In today's highly competitive shipbuilding market the emphasis is on the production of acceptable design proposals within a very short timescale. A computer-aided conceptual ship design system, which utifises the latest developments in workstation technology, has been developed. It is intended to help reduce the technical and commercial risks associated with the process of tendering for newbuilding contracts. The system as a whole, uses fundamental modeffing techniques to enable areas such as dimensions generation, huilform development, layout design, powering estimation, mass estimation, motions prediction, work content estimation and cost estimation to be considered at a much greater level of detail at the concept design stage than was previously possible. This thesis describes the specification and development of those parts of the overall design system concerned with the generation of vessel dimensions and huliform and layout design. In order to improve the flexibility of the system, a so-called expert system approach has been adopted to provide the mechanism for the control of the design methodology. For this purpose, a unique expert system shell named INCODES (INtelligent COncept DEsign System) was specified and developed. The development of this shell is described in some detail. The application of the INCODES shell to the control of the logic involved in the development of design proposals for containerships is discussed, and the knowledge base developed for the generation of these design proposals is described. The knowledge base is shown to incorporate fundamental procedures for the generation of vessel dimensions and for huliform and layout design, as well as a comprehensive suite of analysis routines to assist in the verification of the design proposals. The knowledge base is also considered to be unique in its treatment of the investigation of the loading arrangements of containership design proposals. The flexibility of the procedures developed is demonstrated by their application to the generation and examination of containership design proposals which possess a range of physical and operational characteristics.

The main objective of the project is to investigate the influence of surface roughness of marine propeller blades on propulsive power. The work has involved studies in the concept and practice of surface roughness measurement and characterisation as well as application of boundary layer theory for the analysis propeller-ship hull flow interaction of propeller flow and propellar-ship hull flow interaction. From extensive measurements of the surface topography of in-service propellers, a standard measurement procedure using different commercially available propeller-surveying instruments is described. A development of turbulent boundary layer procedures has been made to determine sufficiently accurately the increment of drag coefficient of propeller blade sections due to propeller blade surface roughness. The roughness function used for this integral boundary layer analysis is derived using, principally, Musker's experimental data. In addition, an experimental determination of the roughness function of a replicated propeller surface using a rotor apparatus has been carried out and described in detail. The turbulent boundary layer procedures require a knowledge of the surface variation of pressure over the propeller blade. For this purpose a program based on Riegels method has been used to give the velocity distribution for a given propeller section geometry. This is used with the boundary layer procedures for developing a complete program "PROFNESS" to calculate the increment of drag coefficient of the blade section. Results from different propellers analysed indicate that the power penalty is proportional to the relative blade roughness to the 1/3 power. An investigation has been made to compare the increment of frictional coefficient for a flat plate and propeller section profiles. It is shown that a "rough" flat plane calculation is quite adequate for such work.' The use of a flat plate analogue as a reference to calculate the skin friction resistance of both propeller and hull surfaces is considered. It is shown that the proposed solution of flat plate momentum integral equations provides a valid, simple and practical solution to the problem of predicting the hull and propeller roughness drag penalties. It also provides, particularly for ship hull resistance, a strong support for the ITTC Correlation Line, not only, and importantly, in regard to its slope, but also its level. For shipowners and operators who may not wish to access advanced computer programs, a simplified method has been proposed to calculate the propeller roughness penalties. There is a good agreement between the two simplified and detailed propeller analysis methods. The propeller roughness penalties, which can be obtained from either the simplified or the more rigorous method, can be related to the Rubert Propeller Comparator Gauges in order to quantify the benefits and justify the cost of the blade surface roughness. Analytical procedures have been included which can be used to calculate the combined effects on ship performance of propeller blade and ship hull surface roughnesses.

A description is given of a new computer based techno-economic model designed with particular reference to investments in improved hull and propeller maintenance. The model combines the principles of accountancy with technical and operational variables so as to facilitate an operational simulation of most ship types in a selected economic environment. The technical and engineering economic basis for the proposed new model is discussed with particular emphasis on the relationship between hull surface roughness and ship resistance, the effects of hull roughness and fouling upon propulsion efficiency and quantitative measurements of hull roughness and fouling experienced on ships in service. Results from a set of full scale experiments on two sisterships are also presented in support of a proposed modification to an existing approximate relationship between roughness and ship resistance. The new techno-economic model is sub divided into three principal parts, based respectively upon deterministic analysis, dynamic programming and probabilistic cash flow simulation. Each part serves a different function in the decision making process between alternative hull and propeller maintenance strategies. A new technique is presented for obtaining probability distribution functions of individual variables associated with uncertainty when only a limited amount of subjective information is available. This new method serves as a basis for the proposed probabilistic cash flow simulation model, having the primary function of providing quantitative assessments of uncertainty in investment calculation. The initial requirement for considering the hull maintenance problem within the complete commercial context of ship operation has been confirmed in a series of case studies for different ship types where principal variables and recommended maintenance strategies have also been identified. Quantitative assessments of uncertainty are provided, indicating a potential high degree of uncertainty associated with this type of investment. A separate case study on the hydrodynamic and economic penalties of propeller roughness has established the relative difference between hull roughness and propeller roughness in economic terms. Finally, the deterministic case study evaluations have resulted in the introduction of two simplified methods of calculation from which approximate solutions to alternative hull maintenance strategies may be obtained.

No description available.

A particular problem that has been encountered in modelling the forces and moment acting on a manoeuvring ship, has been the correct estimation of the distribution of side force along its length. If traditional slender body theory is used, reasonable agreement can be obtained between theoretical and experimental result over the forebody of the ship. However, moving aft, the two increasingly diverge until there are significant differences at the stem. For this reason manoeuvring coefficients cannot be accurately predicted by this approach. In a number of studies, the reason for the discrepanciesh as been attributed to the influence of trailing vortices that develop along the hull. The conclusion is consistent with sensitivity analyses carried out with augmented slender body theory incorporating vortices of specified location and strength along the ship. The present thesis is concerned with modelling trailing vortices along a ship in drift motion so that they can be used in the calculation of the associated distribution of forces and manoeuvring coefficients. A numerical model based on the Discrete Vortex Method has been developed for the analysis of vortex flow around the ship which is representedb y slender body approximation. The trailing vortices are modelled by a series of transverse two-dimensional multi-vortex solutions marching longitudinally down the hull. Results are presented for six different hull types; a flat plate, the Wigley hull, a block hull, a Series 60 hull, the British Bombardier and the British Bombardier with a pram stem. The effects of varying drift angles are also investigated for each hull types. Good qualitative agreement is shown between the predicted velocity and vorticity fields and results from experimental studies. The distribution of side forces and yaw moments along the hull is also well predicted. The results explain manoeuvring phenomena occurring for the hull forms considered that have been observed experimentally and at full scale.

No description available.

The behaviour of the hydrodynamic loading experienced by a circular cylinder in the presence of boundaries has been the subject of investigation by various investigators in recent years. Amongst other things it is relevant to the design of offshore structures and subsea pipelines. It is important to be able to assess the behaviour of such components of an offshore structure because it has to be designed to withstand loading due to flow interactions which are complicated in nature and not yet fully understood. To gain a clearer insight into the effects of anodes on the overall loading of an offshore structure, for example, the local flow around a cylindrical member in the presence of boundaries must be understood. In the present study, a numerical model based on the Discrete Vortex Method has been developed as a means of analysis of such flows since, in comparison to experimental methods, it is a less expensive and less time consuming approach in gaining that knowledge. The algorithm is developed in such a way as to enable application to a range of cylinder / cylinder, cylinder / anode, and cylinder / wall configurations subject to a variety of steady and time dependent flows. The technique has been applied in a number of case studies which include the investigation of the flow interactions occuring when two cylinders are in close proximity and also when a cylinder is close to a plane boundary. The engineering applications are the interference of structurel members, the loading on structural elements due to the presence of anodes, and the loading on free spanning subsea pipelines. The in-line and transvese force coefficients arising from the case studies and also the flow patterns obtained are presented in order to provide a more detail description of the flow phenomena and interactions involved. The comparison of the results with both experimental and numerical evidence is also presented and the range within which the algorithm produces good results is identified.

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Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 399-404). Available also in a digital version from Dissertation Abstracts.