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Catenary moored ship and offshore structures exhibit large amplitude horizontal oscillations caused by low frequency components of the environmental loading, due to waves, wind and current, at the system resonant frequency. As a result of these large oscillations the mooring lines can undergo significant motion inducing large hydrodynamic drag forces. In many situations this line loading provides the major damping mechanism and reduces the resonant response of the floating vessel. The ability to predict induced mooring line tensions with accuracy, and the contribution of mooring line damping to total system response, is therefore of relevance to the offshore industry. Although a number of numencal models exist for the prediction of line tension and damping, the excitation of the mooring line at the point of suspension creates a complicated non-linear line response that is presently not well understood and inherently difficult to model. Given the nature of the line response, validation of numerical results with experimental data is of importance. This validation has however not been possible to date due to the extremely limited quantity of experimental data available. This thesis presents an experimental investigation into the response of small and large scale, single chain catenary mooring line models subject to a comprehensive range of top end excitation parameters. Measurements from the experimental investigation are compared with results from established numerical methods and those from a time domain numerical model developed in the thesis. Results from small and large model scale experiments are shown to be in reasonable agreement, providing further validation of existing numerical models. The new numerical model also shows good agreement and is demonstrated to be efficient and robust in its application to a wide range of line oscillation parameters.

This thesis describes a course of work aimed at developing practical methods of implementing compliant force control to enable the automation of sub-sea inspection of existing offshore structures. The overall system is based on a six degree-of-freedom (dof) hydraulic manipulator mounted on a two dof platform which is mounted on a remotely operated vehicle (ROV). For inspection tasks, the ROV attaches itself to the structure using three vacuum feet to maintain a reasonably stiff working platform. The manipulator may then be deployed to surface track the weld of two or more intersecting structural members whilst holding the appropriate inspection probe. For this project an Alternating Current Field Measurement (ACFM) probe is used. This does not need electrical surface contact but instead can operate with a constant elevation above a surface provided by the probe's own casing. This thesis also considers the likely motions that will be experienced by the real system and examines the use of vision systems to compensate for unwanted movement. It further examines the design of an appropriate compliance to sit between the manipulator and the probe and describes the construction of this compliance device. A novel method is offered that uses an artificial neural network (ANN) to simplify the problem of mapping a robot tool position in space when using compliant force control. For this case, the compliant device is a network of springs between plates situated between the manipulator end flange and the tool. A force sensor is mounted between the tool and the compliant device. To overcome the difficulties of accurately modelling the non-linear and highly coupled characteristics of the compliant device, a back propagating ANN was trained to relate the forces to positions for real data sets. The finished ANN was used as part of a computer model of the overall manipulator system. The ANN was then used as part of a force control loop to enable surface tracking.

This work presents a study of the vernacular boats of modern Greece. A new typology of boats is offered, and an account is given of tools and boatyard practice, design and construction techniques. Evidence for these subjects is drawn from field surveys, museum collections, iconographic studies, and interviews with old boatbuilders. Although most of the information presented comes from the first half of the 20th century, background information from the 18th and 19th centuries is also covered. This longer historical perspective is particularly important in making comparisons between 20th century practices and the boatbuilding techniques of the past. There is evidence for the existence of two main periods of technical change in the industry, namely, the late 18th century, when new methods such as lofting were introduced, and the late 19th century, when changes in the wider shipbuilding industry initiated a process of decline in vernacular boatbuilding. At the same time however, a number of older techniques, for example certain moulding methods, survived at least into the first part of the 20th century. This work offers new insights into the design methods involved in the control of hull-form during "skeletonfirst" boatbuilding from the last two hundred years. It also offers an analysis of the structural integrity and strength of vernacular boats and shows how the structure of boats has evolved across time to incorporate new techniques and changes in boat function.

Predictions of the environmental loading and induced motional and structural responses are among the most important aspects in the overall design process of offshore structures and ships. In this thesis, attention is focused on the wave loads and excited bodily motion responses of large offshore structures and special vessels. With the aim of improving the existing theoretical methods to provide techniques of theoretical effectiveness, computational efficiency, and engineering practicality in marine and offshore applications, the thesis concentrates upon describing fundamental and essential aspects in the physical phenomenon associated with wave-structure interactions and deriving new methods and techniques to analyse offshore structures and unconventional ships of practical interest. The total wave force arising from such a wave-structural interaction is assumed to be a simple superposition of the potential and the viscous flow force components. The linear potential forces are solved by the Green function integral equation whilst the viscous forces are estimated based on the Morison's damping formula. Forms of the Green function integral equation and the associated Green function are given systematically for various practical cases. The relevant two-dimensional versions are then derived by a transformation procedure. Techniques are developed to solve the integral equation numerically including the interior integral formulation and, in particular, to tackle the mathematical difficulties at irregular frequencies. In applying the integral equations to solve problems with various offshore structures and special vessels, some modified, improved or simplified methods are proposed. At first, simplified method is derived for predictions of the surge, sway and yaw motions of elongated bodies of full sectional geometry or structures with shallow draft. Then, a new shallow draft theory is described for both three- and two-dimensional cases with inclusion of the finite draft effect. Furthermore, a three-dimensional strip method is formulated where the end effects of the body are fully taken into account. Finally, an approximation to the horizontal mean drift forces of multi-column offshore structures are presented. Some new findings are also discussed including the multiple resonances occurring in the motions of multi-hulled marine structures due to the wave-body interaction, the mutual cancellation effect of the diffraction and the radiation forces arising from a full shaped slender body, and so on. Further to those verification studies for individual methods developed, more comprehensive example investigations are given related to two industrial applications. One is a derrick barge semi-submersible with zero forward speed; and the other, a SWATH ship with considerable speed. By correlation of all the proposed approaches with available analytical, numerical and experimental data, the thesis tries to demonstrate a principle that as long as principal physical aspects in the wave-structure interaction problem are properly treated, an appropriately modified or simplified method works, performs well and, sometimes, even better.