of the studied characteristics to the real process of organizing the movement of tankers according to the established schedule, taking into account the time of technological operations during oil shipment and changes in fleet composition. Modeling using object programming technologies allows you to study the various schemes of the tanker fleet composition by simulating variable and observable alternating states and make informed decisions based on quantitative estimates of the results of a machine experiment. The program and examples of evaluating the operating parameters on the model are given.

Navigating a Vessel without an Ice Class on the NSR Close to the Front of Ice-free Zone During Ice Melting Period

Navigating a Vessel without an Ice Class on the NSR Close to the Front of Ice-free Zone During Ice Melting Period

Industrial production of natural gas in the North and Arctic regions of the Russian Federation and prospects for its implementation in the EU market

The paper is devoted to the study of industrial production of natural gas in the regions of the North and Arctic of the Russian Federation and the prospects for its implementation in the market of the European Union. It is shown that the main production is concentrated in the Yamal-Nenets Autonomous district, where up to 75% of the total gas production is produced. Gas is transported both by means of a well-developed pipeline network connecting the Yamal Peninsula with European countries, and in a liquefied state, using gas carriers of the appropriate ice class. At the same time, despite all the efforts of the EU countries to reduce energy consumption, gas consumption is growing. This is due to the decline in production within the Union itself, as well as the desire to use more environmentally friendly energy sources. The analysis conducted in the course of the study showed that Qatar and Russia can actually increase the volume of deliveries in the near future. These exporters have a number of advantages that, in our opinion, will allow them to increase their presence in the energy market of the EU countries - significant reserves of natural gas, availability of production capacity, opportunities to increase the volume of transportation, and the most attractive price for end users.

Organizing an oil transportation system in the Arctic

Development of the Arctic has become the subject of intense attention due to the region’s vast hydrocarbon resources. However, severe environmental conditions and large distances greatly increase the development costs. Because of this, it is crucial to organize rational logistics routes within the Arctic communications system. In recent years, Russia has been taking on a leading role in transportation of hydrocarbons, including oil; there is growing demand from the global community for steady supply of Russian crude oil and petroleum products. At the same time, difficult weather and ice conditions along with poor infrastructure make it a challenge to establish a system for offshore transportation of oil in the Arctic. The paper reviews the Russian experience of sea transportation of oil from the Pechora Sea and the Gulf of Ob, describing a scheme using modern shuttle tankers of reinforced ice class. Apparently, ice tankers of Arc6 and Arc7 classes can be used with virtually no assistance from icebreakers provided that ice conditions are relatively favorable. The unique experience of cooperation in transportation projects accumulated by Russian oil and gas operators, shipping and shipbuilding companies, and financial organizations should prove useful for further development of natural resources of the Arctic.

Scheduling Transit Voyages of Vessels of Various Ice Classes Across the Northern Sea Route

Abstract Main problem for scheduling vessel transit voyages through the Northern Sea Route is the difficulty in predicting distribution of ice boundaries in regions that cannot be overcome by individual ice classes of vessels. Scheduling of voyage is related to speed that vessels can develop and moment of time when vessels will be able to commence and complete passage safely through areas that are main obstacle and are blocking longest transit passage through the Northern Sea Route. This applies to voyages carried out by vessels navigating on their own and with support of icebreakers. Additional problem is lack of consistency of content of maps of ice cover, which can be used for vessels voyage planning through areas where ice cover occurs. Results of this research on influence of uncertain information related with time window of conditions favorable for navigation of vessels of different ice classes on schedule of theirs voyage on example of summer navigation season 2017 are presented in this work.

Design features for Arctic ports berths for accepting the ships with a deep draft

Construction of new Arctic ports is a complex scientific and technical challenge. The experience extends to the berths that can accept the vessels with a small draft only during the summer navigation period. Commercial efficiency of shipping in the Arctic seas is possible only with year-round use of large-tonnage vessels of high ice class with a draft of 12 meters or more. The Arctic seas basin is mostly shallow, and the main transport task is the regular export of liquid natural gas and crude oil by shuttle ships. We analyze a currently used berth structures and their operational features. It has been revealed that the berths of the overpass type on piles of shells with a concrete grillage require additional ice protection structures in the port water area, since power loads from the vessel mooring and ice may be critical. The infrastructure of the modern marine port in the Arctic should combine with production and logistics capabilities, since the internal transportation of goods is labor intensive. A mooring structure from the arrays of concrete gravity caisson wharf is proposed, which can be quickly constructed and they can accommodate additional equipment for transporting or transferring cargo. The studies are performed at the Department of Hydraulic Port Construction in Admiral Makarov State University of Maritime and Inland Shipping.

Interannual variability of the ice-free period duration in the southwestern Kara Sea

In the coming years, exploration drilling in the geological structures in the Kara Sea is planned. It will be carried out during the ice-free period using floating drilling facilities of a different ice class. The aim of the work is analysis of the interannual variability of duration of the ice-free period in the area of the geological structures the results of which are necessary for planning operational activity of the drilling platforms and optimization of expenses for exploration drilling on the Arctic shelf. For an assessment of interannual variability of the ice-free period duration in the area of the geological structures there were used data on the dates of water area clearance from ice and beginning of ice formation in the southwestern part of the Kara Sea for the period of 30 years on the basis of the AARI weekly ice charts. An analysis of interannual variability of the ice-free period duration showed that a 20-year summer (1989–2008) and a 10-year (2009–2018) intervals could be identified. It is shown that in the last decade as a result of combination of favorable hydrometeorological conditions the ice-free period duration has increased by more than 1 month. An analysis of the main hydrometeorological factors determining the ice-free period duration indicated that it is possible to perform an assessment of duration of exploration drilling operations in the water area of the East-Prinovozemelsky license blocks with a period in advance of several months. Drilling with the use of ice-resistant drilling platform allows us to extend the operation period, as drilling could be started after disappearance of close ice and finished after the ice thickness growth up to 30 cm.

Experimental testing and simulations of an autonomous, self-propulsion and self-measuring tanker ship model

Improving the energy efficiency of ships has generated significant research interest due to the need to reduce operational costs and mitigate negative environmental impacts. Numerous hydrodynamic energy saving technologies have been proposed. Their overall performance needs to be assessed prior to implementation. A new approach to this evaluation is investigated at model scale which applies an approach comparable to that applied for the performance monitoring of a full scale ship. That is long duration testing that measures power consumption for given environmental and ship operating conditions and can use statistical analysis of the resultant large amount of data to identify performance gains. As a demonstration of the approach, an autonomous, self-propelled and self-measuring free running ship model of an Ice Class tanker is developed. A series of lake based and towing tank tests experiments have been conducted which included bollard pull, shaft efficiency, naked-hull, self-propulsion, and manoeuvrability tests. These investigated the efficiency improvement resulting from changing the ship operational trim and testing different bow designs. An associated mathematical model for the time domain simulation of the autonomous ship model provides an effective tool for data analysis. It has been demonstrated that the use of a suitably instrumented self-propelled autonomous ship model can provide long duration tests that incorporates the influence of varying environmental conditions and thereby identify marginal gains in ship energy efficiency.

극지운항용 선박에 적용되는 방한기술 동향 분석

Ice accretions on the ship equipment and areas are the most common issues for vessels operating in cold climate and ice-covered waters and it has effect on the vessel safety and operability of equipment and systems, thus ship machineries and structures exposed to low temperature environments should satisfy the winterization requirements specified in ice class rules. The main objective of this study is to review the state-of-the-art of winterization trend for vessels navigating in ice-covered waters. The hazard of icing and how ice accretions affect operations and safety are investigated firstly, and then winterized notations for each classification are summarized. In addition, winterization methods currently used in vessels operating in ice-covered waters are investigated for a better understanding of effective approach and its application. This information will provide a framework for future winterization issues to mitigate the ice accretion phenomena.

Особенности расчетов металлоемксоти ледовых усилений нефтеналивного судна при смене ледового класса

This paper discusses the assignment of this or that ice class as per RS system. The calculations have been prepared to develop a universal tool for comparative metal consumption assessment of ice belts aboard ice-going ships, which might be implemented by determination in terms of the two classifications of ice-going ships and icebreakers of all ship parameters that influence, directly or indirectly, on required metal weight of ice belt structures. This approach is illustrated by a case study: calculation of required ice belt size for a tanker to change her ice class. These results made it possible to judge about metal consumption of ice belt structure and suggest a possible way for its optimization. Additionally, cost effectiveness of hull upgrade was compared for the two variants of ice belt design. The conclusions of this paper underline the necessity of automated calculations for fast assessment of metal consumption and repair costs.

RELIABLE AND SAFE ENERGY RESOURCES TRANSPORTATION FROM RUSSIA TO CHINA

Background The most important role of pipeline transport in hydrocarbon raw materials supply to the countries of near and far abroad is obvious and is the subject not only of scientific and economic researches, but also of political research. The interest of Russia and China in the development of bilateral mutually beneficial relations in the field of production, transportation and consumption of energy resources is obvious. First of all, it is oil and gas pipeline transport. The East Siberia - Pacific Ocean (ESPO) oil pipeline has been built and is successfully operating. Construction of the Siberia-1 Power Pipeline (Eastern route) is being completed. The leaders of our countries V. Putin and Xi Jienping have indicated the design and construction of the Siberian-2, or Altai Power Pipeline (Western route). The liquefied natural gas and oil transportation by new ice class ships across the Arctic Ocean (Northern Route) is very promising for the near future. An important object of cooperation is the construction completion of the Amur Gas Processing Plant, which will supply helium and processed gas to China. Our countries also have long-term agreements for the construction of new power plants in Russia to meet the needs of the northern regions of China. Aims and Objectives To study the current state of pipeline transport in Russia and China, to identify existing problems and to propose ways of their solution, which allow to significantly increase the reliability and safety of pipelines, to review promising ideas in the field of diagnostics and repair of linear part of pipelines, to offer recommendations for further research and implementation of scientific innovations. Results There have been developed a scientific and technical concept of increasing the reliability and safety of oil and gas transport from Russia to China, presented the directions of this concept, a list of problems to be solved. These decisions assume high efficiency of technical and organizational measures for application of modern technologies for pipeline systems construction and operation. The concept ensures rational use of natural resources, creation of diagnostic and control systems for facilities, design and construction at the global level, as well as environmental protection, improvement of environmental conditions of pipeline transport facilities and increase of environmental safety of the population.

Variability of Winter Snow Properties on Different Spatial Scales in the Weddell Sea

AbstractThe snow cover on Antarctic sea ice persists during most of the year, contributing significantly to the sea ice mass budget due to comprehensive seasonal transition processes within the snowpack as well as at the snow/ice interface. Consequently, snow on sea ice varies not only in depth but also in particular in its physical characteristics such as snow density and stratigraphy. In order to quantify the heterogeneous nature of the Antarctic snowpack on different spatial scales, that is, small (<10 m), floe‐size (1‐2 km), and regional (seasonal/perennial ice) scales, we present here a case study of snow analyses in the Weddell Sea in austral winter 2013. The resulting high variability of snow parameters in the basal snow layer reveals the need to distinguish between seasonal and perennial ice regimes, when retrieving, for example, snow depth using satellite microwave radiometry. Considering the full vertical snow column, a more detailed distinction of the perennial sea ice regime into, for example, more ice classes is suggested in order to represent the high variability range. For the internal snowpack variability, however, we identify the grain size variability as the main driver, while snow density variations can be neglected. Moving from regional to floe‐size scales, a similar variability range of the studied snow properties is found, suggesting that a large number of snow samples on a few floes is more crucial than covering a large region with fewer floe‐scale measurements. The spatiotemporally heterogeneous variability in snow accumulation, redistribution, and metamorphism is, however, too large to upscale the given findings beyond regional scale.

Numerical and experimental comparison of the dynamic behaviour of superyacht structure

ABSTRACTA new trend in motoryacht design is represented by Explorer vessels; as this new typology encountered a large appreciation among potential owners, many shipyards started to develop new projects in this regard. From the operative point of view the main characteristic, which differentiate Explorer vessels from traditional ones, is the higher strength required by the hull structures in order to be compliant with Ice class rules. On the other hand, in the owner’s perspective, the on-board comfort remains the driving parameter to be fulfilled. Therefore, more detailed studies on the dynamic structural behaviour, supported by experimental investigations, became mandatory. In this paper, a 40 meter ID Ice class superyacht built by Cerri Cantieri Navali (CCN), under delivery at the time being, has been elected as a study case and a comparison between experimental FE vibration analyses has been carried out during the construction period in order to validate the numerical procedure and highlight any criticisms in early design stages.