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A mathematical method for calculating turbulent boundary layer develop- ment on ship hulls is based on convergence and divergence of external flows. It is applied to a two-dimensional test case a mathematical hull form and the forms of a high-speed liner a containership and a tanker.

DRDC (Defence Research and Development Canada) Atlantic has a number of sonar projects that require the underwater transmission of acoustic energy. Because of potential adverse environmental effects a number of international and Canadian laws as well as DND (Department of National Defence) policies impact on these research activities. Of particular interest for this paper are the Canadian legislation and departmental policies relating to the potential impact of active sonar research sea-tests on marine mammals. The relevant legislation and policies in place to protect the natural environment from undue stress from human activities are sumarised. The emphasis is on legal and policy vehicles that are directed towards the protection of the living marine environment. DRDC activities must adhere to many other Canadian laws both federal and provincial; however only the environmental protection legislation and policies affecting sea-trial activities are discussed.

Conference held 26-27 September 1995 in London UK. Papers are - Britannia - enlarging the operational envelope of an old warrior Structural design of a harsh environment - 4 legged jack-up boat The use of DNV classification systematics as a means of satisfying the NPD requirements to structural strength for a jack-up unit Evaluation of hydrogen assisted cracking resistance of high strength jack-up steels Voyage acceleration climate - a new method to come to realistic design values for ship motions based on the full motion climate for a particular transport Verification of methods for simulation of nonlinear dynamic response of jack-up platforms Systematic model tests on a harsh environment jack-up in elevated condition Effects of non-gaussian waves to the dynamic response of jack-up platforms An introduction to the PFEER regulations Estimation of foundation fixity parameters for a simplified jack-up model Some aspects of the safety of jack-ups on location and during transit

The international climate change negotiations have identified options for countries to achieve their greenhouse gas emissions reduction targets by either contributing to emissions-reducing projects in other countries or through the international exchange of emissions-reduction credits (trading). Such approaches offer significant opportunities to achieve greenhouse gas emissions reductions at lower societal costs than other measures while providing significant additional contributions to environmental protection and sustainable development. Businesses have the ability to play an important role in enabling these 'mechanisms' to function to their maximum potential. The prospects for realising these opportunities will depend on decisions concerning the international operation of the 'mechanisms' and on the manner of implementation of these 'mechanisms' by national governments. These factors will in turn largely determine the role of businesses in the 'mechanisms'. A business perspective on the opportunities issues and barriers surrounding the practical application of these 'mechanisms' is provided through examination of some opportunities to apply them within the petroleum industry and the identification of the issues that must be addressed to enable such commercial applications.

A numerical modelling toolset is described which has been produced to study the survivability implications of a trimaran hullform subjected to non-contact UNDEX (underwater explosion) attack. The validation process carried out on the toolset is discussed and numerical prediction versus experiment comparisons are presented. The shock analyses used a finite element model based on RV Triton scaled up by 3-2 to represent a full-scale trimaran warship. The whipping studies used a 1-25th scale trimaran pipe model based on an indicative trimaran design and also a full-scale beam idealisation of the indicative design with which initial parametric design studies have been performed.

The extreme loading on structures caused by the impact of breaking waves has long been known and has recently been brought into focus again as a result of the occurrence of unexpectedly high or steep waves around both fixed offshore structures and FPSOs. This has prompted work on re-analysis of wave records and on numerical modelling of temporally and spatially extended wave fields in order to investigate whether for example nonlinear effects may increase the probability of occurrence of extreme waves. In this paper consideration is given to wave breaking the geometrical scale of breaking crests and the criteria which determine the type of breaker by reference to selected sources from the literature more-or-less in a qualitative manner

Despite all the new worldwide information about ice-structure interactions locating a fixed structure in the Baltic Sea is in general considered to be costly and hazardous. When discussing suitable locations of offshore wind generators along the coastline of the Baltic Sea the potential of ice loads is essential. Selected data from full-scale measurements of extreme ice pressure on structures in the Baltic Sea are discussed. Simplified empirical design rules are challenged with a proposed method using statistics on ice crushing climate and ice conditions. Indications of strong influence of structure diameter on the effective ice pressure are confirmed by results obtained from other lighthouses in the area. The results can be used in simulating ice-load probabilities for fixed vertical structures with small diameters located in the Baltic Sea.

This paper makes clear the concept of the ecological development policy for the model of the coastal city. The paper shows the general concept of the future development and the ecological development coastal city on Osaka Bay coastal zone based on the various relations of the land and sea in the coastal zone. The paper shows that it is desirable that the new coastal city and social economy is established where sustainable development with the ecosystem is aimed at based on the ecological development of the coastal zone.

A set of experiments performed in a closed-circuit wind tunnel in order to investigate the aerodynamic characteristics of a typical offshore supply boat are presented. The test facility is described along with wind speed measurement simulation of the marine boundary layer force and moment measuring system and data collection and processing system. Results are discussed in terms of Reynolds Number effects the effect of boat heading on the un-iced vessel effect of severe ice accretion accuracy of wind tunnel tests and influence of wind forces on ship dynamics. The results are compared with previous work. Severe ice accretion was found to cause a significant increase on wind loading and to reduce drastically the dynamical stability of the ship.

The principal aim of this paper is to study the dynamic behaviour of offshore platforms subjected to wave loading. A general review of offshore structure wave loading and their effects on offshore structures are presented. A brief review on the basics of Wavelet analysis is also mentioned in this study. The techniques for modeling wave loading in finite element analyses are described and discussed in detail. A series of 3D analyses were carried out using the ABAQUS finite element software to study the effects on the dynamic response of the change in support conditions at the seabed. The effects of wave height wave period and wave velocity on platform behaviour were studied. The results from time history analysis are characterized using Wavelet Analysis in order to obtain the response pattern due to wave loading. These analyses allow the frequency response of the jacket structures to be described in the time domain. These results give a clear view on the response of jacket structure. The important parameters on offshore modeling have also been identified and discussed in this paper.

The character of the current and temperature records from an array of moorings on the San Pedro shelf are discussed briefly. The circulation of the San Pedro shelf is shown to have three major components: low-frequency flows derived from the large-scale oceanography of the southern California Bight; the sea breeze-induced upper-layer flows on the outer shelf; and tidally forced currents. The low frequency (sub-tidal) flow variability observed is discussed (section 2); the effects on the current field of the daily fluctuating winds of the coastal sea-breeze system are considered (section 3); and the semidiurnal surface and internal tide are studied (section 4). These three processes in this order of importance account for most of the observed variability in the current and temperature fields over the eastern part of the San Pedro shelf.

In-service monitoring systems for safe ship navigation can be used for decision support for course and-or speed changes if the on-site directional wave spectrum in combination with the frequency response function(s) is known. Therefore it is interesting to have a method which on the basis of ship response measurements facilitates a continuous update of the directional wave spectrum. Thus the problems related to the fixed position of wave buoys and current meters are overcome. Moreover since the sensor measurements are already inhand from the in-service monitoring system a ship response-based estimation method has no initial cost as opposed to for example wave radar systems not to mention the calibration and maintenance of such systems. Two ship response-based methods for the estimation of onsite directional wave spectra are compared: a non-parametric method based on Bayesian modelling and a parametric method

Control structures such as weirs and barrages constructed on a river will change the hydraulic regime of that river by increasing water depths and reducing velocities in the zones of developed backwater curves. The impact of water level control structures on the self-assimilative capacity of rivers is studied and possible changes in the ecosystem and fish habitat are assessed. A mathematical model is developed to simulate the river hydraulics water quality temperature and fish habitat. The diurnal dissolved oxygen concentrations are investigated to see their impact on the fish. A case study of a Nile River reach was examined to investigate the impact of the existence of the Esna barrage on the water quality in its upstream reach. To do this water quality indicators were developed to express the impact in a quantifiable manner. It is concluded that the barrage has negative impacts on the upstream self-assimilative capacity of the rivers that it has a positive effect on the fish habitat and that it causes a slight decrease in water temperature.

A probabilistic model for fatigue crack initiation and propagation in welded joints is used to determine the likely effect of plate (specimen) width and free edges on crack shape development and on fatigue life for T-plate joints with full penetration welds. This probabilistic model explicitly considers multiple crack initiation and coalescence. Its predictions of the influence of free edges on crack shape development including edge cracking are consistent with experimental observations.

As one of the most important materials for industrial components eutectoid steel has been used in many industrial areas. In practical structure component the shapes of notches or steps are necessary and very useful according to the structural requirement. However the fatigue strengths of these components are significantly decreased because of the stress concentration at this position. Based on the statistical analysis more than 90% of failure of machine and mechanical parts are directly or indirectly caused by fatigue and nearly 90% of the fatigue cracks are initiated at stress-concentrated parts. Improvement of fatigue strength of these components is a serious challenge in engineering. Reports on the improvement of the fatigue strength of notched specimens are seldom observed. There are many methods to improve the fatigue properties through surface modification such as plasma technique surface chemical heat treatment etc. Among these methods roller working can be considered as an effective and low-cost method to improve the fatigue properties of bar shape components. A fatigue test is carried out to investigate the effect of roller working on notched specimen using eutectoid steel. Results are presented and and the reason for the improvement is also discussed.

The application of stern flaps to large combatant-sized Naval vessels is a fairly recent innovation. A stern flap is an extension of the hull's bottom surface which extends aft of the transom. It is a relatively small and inexpensive addition which reduces the power required to propel a ship through the water. The US Navy has been investigating the powering improvements due to stern flaps on many different types of ships. The flap design and performance is optimised for speeds at which the ship expends the most power thereby maximising the potential for propulsion fuel reduction. The US Navy has installed prototype stern flaps on three ships and conducted ship trials to assess their effect on ship powering performance. The concept is presented and described. The design selection and analysis of the stern flaps are considered and their application to the three ships is described. The estimated fuel saving s and decrease in exhaust gas emissions for these applications are summarised.

In this paper an attempt is made to show the time domain analytical method of the deformation on VLFS in irregular waves and estimate the responses in time domain. As this analytical method is based on Fourier transformation and inverse Fourier transformation much calculation time can be saved. The corresponding experiment was carried out in a model basin. Some responses of elastic models were measured in uni-directional and two-directional irregular waves. It is confirmed that this is a very effective analytical method comparing with the time series of the experimental results. Also the linear superposition theory on the response analysis of VLFS was validated. Finally such time domain analytical method is expanded to 2nd-order response problem.

It is well known that the strain rate has notable effect on fracture behavior of steel and its weldment therefore it is important to require adequate toughness taking into account the effect of strain rate on the fracture behavior of structures for securing the safety of those structures subjected to dynamic loading such as offshore structures working in arctic region and buildings under the seismic conditions. In this paper an evaluation method of the strain rate effect based on the strain rate temperature parameter derived from the quasi dynamic fracture mechanics consideration is introduced first then the application results of the evaluation method for the clarification of fracture behavior of architectural beam-to-column connections under dynamic loading is described.

In this paper a series of undrained cyclic triaxial loading tests was carried out on compacted intermediate soils to investigate the effect of soil properties on their cyclic behavior. The effect of clay content and clay type on the rate of build-up pore water pressure double amplitude (IDA) axial strain and degradation of stiffness during cyclic loading of the tested intermediate soils was studied. It was found that the increase of clay content in the soils increased the rates of build-up pore water pressure and DA axial strain and degree of stiffness degradation during cyclic loading. The clay type was an important parameter to control cyclic behaviour.

Recent years have seen some severe sterntube bearing damages often following a sharp course change. This paper presents the development of a simulation model for oil lubricated journal bearings along with extensive measurements of the conditions in the aft sterntube bearing of a twin propeller Ro-Ro vessel. Results of these investigations demonstrate that hydrodynamic forces at the propeller during manoeuvring considerably influence the performance of the aft sterntube bearing. Depending on the character of the manoeuvre the journal gets tilted downwards to the aft end of the bearing or in a more horizontal direction towards the oil grooves respectively. The measurements confirm the suitability of the calculation program to simulate the bearing conditions. Therefore it is possible to evaluate the effect of design modifications on bearing performance and particularly on oil film thickness