This thesis analyses the reasons why the system of industrial relations on the United Kingdom continental shelf is very different from that which prevails both onshore and on the Norwegian continental shelf, where the same technology is used to produce an identical product. The scopeo f the researche ncompassesth e relationships of the trade unions and the offshore companies, both Norwegian and British, where they concern employment and related matters such as accident prevention and those interventions which govermnents have made in response to particular events. In addition research papers and other reports which have a close bearing on the human resource management of offshore employees have received attention. British trade unions have failed to win full recognition offshore after "first oil" because the oil companies have been determined to exclude them and have exhibited a cohesivenesso f purposei n this respectt hrough their formidable employers' association, UKOOA. By comparison trade union efforts have lacked cohesion on account of internal disputes and the indeterminate position of the IUOOC within the trade union structure. Even the assistance of a friendly disposed government which persuaded the employers to permit recruitment visits offshore has had no effect on membership which remains derisory. Although the Norwegian LO recognised as early as 1975 that a new union for all offshore workers was necessary, the TUC has never shown the same realism. OILC seeks to cater for all UK offshore workers, but survives only as a small independent union outside the STUC. It arose spontaneously in 1989 as a crossunion group of workers who wanted a national offshore agreement but after initial support from the official trade unions was later abandoned by them. There have been some dramatic accidents offshore, none worse than Piper Alpha in 1988 with its 167 fatalities. This has concentrated attention on the maintenance of safe working environments and trade unions have sought, unsuccessfully, to win recognition from the employers by demanding representation on installation safety committees. As the oil industry now implements a programme of cost savings there have been accompanying assertions in some publications that the oil industry's commitment to accident prevention remains secondary to profitability, assertions this thesis finds groundless.

No description available.

No description available.

No description available.

A survey of literature concerning methods of predicting the effect of weather on ship speed performance at sea has been made covering the following topics: - - Added resistance due to regular waves, - Wave diffraction, - Wave drift force, - Added resistance due to irregular waves, - Added resistance due to wind, - Wind and wave conditions at sea, - Involuntary speed loss and power increase for a given added resistance, - Effect of rough weather on ship speed performance. The survey revealed that it is difficult to determine numerically the speed loss and power increase due to inclement lather. A principal reason for this is that none of the existing theoretical methods available for determining the added wave resistance are convincingly accurate, in particular over the range of wavelengths which are short compared to the length of a ship. An approximate method for calculating added resistance due to regular wave reflection has been established by the Author. The basic steps of the method are as follows: - (1) To find a mathematical model of a ship by making use of the NAG subroutine based on a minimax polynomial fit method. (2) To evaluate the wave drift force due to very, short waves(i. e. When it may be assumed that the incident wave potential is the same as the potential due to body disturbance) for a vertical axis cylindrical body having infinite draught, and for which the waterline shape is the same as the actual ship, using the mathematical formula obtained at 1(1)1 and Bessho's formula. (3) To correct the result of '(2)' with a correction factor for the effect of wave scattering, based on the wave scattering coefficient derived by Jones et al. using ideas developed in the shady of geometrical optics. (4) To correct the result of '(3)' for the effect of finite draught considering the orbital motions of water particles. (5) To correct the result of '(4)' for the effect of forward speed with the correction factor given by Fujii-Takahashi but modified for the case of oblique waves by the Author. In order to confirm the applicability of this method, an experimental work was carried out by the Author using a Series 60 model with oscillations in the 6-degrees of freedom restricted. Particular attention was paid to the case of the shorter wavelength range where the effect of wave reflection is dominant cared to the effects of the ship's motions (Wave steepness = 10.6 ~ 101.0, A/L = 0.23 ~ 1.18, Fn = 0.10 ~ 0.25). When comparing the measured and the computed resistance due to wave, reflection in a head sea, good agreement is shown. To modify the results of most conventional methods for added resistance due to regular waves, it is assumed that the total resistance increase of a ship in regular waves can be approximated by the sum of the resistance due to wave reflection and the resistance due to the ship's motions. Modifications of results determined by Gerritsma's method and by Maruo's method were made using the Author's routine. The modified results were compared with results using Fujii-Takahashi 's method, that of Gerritsma, and that of Maruo as well as with some experimental data measured by Strom-Tejsen et al., van Sluijs et al., Loukakis, Shintani, and Fujii et al. for Series 60 and tanker forms in head and oblique regular waves. Fran the comparisons, the Author concludes that his method of determining added resistance due to regular waves provides a good approximation for practical purposes, bearing in mind, however, that an increased error may be found with longer wavelengths and higher speeds in the range Fn > 0.25. Using the Author's method and the linear superpositiari technique, added resistance due to irregular waves was calculated for a Series 60 model in several experimental spectra used by Sibul. The computed results were compared with the model data measured by Sibul in irregular waves. The comparison reveals that the results of the Author's method agree well with the measured data. A comparison was made by the Author to find differences between the results of added wind resistance calculated using methods due to Isherwood, van Berlekan, Aage, Wilson et al., Tsuji et al., Wagner, Gould, and Shearer et al.. The mean difference between the results of Isherwood's method and the others quoted above was 7% for a given relative wind speed for a tanker in head winds where the added wind resistance may be larger than that for oblique winds. Using the following routines :- - the Author's for added wave resistance, - van Berlekan's for wind resistance, - van Berlekan's for speed loss and power increase due to a given added resistance. and using the I. T. T. C. standard spectrum and particular sea conditions, various effects of weather on ship speed performance at sea were investigated. The following topics were covered: - - Effect of weather intensity and ship type on added wave resistance (Tanker, Containership), and comparison of the result with full scale data (Tanker). - Caparison of the result of the Author's method with those based on experimental data for the thrust increase due to waves (Tanker). - Effect of ship size, ship type, and weather intensity on the ratio of added wave resistance to the total added resistance (Tanker, Containership, Passenger liner). - Comparison of the results of the Author's method with full scale data for speed loss (Ore carrier). - Effects of ship speed and draught on power increase in certain cases (Tanker). - Effect of weather intensity on the additional energy expenditure per nautical mile (Tanker). - Comparison of the result of van Berlekan's formula for speed loss due to a given added resistance with the result of Townsin's empirical foi hula based on full scale data (Tanker). - Establishing approximate formulae (the Townsin/Kwon formulae) for speed loss due to the effect of head wind and waves (Tanker, Container-ship). - Comparison of the relative effects of weather and hull roughness on power increase and speed loss (Tanker). To conclude, the Author considers that the thesis provides an improved understanding of the effect of weather on ship speed performance, particularly in short sea waves. The Author expects that his work will facilitate the following: - Analysis of sea trial data. - Improved estimation of service power margins. - Accurate determination of optimum speed for fuel economy etc.. This thesis is based on research done by the Author as a member of the Ship Performance Group in the Department of Naval Architecture and Shipbuilding of the University of Newcastle-upon-Tyne in England, under the supervision of Dr. R. L. Townsin.

No description available.

The harsh environment in which offshore structures must operate, their intended service life and the uncertainties inherent to the load processes, have been the impulse for investigation of their reliability. The method most extensively applied for this purpose during the last two decades was the Structural Systems Reliability, which can not be coupled with the finite element method. Therefore the objectives of the present work are to investigate the applicability of a technique which allows the utilization of the reliability analysis methods with a marine riser modelled by the finite element method, FEM, and revision of the reliability levels associated with this riser, including the fatigue life. For these purposes the response surface methodology was selected, among a number of methods. A response surface approach which requires a low number of experiments with the FEM model was elected, calculations for construction of the response surface are further simplified by the assumption of statistical independence among the basic variables. It is demonstrated in the present study that the response surface is capable of producing an equivalent and explicit limit state function which is used at a second stage with the First Order Reliability Method and the Adaptive Importance Sampling simulation technique. However, it was found that the assumption of independence is not always valid. In this case, a method is proposed in which the correlated variables are implicitly considered at the level of the mechanical model. The reliability of the marine riser was reviewed with the proposed algorithms, finding that the validity of the reliability levels depend on the number of basic variables considered and their statistical properties. The significant reduction in required computing time achieved with the response surface methodology allowed parametric studies to be carried out, in order to investigate the impact of different statistical properties of the basic variables. The fatigue reliability case was also investigated with the S-N approach. The introduction of uncertainty in the fatigue life estimation proved that acceptable levels of deterministic fatigue life may render unacceptablelevels of reliability. The uncertainty associated with the stress range is the most significant variable, though the present fatigue reliability formats consider it in a very simplified manner, therefore an approach is suggested with which the stress uncertainty can be considered in a more detailed fashion. However, the algorithm used here for construction of the response surface was unable to produce the required surface. Therefore it is concluded that though the response surface is capable of handling a large number of structural reliability cases, there are instances in which more research efforts are needed.

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.