Traditionally the problem of calculating the motion responses of a ship in a seaway has been formulated in frequency domain in terms of linear potential theory. By using the potential flow method in roll calculation, the fluid is assumed to be ideal, irrotational and viscous effects are neglected. Experiments have shown that the roll amplitude responses of rectangular bodies floating in beam waves are overestimated when calculated by potential flow method. This is largely attributable viscous effects [1]. For this reason seakeeping calculation methods introduce empirical factors to account for viscous effects. On the other hand, much of the nonlinear forces and moments experienced by ship in a seaway may be due to the viscous effects leading to flow separation and generation of vortices [2]. One approach to modelling flow separation and vortex shedding is to solve the Navier-Stokes equations. However, for moving bodies in the presence of a free surface at high Reynolds numbers (which implies the use of fine computational meshes) the software and hardware resources required, supposing the problem is even viable, are often so large as to be prohibitive. Another approach is to use methods based on vortex dynamics for modelling separated flows about bluff bodies. These methods were developed as a means of modelling high Reynolds number flows in which the vorticity is confined to small sub-domains of otherwise irrotational flows [2]. This work concerns development of a purely theoretical model for estimating the roll response of vessels that takes these effects into account. The objective of this thesis is to develop a model including viscous effects that can be used in seakeeping and survivability calculations. The idea being proposed is to match a local discrete vortex based method to a global model of a body floating with six degrees of freedom. A software is developed that can be bolted on to conventional seakeeping software so that the motions of sharp edged bodies floating in waves can be calculated without recourse to empirical methods. The theoretical approach to predict roll damping for a three-dimensional barge shaped floating vessel in the frequency domain is described here. The approach consists of matching a simple discrete vortex method (DVM) describing local separated flow, to an inviscid three-dimensional seakeeping code. Model tests have been carried out to validate the theoretical model and the associated add-on software. As demonstrated in this report, there is a good agreement between the model test RAO and the damped RAO indicating the theoretical method provides a good estimate of the viscous damping of the vessel due to vortex shedding from its edges. Although viscous damping in sway and heave motions is not as significant as for the roll for a barge the same methodology can be used to calculate viscous damping for both sway and heave as well. As tangential relative fluid velocities are used in this method the same final relative velocities can be used to calculate skin friction damping component. In this study skin friction damping is considered to be negligible and is ignored in the final calculated damped RAO.

The use of catamarans as an alternative to more conventional monohull high speed vessels for transport, naval and offshore applications is on the increase. This uprising trend is a direct consequence of the global demand for commercially and militarily efficient vessels that offer high speed, potential for improved Sea-keeping at speed, relatively low hydrodynamic resistance in waves and a more useable deck area. The configuration and hull geometry of catamarans are very critical to achieve improved sea-keeping and other hydrodynamic performances. The Round Bilge hull form is one of the most prominent hull geometries in use for the design of displacement-type multi-hull vessels. An alternative hullform series to the Round Bilge, catamarans, named the Deep-V Catamaran series (DVC), has been developed recently at Newcastle University. Early studies on the DVC concept based on this series indicate that the hull form may have better resistance performance than the Round Bilge. However, other important characteristics of this concept such as the motions and wave-induced load response characteristics are still unknown. There is also a lack of understanding of the general hydrodynamic characteristics of the DVC concept in comparison to the Round Bilge hull form. This study contributes to the understanding of the motions and wave induced load response characteristics of the DVC concept. It is also intended to advance the structural design methodology of the DVC concept and its subsequent application as better alternative to the Round Bilge hull form. The study involved the experimental and numerical investigations of the motions and wave-induced load response characteristics of the DVC concept by using a prototype model of “The Princess Royal” which is the current research vessel of Newcastle University. The experimental studies involved the motions and wave-induced response measurements in regular waves at both zero and forward speed conditions. The results obtained were validated using alternative potential flow-based numerical codes in frequency domain. The benchmark study indicates that the numerical codes are capable of producing acceptable results. A comparative study using a representative model of the Round Bilge hull form with the DVC model was conducted in order to establish a direct basis for the comparison of the motion and hydrodynamic load performances. The results obtained from this comparison reveal that the DVC may have better sea-keeping characteristics and is less sensitive to wave loads than the Round Bilge hull concept in critical heading conditions. A further comparison of the experimentally validated numerical predicted loads with those obtained using the International Association of Classification Societies (IACS) approach was completed. The study confirms that the IACS approach over predicts the loads by up to 40% in Beam Seas and Quartering Seas when other components of IACS rules are not considered. A simplified structural analysis of the DVC model using the Finite Element Method was also completed to demonstrate the effects of the predicted loads on the strength of the hull structure with emphasis on the cross-deck structure, which is the most sensitive structural element of the vessel. Overall, the study highlights the promising characteristics of the DVC concept in comparison to the Round Bilge hull form and provides data required for the preliminary design of catamarans using this concept.

This thesis reports on research conducted into the roll motion of trimaran ships. After reviewing the relevant literature to determine the state of the art of roll motion prediction for both monhull and multi-hulled ships a hypothesis is set out that:- Accurate trimaran roll motion predictions can be obtained using linear Potential Flow Seakeeping theory with the roll damping term either obtained from a roll decay experiment or augmented with empirically based theoretical roll damping components developed for monohulls. This hypothesis underpins the work of many of the existing researchers who have investigated the seakeeping performance of trimaran ships, although none have formally proved it to be true. After conducting theoretical, experimental and combined theoretical and experiment studies using a single trimaran model this hypothesis is subsequently disproved. This leaves a problem: How can accurate trimaran roll motions be deteraiined The focus of the remainder of the thesis is to understand why the hypothesis is incorrect, investigating in turn each of the assumptions that underpin it. Finally, as a recipe for future researchers, a series of experimental and theoretical investigations has been devised to explore the physics of trimaran roll motion from first principals. This work has shown that, for a trimaran with significant flare above the waterline on the side hulls, roll decay coefficients cannot be measured from free decay experiments if the motion is characterised by a single degree of freedom roll equation with constant coefficients. Furthermore, it is postulated that heave and roll are strongly coupled for all trimarans. It is shown, using the results of model experiments, that this coupling breaks the assumption of linear theory where an input sinusoidal wave of constant amplitude and frequency leads to output motions which are also sinusoidal with constant amplitude and frequency.

The complete ban on TBT in marine antifouling coatings in 2008, rocketing fuel prices over the past six years, environmental concern and upcoming energy efficiency indices for ships have resulted in a strong interest of the shipping industry to monitor, evaluate and optimise ship performance. Furthermore, the complete ban on TBT in anti-fouling coatings resulted in new types of foul-release hull-coatings, based con silicon, whose effectiveness and performance still needs to be evaluated. Because of the difficulty of measuring coating roughness in service and the large effect of marine bio-fouling on ship performance, a research project was setup at Newcastle University in collaboration with a major paint company to investigate the ways to evaluate hull coating through ship performance monitoring. This thesis describes the details of this project which aimed to investigate the feasibility of a real-time ship performance monitoring and analysis (PM&A) system by implementation and evaluation onboard a 16m research vessel and 300.000dwt VLCC. The thesis starts with a review of the state of art of PM&A systems. The main weaknesses of existing PM&A systems is that often abstract logbook data is used as input and that too little attention is paid to data quality. Furthermore, the systems often act as a black box, showing little insight in data analysis, harming the reliability and trustworthiness of output indicators. Additionally, there are large differences in the way that performance data is corrected to standard conditions, resulting in contradicting and unreliable performance indicators. The thesis focuses therefore on theoretically sound, transparent data analysis and improved data collection. In the thesis, all performance affecting environmental and operational conditions have been reviewed including sensor characteristics and data acquisition aspects. Based on the experience from the analysis of the data collected from both vessels, it reveals that automatic, real-time data collection and rational filtering for periods of acceleration, deceleration, course deviation, drift, shallow water and ship motion is the way forward for accurate performance monitoring. Performance analysis is highly sensitive to errors in shaft torque and ship speed through water. A frequently calibrated/validated shaft torque & RPM sensor and Doppler speed log are therefore the most important sensors for performance monitoring. Speed logs are T.W.F. Hasselaar PhD thesis, 2010 ii affected by many environmental conditions and cannot be used directly for performance monitoring. Other ways to determine ship speed through water, e.g. using the propeller inflow speed, are however affected by hull fouling and loading deviations unless corrected for accordingly. Corrections using full scale trials are then necessary to avoid overestimation of the effects of hull fouling on ship performance. To avoid these errors, a method is described to use the speed log by evaluating its reliability and utilise its reading for performance analysis only in periods where it can be considered reliable. A new transparent analysis method is described to analyse ship performance based on conversion of torque and rpm at constant ship speed. The method differentiates between the hull and propeller performance by empirically correcting the propeller open water diagram for roughness (periodically measured by divers). Evaluation of the proposed PM&A system on both vessels indicates that reliable performance indicatgors can be calculated but that fluctuations in performance indicators of ±12% remain unavoidable due to inaccurate wave observations and errors from the speed log. Trials on the research vessel furthermore show that the system is able to identify fouling, but sensor accuracy requires further research so that fouling can be defined with less performance data and higher reliability. This thesis demonstrates for the first time in open literature that the design and implementation of a transparent and fully automatic, real-time, shipboard PM&A system is perfectly viable and can be installed on any ship with the use of reliable sensors.

The work in this thesis is preceded by a Master of Research in Marine Technology project between September 2004 and October 2005. The project was supervised by Professor Martin Downie and was carried out with significant time present in the field, working closely with Olympic sailors from multiple different classes. This project was funded by UK Sport and considered a pilot project to investigate the feasibility of using data logging equipment with GPS in the marine Olympic environment. A series of prototype systems were engineered to meet the requirements specified by the Royal Yachting Association. The engineering and validation of the software and hardware formed a key part of the project to ensure that the results obtained were accurate and repeatable. This included software design within two different software platforms as well as embedded hardware developments. Significant testing and development were implemented in the laboratory as well as on the water during the beginning of the project and as a continuous background task throughout the project. Over eighty days were spent in the field developing and testing hardware and software as well as determining the optimum performance analysis methods. Data loggers were fitted to several Olympic class boats during the evaluation process to ascertain the performance of the data logging system as well as the performance of the boat and crew. Data was logged from the onboard GPS and accelerometers and analysed post training. Later in the project, wind information was also collected and fused together with the onboard data post training. The hypothesis was to demonstrate performance gains in the participating classes through the means of quantitative analysis. Prior to the project the performance analysis had been almost entirely qualitative. Through the course of the project various techniques were developed allowing quantitative performance analysis to supplement the efforts of the training group and coach. Key performance factors were determined by data analysis techniques developed during the project. One of the significant tools developed was a tacking performance analysis routine which analysed multiple different styles of tacks, calculating the distance lost with respect to wind strength and course length resulting in an important strategic tool. Other tools relating to starting performance and straight line speed were also developed in custom software allowing rapid analysis of the data to feed back to the teams in the debrief.

Exploring the operational links between a sea state and a ship’s heading and speed provides the opportunity to continuously monitor dynamic stability behaviour; and hence to avoid significant changes of stability in adverse weather. Significant changes of stability at sea can lead to dangerous transient situations and eventually stability failure. Despite its importance, the current intact stability (IS) criteria do not evaluate or consider the dynamics of the motion responses of a vessel in a wave environment. In this thesis, the full six degrees of freedom motion responses of two models have been tested in irregular waves under intact vessel conditions. The general modelling approach for a mathematical model was based on numerical simulations at different speeds, sea conditions and angle of heading relative to the waves. In the second model, a physical model was tested in a towing tank under similar simulated environmental conditions to that employed for the first model. The investigation was limited to the effects of encountered frequency components and the associated magnitude of energy of the ship’s motion responses. An analysis of heave, pitch and roll motion confirmed the vulnerability of the model to certain wave-excited frequency ranges. This particular range of frequency results in an adverse effect on the amplitude of the responses, and these were closely related to the natural mode frequencies and related coupling effects. It was confirmed that the roll motion maintains its highest oscillation amplitude at around the natural frequency in all sea conditions regardless of ship heading angles. It was also observed that spectral analysis of the heave and pitch responses revealed the wave peak frequency. Roll is magnified when the peak frequency of the waves approaches the natural roll frequency, therefore keeping them sufficiently apart avoids potentially large motion responses. It was concluded that peak frequency and associated magnitude are the two important inherent characteristics of motion responses. Detection of the most influential parameters of encountered waves through measurements of heave and pitch responses could be utilised to provide a method to limit the large motion of a ship at sea. The measurement of waves whilst a ship is underway is a major challenge, whereas ship motion, which is relatively easily measured, is a good indirect reflection of the encountered wave characteristics and which can be measured, stored and analysed using Prevention of extreme roll motion through measurements of ship’s motion responses iv on-board equipment. Motion responses are considered as continuous signals with a time-dependent spectral content, and signal processing is a suitable technique for detection, estimation and analysis of recorded time-varying signals. The method is fast enough to be considered as an on-board real-time monitoring of dynamic stability. Signal processing techniques are used in the detection and estimation of the influential parameters of a wave environment through the analysis of motion responses. The variables of the system were detected by spectral analysis of the heave and pitch motions. These variables are the peak wave frequencies and associated magnitudes which can cause a large roll motion when reasonably close to the ship’s natural roll frequency. The instantaneous frequency (IF) present in the signal is revealed through spectral analysis of short-time Fourier transforms (STFT) in less than a minute. The IF is a parameter of practical importance which can be used in real-time on-board decision making processes to enable the vessel to take actions in order to avoid large roll motions.

A short review is presented of available instrumentation systems designed to assist the operation of ships in heavy weather by warning against dangerous wave loads. Some systems also give guidance to the master by predicting the outcome of evasive actions, and the bases on which such predictions are made, such as visual observations of the wave system, are questioned. A method is presented in which the motions of the ship are used to determine the sea state in the form of an "equivalent" wave spectrum. Two investigations of the possibility of improving the guidance capability of warning instruments are described, in which the predictions are based on the equivalent wave spectrum. For this purpose, recorded full-scale data from a container ship and a tanker have been analysed and the two methods, spectrum analysis and a statistical method, are described. Using the equivalent spectrum, predictions of the effect of a change of course and estimates of one response from another have been made and compared to measured values. The results of these comparisons, which are presented graphically and in the form of correlations between measured and predicted values, are discussed with respect to error sources and factors which limit the method's applicability. The accuracy in predicting one response from another was found to be higher the closer the correlation between the responses, and correct estimations of the relative heading and the angular energy distribution of the wave system were found to be of importance. Theoretical calculations of ship responses to irregular waves have been made by linear superposition of transfer functions and wave spectra and a new way of extrapolating the transfer functions is described.

Increased autonomy allows autonomous underwater vehicles to act without direct support or supervision. This requires increased complexity, however, and a deficit of trust may form between operators and these complex machines, though previous research has shown this can be reduced through repeated experience with the system in question. Regardless of whether a mission is performed with real vehicles or their simulated counterparts, effective debrief represents the most efficient method for performing an analysis of the mission. A novel system is presented to maximise the effectiveness of a debrief by ordering the mission events using a narrative structure, which has been shown to be the quickest and most effective way of communicating information and building a situation model inside a person’s mind. Mission logs are de-constructed and analysed, then optimisation algorithms used to generate a coherent discourse based on the events of the missions with any required exposition. This is then combined with a timed mission playback and additional visual information to form an automated mission debrief. This approach was contrasted with two alternative techniques: a simpler chronological ordering; and a facsimile of the current state of the art. Results show that participant recall accuracy was higher and the need for redundant delivery of information was lower when compared to either of the baselines. Also apparent is a need for debriefs to be adapted to individual users and scenarios. Results are discussed in full, along with suggestions for future avenues of research.

This research, as a part of the Nature in Engineering for Monitoring the Oceans (NEMO) project, investigated bio-inspiration to improve the performance of Unmanned Underwater Vehicles (UUVs). Initially, the capabilities and performance of current AUVs were compared with Biological Marine Systems (BMSs), i.e. marine animals (Murphy & Haroutunian, 2011). This investigation revealed significant superiority in the capabilities of BMSs which are desirable for UUVs, specifically in speed and manoeuvring. Subsequently, an investigation was carried out on BMSs to find means to make use of their superior functionality towards engineering improved UUVs. It was discovered that due to a mismatch between the purpose of each species evolution and the desired mission of an UUV, all desired characteristics are not evident in a single species. Moreover, due to the multi-functionality of biological systems, it is not possible to independently study each configuration. Therefore, an holistic approach to study BMSs as a system with numerous configurations was undertaken. An evolutionary search and selection algorithm was developed to obtain the myriad of biological information and adjust them to engineering needs (Haroutunian & Murphy, 2012). This Optimum System Selector (OSS) was implemented to output aspects of the appropriate design combination for a bio-inspired UUV, based on its specified mission. The OSS takes into account the energetic cost of the proposed combination as well as the trade-off between size, speed and manoeuvrability. Appreciating the uncertainty in existing measured biological data, the developed code was successfully verified in comparison with BMSs data. Energetic cost of transport is a key factor in selecting a design combination based on desired missions. This is key to the accuracy of the algorithm. Therefore, in another essential research theme, a sophisticated study has been carried out on the understanding, calculating, predicting and comparison of various biological and engineered underwater systems energetics (Phillips et al., 2012). The results of the OSS compared with existing AUVs, showed improvements in the overall capabilities. Therefore, this method is an excellent guide to transform complex biological data for the future design and development of UUVs.

Despite remarkable advances in naval architecture in the past few years, limited effort has been expended to improve the energy efficiency of ships due to the relatively low price of fuel oil and lack of stringent environmental regulations. However, the ever-growing intercontinental trade has resulted in an increase of greenhouse gas emissions from ships that triggered the introduction of mandatory environmental measures and shifted the focus of the shipping industry towards more energy efficient designs and operations. This thesis focus is on improving the energy efficiency of ships during design and operation by adopting a direct approach to estimating the requisite thermal energy on board ships over their life cycle. This is achieved by dynamically modelling the thermal energy flows on board, drawing from the considerable developments in Building Energy Simulation (BES), which precedes developments in the maritime industry by five decades. To this end, and in broad terms, the thesis focus is on and embodies the technology transfer from the Buildings Industry to the Marine Industry ("marinisation of BES") whilst accounting for the differences and complexities implicit in some of the ship types as well as the marine environment and operations. This, in turn, necessitates focus on applicability, functionality and limitations of BES in ships with the view to enable developments to fill pertinent gaps and to demonstrate such developments with purposely selected case studies. During the investigation of the applicability of BES in ships, the main differences between ships and buildings were identified, and their effect on energy simulation was pointed out. The results of this comparison served as the basis for the marinisation of the selected building energy simulation software 'ESP-r', which was enhanced to also cater for energy flows present in the marine environment, leading to the development of 'ESP-r marine'. Despite the ability of the tool to model the majority of thermal energy flows on board ships, several modelling and computational problems were presented during the development of large accommodation models that triggered necessary simplification considerations. In an attempt to allow energy modelling of smaller groups of spaces and drop the requirements for explicit and topologically correct model representation, the geometrical decoupling of major space types was examined. A verification process based on energy simulation was used to construct guidelines, indicating acceptable assumptions for the boundary conditions of individually modelled or groups of accommodation spaces. This methodology was then used to facilitate further simplification of thermal modelling, which was achieved through the concept of space grouping that encompassed the process of the consecutive merging of adjacent spaces, until groups of spaces were represented by a single thermal zone. Throughout this process the loss of accuracy in the results was quantified, and results were used to develop design guidelines for the group representation of major types of on board spaces. All findings were used to form a methodology for the design of the most common ship accommodation spaces and relevant HVAC systems which outer performs current practices, since it provides detailed information about state variables in accommodation spaces and energy systems components, and allows for the calculation of the power consumption of the energy systems serving the accommodation over the ship's life-cycle at a low computational cost. Implementation of the methodology was exhibited with two case studies, one for a cargo and one for a passenger ship. The work undertaken and the derived results clearly demonstrate the applicability of BES to ships and the extent to which it can be simplified during the design process, thus introducing the concept of Dynamic Energy Modelling as a platform in shipping to support life-cycle energy management. This constitutes a significant development in shipping.