Search

A Reynolds averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) model is built to investigate the hydrodynamic response of a circular ice floe under the influence of a passing ship in calm waters. The ship, mirroring the KRISO Container Ship’s hull design, progresses near an ice floe whose diameter is 30% of the ship’s length and its thickness is 3 m. The ship advances at a constant speed, which is handled by using the overset mesh technique. This study focuses on the ice floe’s motions and the hydrodynamic forces induced by three speeds and three transverse distances of the passing ship. Findings reveal that ship-generated wakes notably influence the ice floe’s motions, with a greater influence on sway than surge. Additionally, the ship’s speed and proximity distinctly affect the ice floe’s motions.

An automated process is proposed for horizon detection and tracking using machine vision cameras and in polar, sea-ice conditions. These conditions present unique challenges for machine vision applications, such as a large amount of clutter (e.g. icebergs) and secondary edge lines from broken ice pieces. The process is divided in two parts: a more computationally expensive, yet robust detection algorithm in the first stage, based on Convolutional Neural Networks, and used to detect the horizon line in an arbitrary sea-ice image; followed by a tracking algorithm, responsible of efficiently detecting the horizon line in the subsequent images of a sequence. We propose two tracking algorithms, one based on the traditional Canny and Hough line detection methods; and a second novel approach using entropy as a measure of randomness, to segment between sea-ice and sky. Our automated process was compared to manually obtained ground-truth data and the results indicate good agreement, especially for the texture-based tracking algorithm.

Maritime activity in the Arctic is on the increase, driven by the extraction of natural resources, trans-Arctic shipping, and tourism. To manage the risks to humans and the polar environment, in 2017 the IMO enforced the International Code for Ships Operating in Polar Waters (Polar Code). The safety provisions of this Code are fundamentally goal-based, allowing designers to deviate from established prescriptive safety rules, facilitating design optimization and innovation. However, to enable goal-based design, ship designers need relevant and validated design tools. In this paper, we present examples of such tools, namely (a) accident statistics, (b) a framework for risk-based design of Arctic ships, (c) a simulation model of a winter navigation system, and (d) a sustainability assessment tool for Arctic shipping. The results are based on three different European Union funded research projects (SEDNA, WINMOS I/II), as well as on the Lloyd's Register Foundation funded project CEPOLAR.

ABSTRACTWhile society benefits from Arctic shipping, it is necessary to recognize that ship operations in Arctic waters pose significant risks to people, the environment, and property. To support the management of those risks, this article presents a comprehensive approach addressing both short-term operational risks, as well as risks related to long-term extreme ice loads. For the management of short-term operational risks, an extended version of the Polar Operational Limit Assessment Risk Indexing System (POLARIS) considering the magnitude of the consequences of potential adverse events is proposed. For the management of risks related to long-term extreme ice loads, guidelines are provided for using existing analytical, numerical, and semi-empirical methods. In addition, to support the design of ice class ship structures, the article proposes a novel approach that can be used in the conceptual design phase for the determination of preliminary scantlings for primary hull structural members.

This paper aims to identify the gap between cruise passengers' expectations and the on-board experience (referred to in the text as 'the on-board experience gap') in the context of on-board environmental factors and overall satisfaction. It also investigates the relationship between cruise passengers' pre-cruise expectations and their post-cruise experience. The study adopts a comparative approach that examines three classes of cruise ships through open-source data (N = 2649). The aim of the comparison was to understand what creates a gap between cruise passengers' expectations and the on-board experience, and to explain why some cruise ships are more successful than others. The result of this paper concludes that some of the cruise experiences are not aligned with the customers' expectations, and the on-board experience gap is also clearly observed between the elements. This on-board experience gap concept can be used to provide a dynamic procedure to measure the customers' cruise experience.

A sensor instrumentation and an automated process are proposed for sea-ice field analysis using ship mounted machine vision cameras with the help of inertial and satellite positioning sensors. The proposed process enables automated acquisition of sea-ice concentration, floes size and distribution. The process contains pre-processing steps such as sensor calibration, distortion removal, orthorectification of image data, and data extraction steps such as sea-ice floe clustering, detection, and analysis. In addition, we improve the state of the art of floe clustering and detection, by using an enhanced version of the k-means algorithm and the blue colour channel for increased contrast in ice detection. Comparing to manual visual observations, the proposed method gives significantly more detailed and frequent data about the size and distribution of individual floes. Through our initial experiments in pack ice conditions, the proposed system has proved to be able to segment most of the individual floes and estimate their size and area.

ABSTRACTFull-scale measurements on polar research vessels present an opportunity to advance the state-of-the-art in ship design through high-quality long-term measurements of environmental conditions and ship responses. The approaches, data analytics and synoptic results are presented for a comprehensive measurement campaign on a modern polar supply and research vessel, the SA Agulhas II. It is recognised that the real-time analysis and utilisation of such measurements could benefit the insightful operation and management of this vessel. To this end, the conceptual design of a monitoring and decision-aiding system is presented. Results indicate that significant potential beckons in the integrated acquisition, analysis and utilisation of full-scale ship-board measurements provided that this diverse data can be aggregated, analysed, visualised and interpreted in real time.

ABSTRACTTo achieve increasing emission requirements, the cruise ship industry is working to develop higher efficiency ships. Cruise ships are different from other ship types in their relatively higher consumption of electrical power, steam and hot water. Several novel high-efficiency system concepts are possible for on-board electrical power generation and other utility services, each with differing impacts and first costs. Low-emission concepts novel to the cruise ship industry include combinations of exhaust gas heat recovery, heat pumps, steam turbines and organic Rankine cycles (ORCs). Yet, evaluation of these concepts is difficult given the different operating modes of cruises, and overall efficiency is dependent on the dynamic operational sequences. In this paper, we compare alternative energy efficiency concepts for cruise ships through simulation studies of the ship operations when equipped with different novel power generation systems. We find that the dual pressure steam systems and ORC offer the greatest potential for energy efficiency improvements in the cruise ship industry. We also find that relatively conventional technologies enable cruise ships to comply with planned upcoming higher ship energy efficiency requirements.

ABSTRACTTransportation in ice-prone waters is a timely topic because of the pursuit of natural resources and sea routes. S.A. Agulhas II voyaged in Antarctic waters during the austral summer of 2013–14. This paper studies how the local ice-induced loads on the ship bow are affected by different ice and operational conditions. A hierarchical Gaussian process model was used to study how the load distribution parameters change in different conditions. The operational conditions are described by ship speed, whereas the ice conditions varied from thin, first-year ice, to thick, multiyear ice. Because of this variation, the ice conditions are not represented by ice thickness alone but also by latitude, temperature and voyage time which represent the unmeasured ice strength. The predicted loads from the model match well with the measured loads. According to the model, loads increase in higher ship speed and ice thickness combination, further south, later in the summer and in higher temperatures.

Selection of suitable ice class for ships operation is an important but not simple task. The increased exploitation of the Polar waters, both seasonal periods and geographical areas, as well as the introduction of new international design standards such as Polar Code, reduces the relevancy of using existing experience as basis for the selection, and new methods and knowledge have to be developed. This paper will analyse what can be the limiting ice thickness for ships navigating in the Russian Arctic and designed according to the Finnish-Swedish ice class rules. The permanent deformations of ice-strengthened shell structures for various ice classes is determined using MT Uikku as the typical size of a vessel navigating in ice. The ice load in various conditions is determined using the ARCDEV data from the winter 1998 as the basic database. By comparing the measured load in various ice conditions with the serviceability limit state of the structures, the limiting ice thickness for various ice classes is determined. The database for maximum loads includes 3-weeks ice load measurements during April 1998 on the Kara Sea mainly by icebreaker assistance. Gumbel 1 distribution is fitted on the measured 20 min maximum values and the data is divided into various classes using ship speed, ice thickness and ice concentration as the main parameters. Results encouragingly show that present designs are safer than assumed in the Polar Code suggesting that assisted operation in Arctic conditions is feasible in rougher conditions than indicated in the Polar Code.

ABSTRACTStructures used in Arctic regions must comply with ice-induced loading without failure, asset loss, or loss of life. Current structural design regulations, particularly for ships, rely primarily on the experience gained from first-year ice, e.g. in the Baltic Sea. Therefore, this paper presents first, the most relevant design rules for both ships and offshore structures, and second, first principle-based pressure and occurrence determination methods to obtain corresponding scantlings. To demonstrate these first principle-based methods, the design ice load is assessed for a transit operation along the Northern Sea Route. In conclusion, this paper seeks to motivate a more mission-based design methodology, in addition to the present design methods, using the presented first principle-based methods. The paper is based on the ISSC 2015 V.6 Arctic Technology committee report.

The maritime transportation industry currently employs several mandatory and non-mandatory norms of organizational safety management. These safety norms are commonly included in integrated maritime safety management systems, which aim at developing, monitoring, controlling and improving the safety of all related shipping operations. These systems are typically evaluated by following key performance indicators, which enable defined measures for various safety management components. However, the identification of indicators addressing safety management requirements constitutes a complex and generally unsystematic process for safety managers in the maritime industry. This article proposes a new method to assess the guidelines available in maritime safety management norms. The proposed method is applied to assess the content of two maritime safety management norms. The aim of this assessment is to identify a set of maritime safety management indicators that can systematically measure the most relevant components of maritime safety management. The application of this method resulted in the identification of 53 key performance indicators for monitoring and reviewing 23 identified safety management components that are commonly integrated into the functioning of maritime safety management systems. The method proposed provides guidance to accurately capture the actual aim and function of the key performance indicators. Furthermore, the indicators and safety components obtained with this method can be adopted as the basis for a safety management system and/or for the analysis of a safety management system already established in the industry.

Uncertainty is inherent to risk analysis. Therefore, it is extremely important to properly address the issue of uncertainty. In the field of risk analysis for maritime transportation systems, the effect of uncertainty is rarely discussed or quantified. For this reason, this article discusses a case study dealing with risk analysis for a chemical spill in the Gulf of Finland and analyses the related uncertainties by adopting a systematic framework. Risk is assessed in terms of the expected spill frequency and spill volumes caused by collisions between ships and chemical tankers in the Gulf of Finland. This is done by applying a collision consequence with a novel approach-to-collision-speed linkage model and Gulf of Finland–specific causation factors, which are based on reanalysing accident data. This article also presents a metamodel for assessing collision probability with initial vessel speeds for any given scenario where a chemical tanker is about to be struck by another vessel. Even when conducting a risk analysis using state-of-the-art methods, there is still a medium-high degree of uncertainty in the model presented in this article, which only becomes apparent when conducting a systematic uncertainty assessment analysis. However, an uncertainty assessment is an important part of quantitative maritime risk analysis. For this purpose, a qualitative framework for uncertainty assessment analysis is introduced for general use in the field of maritime risk analysis.

Ship grounding accidents, being one of the major types of maritime accidents, are significant failures putting in danger maritime transportation systems. Moreover, the risks associated with those failures can be catastrophic for the system, society, and the environment. This highlights the importance of appropriate methodology for assessing and managing the associated risk. Many scholars have introduced a wide range of methods for modeling the risk, utilizing the concept of the probability and the consequence of an accident; however, those models very often employ critical assumptions on the behavior of maritime transportation systems, which may seem not to be supported by evidences. This in turn limits models' ability to mitigate the risks, as those simply remain unknown. Therefore, this article has three aims. First, it proposes a methodological framework suitable for knowledge-based risk modeling, fulfilling the recommendations given by the Formal Safety Assessment issued by the International Maritime Organization. Secondly, it thoroughly reviews and discusses all the existing risk models available in the literature developed for ship grounding risk analysis in light of the proposed risk perspective. Third, the models that are more appropriate for risk management and decision making are highlighted and the recommendations are given to future model developments.

The bending strength of the sea ice cover is crucial in the design of ice-going vessels. Therefore, a series of in situ four-point bending tests have been performed earlier, which are now utilized to present a particle swarm optimization–based procedure to identify the material parameters needed for numerical simulations. The resulting numerical simulations are found to comply well with the experimental results in terms of force, failure time, and displacement. Therefore, it can be concluded that the presented optimization-based material parameter identification procedure can also be used in the future if similar material parameters are to be found.

When considering the implementation of a novel risk-control option, the estimation of its possible effects often relies on expert elicitation. This article presents an expert-knowledge–based preliminary assessment of how the deployment of Enhanced Navigation Support Information navigation service would affect the ship collisions and groundings in the Gulf of Finland. Experts probabilistically assess the service’s direct effects on various factors, which are then utilized in collision and grounding probability Bayesian network models. The results indicate that implementing the Enhanced Navigation Support Information service could decrease the number of accidents. However, a comparison of the model outcomes to the experts’ qualitative opinions reveals some discrepancies, which suggest that the elicitation procedure or the applied models might require further improvement. Nevertheless, with the proposed Bayesian approach, the model can be updated and uncertainties in the estimates reduced after more evidences are available later from longer and wider use of the service.

Chemical tanker traffic constitutes a hazard for the environment; large chemical spills caused by, for example, ship–tanker collisions can have catastrophic effects in similar manner to oil spills. For this reason, it is important to have a generalized spill model for chemical tankers, so that the spill size for a given geographical area can be assessed. The spill volume can be used as an indicator of risk in the given area. Furthermore, such a model can be used to analyze the possible effects of potential risk-mitigating measures such as requiring wider double hulls for chemical tankers. In this article, a spill model is proposed, which for a given collision scenario can model the penetration, spill probability, and size caused by a ship striking a chemical tanker. This is done using finite element method, MATLAB, and statistical metamodels with ship particulars extracted mainly from automatic identification system data from the Gulf of Finland.