Underwater radiated noise (URN) from ship propellers has attracted increasing interest in recent years due to its adverse environmental effects on marine life and their communication channels. The environmental concern to reduce shipping noise and the industrial requirements for faster computational tools are driving factors that promote research in the specialized domain of hydroacoustics. This thesis deals with the development of such a computationally efficient numerical tool, which can be used in the prediction of underwater radiated noise in the early design phase of propellers.
The numerical model is developed with two major objectives – versatility in assessing the relative contributions from the major propeller-noise generating mechanisms, and rapidity in prediction of overall noise behaviour. It uses the Farassat-1A solid-FWH formulation of the Ffowcs-Williams- Hawkings equation by defining equivalent acoustic sources on the propeller blade, sheet cavity and tip vortex cavity surfaces. In particular, the application of the solid-FWH formulation to the tip vortex cavity model is the major novelty in this thesis.
The hydrodynamic flow solution is obtained from a potential flow based solver ESPPRO, which includes analytical models of sheet cavitation and tip vortex cavitation. The hydroacoustic numerical model developed within this thesis, DoLPHiN, is a Python-based code that is primarily designed to accept input from ESPPRO; but during the research, the code has also been adapted to read input from the commercial, finite-volume-based Navier-Stokes solver, STAR-CCM+.
The numerical model implementations are verified through analytical case studies for simple geometrical shapes, such as a pulsating sphere and an oscillating cylindrical cavity. The verification study is further extended for propeller geometries by identifying approximate reference solutions in simplified operating conditions. The numerical tool is validated for industrial application through comparison of its noise prediction with model-scale and full-scale noise measurements. Specific characteristics of the propeller noise spectrum are identified in order to evaluate its noise prediction capabilities. The uncertainty factors involved when validating with experimental measurements are also explored in detail. Furthermore, a design study is presented, which shows potential use of the numerical tool in practical propeller design and optimization applications.
Ship collision and grounding events constitute a major hazard for ship operations, and ship collision risk analyses have to be carried out for installations such as offshore structures for extraction of hydrocarbons, offshore wind farms, and bridges spanning waterways. This book provides assessment procedures for ship collision and grounding analysis and includes probabilistic methods for collision and grounding risk assessment, estimation of the energy released during collisions, and prediction of the extent of damage on the involved structures.
The main feature of the book is that it encapsulates reliable and fast analysis methods for collision and grounding assessment and the methods have been extensively validated with experimental and numerical results. In addition, all the described analysis methods include realistic calculation examples so as to provide confidence in their use to eventually conduct the required assessment according to the rules and design codes. The book is intended as a handbook for professionals and researchers in the industry dealing with design and analysis of ships and offshore structures. The book can also be used as a text book for postgraduate courses orientated towards the design and analysis of ship and offshore structures.
Ship collision and grounding events constitute a major hazard for ship operations, and ship collision risk analyses have to be carried out for installations such as offshore structures for extraction of hydrocarbons, offshore wind farms, and bridges spanning waterways. This book provides assessment procedures for ship collision and grounding analysis and includes probabilistic methods for collision and grounding risk assessment, estimation of the energy released during collisions, and prediction of the extent of damage on the involved structures.
The main feature of the book is that it encapsulates reliable and fast analysis methods for collision and grounding assessment and the methods have been extensively validated with experimental and numerical results. In addition, all the described analysis methods include realistic calculation examples so as to provide confidence in their use to eventually conduct the required assessment according to the rules and design codes. The book is intended as a handbook for professionals and researchers in the industry dealing with design and analysis of ships and offshore structures. The book can also be used as a text book for postgraduate courses orientated towards the design and analysis of ship and offshore structures.
The content of Resolution MSC.473(ES.2) can be summarized in five main points and one invitation to IMO Member States.
The first point pertains to the implementation of the Framework of Protocols. The second point pertains to the designation of seafarers as 'key workers' in order to facilitate safe and unhindered movement for embarking or disembarking a vessel. The third point pertains to the consideration of temporary migration measures to ease mobility of seafarers, eg waivers or relaxations of visa or documentary requirements. The fourth point is on the use of prevention measures such as testing crews before embarkation; this requires active conduct by port states, namely providing access to personal protective equipment and testing facilities. The fifth point is on providing seafarers with immediate access to medical care and facilities, as well as with evacuation when the assistance required cannot be provided on board or at port; this aims to prevent humanitarian situations such as casualties on board vessels due to lack of access to intensive care units.
Furthermore, the Resolution invites Member States to designate a National Focal Point on Crew Change and Repatriation of Seafarers ('National Focal Point').
This report presents the results from the project 'Future Fishermen'. The report addresses recruitment challenges in Danish fisheries with a particular focus on the Fisheries School's education. The purpose of the study was to provide a broader and more systematic knowledge base that the industry can use to address recruitment problems and challenges derived from them, e.g. generational change.
The report is based on a literature study and qualitative interviews with students at the Fisheries School (who are apprentices in relation to the internship) and other actors in the fisheries as the central empirical evidence. Along the way, we have sparred with representatives from the three fisheries organizations FSK‐PO, DFPO and DPPO, as well as employees at the Fisheries School. However, the conclusions are solely the authors' own.
The main purpose of the study was to understand young people's values and images of fisheries in order to increase recruitment to (and retention in) Danish fisheries and especially the Fisheries School. In this process, we have addressed 3 overall problem complexes that are important in terms of meeting the recruitment challenges in Danish fisheries: recruitment to the Fisheries School; recruitment to the entire fishing industry; and the Fisheries School's education.
The purpose of this chapter is to introduce the concept of Market Based Measures (MBMs) to reduce Green House Gas (GHG) emissions from ships, and review several distinct MBM proposals that were under consideration by the International Maritime Organization (IMO). The chapter then moves on to discuss the concept of Monitoring, Reporting and Verification (MRV) of CO2 emissions and the distinct mechanisms set up the European Union (EU) and the IMO for MRV. The reason the MBM and MRV subjects are treated in the same chapter is twofold: (a) the MRV discussion essentially started when the MBM discussion was suspended in 2013, and (b) MRV is a critical step for any eventual MBM implementation in the future.
In recent years the issue of sulfur emissions from maritime transport has seen newfound attention. This chapter presents an overview of the main issues of sulfur emissions and the legislative framework that seeks to reduce the sulfur footprint of the maritime sector. It also analyzes potential modal shifts toward less efficient land-based modes which may happen as a result of sulfur regulations and investigates the related potential economic damage to ship operators. To that effect, this chapter presents findings from a recently finished project at DTU and the developed methodological framework that can be used to estimate such modal shifts, as well as to measure the efficacy of policy and ship operators’ measures to reverse such shifts.
The implementation of unmanned vessels will evidently come with its own legal challenges. One of the most crucial of these is the identification of the role and status of the shore-based controller (SBC) for the purposes of determining liability. Different liability regimes apply different legal principles in this regard. This article will explore these issues from the perspective of English law and Scandinavian law.
In this report, the PrimeFish project provides an overview of the European and especially the EU seafood sector in the context of global development; i.e. development in other continents with a focus on large commodity groups for fisheries and aquaculture.
The SEAwise project works to deliver a fully operational tool that will allow fishermen, managers, and policy makers to easily apply Ecosystem Based Fisheries Management (EBFM) in their own fisheries. One of the key uncertainties in fisheries science and management can be linked to (our understanding of) fishermen's behaviour. In this report we describe the project efforts to better understand fisher behavior by assessing literature, interviews and data to advance towards a better representation of fisher behavior in our modelling. A better understanding of fisher behavior is especially needed in the context of change affecting Europe's marine ecosystems. Change is both related to the natural part of the ecosystem (ie climate change) as to the social side of the ecosystem (ie building of wind parks).
To that aim we present nine different case studies in Europe as examples of how fisher behavior has been studied and which factors are (or can be) relevant for a better understanding of fisher behaviour. Each case study ends with a table summarizing the factors influencing behaviour, the categories within that factor and the (potential) application in modeling as well as the implications for management. The table below summarizes the factors found / used in the case studies and the elements (social, cultural, ecological, economic and institutional) to which they relate. A variety of social factors were identified that are promising for use in modelling. A key conclusion is that social data are often context dependent and cannot be copy pasted from one situation to the other and in some cases, additional data needs to be collected. The cases also demonstrate that mixed methods approaches and interdisciplinary approaches are key to get in-depth understanding of fisher behavior in fisheries science.