The Simulator for Arctic Marine Structures (SAMS) has emerged on the foundation of a number of scientific models developed at SAMCoT – Centre for Research-based Innovation - Sustainable Arctic Marine and Coastal Technology hosted by NTNU – as a versatile numerical tool for the analysis of sea ice actions and action effects on Arctic offshore structures. The current capabilities of SAMS allow engineers to analyse icefloe impacts and ice loads on arbitrary marine structures in various environmental conditions; simulations may involve both fixed and floating structures, non-rigid multi floe interactions, ice breaking and ice rubbling, wind, current and propeller-flow effects on both structures and ice. All these capabilities can be combined to model also complex marine operations in the Arctic and subarctic regions. As SAMS can be applied in both full- and model scales, a number of available experimental case studies from the field and ice tanks can be reanalysed with the new simulator to ensure the high fidelity of the simulations and to establish a validation basis. This paper presents several of such case studies and discusses further validation possibilities.

Sea ice forms in a dynamic environment that affects its morphology. This results in the inhomogeneity of ice reflected for example in its thickness variation, flaws in terms of brine channels or cracks, presence of snow cover, and its various deformed states undergoing freeze-thaw cycles. This sea ice inhomogeneity introduces important effects observable in the response of a structure when it is interacting with sea ice. Failure to account for the randomness introduced by the sea ice inhomogeneity would risk producing unrealistic simulations not seen in the actual world. In this paper the proposed approach to model randomness in numerical simulation of ice-induced vibrations is presented. This is achieved by accounting for randomness in the ice crushing force. The study is carried out using a purpose-developed numerical model that simulates the ice-induced vibrations of structures. The model adopts a phenomenological basis that aims to capture the important processes during the dynamic interaction between ice and the structure. Full-scale measurement data is used for comparison in this study.

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.

As offshore activities in the Arctic constitute a relatively new field with only a handful of relevant operations to draw experience from, and since full-scale trials are extremely expensive, there is an expressed need for much more extensive, detailed and cost-efficient analysis of concepts based on numerical simulations. However, until recently simulation tools of sufficient quality to perform such numerical analysis have not existed. The only verification available has been through a limited set of experiments in ice model basins. Today, this has changed, partly through the efforts at the Norwegian University of Science and Technology (NTNU) hosting SAMCoT (Centre for Research-based Innovation - Sustainable Arctic Marine and Coastal Technology), laying the foundation of a versatile and highly accurate high-fidelity numerical simulator for offshore structures in various ice conditions such as level ice, broken ice and ice ridges. Arctic Integrated Solutions AS (ArcISo) is a spin-off company from NTNU established in 2016 with the vision of increasing the technology readiness level of SAMCoT’s numerical models to become a professional software package for the analysis of sea ice actions and action effects on Arctic offshore and coastal structures. This software package is called Simulator for Arctic Marine Structures (SAMS) and it was first released in 2017. This paper introduces the software implementation and the theoretical basis of SAMS, and it discusses the use of full-scale data to validate the simulator.

The research investigates the influence of human expertise on the effectiveness of ice management operations. Ice management is defined as a systematic operation that enables a marine operation to proceed safely in the presence of sea ice. In this study, a method has been applied for assessing the effectiveness of ice management operations in terms of ability to modify the presence of pack ice around an offshore structure. This was accomplished in a real-time marine simulator environment as the venue for a systematic investigation. In the simulator, volunteer participants from a range of seafaring experience levels were tasked with individually completing ice management tasks. Recorded from 36 individuals’ simulations was the extent to which the ice in a defined area was impacted, measured in terms of tenths ice concentration. These responses were then compared to two independent variables: 1) experience level of the participant, categorized as either cadet or seafarer, and 2) ice severity, measured in ice concentration. The results showed a significant difference in ice management effectiveness between experience categories, where effectiveness was defined as the average drop in ice concentration during simulation. Results also showed that the human factor of experience and the environmental factor of ice concentration both had significant effects on average concentration drop. The research provides insight into the relative importance of vessel operator skills in contributing to effective ice management, as well as how this relative importance changes as ice conditions vary from mild to severe. This may have implications for training in the nautical sciences and could help to inform good practices in ice management.

The objective of this paper is to develop a realistic numerical model for ice–pre swirl stator (PSS) structure interaction problem under collision circumstance. PSS structure has been installed in front of a propeller of oil carrier or container vessel operating non-arctic region in order to increase efficiency of propulsion system, which was designed by Daewoo Shipbuilding and Marine Engineering (DSME). Recently, according to increase of port traffic in arctic region, it is being anticipated that market of PSS installed vessel operating in arctic region will be extended to pursue raised ship’s efficiency but in strength point of view, quantified assessment for dynamic interaction between PSS and sea ice is not specified in any design codes or classification rules. This standpoint will be led to an increased demand for the safe structural design of arctic vessel’s PSS structure subject to collision with sea ice. In this study, DSME’s PSS structure design will be introduced and five types of numerical model to represent ice crushing behavior which were well-known though previous study will be investigated. The parameters of each material model of ice will be defined and more realistic numerical model for ice will be proposed through comparison study with experimental results. After that, the results of numerical simulations for a collision between PSS and sea ice with five numerical models using LS-DYNA software will be represented. In here, dynamic responses of PSS and failure behaviors of each ice model at each load case will be thoroughly evaluated. Collision loading scenarios and ice dimension were properly assumed based on polar class rule for propeller-sea ice interaction. Consequently, simplified analytic method and proper numerical model for ice corresponding to PSS-sea ice collision simulation will be proposed and discussed, respectively.

The Flemish Pass is a region off the coast of the province of Newfoundland and Labrador in which large oil discoveries have been made in recent years, making it a promising site for future offshore oil and gas developments. The site is located approximately 200 kilometers North-East of the currently producing Jeanne D’Arc Basin. This results in some additional challenges, including: higher waves and rougher seas on average, longer transit time from shore to any potential production facilities, and an increased risk of sea ice. Crew transfers from Offshore Supply Vessels (OSVs) to current production platforms offshore Newfoundland and Labrador are typically accomplished with a FROG-6 personnel-transfer capsule lifted by a platform-board crane. In current practice, for fixed platforms, this is only done when there is a Significant Wave Height (Hs) of 4.0 m or less, regardless of the OSV being used. In the winter months, this general-purpose approach does not allow for an acceptably high operational fraction of time in which crew transfers could be completed in the Flemish Pass. The FROG-6 capsule has designated operational limits based on the relative velocity between the capsule and the vessel deck, which will vary based on ship size, loading condition, and sea-state. Considering this, a series of geometrically similar OSV hull forms are created to represent the range of currently operating vessels. The developed models are between 70.0–90.0 m long, have a maximum breadth between 17.0–22.0 m, and block coefficients ranging from 0.65–0.79. Using ShipMo3D, a potential flow / panel code seakeeping solver, a 20 minute time history of ship motions is determined for all the modelled OSVs, across the range of sea-states realistically expected in the Flemish Pass. Then, a MATLAB script is used to transform these motions into deck velocities. From these results, the operational limits for crew transfer can be re-defined as a function of ship size, loading condition, and sea-state. This results in higher operability percentages than those achieved from using the flat wave height limit alone, with relatively large variations between differently sized and loaded ships. Further work must be done to officially implement new limits, such as: analysis of additional wave period and height combinations, further analysis of the time between limit exceedances, computational fluid dynamics simulations, “smart crane” modelling, and/or full scale sea trials.

Using wind speeds and sea ice fields from the EC-Earth global climate model to run the WAVEWATCH III model, we investigate the changes in the wave climate of the northeast Atlantic by the end of the 21 st century. Changes in wave climate parameters are related to changes in wind forcing both locally and remotely. In particular, we are interested in the behavior of large-scale atmospheric oscillations and their influence on the wave climate of the North Atlantic Ocean. Knowing that the North Atlantic Oscillation (NAO) is related to large-scale atmospheric circulation, we carried out a correlation analysis of the NAO pattern using an ensemble of EC-Earth global climate simulations. These simulations include historical periods (1980–2009) and projected changes (2070–2099) by the end of the century under the RCP4.5 and RCP8.5 Representative Concentration Pathway (RCP) forcing scenarios with three members in each RCP wave model ensemble. In addition, we analysed the correlations between the NAO and a range of wave parameters that describe the wave climate from EC-Earth driven WAVEWATCH III model simulation over the North Atlantic basin, focusing on a high resolution two-way nested grid over the northeast Atlantic. The results show a distinct decrease by the end of the century and a strong positive correlation with the NAO for all wave parameters observed.

Using autonomous underwater vehicles (AUVs) for mapping the underwater topography of sea-ice and icebergs, or detecting keels of ice ridges, is foreseen as an enabling technology in future Arctic offshore operations. This paper presents a method for online iceberg drift estimation using a Simultaneous Localization and Mapping (SLAM) approach using an AUV with a multi-beam echosounder (MBE) during such survey/monitoring operations. Iceberg drift is affected by wind, current, and Coriolis forces. This can be hard to predict, making automated mapping of icebergs difficult. The method proposed in this paper estimates the iceberg’s pose using a particle filter, where each particle uses extended information filters to estimate the topography of the iceberg. A grid map is used to store the iceberg topography, and distributed particle mapping is used to avoid expensive copy operations during particle resampling. The proposed method is verified through a simulation study, using a 6 DOF AUV model, an MBE sensor model, and an iceberg topography taken from the PERD iceberg sightings database. The method is able to provide a georeferenced iceberg position, thus, estimating the iceberg’s drift trajectory. A topography estimate of the iceberg, corrected for iceberg drift, is also generated. Furthermore, the algorithm estimates the iceberg drift velocity, as well as the relative iceberg-AUV pose, for use in future iceberg mapping guidance algorithms. The simulation study illustrates the performance of the method, and a short execution time analysis is presented to illustrate the method’s real-time potential.

It is inevitable that commercial shipping and oil and gas resource exploitation activities in the Arctic will increase due to decreasing sea ice extent caused by global climate changes. Significantly more demanding and at the same time less well known environmental conditions create a need for reliable methods to assess icebreaking performance guaranteeing safe performance of the ships operating in this area subjected to various ice conditions. The classic approach of assessing ice-going performance, which combines class rules, experience and model tests, may not be applicable for the Arctic region in full. Furthermore, ship yards experience difficulties due to decreasing time frames and financial restrictions. Therefore this paper seeks to introduce a new development for a realistic and validated direct simulation approach for prediction of the hull load and icebreaking resistance that covers all aspects of the industrial design process and allows a more comprehensive analysis. The breaking model will provide a variable breaking pattern and is able to mimic the influence of the vessel speed and the environment on the ice loading and the predicted breaking length. In order to predict the extreme representative conditions to be simulated, a reverse extreme load prediction methodology is incorporated. An efficient, time dependent dynamic coupling between broken ice fragments, ice features, the 3D flow field and the ship’s hull provides resistance values for performance calculations. The computational model will be validated against full-scale data and class rules using deterministic and probabilistic measures. This simulation approach is developed within international research collaboration between Pella Sietas, Rolls Royce Marine, TUHH and NTNU. An overview of the project together with the current status of the ongoing work including first results is presented.

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.

Ship navigation performance in the Arctic ice-covered sea was investigated from various kinds of satellite data and a numerical model of sea ice. The effect of dynamical processes of ice on the performance was especially examined, for it was not focused enough in previous studies. As a result, it was found that ice stress can explain some parts of the navigation when high amount of speed reduction occurred in thin ice area, and vice versa. The result indicates an importance of considering dynamical processes of ice in addition to static condition of ice, to improve an accuracy of an ice navigation performance estimation.

The marginal ice zone (MIZ) is the outer part of the sea-ice covered ocean, where ice can be found in the form of large floating chucks better known as floes. Since it is the area where the most part of the interaction between ice cover and ocean waves takes place, it requires careful modelling. However existing mathematical models, based on the traditional thin-plate theory, underestimate waves attenuation for the most energetic waves, since the energy dissipation occurring during the process is not taken into account. New laboratory experimental and direct numerical models are presented here. In the experimental model a thin plastic plate is tested under the action of incident waves with varying amplitudes and periods. The same experimental set-up was reproduced using a numerical model, which was developed by coupling a High Order Spectral Numerical Wave Tank with the Navier-Stokes solver IHFOAM. Data from the experiments and numerical models confirm that non-linear effects lead to a decrease of wave transmission.

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.

Sea ice can interact with offshore structures in regions with at least seasonal ice coverage. Therefore the prediction of ice loads on offshore structures is required by many standards or classification rules and guidelines. In order to do this, empirical formulas are often prescribed. These are based on assumptions in combination with model or full scale tests. Yet there are very few publications where the results of the formulas are actually compared to measurements. A case study is made for ice loads on the Norströmsgrund lighthouse. First of all current empirical formulas given by standards bodies or classification societies are reviewed with focus on applicability. Secondly, the ice loads predicted by the empirical formulas are compared to measurements. It was found that for the given case most methods significantly overestimate the load. The applicability of some methods is disputable.

Co-occurrence probability analysis of sea ice between adjacent areas is very helpful for the hazard prevention and protection strategy making of coastal and offshore engineering. Yingkou and Huludao with similar latitudes are located on the opposite sides of Liaodong Bay of China. Their sea ice conditions are both apparent in winter and early spring, so it is useful to study on the co-occurrence situations of sea ice conditions between these two areas. Based on the annual maximum sea ice thickness of Yingkou and Huludao observation stations, the co-occurrence probability analysis of sea ice thickness is conducted. The joint probability distributions of sea ice thickness between these adjacent areas are constructed by using univariate maximum entropy distributions and four bivariate copulas. Both marginal curve fittings are very well, and the model determined by Gumbel-Hougaard copula describes the bivariate sea ice thickness data best. Then different cases of co-occurrence probabilities of sea ice thickness between Yingkou and Huludao are presented, and they can provide references to the hazard protection of the coastal and offshore structures between these two areas.

The metocean conditions in the Barents Sea entail lower temperatures, and more snow and icing on offshore structures than what can be expected further south on the Norwegian Continental Shelf. The conditions are not considered extreme compared with other Arctic waters, but low temperatures, accumulation of snow and icing on structures and equipment may affect operations and equipment functionality. To manage these issues and ensure a safe working environment, winterization of installations is necessary. This article describes some results from a winterization study executed for the Petroleum Safety Authority Norway. The study objective was to provide an overview of known solutions and measures for winterization related to low temperatures, snow and icing for drilling rigs and production platforms operating in the Norwegian part of the Barents Sea. The study also describes solutions and measures that may be applicable at different locations in the Barents Sea, and available standards and guidelines related to winterization. Issues related to sea ice, bergy bits and icebergs have not been addressed. As a part of the study, winterization standards and manuals for drilling rigs and production platforms were reviewed, along with available experience from previous and ongoing projects. The information was systematized, and a high level summary produced. The results showed that the main issues related to low temperatures, snow and icing for rigs and platforms operating in the Barents Sea can be simplified and summarized as follow: 1) Snow and icing on exposed surfaces. 2) Freezing of fluids in piping/equipment/tanks. 3) Personnel exposure to low temperatures and weather. These issues were further categorized to include typical areas and equipment types. Several solutions and measures were identified for each of them. The study showed that most of the identified solutions and measures are applicable for most locations in the area open for petroleum activities. However, more permanent and robust solutions should be selected for the coldest areas, as icing rates increases, and wind chill temperature decreases with lower temperatures. The review of winterization manuals also showed the importance of implementing organizational and operational measures related to winterization. Education and training in proper use of winter technology, and defensive behaviour with respect to falling ice and slippery surfaces were identified as some of the most important measures to avoid incidents. Checklists for inspections, before and during the winter season, are important measures to secure areas and equipment when temperatures fall towards freezing point. The study results show a large variety in available solutions and measures for each issue. These shall, combined with organizational and operational measures, ensure safe operations in the Barents Sea. The study shows that the challenge is not whether solutions and measures exist, but in finding the right combination of them for different conditions at specific locations.

This paper provides a statistical description of the sea ice occurrence in the Barents Sea, using yearly maximum sea ice data for the last 36 years from the European Centre for Medium-Range Weather Forecasts (ECMWF). A set of four distribution functions have been estimated with the maximum likelihood method. The distribution functions used were Extreme Value distribution, Gumbel distribution, Normal distribution and kernel density estimation. The normal distribution was found to fit the data best and provide the most likely result. Our results verify dependency of the North Atlantic current on the sea ice edge. Warm water northwards prevents the ice from extending south; this makes the extreme value distribution unlikely since this will prevent long tailed distributions. The results for sea ice occurrence are compared to the boundaries given in the proposed revision to NORSOK N-003. These boundaries were found to be too simplistic and not necessarily conservative. Here we have proposed new and more accurate boundaries for the sea ice occurrence. We have found trends indicating northwards movement of the sea ice edge in the Norwegian Sea and eastern parts of the Barents Sea. These trends are mostly due to less ice in the last ten years and not trends for the whole period. In the south-western parts of the Barents Sea where oil and gas operations are imminent no trends have been discovered. The lack of trend is related to the islands in the western Barents Sea.

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.