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The safety of life at sea is a top priority in maritime operations. Therefore, essential procedures and regulations are enforced to prevent loss of life. However, human error is one of the main contributors to accidents in safety-critical industries. For a human reliability assessment in the maritime domain, the main question is how we correctly understand the human factors in the maritime situation practically. This research study aims to develop practical frameworks, which are different optimal combinations of analysis methods corresponding to the different research scope, to evaluate human errors in maritime operations that can more cleverly be identified, quantified, and integrated into the probabilistic risk assessment. Thus, achieving the aim is expected to improve overall safety within the maritime domain. This research proposes four human reliability assessment frameworks corresponding to maritime systems' different complexities and interactions. Firstly, this study introduces the Bayesian CREAM framework, which is a method of determining the contextual mode for overall human error probability estimation. This method aims to determine the need for more specific HRA research and to support the quick analysis required by providing a simple and imminent calculation method. Second, the CREAM-based framework is developed to extend human errors to various human activities. This method minimises the expert's subjectivity while achieving a quantified human failure probability with a systematic and logical approach. Third, the SPAR-H-based framework is proposed to integrate human errors into a probabilistic risk assessment framework. This framework offers a new approach to human reliability, assessed through a customised reliability block diagram analysis to provide a new risk model. Finally, for a complex modern socio-technical system, a hybrid method is proposed to assess system reliability by combining the System Theoretic Process Analysis (STPA) and the Success Likelihood Index Method (SLIM). The proposed frameworks were applied to emergency response operations, including emergency steering, engine room fires, man overboard, and emergency shutdown system for the LNG bunkering process. The various frameworks established for human reliability evaluation will contribute to the wider utilisation of human reliability assessment, ranging from simple and convenient analysis performed by ship's crew to complex analysis performed by expert human reliability analysts. Eventually, this study will enhance maritime safety by analysing human errors, identifying further problems, and adopting safety measures.

Inadequate machinery maintenance and inefficient sailing performance comprise two major hindrances to vessel operational sustainability and profitability. To ensure that vessel operation remains competitive while its environmental impact is mitigated, the development of a systematic approach for vessel monitoring and operational enhancement is required. Currently, the maritime industry predominantly operates on a hybridisation of corrective and preventive maintenance, along with monitoring and decision making based on past experience. More intelligent, data-driven approaches are slowly permeating the industry; these offerings however remain largely rudimentary, retaining considerable assumptions and data requirements for their application. In this respect, this thesis aims to enhance operational efficiency in the maritime industry through the development of an integrated machine learning framework combining efficient and robust machinery anomaly detection, vessel performance degradation monitoring, and routing decision support. This is achieved through a number of key objectives, including: a) the identification of research gaps; b) the extraction of meaningful information for available data sources; c) the monitoring of machinery condition and detection of incipient anomalies; d) the identification of optimal data-driven Fuel Oil Consumption (FOC) modelling architectures; e) the monitoring of vessel performance based on FOC modelling; the facilitation of optimal routing through a suitable Decision Support System (DSS); and f) the demonstration and validation of the above through appropriate case studies. The proposed aim and objectives are accomplished through the combination of a robust pre-processing methodology with a number of data-driven modelling methods (e.g. One-Class Support Vector Classifiers (OCSVCs), Deep Neural Networks (DNNs)), and a novel modification of Dijkstra's algorithm. A key novelty aspect of this proposed framework is derived by the development and combination of a number of data-driven methodologies for the operational efficiency enhancement of a vessel. Moreover, a novelty of the approach lies upon the minimisation of the inherent assumptions required, streamlining its use in a diverse set of applications. In the same vein, a novel aspect of the proposed framework concerns its flexibility to operate using datasets from different sources, exhibiting different levels of granularity and frequency. This framework is applied to a number of case studies, covering data pre-processing, engine condition monitoring, a FOC modelling comparison, FOC-based performance monitoring, and optimal routing. This helps verify the framework's robustness in a range of realistic scenarios applicable to a variety of vessel types (e.g. reefer, containership, bulk carrier). These case studies, among others, demonstrated the robustness of the anomaly detection methodology when examining different parameters and systems, the accuracy deviation when predicting a vessel's FOC using Automated Data Logging & Monitoring (ADLM) or noon-report data and the optimal models for each case, a successful evaluation of the performance monitoring methodology as a vessel's fouling increases; and the identification of optimal routes as a vessel sails from the Gulf of Guinea to Marseille anchorage.

Digital design of engineering systems, using Computer-Aided Design (CAD) tools for developing and optimising products, has been used in the manufacturing process since 1957, when Patrick Hanratty built the first commercial numerical-control programming system known as PRONTO, while he was working for General Electric. One year later, the French physicist and mathematician Paul de Casteljau invented a system based on the use of Bernstein polynomials, during his employment with the French automobile manufacturer Citro¨en. In 1968, another French engineer named Pierre B´ezier, launched on behalf of the automobile manufacturer Renault the CAD/CAM UNISURF system for surface design, which was fully in use by 1975. The stepping stone of Computer-Aided Ship Design (CASD) was set in 1963, when the Norwegian CAD/CAM software Autokon was first used, developed by Trygve Reenskaug. It was 14 years later when parametric modelling in ship design introduced by Prof. H. Nowacki who pioneered in CASD via coupling form parameters with the then novel technology of B-splines. Since then, Parametric Modellers (PM) play a crucial role in the development and -most importantly- shape optimisation of free-form objects with increased complexity such as ship-hulls, for they have to represent robustly and efficiently every solid object. The purpose of the current work is three-fold: Firstly, it is meant to develop and present the corresponding methodology of two tools: a) an innovative, robust, and cost-efficient parametric modelling tool for container and tanker ship-hulls, which are hull forms of increased complexity. The tool is named TshipPM and is an extension of the work presented in, b) a ship-hull shape optimisation tool based on geometric criteria, namely volume moments up to 2nd order. Secondly, to evaluate the performance of TshipPM by comparing it with a wellestablished, commercial parametric modelling tool, CAESES®1 , opting for its NURBS functionality. Finally, was to provide an easy to follow "handbook" for developers and users on the development of parametric modelling tools, illustrating as well how a PM can be utilised for the construction of a given ship-hull. The key findings of the current work which also coincide with the main objectives, are: A method of constructing a T-splines-based parametric modelling tool (TshipPM) for complex ship-hull design, the development of which is taking into consideration the detailed characteristics of two different ship-hull types, i.e., tankers and containers. A set of geometric and design constraints imposed to TshipPM to tackle the intricate and complex issue of Geometric Validity, ascertaining the production of valid models for the whole design space the modeller covers. A step-by-step method to remodel (using TshipPM) a great variety of complex hulls with complexity not-higher than that of tankers and containers. The exceptional performance of TshipPM. A comparative study is conducted to evaluate the performance of TshipPM against CAESES, a well-established commercial parametric modeller for ship design. This work is published in the Ocean Engineering2 international journal, titled "A T-splines-based parametric modeller for computer-aided ship design". A method for ship-hull shape optimisation with respect to geometric criteria and especially volume moments up to 2nd order, utilising TshipPM and a multiobjective Teaching-Learning-based optimisation tool. This part of the work also stresses the insufficiency of 2nd order moments to perform as complex-shape optimisers. TshipPM is a parametric modelling tool for ship-hull design under geometric and design constraints. It uses as a mathematical representation of surfaces -and to some extend solids- the fairly new technology of T-splines, introduced by Sederberg et al. in 2003, which constitutes a generalisation of NURBS, exhibiting several advantages over the latter. T-splines technology aids towards the development of modellers for complex ship forms, by providing geometrically valid objects with smooth surfaces and increased fairness throughout the model's surface, and much lower complexity in comparison with PMs employing the standard NURBS technology. TshipPM uses 27 external (or input) parameters to produce the control cage of the ship-hull, 3 of which are global and dimensional, while 24 are non-dimensional and of local nature. It employs Autodesk® T-splines plug-in® v.4.0 for Rhino5® 3D to create the final, smooth T-splines surfaces using as input the control cage created by TshipPM. The PhD thesis consists of 6 Chapters, structured in the following way: The Novelties of the current work and its contribution to the field of parametric modelling in CASD. Chapter 1, after a brief discussion on the historical background of splines, it delivers a comparison between T-splines, the representation underlying TshipPM, and NURBS, the industrial standard in CAD, which is also used in the context of CAESES (§1.1). In addition, it introduces the reader to parametric modelling, reviewing in brief the main advancements in the field (§1.2). Chapter 2, after the necessary introduction to TshipPM's features and characteristics (§2.1), analyses the structure of TshipPM regarding the parameters involved (§2.2), making the distinction into internal and external, dimensional (or physical) and nondimensional. §2.3 demonstrates the process of creating a ship-hull model, starting from building the control cage along with its link to external parameters, which are used as input for TshipPM, up to its conversion into the resulting ship-hull surface with the aid of T-splines plug-in. Chapter 3, after a brief introduction on the importance of robust PMs (§3.1), defines the constraints encountered in ship-hull design and introduces the reader to the concept of geometric validity, illustrating examples of invalid ship-hull models (§3.2). §3.3 presents the geometric and design constraints imposed to TshipPM to ascertain its robustness as far as the production of geometrically valid models is concerned. In §3.4 we provide an experimental indication of the robustness of TshipPM in its response to strong parameter values variation. Finally, in the last section (§3.5), we present the output of a Monte Carlo sampling of 200,000 ship-hull instances produced by TshipPM for both containers and tankers, and we analyse its output information to determine the design space of the PM, by measuring TshipPM's flexibility with regards to geometric characteristics, namely volume centroid and moments of inertia. Chapter 4 begins by stressing the need of remodelling a given ship-hull with PMs to use it as basis for optimisation (§4.1), while §4.2 refers to the remodelling evaluation criteria. The remodelling process is thoroughly described in §4.3 using as a case study the MOERI KCS container ship-hull, and aims to the reconstruction of a parent ship-hull CAD model; we use TshipPM for the construction of model's control cage and we feed it into Rhino5 to create the corresponding surfaces with the aid of the T-splines plug-in. Finally, in §4.4 the evaluation of the remodelled MOERI KVLCC tanker [10] ship-hull is conducted, under a predefined set of criteria, providing feedback to users and developers for any adjustments and their specific locations. The evaluation of MOERI KCS container hull is conducted in Chapter 5. In Chapter 5, TshipPM is compared against CAESES with regards to their outputs against a parent hull, the KCS container ship-hull, which has been extensively used by the research community for CAD and Computational Fluid Dynamics (CFD) benchmarking purposes. The comparison criteria are described in §5.1. §5.2 presents the basic characteristics of the CAESES parametric modelling tool, as well as a description of the physical (or dimensional) parameters CAESES uses to remodel KCS ship-hull and the corresponding external non-dimensional parameters, while §5.3 refers to the common external parameters both PMs use. Finally, in §§5.4 - 5.8 the comparison of both PMs is conducted. Lastly, Chapter 6 presents an in-house, C#-built, shape-optimisation tool using TshipPM and an adjusted to the needs of the current work Multi-objective TeachingLearning-based Optimisation (MO-TLBO) method. TshipPM MO-TLBO is optimising the shape of a given hull (MOERI KCS) against a set of ship-design criteria, and especially volume moments up to 2nd order. After the required introduction to the chapter (§6.1), a brief presentation of the TLBO method is conducted (§6.2). The set of the objective functions against which the optimisation is conducted is provided in §6.3, while in §6.4 the method of building TshipPM MO-TLBO, its features and functionality are presented in detail. The chapter concludes with §6.5, illustrating the resulted KCS-ship-hull instances produced by TshipPM MO-TLBO. The thesis concludes with the Discussion and Summary of the current work, highlighting its key points, stressing the delivered novelties and main contributions to the field of parametric modelling in CASD.

Global climate change is presenting opportunities for new networks of maritime transportation through the Arctic. However, these sea routes are often infested by floating sea ice, which brings uncertainties to shipping operators, designers and builders. This work aimed to develop reliable simulation approaches for shipping scenarios in the presence of sea ice and investigate the associated changes to ship calm water resistance. For this purpose, computational fluid dynamics and ice solid mechanics were combined to model the potential ship-wave-ice interactions. Specifically, models were developed to simulate the two primary scenarios of a cargo ship operating in the Arctic, respectively a waterway with floating ice floes and an open-water channel created by icebreakers. Additionally, to build understanding of the Arctic sea condition, two other models were developed simulating the interaction of ocean waves with a rigid ice floe and then an elastic ice sheet, which provided a new solver capable of modelling hydroelastic fluid-structure interactions. Based on validation against experiments, these models provided the ability to accurately predict the ship-wave-ice interactions and the ice-induced resistance changes. Through conducting a systematic series of simulations, it was found that ice floes can increase the ship resistance by the same order of magnitude as the open water resistance, but this is strongly dictated by the ship beam, ice concentration, ice thickness and floe diameter. An open-water ice channel was found to increase the ship resistance by up to 15% compared to the situation without ice, particularly when the channel width is less than 2.5 times the ship beam and the ice thickness is greater than 5% of the ship draught. Moreover, this work developed a procedure to derive simple ice-resistance equations from the simulation results, enabling fast prediction of ship fuel consumption in sea ice fields and incorporation into a new Arctic Voyage Planning Tool.

Corrosion is recognised as a significant degrading mechanism which influences the marine structural integrity. The structural deterioration affected by corrosion can significantly degrade the ultimate strength. Even though some countermeasures of corrosion, such as coatings and cathodic protection have been applied, in-service observations have revealed that these protections are not always sufficient. To minimise the failure risk due to corrosion, an accurate prediction of the corrosion is essential. However, most of the corrosion prediction models rely only on historical datasets which are taken from a small range of ships in a limited range of conditions. The models give little insight into what happens when the conditions change. More importantly the factors causing corrosion are not linked, especially the interaction between mechanical stresses and corrosion kinetics, termed mechanoelectrochemical corrosion. To better understand how structural response changes based on corrosion under service loads, this thesis presents a series of finite element analyses which consider the coupling relationship between the surface mechanical stresses and the resulting change of corrosion rate. The coupling provides a complex corrosion-stress interaction depending on the experimental datasets. Quantification of this interaction is based on in situ experimental measurements of corrosion kinetics at different stress levels. Three studies, performed at different structural scales, compressive loadings, and corrosion-stress relationships have been performed to provide an understanding of the coupled corrosionstress effects on ultimate strength and corrosion surface topography. Study 1: utilises a stiffened plate model (1.5 m  0.95 m) with an explicit stress factor to assess the feasibility of corrosion-structural response under different loadings (20%, 50% and 80% proportion of yield stress) and various flange corrosion location, i.e., centre and end flange corrosion, with the same corrosion area (0.75 m  0.045 m). The study results in an irregular thickness reduction and local buckling, with failure mode changes triggered even with slight material loss, due to the non-uniform surface featureand stress concentration. The corrosion location provides different structural and corrosion responses. Study 2: utilises a two-bay/two-span stiffened panels (17.1 m  9.5 m) to assess two different corrosion locations: central corrosion and two-patch corrosion, with identical corroded surface areas (25.46 m2). This study aims to confirm the findings of the stiffened plate study by analysing larger structures, reducing the simplicity of boundary conditions and introducing realistic maritime structural loading scenarios. Distinct changes in the corrosion pattern are observed and up to 23% loss in ultimate strength, or 8% compared to uniform thickness reduction. Study 3: establishes a fuller understanding of the mechano-electrochemical corrosion, where the Study 1 stiffened plate model is coupled with a more complex corrosion-stress interaction through a multiscale multiphysics mechano-electrochemical corrosion model. A surface stress-based anodecathode relationship is defined with a level-set function at a single boundary to solve the Nernst-Planck equation with the help of moving boundary technique based on the Arbitrary Lagrangian-Eulerian method. The results demonstrate the evolution of broad pit corrosion features (1 cm to 10 cm width) with benching, closely resembling that observed in actual inspections/surveys, with up to 6% ultimate stress changes.

The purpose of this study is to investigate novel methods on model identification, navigation, guidance and control of autonomous sailboats in order to sail robustly and efficiently in a wide variety of situations. The study has focused on the development of a robust platform, a model identification process for sailboats, robust control and path-planning methods. A hardware and software system was developed in order to build a research plat- form on which to experiment. Five sailboats were effectively adapted to be able to sail autonomously. Two one-meter long model sailboats, a two-meter long sailboat, a trimaran and a catamaran were tested using this system. Of which, a one-meter long sailboat was used to test developed model identification and navigation methods. A complex sailboat model identification process has been proposed to be, afterwards, used in Model Predictive Control (MPC) scheme. Moreover, a path-planning method for the shortest-length manoeuvre was proposed using the Dubin's path. This method was then applied in an area scanning task formulated as a Traveling Salesman Prob- lem. The ability for an autonomous sailboat to be used in a wide range of applications was demonstrated through the design and development of novel control methods, a robust hardware configuration and a modular software system. This study has proven that the autonomous sailboat can be a genuine solution to challenging marine applications by providing a durable, sustainable and highly-controllable platform.

It has often been said that, from a fundamental Naval Architecture perspective, the primary design objective to be achieved is for a ship to remain afloat and upright (safety-related objectives). This is particularly true in case of vessel flooding, where this objective becomes harder still. The traditional risk control option adopted in Naval Architecture to meet safety related objectives is by rules and regulations, targeting damage limitation, nominally instigated in the wake of maritime accidents claiming heavy loss of life. The first Merchant Shipping Act of1854 is the earliest known legal requirement addressing safety at sea and concerning watertight bulkheads, i.e., permanent (passive) reconfiguration of the internal ship environment to enhance safety. This has been the most common measure, manifesting itself in the wake of every serious flooding accident since the beginning, back in the 19th century. Notably, with accidents providing the main motivation, emphasis has primarily been placed on reducing consequences, i.e., on cure rather than prevention. The key reason for this, derives from the fact that the residual risk post flooding accidents is unacceptably high, meaning that the most-cost-effective way to reduce flooding risk is to target the residual risk. This being the case, the prevailing situation can be drastically improved through understanding of the underlying mechanisms leading to vessel loss and to identification of governing design and operational parameters to target flooding risk reduction more cost-effectively. On one hand, this necessitates the development of appropriate methods, tools and techniques capable of meaningfully addressing the physical phenomena involved. On the other hand, this nurtures wider understanding and wisdom. Safety is normally a compromise to vessel earning potential and, as public demand for higher safety standards grows, industry is forced to choose between viability of business and safety of customers. Unfortunately, in any such compromise, safety loses. However, the key reason for this is strongly linked to the traditional myopic focus on only permanent, designed-related safety measures, pertaining in particular to flooding incidents. Traditional flooding protection through watertight subdivisionis largely dictated by IMO regulations and has a physical limit which, if exceeded, a safety plateau is reached. This is currently the case and with damage stability standards progressively increasing, the safety gap between existing and new ships is dangerously widening. Adding to the problem is the progressive erosion of design stability margins, making stability management unsustainable and leading to loss of earnings at best. The need for monitoring and managing the residual risk through active intervention/protection over the life-cycle of the vessel drives the industry in searching to adopt a new normal. This new normal is the innovation being explored in this thesis, by addressing safety enchantment through a systematic reconfiguration of the ship environment for passive and active protection in flooding (and to some extent fire) accidents. In this respect, the “design-optimal” internal arrangement of a vessel, is adapted and reconfigured, using passive and active containment systems for flooding/fire incidents, in the form of high expansion foam products. Several case studies are being presented to explain and explore the safety-enhancement potential. This demonstrates transformational reduction in flooding/fire risk, in the most cost-effective way available.

The maritime sector has strived to reduce accidents and their consequences since its beginning, by addressing safety as the priority from the design stage to decommissioning of any vessel. Previous accident studies are focused on identifying Human Factors (HFs) in past maritime accidents. However, these studies have failed to identify deeper relations amongst the aforementioned HFs. Then, there has been a lack of detailed technique, which is capable of modelling the complex interrelations between these factors. In addition, the maritime sector has traditionally presented a reactive approach to accidents, as regulations are generally developed to prevent reoccurrence rather than to avoid accident scenarios. However, a higher percentage of the time the system is safe, so it is possible to obtain additional useful information when focusing on the positive events and by learning from them. The aim of this research study is to develop a theoretical understanding and a practical framework to describe how HFs in maritime accidents can more cleverly be identified and linked to the resilience engineering abilities, which will allow assessing the resilience level within a shipping company. Thus, by achieving the aforementioned aim, it is expected to improve overall safety within the maritime domain. Therefore, in this research study, a new technique for Marine Accident Learning with Fuzzy Cognitive Maps (MALFCMs) is introduced and explained. The novelty of MALFCMs is the application of fuzzy cognitive maps (FCMs) to model the relationships of accident contributors by utilizing information directly from an accident database with the ability to combine expert opinion. Therefore, a key aspect to consider in this approach is the data selection, as a qualitative database will increase the success of the aforementioned MALFCMs technique. In addition, as each fuzzy cognitive map will be derived from real occurrences, the results can be considered more objective, and MALFCMs may overcome the main disadvantage of fuzzy cognitive maps by eliminating or controlling the subjectivity in results. Moreover, in this research study, the resilience assessment framework that was developed in EU funded FP7 SEAHORSE project is modified to incorporate additional resilience abilities, and applied to a shipping company. The modified resilience assessment framework, which consists of six phases, is proposed with the aim to assess the resilience level in a shipping company, based on how the company performs on certain resilience abilities, which are linked to common human causes of accidents. Thus, the resilience assessment framework allows first to measure the resilience level in a shipping company by providing a resilience score, which can be benchmarked with other shipping companies. Second, it allows identifying areas for improvement to increase the company resilience level. Finally, it provides a set of recommendations for resilience improvement that may serve the company for future research.

There is a significant research gap in understanding how socio-economic, socio-political processes and ‘protective spaces’ shaped by them can lead to alternative fuel transitions in maritime shipping. Use of LNG as a marine fuel in northern Europe since the 1990s has elements of such a transition and is used as a historical case study in this thesis. LNG, even though a fossil fuel, due to its requirement for novel bunkering infrastructure and significant technological innovation has elements of a ‘radical’ innovation introduced to address societal challenges (in particular SOx and NOx emissions). In order to understand what insights LNG can give on ‘sustainability transitions’ in shipping, this thesis asks the following research question: What do the historical adoption dynamics of LNG as a marine fuel in northern Europe tell us about the nature of fuel transitions in the maritime transportation industry? The research question is divided into two sub-questions: 1. How has the adoption of LNG as a marine fuel in northern Europe unfolded? 2. What insights can the historical adoption of LNG give on the future maritime industry fuel mix? This thesis contributes to addressing three specific research gaps: firstly, the empirical gaps in studying ‘sustainability transitions’ in maritime shipping and secondly in understanding the historical spread of LNG as a ship fuel in northern Europe. The thesis also contributes to the theoretical gap in studying scale and space in ‘sustainability transitions’ literature. To answer the research question and address the research gaps, the thesis develops a novel conceptual framework, the MarSTF – Maritime Sustainability Transitions Framework that applies concepts from ‘sustainability transitions’ literature with insights from ‘economic geography’. The MarSTF develops novel conceptual categories in ‘sustainability transitions’ literature to understand the role of ‘protective spaces’ in maritime transport transitions, taking place over time, space and scale.

Since the United States Coast Guard (USCG) reported in 1993 that human factors had essentially caused approximately 80% of maritime accidents and near misses, there has been an overwhelming understanding that human factors play a significant role in a considerable number of incidents or catastrophes by triggering chain events. The work has initially documented a literature review underlining human factors in maritime accidents, mental workload study and functional Near-Infrared Spectroscopy (fNIRS) technique to imply how it can be studied for human factors in maritime transportation. It investigates how different risk factors generate an impact on different types of human-related maritime transportation accidents using a data-driven approach, and how mental workload influences neurophysiological activation and decision- making of seafarers by conducting an experimental study in bridge simulation. The results of the developed models formalise the causal interdependencies between the risk factors with human factors perspectives and highlight the implications through scenario analyses. On the other hand, the findings of the fNIRS experimental study revealed the role of the prefrontal cortex and functional connectivity in watchkeeping and collision avoidance during maritime operations. It is concluded that the understanding of risk factors contributing to human errors will help reduce the risk level or eliminate the potential hazards of ships, and provide the clue for accident investigation and generate insights for accident prevention. Also, the experimental study supports fNIRS as a valuable neuroimaging technique in realistic situations. It examines the mental workload and functional connectivity of seafarers, which helps generate insights for human performance and seafarers’ training. Finally, the inclusion of a broader range of human factors and experimental methods shows promise by associating neurophysiological experiment in the maritime section.

Hull and propeller roughness can be caused by various factors such as mechanical causes, chemical and electrochemical processes (e.g. corrosion), and finally the colonisation of biofouling, which is often the most critical. The associated economic and environmental problems include increases in ship resistance, fuel consumption, and greenhouse gas emissions. The mitigation measures are also associated with costly antifouling coatings and dry docking. Therefore, accurate predictions of the roughness effect on ship performance are of great importance in the economic and environmental perspectives. Although many studies have been carried out to investigate the roughness effect since the age of William Froude, our understanding in this field is still limited. More specifically, the validations of the two most prevalent prediction methods are not complete. Also, the conventional studies have mainly focussed on the roughness effect on ship resistance, whereas the impact on propulsion performance has been less highlighted. Furthermore, the hull surfaces have been treated as uniformly rough in the conventional studies, while real ships’ surfaces are not uniform as they are exposed to heterogeneous fouling accumulation. Based on the above background, this PhD study aims to develop computational and experimental techniques to investigate the effect of biofouling on ship hydrodynamic performance. This aim has been realised by achieving several milestones using Computational Fluid Dynamics (CFD) and Experimental Fluid Dynamics (EFD). This PhD thesis consists of three distinct parts. Part I includes experimental validations by means of tank testing to demonstrate the suitability of the methods for the added resistance prediction due to hull roughness: Granville’s similarity law scaling method and the CFD method involving modified wall-functions. Part II presents the full-scale applications of the CFD approach to predict the effect of biofouling on the full-scale ship hydrodynamic problems, including ship resistance, propeller performance and ship self-propulsion performance. Finally, extended investigations are presented in Part III, including the investigations into the effect of heterogeneous distributions of hull roughness on ship resistance as well as the roughness effect with the variations of hull forms, ship lengths and speeds.

Experimental research in laboratory is a necessary and useful method to explore the full potential of a device. Because it does not only require much less money than the prototype at sea test, it also provides more reliable results compared to numerical simulations. Hence, it is significantly vital to make accurate model tests of the concerned ocean renewable energy (ORE) devices possible. For this reason, this study for a PhD degree has been finished and a thesis, therefore, is produced. There is a need for a method to provide linear or nonlinear real-time power-take-off forces to the wave energy converting mechanism in the water during the experiment. More urgently, it is essential to overcome the discrepancy caused by following Froude-scaling law and Reynold-scaling law in the test of a model-scaled FOWT. Two applications for WECs and FOWTs are proposed separately, to meet the challenges. Following the conceptual design of the software-in-the-loop (SIL) application for a WEC, an innovative generic platform, which can explicitly provide a real-time PTO damping force in terms of either linear or non-linear (at different scales) is developed and characterised by 1349 drop tests. Subsequent physical model tests of a OWSC WEC device are carried out. The power efficiency of the OWSC WEC device under different PTO strategies is then estimated based on the analysis of experimental results. The best linear damping in regular waves is driven by gaining 80 in the control function, while 160 for nonlinear PTO damping. Furthermore, it is revealed that nonlinear PTOs have no distinct advantage in the amount of electricity output, but can lead to better stability and broader damping range. Following the conceptual design of an AI-based hybrid testing application for a FOWT system, a prediction module of the rotor thrust is needed to be estimated and optimised in the first place. For this reason, a considerable amount of simulations under various conditions are carried out by fully-coupled computation software, and the results obtained are used to train an artificial intelligence structure. Then a prediction module which depends on five inputs, and gives one output rotor thrust, is estimated mathematically. The mathematical module is converted to the control function in the program in a controller to execute it in real-time tests. Therefore, the AI machine is sometimes referred to as the SIL application for FOWTs, which consists of a prediction module obtained by AI training, a controller, and the program in the controller. The AI machine is the key component to implement the AI-based real-time hybrid model (AIReaTHM) testing methodology. As one of the highlights in the present study, the AIReaTHM testing rig is developed, and bench tests are carried out with a manoeuvrable motion simulator. The comprehensive testing results are analysed for three purposes: 1, validating the AIReaTHM testing methodology. 2, assessing the influences of wind speed, wind turbulence intensity, wave spectrum, input hydrodynamic motions on rotor thrust are reflected by the SIL application.3, evaluating the systematic uncertainty in the testing rig, which is to be compensated by further improving the testing system. The effect of the surge frequency, wave spectrum and wind models have on the targeted thrust is discussed. The time delay in the testing system is identified as within 0.1s, and the overall uncertainty from the testing rig is 5-15KN (the minimum rotor thrust is 508KN, hence the uncertainty is 0.98%-2.95% in percentage) when compared to the AI prediction. The testing rig developed is further applied to a 1:73 model of a Hywind floating wind turbine. 4 testing campaigns are carried out, and 303 independent tests are conducted. Testing results with the real-time rotor thrust provided by the AI-based software-in-the-loop application are compared with the other three comparative testing patterns. They are tests with a constant rotor thrust, without any rotor thrust, with AI predicted rotor thrust but without wave inputs, and in only wave conditions respectively. The performance of the rotor thrust obtained by the AI prediction agrees well with the benchmark testing results. Then, the hydrodynamic responses of the model are compared among those four testing patterns, for both regular wave tests and irregular wave tests in terms of time histories, RAOs, statistical analysis, and spectral analysis. The RAOs of the model under three testing patterns are given for regular wave tests. The hydrodynamic response revealed that the AIReaTHM is better than applying a constant rotor thrust atop of the model, though further improvement is required to meet realistic response. In the final chapter, conclusions are drawn and original contribution of this PhD study is outlined. Besides, a few points concerning future work are addressed.

Although modern warships routinely operate with on-board helicopters, the effect of the ship superstructure aerodynamics on the flying environment around the ship is generally not considered in the design process. The modern warship is now well designed for stealth in warfare, but the now bulkier, smooth-sided and sharp-edged superstructures create a significant disturbance to the oncoming wind, resulting in turbulent flow features in the lee of the ship, most often across the stern where the ship's flight deck is located. Such conditions, coupled with hot exhaust gases from the ship's gas turbine engines, everchanging weather resulting in various sea-states, sea-spray, rain, fog, etc. create a potentially very hazardous operational environment. In addition, as the launch of unmanned aircraft (UA) vehicles from the flight deck is becoming commonplace, their successful launch and recovery is also directly impacted by the scale of the turbulent flow features in the vicinity of the flight deck. Through the use of time-accurate Computational Fluid Dynamics (CFD), this thesis addresses the impact of modern warship aerodynamics on helicopter and UAV operations. Full-scale, time-accurate, unsteady airwakes have been produced for an early design of the UK Royal Navy's new Global Combat Ship (GCS), the Type 26 City-Class, and its predecessor, the Type 23 Duke-Class. The larger, stealthier design of the GCS has been shown to produce a more aggressive airwake compared with its predecessor, resulting in higher turbulence levels across the flight deck and greater aerodynamic loading on a helicopter. The larger main mast of the GCS also has a clear effect on the accuracy of the ship's anemometer readings when compared with Type 23 thereby making it difficult to determine if the wind conditions are safe for helicopter launch and recovery. Simulation of the Type 23 and GCS exhaust gas efflux has shown that the more turbulent airwake of the GCS aids the cooling and dispersion of the ship's exhaust gases with air temperatures above the flight deck being comparatively lower for the GCS in headwind and Green 30 wind-over-deck (WOD) conditions. As such, the dispersing engine exhaust plume of Type 23 presents a greater threat to the helicopter. Detailed analysis of the air flow around the GCS main mast has shown how CFD can be used to predict flow distortion at the ship's anemometers. Issues with current practice for positioning anemometers on bulky main mast structures, detailed in the defence standard, DEFSTAN 00-133 Part 2, have been highlighted. Findings show that the defence standard should be modified to take account of the new ship geometries that are emerging; at the least, anemometers should be placed as high up the mast structure as possible on yard arms of suitable length. Additionally, an appropriately placed aft anemometer is recommended to yield more accurate wind measurements from astern. Analysis of the exhaust gas dispersion from the GCS has shown that significant cooling of the plume is achieved through the hot exhaust gases mixing with the ship's turbulent airwake, but elevated, unsteady temperatures are present in the vicinity of the flight deck, particularly in the port side hover position in a Green 30 WOD, that can adversely affect an operating helicopter. The addition of an eductor to the exhaust outlet does reduce temperatures above the flight deck, but the temperatures remain elevated and unsteady. A new method for simulating the launch of lightweight unmanned aircraft into the turbulent CFD-generated ship airwake has been also developed. The simulation environment has shown potential for developing Unmanned Aircraft (UA) for maritime applications, for developing appropriate flight controllers, and for developing appropriate launch and recovery operational procedures.

Multi-objective optimisation that considers the energy efficiency and economic success is an important aspect of ship design and operation. Both the hydrodynamic and economic performance characteristics need to be addressed in the early stages of the design, and secured during the life span of a ship. Because of the conflicting nature of these two objectives, there are various trade-offs at stake in the goal for making ships more efficient and greener to comply with IMO regulations while reducing the building and operating costs and increasing the profitability at the same time for all stakeholders especially owners and operators. In attempt to reduce the amount of greenhouse gas emissions from ships, and hence to achieve a lower EEDI value, this research approaches the problem of improving the energy efficiency of ships. That is achieved by optimising the hull design over a speed range through parametric modification to reduce resistance and required power, and also through adopting slow steaming concept. Moreover, the research aims to determine the best practice to reduce the annual cost of running a ship and to increase the annual revenue as well as to make the ship a more profitable investment over her life span. The profit per tonne.mile and the net present value NPV are estimated in the economic analysis to be used as indicators to compare alternative designs for different routes and market conditions scenarios. To achieve this aim, the main operational and economic aspects such as the fluctuations in the fright rates and fuel prices in the shipping market are covered in the economic analysis. In addition, the acquiring price and salvage value are included in order to obtain solid comparisons. An optimisation framework using a VBA macro code has been developed based on the concept of Pareto optimality to assess decision making, and to determine robust designs as well as operational profiles based on results from the hydrodynamic model, environmental impact model, and the economic model. The optimisation process is carried out for a Panamax tanker case study using 5 parameters and a set of constraints for the hull parameters and speed. The outcome from the optimisation framework is a set of Pareto optimal solutions where weight factors are appointed to give the flexibility when addressing the importance of each individual function. The solutions are presented graphically to form what is known as Pareto front which determines the design space and the trade-offs between the different competing objective ii functions. This optimisation framework could assist decision making where it is possible to choose a robust design or designs that offer a near-optimum performance regardless any fluctuations in the market and or the operation profile, and eliminate any significant sub-optimal designs.

Cu2O is an active antifouling substance which is commercially produced with different particle sizes before being formulated into antifouling products, and this consequently leads to different surface finish roughness conditions. The further effects of particle size on the drag performance of antifouling coatings and hence on ship hull resistance, as well as biofilm attachment, has not been explored and studied systematically. Accordingly, about the question of how to make an optimised selection of Cu2O size remains for the ship owners or paint developers. In this research, a number of different sized Cu2O (2μm ≤D50≤250μm) were applied to Newcastle University’s (UNEW) flat test panels. The boundary layer characteristics of the coated surfaces and the uncoated reference surface were measured using two-dimensional Laser Doppler Velocimetry (LDV) in the Emerson Cavitation Tunnel. Pressure drop measurements were carried out using a turbulent flow channel under dynamic flow conditions. The effect of biofilm on the drag characteristics of the Cu2O surfaces under “in-service” conditions was investigated by mounting the test panels the research vessel, The Princess Royal, and examining them every six weeks during a six-month dynamic/static immersion period. The subsequent streamwise pressure drop measurements were conducted on all of the test panels along with uncoated reference panels. In addition, roughness characteristics were analysed by using an optical surface profilometer and the microstructure was studied using Scanning Electron Microscopy (SEM). Based on the roughness function results obtained from the tests, the additional resistance diagrams for full-scale ships were developed according to the Granville similarity scaling law by employing an in-house programme. The research study has systematically explored the effect of different sized Cu2O on the drag and roughness characteristics of marine coatings for the first time in the open literature and hence demonstrated the significant potential impact of this effect on ship performance in-service. It was found that the lowest roughness surface was not desmonstrated by the smallest sized particles because of aggregations which caused an unexpectedly rougher surface and higher fricitonal drag. Apart from the aggregated particles, the overall fricitonal drag was found to increase with particle size and this can be expressed by an empirical linear equation. Details of the time-dependent influence of biofilms on the Cu2O surfaces have been presented. Based on this, the frictional drag changes on different size full-scale ships under similar surface conditions may become more predictable. It was also observed that significant fluctuation occurs on the roughness and frictional drag values for surfaces coated with larger sizes of Cu2O particles, e.g. D50=60μm and therefore, similar behaviours are expected for ship surfaces which have similar or rougher characteristics than this particle size. It has to be noted that the test coatings were purely experimental, having exceptionally high Cu2O contents in the dry film that do not correspond to any commercial antifoulings.

Marine biofouling has a significant impact on the overall hydrodynamic performance of a vessel. The literature shows that powering penalties for heavy fouled ships may reach up to 80% in the worst-case scenario, clearly resulting in higher operational costs and overall greater CO2 emissions. In the 1920’s, ship performance monitoring emerged as one of the most suitable means of estimating these effects using full-scale on-board measurements coupled with various analysis techniques. The primary difficulty of such method stands in differentiating the effect of biofouling from the effects of such disturbances as waves, wind, change of operating conditions and so forth. A deterministic approach to this problem employs physical laws to estimate the contribution of the most relevant disturbances and hence to ‘deduct’ them from the measured in-service resistance. However, very few deterministic Ship Performance Monitoring Systems (SPMSs) have been successfully implemented to estimate all the effects of hull and propeller performance monitoring with both a scrutinised uncertainty and state of the art standards. The present research investigates this knowledge gap. The main aim of this research is to develop a working on-line SPMS based on the first published deterministic performance analysis method dedicated to the measurement of the effects of hull and propeller fouling on ship performance. In achieving these aims, Newcastle University’s R/V The Princess Royal was employed as a development and testing platform of the prototype SPMS, proving to be one of the few applications on small-size vessels. Four Key Performance Indicators (KPIs) were developed to estimate the impact of biofouling on hull and propeller. A novel method to derive Cf is also proposed. The accuracy of the estimations provided by the SPMS developed on-board The Princess Royal was assessed conducting a comprehensive Uncertainty Analysis, which includes all data treatment stages, from acquisition to performance analysis.

The use of experiment remains the most accurate method in the prediction and evaluation of roll damping. Several models ranging from CFD to analytical and empirical techniques and tools have been developed over the years for this purpose. However, the issue of accurately capturing the adherent multilinear behaviour for hulls with sharp edges and bilge keels remains a challenge until date. The elaborate works of Oliveira and Fernandes (Oliveira and Fernandes ,2006,2010,2014) identified and characterized the existence of two regimes using the bilinear model, later modified to the hyperbolic model. Following their work, and identifying this gap, an enhancement in their formation lead to the introduction of a third damping term, which represented the transition between the large angle side and the small angle regions. A modified hyperbolic model has been proposed and tested against existing models with reasonable agreement in terms of regenerating the measured decay. The model’s capture of the transition region was validated using the rigorous procedure of the bilinear methodology. The relative uncertainty associated with the predictive model was evaluated to fall within 3.5% to 5.9% .The decay data were used to modify the regression model of Oliveira and Fernandes and the enhanced model reduced the predictive error in the model parameters from second to first order range. The extracted damping coefficient and model where implemented in a code to study the influence of directionality and spectrum type on the roll motion response of the freefloating unit (typical FPSO) in real sea environment. Interactive contour plot representation was used to capture the sensitivities of spectrum type, directionality and the multidirectional wave streams summation techniques developed prior to roll motion response simulation. A barred region for the number of regular waves to be used was established using the maximum spectra energy density and the estimated significant wave height as the indicators. A 6dof code was developed using simplified methods and techniques. The novel frequency-spectra weighted technique was proposed for the estimation of the excitation force components of the equation of motion in irregular short crested seas from regular wave formulations. The method was validated by running similar scenarios in HydroD and the irregular wave test on scaled model. The roll motion response from the proposed method compared favourably within first order error range against the HydroD simulations and the irregular wave experiment conducted for ii JONSWAP spectrum for the targeted significant wave heights. Similar error margins were also observed for the measured as well as the estimated wave elevations and all other motion modes. The interactive results from the contour plots when translated into roll motion was very evident in the estimated magnitudes in different sea state spectra combinations (type and directions). The use of the suggested spectra form (lognormal or triangular for the swell sea and JONSWAP-Glenn for the wind sea) for the West African region identified variations in the roll response of between 1-23% or more than 5.5o This goes to further show the need to use site or region specific spectrum for the determination of design and operational parameters for offshore structures and associated units and for personnel seakeeping comforts.

This thesis presents a functional approach to improve the structural design and operation of small high-speed craft through the direct calculation of seakeeping loads and structural response. A novel procedure, combining computational and experimental methods, is developed to superimpose static, slowly varying and transient loads on a structural model of the craft. The approach is validated on a 17-metre search and rescue vessel with a maximum operating speed of 25 knots. Current structural design methods for small craft follow a relatively simplistic process and do not explicitly calculate the loads sustained and the response of the structure. To better inform the level of structural adequacy in different possible operating conditions of the craft, both loads and structural response need to be explicitly analysed. In this thesis, hydrostatic and wave loads are determined with hydrodynamic simulations, validated against towing tank tests and seakeeping trials. Slamming loads are estimated by matching strain measurements, taken during the seakeeping trials, to local finite element models of the structure. The single load components are superimposed in the generation of a load case, which represents the extreme loads expected to be sustained within a given return period. The structural response is computed using a global finite element model of the vessel and results are presented as graphs showing the structural response as a function of vessel speed and sea state severity. These graphs contribute to defining the ‘operational envelope’ of the craft, which informs designers and crews on the limits to speed for the safe operation in waves. The study finds broad applicability in the design of small high-speed craft. The approach has the potential to provide designers with better control over the structural design and maintainers with a vessel-specific understanding of the lifetime load patterns and of the structural behaviour, hence aiding targeted inspections. It also increases the awareness of the implications of high speed to the structural integrity of the vessel, enabling coxswains to make informed decisions on the risks being taken and enhance the safety of the on-board crew.

Computational modelling of tip vortex cavitation of a ship propeller has its challenges particularly to extend the cavitating tip vortex trajectories in the propeller's slipstream for investigating their influence on the propeller-rudder-hull interaction. Although the prediction of sheet cavitation on the propeller blade surfaces has been tackled successfully by many researchers, the research to extend the prediction model for the tip vortex cavitation from all propeller blades simultaneously and throughout the rudder is rather scarce. This PhD study, therefore, aims to contribute in this area of research to investigate the cavitation influence on propeller-rudder-hull interaction, especially due to the tip vortex cavitation, by using a commercial Computational Fluid Dynamics (CFD) code. To achieve the above aim, an investigation on the propeller-rudder-hull system is conducted in steps; first by modelling the propeller performance and cavitation in CFD for the isolated propeller case, and next to continue with the propeller-rudder system and finally by modelling the propeller-rudder-hull combination case to represent the ship system. The CFD modelling for these cases are conducted using the commercial CFD software STAR-CCM+ and validated by the available Experimental Fluid Dynamics (EFD) data for three benchmark propellers including the Potsdam Propeller Test Case (PPTC) VP1304, INSEAN E779A model propeller and The Princess Royal research vessel model propeller which are all tested in different experimental facilities. The cavitation model used in the commercial software is the Schnerr-Sauer model based on the Rayleigh-Plesset equation. This model together with the new meshing technique called MARCS, which is developed by the Author as an advanced Mesh Adaption Refinement procedure for Cavitation Simulations, is applied successfully to simulate the cavitating tip vortices from all blades simultaneously in the propeller's slipstream beside other cavitation types. The cavitation simulations are conducted to test and validate the MARCS procedure to include the presence of the rudder and to study the interaction between the propeller and rudder including the effect of the hull wake in the model scale. The simulation results are validated for two different types of propeller-rudder arrangements involving a typical container ship propeller-rudder arrangement and The Princess Royal propeller-rudder arrangement with an inclined shaft and flat rudder section tested in the Emerson Cavitation Tunnel. Further cavitation simulations with the commercial code using the MARCS procedure are also conducted for the scaled full-model of The Princess Royal research vessel to simulate the model tests conducted in the depressurised large circulating water channel of CNR-INSEAN and to validate the simulation results with the EFD measurements available from this facility. Finally, the same computational tool and procedure are used for the cavitation simulations of The Princess Royal in full-scale, and the simulation results are compared with the cavitation observation images available from sea-trials with this vessel. In spite of various shortcomings, which can be further improved, implementation of the new meshing procedure developed has proven that using a state-of-the-art commercial CFD code can be a practical and attractive analysis tool to investigate the influence of cavitation on propeller-rudder-hull interaction in the model and full-scale with confidence. Furthermore, it is feasible, and may be more attractive, to simulate the propeller cavitation directly in full-scale in order to save the additional time, effort and expense required for model tests. Due respect is given to the invaluable contributions made by the EFD in the validation stage of the CFD methods.

With increasing water depth of oil and gas exploration, greater importance has been attached to the damping force from mooring systems. The effect is significantly important to slow drift motion of the floating structure, and it is also coupled with its motions. Coupled analysis is thus preferred to be applied to estimate the floating structure motions and to calculate the mooring system response, especially for offshore structures in deep-water. In this study, the aim is to achieve a better understanding of mooring line induced damping estimation. Drag forces normal to the mooring line due to the motion of the mooring line through the water, are the main source of hydrodynamic damping of the mooring line. A method of energy dissipation based on the mooring line dynamic response obtained by Orcaflex is developed. The validation is established through two types of mooring lines in shallow water and deep water. The present approach shows a good agreement with the published results, but with two exceptions. One is for the mooring line oscillated by a very slow LF motion in shallow water, when the hydrodynamic damping is very small. Another one is for the wire mooring line oscillated by WF motion in deep water, the result shows significant discrepancy with that from the quasi-static method. Then a non-dimensional analysis is completed, due to the strong complexity of the mooring line induced damping. The effects of the factors can be divided into three groups: first, the effects from pretension and scope are related to the geometry changes of the mooring line; second, the oscillation, current velocity and drag coefficient make contributions to the drag forces of mooring line directly; and the last, the effects of stiffness and seabed friction which, it was found, can be neglected. In order to experimentally investigate the chain behaviour moving in water, a series model tests for the damping characteristics of a single chain line is implemented through oscillation tests of various parameters. The drag coefficient ( C D ) variations with different Reynold ( Rn ) and KC numbers are investigated. The drag coefficients in this study range from 1.5 to 4.0, which is case-dependent, because both Reynold ( Rn ) and KC number affect them. With the increase of KC number, the drag coefficient shows a decrease with exceptions occurring in low KC cases. In addition, it is shown that the chain segments near the fairlead and touch down area are most sensitive to the drag coefficient, which is consistent with the velocity distribution along the mooring line. Finally, the validation is established by comparing the results of experimental tests and numerical simulations. Based on the assessment of drag coefficient from the scaled experimental investigation, numerical simulations of estimated drag coefficient are carried out within Orcaflex. A good agreement is achieved between the numerical calculations and experimental measurements, which illustrates that the present method can be applied for mooring line damping estimation. Meanwhile, the effects of the amplitude and frequency of the oscillation are studied.

The inherent complexity of the flooding process on large passenger vessels has, in recent years, been recognised. Accounting for the fact that traditional emergency response is a highly time consuming and manual process, prone to human misjudgement or error, this might lead to severe consequences. This is also highly paradoxical given that the most important variables in an emergency are Time-to-Capsize and Time-to-Evacuate. The research culminating in this PhD dissertation has, therefore, been directed towards the development of a framework where sensor-technology and analytics are utilised to a higher degree, in an attempt to improve real-time information providing risk-informed situational awareness in flooding emergencies involving large cruise vessels, thus enabling optimised emergency response. A fully probabilistic prediction methodology has been developed and presented. The methodology takes advantage of available sensor readings as supportive evidence and utilises inference in the form of probabilistic multi-sensor data fusion techniques for manipulating conditional probability distributions. This targets the observed distribution, enabling reduction in uncertainty (probabilistic inference). The framework and its corresponding comprehensive probabilistic models are further seen to be highly suitable for implementation as a Life-Cycle flooding risk management framework. A range of probabilistic models in the form of likelihood functions have been developed for a specific sample vessel using the state-of-the-art time-domain simulation code PROTEUS3. This enables the simulation of a damaged ship in a dynamic operational climate imposed by waves. Implementation and testing of the framework on a range of realistic test scenarios reveals that the method identifies the expected damaged region for all cases despite not having an exhaustive sensor array. This clearly provides improved survival assessment to enable the crew to implement emergency response in a more timely, targeted and efficient manner in accordance with the main aim set out in the thesis. Finally, having implemented the framework on an existing cruise vessel with the as-built sensor array indicates that the methodology may be implemented on a large cruise vessel without changes to the flooding detection system, as it is seen that the as-built sensor arrays allow for accurate predictions by relying entirely on the presented methodology. This allows for reliable estimation of realtime flooding risk in passenger ships through its life-cycles and most importantly, when it really matters, namely in emergencies. This is an innovation offering unique tangible benefits.

This PhD work is done as a trilogy. In the first stage, a dynamic single degree-of-freedom ice-structure interaction model is developed based on a novel physical mechanism combination between self-excited vibration and forced vibration. Van der Pol equation, together with ice stress-strain rate curve and ice-velocity failure length are coupled to model the internal fluctuating nature of ice force in conjunction with the relative velocity caused by the structure as an external effect. Three basic modes of response were reproduced, such as intermittent crushing, frequency lock-in and continuous crushing. The results are in good match with experimental data at different ice velocities and different structural stiffnesses. Ice force frequency lock-in phenomenon during ice-induced vibrations (IIV) is also observed. In the second stage, analysis on physical mechanism of ice-structure interaction is presented based on feedback mechanism and energy mechanism, respectively. Internal effect and external effect from ice and structure were both explained in the feedback branch. Based on reproduced results, energy exchanges at different configurations are computed from the energy conservation using the first law of thermodynamics. A conclusion on the predominant type of vibration when the ice velocity increases during the interaction process is forced, self-excited and forced in each three modes of responses. Ice force variations also shows that there is more impulse energy during the lock-in range. Moreover, IIV demonstrates an analogy of friction-induced self-excited vibration. The similarity between stress-strain curve and Stribeck curve shows that static and kinetic friction force variations are attributed to ice force characteristic, and can be used to explain the lower effective pressure magnitude during continuous crushing than the peak pressure during intermittent crushing. In the third stage, a two-dimensional non-simultaneous ice failure model is developed. The concept of multiple ice failure zones is proposed to fulfil non-simultaneous crushing characteristics. The size of ice failure zone is assumed to become smaller with increasing ice velocity, which increases the occurrence of non-simultaneous ice failures. Similarly, the decreasing size of ice failure zone as velocity increases is explained as the reason of different ice failure modes shifting from large-area ductile bending to small-area brittle crushing. In addition, an analysis of the ice indentation experiments indicates that the mean and minimum effective pressure have an approximately linear relationship with ice velocity, which testified the assumption on variations of ice failure zone in the model. The simulation results from a series of 134 demonstration cases show that the model is capable of predicting results at different ice velocities, structural widths and ice thicknesses. To sum up, this Van der Pol based model is more powerful than the others in kind by far because of its accurate results, wide applicability and novel physical mechanism behind. Thus, the numerical models produced as part of this research can be helpful in ice failure analysis and in the design of ice-resistant structures.

Eco-friendliness and energy efficiency are now key criteria in the design and construction of all new ships due to stringent environmental regulations aimed at reducing their carbon footprint. An efficient hull form helps in reducing the overall drag acting on a ship, as well as reducing fuel consumption and harmful emissions to the environment. More recently, Simulation-Based Design (SBD) methods have been proposed to improve the efficiency of the hull form design process. However, the entire process still requires considerable human inputs, and success depends heavily on the designer's experience and knowledge. To address these limitations, an industry-first design automation tool based on Morphing and Evolutionary Computation (MEC) was developed in this thesis. This was achieved by combining a novel two-dimensional (2D) curve morphing method and a Non-dominated Sorting Genetic Algorithm II (NSGA-II) using proven hull form designs as initial starting points. The 2D curve morphing method provides an efficient way to modify the hull form whilst providing more flexible geometric variations. NSGA-II is a multi-objective optimisation algorithm that uses nature-inspired operations to optimise a population of candidate solutions in a generative manner. This tool supplements experienced designers in modifying the shape of the hull form, in a more automated manner, helping them to achieve more diverse and optimal design solutions. Central to the working of MEC are novel crossover and mutation mechanisms, developed using cross-morph and boundary-morph. Together, these two morphing techniques enable geometric manipulation to be performed directly on the hull, instead of modifying the design parameters as is the case in traditional approaches. By applying the two morphing techniques within NSGA-II, more diverse shapes can be discovered, and the entire design process can further be automated. MEC is particularly well-suited for the initial design stage, where shape diversity and efficient performance evaluation are key to finding more optimal designs. The final output of this method is a set of Pareto optimal designs, which can further be refined by the designer. Through digitisation and computational intelligence, it is envisioned that automated design will help to improve the overall design efficiency and capability to produce more efficient and smarter ships in the future.

With growing advances in technology and everyday dependence on oceans for resources, the role of unmanned surface vehicles (USVs) has increased many fold. Extensive operations of USVs having naval, civil and scientific applications are currently being undertaken in various complex marine environments and demands are being placed on them to increase their autonomy and adaptability. A key requirement for the autonomous operation of USVs is to possess a multi-vehicle framework where they can operate as a fleet of vehicles in a practical marine environment with multiple advantages such as surveying of wider areas in less time. From the literature, it is evident that a huge number of studies has been conducted in the area of single USV path planning, guidance and control whilst very few studies have been conducted to understand the implications of the multi vehicle approaches to USVs. This present PhD thesis integrates the modules of efficient optimal path planning, robust path following guidance and cooperative swarm aggregation approach towards development of a new hybrid framework for cooperative navigation of swarm of USVs to enable optimal and autonomous operation in a maritime environment. Initially, an effective and novel optimal path planning approach based on the A* algorithm has been designed taking into account the constraint of a safety distance from the obstacles to avoid the collisions in scenarios of moving obstacles and sea surface currents. This approach is then integrated with a novel virtual target path following guidance module developed for USVs where the reference trajectory from the path planner is fed into the guidance system. The novelty of the current work relies on combining the above mentioned integrated path following guidance system with decentralised swarm aggregation behaviour by means of simple potential based attraction and repulsion functions to maintain the centroid of the swarm of USVs and thereby guiding the swarm of USVs onto a reference path. Finally, an optimal and hybrid framework for cooperative navigation and guidance of fleet of USVs, implementable in practical maritime environments and effective for practical applications at sea is presented.

Concerning the environmental challenge caused by the shipping industry, particularly diesel exhaust and toxic biocide-based anti-fouling system, the author proposed a new micro-patterned surface as a promising ship coating system, which is inspired by the shark skin surface. The new surface pattern combines the core working pattern of two existing surface technologies: Riblet and Sharklet AF™, and is expected to possess both drag-reduction and anti-fouling performance. Computational Fluid Dynamics (CFD) is employed as the main approach in this work to examine the drag-reduction performance of the new surface pattern. The RANS engineering turbulence model, Realizable K-Epsilon Two-Layer (RKE 2L), is used by the author to simulate the new design surface in the turbulent channel flow. The specific RKE 2L turbulence model is firstly used for the drag-reduction investigation of the riblet surface and is validated by a case study of symmetric v-groove riblet surface. The drag-reduction performance of the new surface pattern is directly justified by comparing the skin friction of new surface and reference smooth surface, and indirectly justified by observing the upwards velocity shift in the log layer. Finally, a parametric study is conducted for the new surface pattern to explore the drag-reduction mechanism and the optimization direction. To understand the riblet coating's practical impact on the full-scale ship, the similarity law scaling method is adjusted and written into the in-house code to extend the drag-reduction results from channel flow scale to full ship length scale. Moreover, a three-step procedure is proposed by the author to provide naval architects a guidance to derive the suitable riblet coating size where maximum riblet drag-reduction performance can be achieved in the most of voyage time. Finally, five real-world case ship types and relevant speed distribution are considered to predict the riblet coating's impact, which is quantified by the drag-reduction percentage and fuel savings. The author believes that the shark skin inspired micro-patterned surface would pave a basement for the road to new innovative energy efficient approaches for the shipping industry.

Ship recycling, similar to any other recycling industry, can be considered as the most environmentally friendly option for end-of-life ships than the other alternatives. However, lack of safety, lack of environmental awareness as well as lack of a global and local regulatory framework resulted in ships being dismantled in undesirable conditions which forced international regulators to focus on developing international regulations and standards. The International Maritime Organization's (IMO) Hong Kong Convention and the European Union'€™s Ship Recycling Regulation are examples of the aforementioned new regulations. Both regulations require ship recycling yards to improve existing HSE standards to stay compliant. These HSE measures will negatively impact on running costs, therefore, ship recycling yards will need to increase their production efficiency to remain competitive. Even though the industry requires support during this transition, there is no study within the current body of literature that focuses on increasing the productivity of the ship recycling facilities. Hence, there is a need to develop a framework to design contemporary and efficient ship recycling yards. Increasing production efficiency in ship recycling yards will not only decrease the costs, but it will also increase the throughput of the yards which will generate more income and positively impact on overall profitability. Therefore, this PhD study addresses this gap through the development of a simulation framework for ship recycling industry to design and optimise the ship recycling yards. The study adopts a case-based approach where numerous design alternatives will be studied through the proposed framework. The main aim of this study is to increase the productivity of ship recycling yards and optimise their procedures towards achieving cost-efficient facilities. Overall research conducted in this study will be significant contribution to the maritime literature as a novel framework for ship recycling yard design and optimisation is developed. The process models of this framework are developed based on real ship recycling procedures, therefore, the framework can be considered ready for practical implementation.

With an increasing pressure to use cleaner fuels in shipping, LNG has become a realistic marine fuel of choice by many ship-owners. Although it will undoubtedly contribute towards cleaner shipping, there is a general concern about the safety of its use. Such fears are based on the fact that an accidental release of this flammable mixture may lead to potential incidents, in particular, of fire and explosion. In this context, ensuring the safety is one of the most crucial tasks for the industry in adopting LNG as a marine fuel. It is hardly surprising, therefore, that several rules, regulations, standards and guidelines have been produced at both international and local level. Nevertheless, due largely to the brevity of their history, the existing regulations and class rules appear to have some limitations and shortcomings, in particular, they lack explicit requirements in quantitative terms. It is true that there are rules and guidance for design and operation of LNG process systems in chemical industry with a relatively long history, and they can to some extent be used to safeguard the use of LNG as a fuel, but the arrival of LNG-fuelled ships has made it essential and urgent that their safety should be investigated in detail. In an effort to examine the existing regulations more intimately a conceptual design exercise to retrofit a 300,000 DWT very large ore carrier to use LNG as one of the marine fuels was carried out in accordance with current regulations. Although it was felt that the most hazardous areas of such a ship are with the fuel preparation room with high-pressure fuel supply system and the bunkering systems, the current regulations were not of much help during this process. In order to obtain meaningful insights into their threats, the safety of these critical areas were systematically evaluated using quantitative risk assessment models that have been proven to be an effective and efficient tool for evaluating risks in oil/gas process systems. It became obvious from the outset that an efficient computation tool is essential for the investigation. Consequently, the conventional quantitative risk assessment methods were modified and augmented to best suit the current problem and implemented in a computer program called Integrated Quantitative Risk Assessment (IQRA). One of the main strengths of IQRA is that it can carry out the whole process of risk analysis from frequency calculation to evaluation of consequence in a seamless process, unlike existing software which require tedious post-processing to obtain the risk values. It has more than proven its worth during the course of this project. LNG bunkering, at the two weakest ends (on-board LNG receiving point and LNG supplying point) were examined first. Usually such weak points are made relatively safe by imposing a 'safety exclusion zone' where non-essential personnel are not allowed entry during the process in question is in progress. However, there is no realistic regulation or guidance to help determining the extent of the zones. One of the few existing guidelines based on population-independent analysis requires an exclusion zone far too extensive and impossible to implement. A realistic method of determining the exclusion zones based on statistical quantitative risk assessment was developed and demonstrated in this thesis. An interesting fact discovered through this study was the fact that short duration bunkering at large scale tends to require smaller exclusion zones than smaller scale bunker for longer duration. The next area to examine was the fuel preparation room with a high-pressure fuel gas supply system. In this study, an event tree analysis was used to identify events that may cause vapour cloud explosion. General frequency data from various sources was used, and fault tree analysis was applied. Consequence was analysed in terms of the impact from explosion using a CFD and an FEA program. It was found that the structure of some sections of the fuel preparation room must be strengthened in addition to the scantling required by the classification rules. Additionally, the safety of a medium-sized floating regasification unit was investigated by applying a hierarchical system modelling method newly put forward in this thesis. It demonstrated the excellence of the hierarchical system modelling in assessing the overall risk of complex process systems. The results were compared to the recommendations produced by a benchmark HAZOP study and selective quantitative risk assessment method. This project established and demonstrated the way that the quantitative risk assessment techniques can be used to investigate the safety of a variety of novel marine LNG plants. A series of studies have proven that the framework and methodology developed in this thesis provides structured guidelines to conduct quantitative risk assessment associated with LNG-fuelled ships as well as LNG process systems regarding fire and explosion. The facility for parametric and sensitivity analyses have also been shown to be an excellent tool in gaining insight into the nature and characteristics of risks that are inherent in oil/gas process systems while improving understanding of contributing factors to risks and methods of mitigating them as well as points to note during quantitative risk assessment. It is thought that such a tool will be a very useful aid in future rule development. Last but not least, the safety of people and ships in using and/or processing LNG is paramount. If it is agreed that enhancing the current regulations is an urgent task, it is expected that the results of the studies carried out in this thesis can make a significant contribution to decision-making and further regulatory framework for port authorities and rule-makers.

In shipping, condition monitoring (CM) has the capacity for big data but also very high communications costs. Thus, the use of continuous condition monitoring in the shipping industry is not as prevalent as in others. It is found that trust in technology, data security/ownership, the capital cost of investment, cost of training, operational cost and direct benefit association are some of the most important inhibitors. To reduce the volume of data, edge processing is a new paradigm of computing. Its goal is to address the issues generated through the increasing flow of recorded data to central locations for big data analytics. aThe existing solutions are adopted by 12% of the global fleet corresponding to the newbuilt ships, while sensors and monitoring infrastructure exists in the majority. Solutions targeting newbuilt ships have a requirement of extensive refitting and training overheads. Solutions for existing vessels are mostly hand-held equipment, do not support continuous monitoring and do not display the information in business relevant terms. A wireless ship CM reduces capital investment costs but has high operational costs due to the centralised data processing software. The proposed novel system is edge processing wireless ship CM data under constrains. The system's traffic reduction is achieved through feature and event extraction on the data acquisition devices. Also a data management strategy is implemented along with decision support which provides direct benefit association with maintenance actions. The multi-constrain multi-parameter approach identifies the best maintenance action to be taken onboard the ship. Finally, minimal satellite data transmission provides visibility of condition to shore. The system was successfully applied in case studies. According to the evaluation results, the system is reliable and suitable for the application, is able to identify and suggest appropriate maintenance actions and offers several benefits against other maintenance and condition monitoring approaches.

The energy consumption and the Greenhouse Gas (GHG) emissions from shipping field are vast and very important which cannot be ignored for both economic and environmental reasons. Improving energy efficiency of the ship through the technical and operational means has become a pressing issue faced by the shipping industry. In this context, ship weather routing technique, as one of the effective energy efficiency improvement methods has attracted more and more interests from technical staff. A ship weather routing system towards energy efficiency is developed in this study. This system consists of six modules which are ship performance calculation module, grids system design module, weather data module, ship safety module, weather routing module and post-processing module. These modules basically cover the essential elements of a ship weather routing system. Among them, the calculation methods of various ship performances are utilised in ship performance module; The design principle of grids system and an intelligent land avoidance function are developed in grids system design module; The acquisition and decoding of weather data files are introduced in weather data module; A ship safety guidance is selected and followed in ship safety module; A combination of global and local optimization algorithm is adopted in weather routing module; A backward iteration algorithm is developed and the visualization of result routes is implemented in the post-processing module. The role of each module and the data transfer relationship between these modules are described in detail. Next, seven effective methods are introduced to upgrade the system. The role of each module and the data transfer relationship between these modules are described in detail. Next, seven effective methods are introduced to upgrade the system. These methods which can greatly improve the working efficiency of the system are respectively: create ship performance database, redefine ship travel principle and adjust the grids system scale, merge ship safety module to ship performance prediction module, delete results in every waypoint which cannot meet the time schedule, set the speed control parameter, delete results in every waypoint which cannot meet expected fuel consumption and optimise programming codes. With these methods introduced, the structure and operation logic of the system also becomes more effective. A series of representative case studies are carried out to verify the proposed methodology and the tool. Finally, the approach is implemented on a container ship in both purely motorised and Flettner rotor assisted propulsion conditions, to see the energy efficiency gained through Flettner rotor technology. Case studies in various shipping routes, departure times and ship speeds are carried out based on this system and finally a framework for assessing the performance of wind assist technology is proposed. The proposed weather routing system has significant practical application and can provide an effective reference for related research in the shipping industry.

Container ports are indispensable parts of the container transport operations. In terms of container transport operations even better port services are desired to provide viability of reliable liner shipping service. Therefore, port competition to supply better port services is one of the natural consequences of the container transport evolution in the globalisation era. This thesis offers a port competition analysis as total transportation time and cost based between the container ports which serve to collided hinterlands with the integration of offshore container port system (OCPS) and ultra large container vessels (ULCV). An OCPS adaptation is assumed to create offshore container port related an inter-port container competition with other conventional container ports which can handle ULCVs. This OCPS is going to complicate competition game and conditions even much more between ports. The methodological approach of this study aims to develop a hybrid port competition analysis model to analyse port competition in terms of commercial and operational aspects. The model is divided to two different methodological stages. First proposed method is to apply total transportation time and cost based door-to-door container network analysis in order to determine the competitiveness of the given port alternatives. In this approach, according to total time and cost values, the weights of each competitive port are determined to define the position of ports in the competition in order to attract interest of the industrial customers. Operating costs, voyage costs, cargo handling costs and hinterland transportation cost, and also port construction costs are considered as main criteria to clarify the ports' position in the competition. Second method is to develop a game theoretical strategy concept to apply on the port competition regarding to lucrativeness and investment opportunity expectations of the port authorities. Integration and comparison of the both methodological approaches is going to provide valuable findings to analyse competitiveness level of container ports more accurately. Outcomes of this research may help for future business development strategies of port authorities, port operators, shipping liners and private and public port investors. This study is expected to provide a clear holistic comprehending about the underlying dynamics of the port competition for all counterparties involved in container transport operations.

Inadequate ship machinery maintenance can increase equipment failure posing a threat to the environment, affecting performance, having a great impact in terms of business losses by reducing ship availability, increasing downtime and moreover increasing the potential of major accidents occurring and endangering lives on-board. With high cost of ownership and overburdened crew, ship maintenance has become one of the major challenges in the marine industry. Though the industry is still predominantly reliant on a time-based, prescriptive approach to maintenance, technological advances, heightened expectation and competitive requirements as to ship availability and efficiency and the influence of the data revolution on vessel operations, have resulted in considerable interest in advanced maintenance techniques and favour a properly structured condition-based maintenance regime. In this respect, this thesis develops a hybrid framework oriented towards ship machinery condition monitoring utilising a combination of reliability tools (Fault Tree Analysis, Failure Modes & Effects Analysis, Reliability Block Diagrams) and data-driven approaches based on artificial neural networks (Self-Organising Maps, Nonlinear Autoregressive, Multilayer Perceptron). The above assist in identifying critical ship machinery systems and components and subsequently monitoring their condition through the employment of data clustering, time series forecasting, diagnostic and health assessment, leading to advisory generation of appropriate maintenance actions and recommendations. The above framework is applied to the case study of a Panamax container ship main engine for system, subsystem and component level and the results are validated with actual data recorded onboard. Sensitivity and cost benefit analysis are also presented. Key results include amongst others the identification of critical systems through a systematic approach, the ability of the Self-Organising Map to cluster data and monitor the status of the main engine and the forecasting capabilities of the Nonlinear Autoregressive time series neural networks to analyse available main engine data with high forecasting accuracy.

Wave propelled vessels utilize submerged flapping foils to convert wave energy directly into propulsion. This works by coupling the response of foils operating in a wavy flow with the flapping motion driven by the wave-induced hull motions. For platforms that are solely propelled using this method the free running forward speed is dictated by the magnitude and frequency of the ambient wave energy. Submerged flapping foils also have the potential to recover wave energy for onboard power generation, and, in this way, a vessel could be both powered and propelled by the ambient wave energy. This thesis both numerically and experimentally investigates the coupled dynamic response of a wave powered vessel, which enables the prediction of the free running forward speed and an assessment of the potential for wave energy recovery. A hybrid numerical model has been developed to capture the free running response of a flapping foil wave powered vessel, and this model has been validated by the experimental analysis. The hybrid method combines the frequency domain strip theory approach for solving the seakeeping response with a time domain solution for the response of a spring loaded flapping foil. The numerical model also evaluates the electromechanical conversion of wave energy by modelling the power generated by a permanent magnet tubular linear generator. Free running wave propulsion experiments were performed in both regular head and following waves using a model with spring loaded flapping foils at the bow and stern over a range of wave frequencies. The experimental setup incorporated wave energy recovery in the form of electrical power by linking the flapping foils with a power take-off device, and a series of experiments were conducted for different wave heights and frequencies. In addition to validating the numerical model, the experimental results show a notable difference in the response of the forward and aft foils in head and following waves, and confirm numerical predictions that the optimal location of the foils is at or beyond the perpendiculars of the vessel. Furthermore, the experimental and numerical analysis demonstrate that it is possible to recover wave energy from the use of submerged foils. Numerical simulations have been carried out to provide a more detailed insight into the effect on the coupled response of: foil size and location; flapping parameters; and seakeeping characteristics. In particular, it is shown that the wave-phasing parameter and the foil spring constant is of significant importance for the efficiency of wave propulsion. Lastly, the numerical analysis provides guidance for the design of flapping foil wave powered vessels, and highlights the importance of the wavelength to vessel length ratio.

The decline of defence budgets coupled with the escalation of warship procurement costs have significantly contributed to fleet downsizing in most major western navies despite little reduction in overall commitments, resulting in extra capability and reliability required per ship. Moreover, the tendency of governments to focus on short-term strategies and expenditure has meant that those aspects of naval ship design that may be difficult to quantify, such as supportability, are often treated as secondary issues and allocated insufficient attention in Early Stage Design. To tackle this, innovation in both the design process and the development of individual ship designs is necessary, especially at the crucial early design stages. Novelty can be achieved thanks to major developments in computer technology and in adopting an architecturally-orientated approach to early stage ship design. The existing technical solutions aimed at addressing supportability largely depend on highly detailed ship design information, thus fail to enable rational supportability assessments in the Concept Phase. This research therefore aimed at addressing the lack of a quantitative supportability evaluation approach applicable to early stage naval ship design. Utilising Decision Analysis, Effectiveness Analysis, and Analytic Hierarchy Process, the proposed approach tackled the difficulty of quantifying certain aspects of supportability in initial ship design and provided a framework to address the issue of inconsistent and often conflicting preferences of decision makers. Since the ship's supportability is considered to be significantly affected by its configuration, the proposed approach utilised the advantages of an architecturally-orientated early stage ship design approach and a new concept design tool developed at University College London. The new tool was used to develop concept level designs of a frigate-sized combatant and a number of variations of it, namely configurational rearrangement with enhancement of certain supportably features, and an alternative ship design style. The design cases were then used to demonstrate the proposed evaluation approach. The overall aim of proposing a quantitative supportability evaluation approach applicable to concept naval ship design was achieved, although several issues and limitations emerged during both the development as well as the implementation of the approach. Through identification of the research limitations, areas for future work aimed at improving the proposal have been proposed.

One of the fundamental requirements of a persistently Autonomous Underwater Vehicle (AUV) is a robust navigation system. The success of most complex robotic tasks depends on the accuracy of a vehicle's navigation system. In a basic form, an AUV estimates its position using an on-board navigation sensors through Dead-Reckoning (DR). However DR navigation systems tends to drift in the long run due to accumulated measurement errors. One way of mitigating this problem require the use of Simultaneous Localization and Mapping (SLAM) by concurrently mapping external environment features. The performance of a SLAM navigation system depends on the availability of enough good features in the environment. On the contrary, a typical underwater structured environment (harbour, pier or oilfield) has a limited amount of sonar features in a limited locations, hence exploitation of good features is a key for effective underwater SLAM. This thesis develops a novel attentive sonar line feature based SLAM framework that improves the performance of a SLAM navigation by steering a multibeam sonar sensor,which is mounted on a pan and tilt unit, towards feature-rich regions of the environment. A sonar salience map is generated at each vehicle pose to identify highly informative and stable regions of the environment. Results from a simulated test and real AUV experiment show an attentive SLAM performs better than a passive counterpart by repeatedly visiting good sonar landmarks.

Accurate and meaningful representations of the environment are required for autonomy in underwater applications. Thanks to favourable propagation properties in water, acoustic sensors are commonly preferred to video cameras and lasers but do not provide direct 3D information. This thesis addresses the 3D reconstruction of underwater scenes from 2D imaging SONAR data as well as the recognition of objects of interest in the reconstructed scene. We present two 3D reconstruction methods and two model-based object recognition methods. We evaluate our algorithms on multiple scenarios including data gathered by an AUV. We show the ability to reconstruct underwater environments at centimetre-level accuracy using 2D SONARs of any aperture. We demonstrate the recognition of structures of interest on a medium-sized oil-field type environment providing accurate yet low memory footprint semantic world models. We conclude that accurate 3D semantic representations of partially-structured marine environments can be obtained from commonly embedded 2D SONARs, enabling online world modelling, relocalisation and model-based applications.

The phenomenon of cavitation is of great importance when ship propellers and rudders are considered, as it can often be the cause of vibrations, noise, reduced efficiency and even erosion in some instances. The underlying fracture mechanisms of erosion, however, have not been fully understood yet. As such, this study aims to expand our knowledge regarding the fracture mechanisms of common shipbuilding alloys and explore whether cavitation erosion can be monitored, by using the relevant quantitative and qualitative data. As such, an experimental test rig was built, based on the induction of cavitation by ultrasonic means, in order for a series of tests, including mass loss and acoustic emission measurements as well as microscopic observations to be conducted. Due to the interest of BAE Systems, a number of protective coatings were also examined under an analogous context. Specimens were initially exposed to ultrasonically induced cavitation under identical experimental conditions. Mass loss was periodically measured thus materials were categorized in that respect while the positive effect of cathodic protection on the resulting erosion was confirmed. Examination through optical and scanning electron microscopes was also conducted thus the fracture mechanisms and macroscopic characteristics of cavitation erosion were identified, for each of the examined materials. Results showed that, erosion initiates through plastic deformation (orange peeling) before proceeding into ductile and brittle, due to work hardening, fracture, whereas the extent and crack propagation characteristics of each phase, depend on the material’s mechanical properties and crystalline structure. Acoustic emissions were also examined, with the aim of, characterizing the materials and potentially be utilized for erosion monitoring. Upon the successful establishment of acoustic thresholds for cavitation erosion, in the case of small specimens, a small model rudder was also examined under an analogous context, although in that instance, cavitation localization was also considered, through a triangulation source location technique. In that instance, cavitation induced erosion, was effectively monitored and characterized both in terms of intensity and location. A model rudder twice as large as the small one was also examined in order for any possible scale effects to be identified. Cavitation induced erosion, was again effectively monitored, both in terms of intensity and location, although results indicated that the method should be optimized, with respect to the parameter of size. As such, the future researcher could further promote the evolvement of the aforementioned ship rudder monitoring system, by means of optimizing the analytical procedures in order to overcome any possible scale effects, further adapting the characteristics of the system to match the size of the objects to be monitored and eventually lead to the full – scale application of the system. The conduction of sea trials would also be of great benefit and importance towards the direction of forming a solid cavitation erosion monitoring system.

Until recently limited effort has been expended to improve energy performance in ships, due to relatively low operational costs and lack of stringent regulations concerning environmental impact. As a result, energy systems were designed to safeguard against worst case operational conditions and their design was based on experience or steady state calculations, which resulted in oversized ship components and plants, operating away from their optimum efficiency. Cruise ships operating in the Mediterranean use HVAC (Heating, Ventilation and Air Conditioning), which anecdotally represent 30% of the total energy consumption of the vessel (Boden 2014). The aim of this study, was to identify the potential of solar Passive Design (PD) strategies (a proven architectural design approach) in reducing thermal loads on the HVAC system within the context of cruise ships operating in the Mediterranean (McCartan and Kvilums 2014a). This was achieved through the development of design tools adopting a bioclimatic methodology to support engineers and designers in making critical design decisions at the beginning of the design process - to effectively estimate the potential of PD for a given climatic range. The focus of this research was a quantitative thermodynamic analysis - through simulation - of the thermal environment of cruise ship cabins. This was executed using existing validated PD simulation tools from the architectural industry. Attention was placed on specific solar passive practices concerning the physical form of the façade and fenestration. The simulation results showed the increase in shading depth from 0.5 to 2.0m in depth resulted in a decrease in annual combined heating and cooling loads of between 25.9% to 13.6% for a zone orientated in a northerly direction whilst a reduction between 60.5% to 40.2% was observed for zones orientated in a southerly direction. It appeared therefore, that zones in a southerly orientation benefited most from shading. Overall shading decreased annual sensible loads across all the test locations especially in locations with latitudes below 41.28°N. The application of solar passive technology reduced solar gains by as much as a 71.6% when a 2.0m shading device was added to south facing 80% glazed façade. A comparable decrease of 69.8% was also observed in relatively northerly territories such as Trieste for the same zone configuration. Overall, across all test locations a mean reduction of 54.6% is witnessed when shading is applied to a zone with an 80% glazed façade. In addition to the physical adaptions made to the exterior façade, the optical and thermal characteristics of glazing systems were also considered; for a zone with an 80% glazed façade orientated south. The results indicated that combinations of glazing properties were found to VI produce relatively low annual combined heating and cooling loads, which were between 39.06% to 53.68% less than the glazing systems which produced the highest loads. Overall the parametric study indicated that combined passive strategies resulted in the lowest annual heating and cooling loads as well as the lowest solar gains. Naval Architects and interior designers have a key role to play when it comes to the design of future low-energy cruise ships. The preliminary design tool developed in this thesis contributes to the need for further development of design tools for solar PD strategies within cruise ships. This focuses on user-friendly visual tools that are easily interoperable within current architectural modelling software packages, and which generate clear and meaningful results that are compatible with the needs of a future interdisciplinary workflow of the Naval Architect and interior designer. The limited knowledge of solar PD technologies within the Naval Architect community, suggest the need for further skills development amongst Naval Architects and tool development to accelerate the implementation of these technologies in future cruise ship designs (Kanters 2014).

There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components. This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components. In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery. The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme.

Liquefaction of fine particle cargoes such as unprocessed nickel ore and iron ore, resulting in cargo shift and loss of stability of ships, has caused the loss of many lives in marine casualties over the recent few years. Since the dangers of cargo liquefaction have long been known to the shipping industry, the question of why the phenomenon is resurfacing now would be a legitimate one. Under the requirements of International Maritime Bulk Solid Cargoes (IMSBC) Code adopted by the Maritime Safety Committee of the Organization, the moisture content of the cargo that may liquefy shall be kept less than its Transportable Moisture Limit (TML) in advance of loading, as determined from one of three laboratory test methods specified in IMSBC code. However, the accuracy of these methods is still not understood and the TML result varies particularly when conducted in different laboratories or in different methods for a given sample (Rose, 2014). Considering the ambiguity of testing (unavailability or non-compliance) and the variability in cargo properties and state as well as conditions that can lead to liquefaction (pertaining to ship design and operation and to environmental conditions), it is necessary to investigate the root causes that trigger the phenomenon and address the problem in a comprehensive manner. On the other hand, despite the positive steps that have been taken towards prevention of such shipping accidents, IMSBC code appears to have certain limitations and leaves the shipper responsible to involve the competent authority and the operator for the characterization of the cargo and the hazards it entails for the ship and its crew, if in doubt. This thesis, therefore, gives consideration to the development of the numerical simulation method to the ship cargo liquefaction, which could be feasibly used as a reference and possibly support a suitable regulatory framework for the liquefaction analysis of cargoes.

Evacuation analysis of passenger ships is mandatory since June 2016 for all passenger ships as prescribed by the International Maritime Organisation (IMO) in the revised guidelines for evacuation analysis (MSC.Circ.1533). The advanced evacuation analysis defined in the IMO guidelines, relies on the usage of computer models to simulate the movement of people and their interactions with the environment and the other evacuees. These models are powerful tools which allow for a detailed representation of theEnvironment and the people specific characteristics and behaviour. Setting up and running simulations is a very time consuming process and the bigger and more complex the ship or building is, the longer it takes. In situations when time is critical such as during emergencies and when a fast assessment of theevacuation time is needed, then relying on evacuation simulation tools might not be an option. Having a simplified model that can capture the different factors influencing the evacuation process and predict the total evacuation time would be a real advantage. In the research presented here, an attempt to develop such a simplified model has been made. The work undertaken during this research focused on investigating the possibility to derive a parametric model that could be simple enough to produce fast estimates of evacuation times but also capture the different elements of the evacuation process to satisfactory accuracy. Different parametric models were investigated. The nature of the problem led to investigate arrival processes, which were a good candidate for the underlying model explaining the evacuation of passengers. A close analysis showed that a Batch Non-Homogeneous Poisson Process (Batch NHPP) was needed to model the problem at hand. The batch arrivals and the NHPP are independent of each other so they were modelled and studied separately. The data used in this research came from a number of simulations (8 000 individual runs) performed with the Evacuation simulation software Evi as well as from the validation dataset produced by the EU-funded project SAFEGUARD and its associated Evi simulation runs (about 200 runs). The work was split between the fitting of the batch sizes of the arrivals and the NHPP. A complete analysis of the data was performed. The fitting of the batch sizes as well as the arrivals with the selected models produced very good results. Then, using the fitted models, new data was generated and analysed. The results were compared to the original data for both the batch sizes and the NHPP.

This thesis intends to study the manoeuverability of a single ship advancing in regular waves which is believed to be important for ship navigation safety as the situation is much more common experienced by a seagoing ship in real seaways instead of the calm water environment for traditional manoeuverability analysis. For this purpose, a so called two time scales model is applied to study the problem, according to the difference of the motion frequencies between the two involved sub-problems. That is to say, the total ship motions are consist of two parts, namely the wave induced motions analysed in a rapidly varying time scale system and the manoeuvring motions associated with a slowly varying time scale system. The two systems exchange data with each other at specific time intervals to reflect the interaction between two sub-motions. By this means, the analysis for an advancing ship executing a maneuver in waves can be achieved. To make concrete analysis of the sub-problems, a boundary element method (BEM) based on the 2.5 dimensional (2.5D) potential flow theory is adopted to solve the 5 degrees of freedom (DOF) rapidly varying wave induced motions, i.e., the seakeeping problem of slender ships advancing at speeds from moderate to relatively high is determined by interactively solving the discrete boundary integrate equation, kinematic and dynamic boundary conditions on the free surface in cross sections from bow to stern in time domain. Besides, this method is also used for the estimation of the manoeuvring derivatives required by the manoeuvring analysis. A numerical scheme called Multi-Transmitting Formula (MTF) is imposed on an artificial boundary to satisfy the radiation condition. The lift force, regarded as a consequence of the 3 dimensional (3D) flow effect which is important to manoeuvring motions but normally be neglected in the 2.5D theory, is taken into account for the evaluation of the total hydrodynamic forces acting on the ship during lateral motions. Furthermore, Non-Uniform Rational B-Spline (NURBS) is used for modelling the body plans of the ship and expressing the unknown quantities on the boundary elements to give more accurate and smoother solutions for the boundary value problems (BVP). To validate the established numerical tool, computations are carried out on a WigleyIII hull, a Series 60 hull and a container ship S175 hull respectively. The results are compared with the available experimental data. Regarding the manoeuvring motion simulations, the model is established based on the modular concept proposed by the Japanese Mathematical Modelling Group (MMG). The forces and moments induced by the propulsion system, the rudder system and the nonlinear viscous effect are estimated separately by empirical formulae or directly obtained from experimental measurements. The mean second order wave drift force is determined by direct pressure integration depending on the solved linear velocity potential from the seakeeping module. Simulations of the standard free running maneuvers, namely turning circle motion and Zig-zag motion, are carried out on the S175 ship in calm water and different regular waves successively. The results are compared with experimental measurements for validation which demonstrates that the present numerical tool can reasonably predict the manoeuvring motions of a slender ship in regular waves.

System-induced human error is the most significant factor in aircraft accidents; for which errors are both inevitable and a frequent occurrence. Human error is a by-product of performance variability caused by system failures, for which undetected error becomes a latent error that can impact system safety and therefore contribute to a future undesired outcome. The phenomenon of Individual Latent Error Detection (I-LED) is proposed. ILED refers to the detection of workplace latent errors at some point post-task completion through the recollection of past activity by the individual who suffered the error. An extensive literature review shows the phenomenon to be a novel concept, indicating a clear gap in knowledge requiring research to explore the nature and extent of I-LED events. A multi-process theory is developed and combined with the systems perspective to provide a theoretical framework upon which to conduct real-world observations of ILED events in cohorts of naval air engineers. Collected data indicate time, location and other system cues trigger I-LED events, for which the deliberate review of past activity within a time window of two hours of the error occurring and whilst remaining in the same sociotechnical environment to that which the error occurred appears most effective. Several practicable interventions are designed and tested, from which the overall benefit of integrating the I-LED phenomenon as an additional safety control within an organisation’s safety system is assessed. This thesis contributes to knowledge on workplace safety by applying systems thinking to understand the nature and extent of I-LED and its benefit to safety resilience in naval aircraft maintenance through enhanced operator competence to detect latent errors. I-LED research arguably offers a step-change in safety thinking by offering a level of resilience within the workplace that has not previously been accounted for in organisational safety strategies.

This thesis investigates the problem of slamming loads on high-speed planing craft and related global rigid body and local structural responses using numerical simulations and full-scale tests. The aim of this work is to improve the safety and efficiency of high-speed craft structural designs for realistic operational loads. A numerical model for simulating the water impact of two- and three-dimensional rigid and flexible structures is developed. The model uses the commercial CFD software Star CCM+ to solve for the fluid flow and the FE code ABAQUS to solve for the structural response. Two different water entry problems are studied - the water impact of a free-falling rigid wedge and the constant velocity water entry of a flexible composite panel - and the results are compared with the experimental data of Lewis et al. (2010) and Allen & Battley (2015), respectively, for validation. The influence of several numerical and experimental parameters on the solution, including grid and time step size, fluid compressibility, three-dimensional effects, structural boundary conditions and hydroelastic effects, is investigated. The model is then applied to simulate the full-scale drop tests of a realistic hull, also conducted within the framework of this thesis, and the results are compared with the measured data for validation. The effect of three-dimensional flow and spray rails is investigated. Full-scale rough water trials and drop tests on a 9.6m high-speed planing craft have also been performed. Measurements of rigid body motions, accelerations, pressures, strains and global hull deflections were made for various sea conditions, speeds and headings (rough water trials) and drop heights (drop tests). Methods for processing the experimental data, including low pass filtering the acceleration signals, removing baseline drifts from the strain signals and identifying the peaks in the pressure and strain signals are developed and successfully applied. Characteristic results from the rough water trials including, segments of the time signals, histograms of the identified peaks, calculated averages of the largest 1/3rd and 1/10th peak values, and the loads and responses recorded in a typical impact event, and characteristic drop test measurements are presented and discussed. The repeatability and symmetry of the drop test is also investigated. Statistical analysis of the rough water trials measurements is also performed. The Weibull and generalized Pareto models are fitted to the samples of identified pressure and strain peaks for estimating extreme loads and responses. Automated algorithms for fitting the statistical models to the peak value distributions are developed and the goodness-of-fit of the models to the data is examined. The suitability of the design loads used in current practice is assessed by comparing the acceleration and pressure measurements from the rough water trials with the predictions based on the ISO (2008) standard and DNV GL (2015) and Lloyd’s Register (2016) rules. Preliminary comparisons between pressure and strain measurements from the rough water trials and the drop tests measurements are also made to examine the relationship between the two tests.

Modern seakeeping computations are carried out using a variety of techniques ranging from two-dimensional (2-D) strip theory employing potential flow to three-dimensional (3-D) computations using fully nonlinear unsteady RANS (Reynolds-averaged Navier-Stokes equations) codes. The ever increasing size of ships and off-shore platforms has resulted in ‘softer’ hull which require hydroelastic effects to be taken into account when predicting fluid-structure interactions. Majority of such investigations are carried out numerically using potential flow solvers. Although nonlinear potential flow methods are also used, RANS/CFD can fully take into ac-count the nonlinearities and viscous effects. It is important, therefore, to verify and validate the predictions from such numerical predictions. This thesis aims to investigate the symmetric motions and responses of flexible floating bodies by coupling RANS/CFD and Finite Element software. The two-way interaction between a fluid solver, Star-CCM+, and a structural solver, Abaqus, is applied by exchanging pressures and nodal displacements more than once every time step, namely implicit scheme. A combination of overset and mesh morphing approaches and finite volume solution to allow for the motions of a body at the free surface is used. The air-water interface is captured using a VOF method and improved using HRIC scheme. The proposed method is applied for a validation case for a flexible barge and a containership in regular head waves for a range of wave frequencies and wave heights. The computational results are compared with experimental measurements and 2-D linear hydroelastic predictions. It is shown that the numerical predictions of flexible bodies can be carried out using the present two-way coupling method. The nonlinearities in wave loads arising from severe flare impact and green water (containership) are well predicted, which also provides some initial insights into the nature of 2-node flexible component.

The thesis examines the place of art and design in the life of the Peninsular and Oriental Steam Navigation Company (P&O). In particular, the thesis examines P&O’s art and design in the context of the company’s evolving role in the networks of the British Empire and Commonwealth from the company’s foundation in 1837 to the closure of its liner service in 1969. This contributes a different perspective to existing debates which have not yet focused on the role of everyday corporate art and design in Victorian maritime empire, the persistence of maritime empire in twentieth century art and design, or the impact of decolonisation on Britain’s maritime identity and culture after 1949. Drawing on P&O’s business archive held at the National Maritime Museum, Greenwich, the thesis illustrates the case for a nuanced view of imperialism and culture beyond the simple monoliths of good and evil, and beyond generic characterisation as either corporate pride or propaganda. The research demonstrates how Britain’s imperial-maritime culture adapted a variety of art and design forms and functions at different times and places in the nineteenth and twentieth centuries. It reveals a story of imperial change, instability and uncertainty, as much as it does corporate power, order and control. The extended post-colonial timeframe identifies how melancholic and nostalgic imperial echoes persist and return in corporate narratives long after the formal end of the Empire.

Local and global loadings, which may cause the local damage and/or global failure and collapse of offshore structures and ships, are experimentally investigated in this study. The big research question is how the aeration of water and the elasticity of the structural section affect loading during severe environmental conditions. A further question is how the scattered waves from ships and offshore structures, the mooring line force and the structural response, which are known to affect local load and contribute to global load, will be affected by wave-structure interaction of a ship or offshore structure under non-breaking wave conditions. Three different experiments were undertaken in this study to try to answer these questions: (i) slamming impacts of a square flat rigid/elastic plate, which represents a plate section of the bottom or bow of ship structure, onto pure and aerated water surface with zero degree deadrise angle; (ii) wave impacts on a truncated vertical rigid/elastic wall in pure and aerated water, where the wall represents a plate section of a hull; and (iii) wave-structure interactions of different FPSO-shaped models, where the models were fixed or taut moored. The experiments were carried out at Plymouth University’s COAST Laboratory. Spatial impact pressure distributions on the square plate have been characterised under different impact velocities. It was found that the impact pressures and force in pure water were proportional to the square of impact velocity. There was a significant reduction in both the maximum impact pressure and force for slamming in aerated water compared to that in pure water. An exponential relationship of the maximum force and the void fraction is proposed and its coefficients are found from drop test in this study. There was also a significant reduction in the first phase of the pressure and force impulse for slamming into aerated water compared with pure water. On the truncated wall, aeration also significantly reduced peak wave loads (both pressure and force) but impulses were not reduced by very much. For the case considered here, elasticity of the impact plate has a significant effect on the impact loads, though only at high impact velocities; here the impact loads were considerably reduced with increasing elasticity. Wave loading on the truncated wall was found to reduce with increasing elasticity of the wall for all investigated breaking wave types: high aeration, flip-through and slightly breaking wave impacts. In particular, impact pressure decreases with increasing elasticity of the wall under flip-through wave impact. As elasticity increases, the impulse of the first positive phase of pressure and force decreases significantly. This significant effect of hydroelasticity is also found for the total force impulse on the vertical wall under wave impacts. Scattered waves were generated from the interaction of focused wave groups with an FPSO model. The results show that close to the bow of the FPSO model, the highest amplitude scattered waves are observed with the most compact model, and the third- and fourth-harmonics are significantly larger than the incident bound harmonic components. At the locations close to the stern, the linear harmonic was found to increase as the model length was decreased, although the nonlinear harmonics were similar for all three tested lengths, and the second- and third-harmonics were strongest with the medium length model. The nonlinear scattered waves increased with increasing wave steepness and a second pulse was evident in the higher-order scattered wave fields for the fixed and free floating models. In addition, the higher harmonics of the mooring line force, and the heave and pitch motions all increased with increasing wave steepness. Incident wave angles of 0 (head-on), 10 and 20 degrees were experimentally investigated in this study. As the incident wave angle between the waves and the long axis of the vessel was increased from 0 to 20 degrees, the third- and fourth-harmonic scattered waves reduced on the upstream side. These third- and fourth-harmonic diffracted waves are important in assessing wave run-up and loading for offshore structure design and ringing-type structural response in fixed and taut moored structures. The second-, third- and fourth-harmonics of the mooring line force, and the heave and pitch motions decreased as the incident wave angle increased from 0 to 20 degrees.

This study explored the potential of further improving the hydrodynamic performance of tidal turbines by applying leading-edge tubercles to the blades inspired by the humpback whales. Within this framework, a wide variety of experimental investigations, supported by numerical studies, has been conducted. The study first focused on the design of the leading edge tubercles for a tidal turbine blade. Numerical simulation has been conducted for various designs and the best candidate was then applied onto a representative tidal turbine blade, a 3D hydrofoil can be fitted with various leading-edge designs. Experimental test was conducted in a cavitation tunnel and demonstrated significant benefits in terms of improving the lift coefficient and lift-to-drag ratio especially after stall. The results were then validated and complemented by numerical simulations for further detailed analysis. This simulation explicitly showed that the contra-rotating vortices generated by the tubercles formed a vortex fence prevented the tip vortex from inducing the spanwise flow, which meanwhile energized the flow and maintained more attached. Following that, a set of tidal turbine models with different leading-edge profiles was manufactured and were tested to evaluate the efficiency, cavitation, underwater noise and detailed flow characteristics in the cavitation tunnel. These experimental investigations confirmed that the leading-edge tubercles could: improve the hydrodynamic performance in the low Tip Speed Ratio (TSR) region without lowering the maximum power coefficient; maintain the power coefficient in the low Reynolds number; constrain the cavitation development to within the troughs of the tubercles; hence mitigate the underwater noise levels.

Smoothed Particle Hydrodynamics, SPH, is a Lagrangian method that has been applied to a number of fields including maritime applications. However little work has been done concerning the simulation of the motion of ships' hulls. A weakness of SPH is in the modelling of boundaries, both permeable and impermeable. This thesis investigates some of the latest SPH methods used to simulate these boundaries. Particular emphasis is placed upon the development of an approach that idealises the permeable inflow and outflow boundaries of a domain that are required to simulate the boundaries of a wave tank. In the method presented the inflow boundary has been designed such that it can also generate waves. This allows for the simulation of a ship hull subject to head waves. The inflow boundary is also capable of creating a mean flow speed along with the wave generation. The outflow boundary serves as both a plane which allows particles that have crossed it to be removed and also incorporates a sponge layer that is designed to damp out incoming waves and prevent any unphysical wave reflection. These developments, used together, allow a small section of a wave tank to be simulated, this requires a minimum of computational resources. Each new development has been tested against published data from experiments or numerical simulation. The computational models discussed in this thesis compare the performance of the new approach against experimental data and simulations using both classic SPH and Reynolds-Averaged Navier-Stokes methods. The wave generation and damping methods have been compared against the motion predicted by the Airy wave theory. The hull motion simulations have been compared against Wigley hull experimental data.

Vortex-induced vibration (VIV) of cylindrical structures is a classical topic within fluid-structure interaction (FSI). In offshore engineering, it often causes the fatigue of slender structures, such as risers, mooring lines and pipelines. Detailed understanding of this FSI phenomenon and an efficient prediction of such self-excited and self-sustained oscillations are required for the reliable estimation of the fatigue damage and the development of VIV suppression techniques. Over the past few decades, VIV has been extensively studied and the majority of the existing publications in the literature are experiments or semi-empirical modelling. In contrast, FSI simulations by combining high-fidelity computational fluid dynamics (CFD) and computational structural dynamics (CSD) solvers have received less attention. The main objective of this thesis is to investigate VIV of elastically mounted rigid cylinders and flexible cylinders using fully three-dimensional (3D) FSI simulations. Apart from important VIV aspects, such as response amplitude, response frequency and fatigue damage etc., the present research is also focussed on the aspects which have not been fully addressed by previous studies such as correlation lengths and time-dependent 3D flow structures. Two-degree-of-freedom (2DOF) VIV of an elastically mounted circular cylinder with varying in-line (IL) to cross-flow (CF) natural frequency ratios (f* = fnx/fny) is first studied using a 3D CFD approach. Numerical simulation is carried out for a constant mass ratio m* = 2 at a fixed Reynolds number Re = 500. The reduced velocity Vr ranges from 2 to 12. Three natural frequency ratios are considered, i.e., f* = 1, 1.5 and 2. The structural damping is set to zero to maximise the response of the cylinder. The main objective of the first study is to investigate the effect of f* on the 2DOF VIV responses and the 3D characteristics of the flow. It is discovered that there is a significant increase in the vibration amplitude and the peak amplitude shifts to a higher reduced velocity when f* increases from 1 to 2. A single-peak cross-flow response is observed for the identical in-line and cross-flow mass ratios when f* = 2. Dual resonance is found to exist over the range of f* studied. The preferable trajectories of the cylinder in the lock-in range are counterclockwise figure-eight orbits, whereas clockwise orbits primarily occur in the initial branch. The number of clockwise orbits decreases as f* increases from 1 to 2. Oblique figure-eight trajectories appear at Vr = 6, 7 and 8 when f* = 1. The third harmonic component which is observed in the lift fluctuation increases with f*. The correlation decreases in the lock-in range and reaches its minimum value around the transition region between the lock-in and post-lock-in ranges. Three vortex shedding modes (2S, P + S and 2P) appear in the present simulation. A dominant P + S mode is associated with the oblique figure-eight trajectories. Variation of vortex shedding flows along the cylinder is observed leading to the poor correlation of the sectional lift forces. Then, a numerical investigation of VIV of a vertical riser subject to uniform and linearly sheared currents is presented. The model vertical riser tested at the MARINTEK by ExxonMobil is considered. The predicted numerical results are in good agreement with the experimental data. It is found that the dominant mode numbers, the maximum root mean square amplitudes, the dominant frequencies and the fatigue damage indices increase with the flow velocity. Dual resonance is found to occur at most of the locations along the riser. At some locations along the riser, a third harmonic frequency component is observed in the CF response and a frequency component at the CF response frequency is found in the IL response apart from the frequency component at twice the CF response frequency. The majority of the vortex shedding shows a clear 2S pattern, whereas a 2P mode is observed near the position where the maximum vibration amplitude appears. The higher IL fatigue damage in the second study emphasises the importance of the IL fatigue damage analysis especially in the design of low flow velocity or low mode number applications. The third study is on VIV of two tandem flexible cylinders at different spacing ratios (Sx/D) at a fixed Reynolds number Re = 500 using a two-way FSI method. The main objective is to investigate the effect of spacing on the hydrodynamic interactions and the VIV responses of these cylinders. It is found that the responses of the two tandem flexible cylinders are similar to the classical VIV responses when Sx/D is small. Once Sx/D is large enough for the vortices to be completely detached from the upstream cylinder, the response of the upstream cylinder is similar to the typical VIV response whereas the downstream cylinder undergoes wake-induced vibration (WIV). The characteristics of the response of the downstream cylinder in the present study are similar to those of the first two response regimes. The third response regime is not observed for the flexible downstream cylinder with both ends fixed. The two changes in the phase relation between the cross-flow displacements of the two tandem flexible cylinders are discovered to be linked with the initial-upper branch transition and the upper-lower branch transition, respectively. The correlation lengths of the two tandem flexible cylinders decrease significantly in the transition range between the upper and lower branches. Three vortex shedding modes (2S, P + S and 2P) have been identified in the present study. It is found that the upper-branch 2P mode is associated with large-amplitude vibration of the upstream cylinder and the P + S mode is related to large-amplitude vibration of the downstream cylinder for Sx/D = 3.5 and 5. On the other hand, the lower-branch 2P mode leads to small-amplitude vibration of the downstream cylinder in the post-lock-in range at Sx/D = 2.5. The relative phase shifts of the sectional lift coefficients on different spanwise cross sections can be attributed to the variation of the vortex shedding flow along the flexible cylinders and these phase shifts result in poor phasing between the forces and the displacements which is related to the decrease of the correlation lengths.