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Wind-generated short capillary and capillary-gravity waves play an important role in ocean remote sensing and air-sea interaction processes. Small-scale ocean wind waves contribute primarily to sea surface roughness elements and affect radar Bragg scattering and air-sea transfer of momentum mass energy and heat. There are few studies on short wave group structure due to the difficulties of measuring short waves in the field even though wave group structure for longer waves (swells) has been studied extensively. Statistics of small-scale (short capillary-gravity) ocean wave groups are studied with in-situ data and group-induced long wave theory. The analysed data show a close relationship between mean length of runs average time duration and significant wave slope of a random wave field. They both tend to decrease as wave slopes increase. Group statistics can be described by group-induced long waves and agree with data well.

Considerable achievements have been made in the development of gas and dual-fuel engines in recent years. Continuous development of new engines and new engine technologies has enhanced the performance the reliability has improved and the fuel flexibility spectrum has increased. An update on two most recent gas engine development projects carried out by Wartsila is presented and some methods to further improve the performance are reported. The W50DF is a highly efficient dual fuel engine with micro pilot ignition and with real 'multi-fuel' capability. The features of this engine are described and the merits in both marine applications like LNG carriers as well as in land-based power production are reported. The 20V34SG is a new 20-cylinder spark ignited gas engine with very interesting performance levels in terms of high break mean effective pressure and high efficiency. Some novel technologies introduced to this engine are also described. Finally by adopting 'skip-firing' EGR or combustion air humidification improvements to engine emissions and output are shown.

The growth of coral in most of the Persian-Arabian Gulf and Arabian Sea Region is subject to extreme environmental conditions in particular wide fluctuations of temperature and salinity. Mass coral bleaching and mortality in 1996 and 1998 reduced live coral cover significantly in many areas. However the effects of the 1998 bleaching event in the Arabian Sea was minimised by the onset of the summer upwelling which moderated the extreme temperatures of Southern Arabia. There are signs that recovery has begun but there are new reports of bleaching in the Gulf of Oman and the Straits of Hormuz and it is too early to determine the ultimate effects of the bleaching on coral health. Threats to coral reef biodiversity are examined and recommendations are made to improve the conservation of coral reef resources.

For several years the 3D product model has been a standard in shipbuilding. However 3D design is still mainly used in the detail design phase. A STEP-based ship product model (STEP) is introduced and proposed as a framework for the integration of CAE applications and related design information in the ship initial design stage. For the design of SPPM an object-orientated hybrid methodology based on IDEF family of methods was defined and introduced as an information-modelling tool for the development of shipbuilding information system. STEP is also proposed as a baseline for the development of new shipbuilding CAD systems because of its qualified data structure and well-proven methodologies.

Tests carried out on the split stern bearing of a 280000 dwt VLCC are described. Programme objectives outlined include establishing the tailshaft position relative to the stern bearing and the minimum clearance between the tailshaft and the stern beam and measuring the axial shaft movement lubricating oil pressure the loads in the bearing holding down jacks and the stress in the hull plating adjacent to the welded joint between the stern bearing and the hull. Results presented demonstrated the unexpected effect of hull deflexions and the likelihood that final alignment of shafting could be more accurately carried out if completed at ballast draught.

The English Channel is a major fishing ground for long-finned squid (loliginidae). Preliminary assessments of English Channel loliginids have been conducted using depletion methods without distinguishing species. This study presents a new species-specific assessment of English Channel loliginids. Two methods are applied to data from four fishing seasons (1993-1996). The first aim of the study is to estimate recruitment levels and interannual recruitment variations for each Loligo population. Results derived from the depletion method and cohort analysis are compared in the light of the underlying assumptions of the models. The second aim is to assess the impact of the fishery on the two exploited populations. For this purpose the first exploitation diagnostic for a cephalopod stock in Europe is provided.

Multivariate analysis of fatty acid profile is a new method in sebastes research. This method was implemented after convincing results were achieved in a pilot test on two reared stocks of cod in the Faroe Islands. The next step was to investigate the method's discrimination power among the three species of redfish: Sebastes viviparus Sebastes marinus and Sebastes mentella in waters off the Faroe Islands and Norway. The positive results at the species level prompted an investigation into the stock structure of Sebastes mentella in the North Atlantic. The purpose of this investigation is therefore to reveal the stock structure of Sebastes mentella in the North Atlantic by the fatty acid profile method. A look is taken at materials and methods followed by results discussion and conclusion.

Since the introduction of high tensile strength steels most oil tankers have experienced fractures at the end attachments of the side shell longitudinals to the transverse web frames or bulkheads. These fractures are due to fatigue originated by a stress range that is much greater than that calculated according to the traditional methods. A simple user-friendly procedure is presented to evaluate the actual stress levels. This procedure takes into account the normal stress induced by the non-uniform torsion acting on the member and the restrictions to the free warping of the section at its ends. This additional stress may be included then within the classical calculations by means of a correction factor which considers the parameters relevant to the un-symmetry of the section. The validity of the procedure is also demonstrated.

Numerical prediction of vortex-induced vibrations requires employment of the unsteady Navier-Stokes equations. Current Navier-Stokes solvers are quite expensive for three-dimensional flow-structure applications. Acceptance of Computational Fluid Dynamics as a design tool for the offshore industry requires improvements to current CFD methods in order to address the following important issues: (i) stability and computation cost of the numerical simulation process (ii) restriction on the size of the allowable time-step due to the coupling of the flow and structure solution processes (iii) excessive number of computational elements for 3-D applications and (iv) accuracy and computational cost of turbulence models used for high Reynolds number flow. The above four problems are addressed via a new numerical method which employs strong coupling between the flow and the structure solutions. Special coupling is also employed between the Reynolds-averaged Navier-Stokes equations and the Spalart-Allmaras turbulence model. An element-type independent spatial discretization scheme is also presented which can handle general hybrid meshes consisting of hexahedra prisms pyramids and tetrahedral.

The principle concern when designing a flexible riser is to ensure that its resistance exceeds the anticipated loads during its life. Load distributions can be predicted from global dynamic analysis which is well covered in literature. The dependence of a flexible riser's structural response on natural variations in its construction can be addressed with a cross-section model that predicts the structural response to various loads. Cross-sectional analysis models are less established in literature and so uncertainties and calibration must be considered in their use. Several issues associated with the structural analysis of flexible risers are addressed including analysis methods design for barrier layer integrity and assessment of risers using a combination of global dynamic analysis and cross-sectional analysis.

The solution of wave equations for a moving elementary charge with non-trivial boundary conditions is considered together with the radiation arising from this. The solution based on the wave approach provides an adequate description of the phenomenon of transformation of an electromagnetic field of the moving charge at the crossing of the interface between media with different dielectric properties - a solution for the transition radiation. With this solution including the transition radiation near to a trajectory of movement the theory of transition radiation is essentially developed and opportunities of research in more thin effects are opened.

Bacterial contamination has caused the OCHCA (Orange County Health Care Agency) to close large sections of the City of Huntington Beach California since summer 1999. Extensive studies have yet to definitively identify the source of these bacteria. One proposal is that the OC Sanitation District's submerged offshore wastewater plume is the source. This hypothesis is explained as the transportation of the wastewater plume towards shore in the summer when the water column is most stratified. It is thought that the plume might then have interacted with a local electrical power generation station's intake and-or thermal discharge plume to cause the observed chronic shoreline microbiological contamination. In response to this hypothesis the District implemented an intensive multi-faceted multi-agency research study in 2001 to study both high and low frequency cross-shelf oceanographic transport processes on the San Pedro Shelf that could bring the plume toward shore. The general study approach is described followed by physical oceanographic studies and coastal ocean studies. Some discussion concludes the paper.

In real-time digital underwater acoustic imaging the size power consumption and cost of the front-end hardware are critical design issues especially for applications like UUV. The number of active array channels and sampling scheme directly affect these specifications. For low-cost front-end a beam-forming architecture is presented based on sub-array processing with non-uniform over-sampling delta-sigma data conversion. The basic principals of the sub-array delta-sigma beam-forming architecture are described. Then experimental test results obtained from a 128-element transducer array are presented. Finally the proposed and conventional beam-formers are evaluated and compared in terms of image quality and hardware efficiency.

Today's sonar systems strive for higher and higher resolution. This utterly leads to the transmission of higher frequency signals. Besides the obvious impairments on using high-frequency signals such as signal attenuation unknown platform motion errors and stability of phase propagation through the medium become increasingly important. High-frequency synthetic aperture sonar systems require demanding tolerances in motion errors and medium-phase stability. This article proposes a new method that mitigates the problems associated with small wavelength-related errors. By dividing the received signal bandwidths into several smaller ones and conjugate complex multiplying them a new signal is obtained with longer effective wavelength thus reducing the impact of motion errors and medium-phase fluctuations. To test the proposed method several tests were carried out in the Douro River Portugal. Results are presented. It is concluded that with the proposed method it is possible to mitigate some of the problems that hinder high-resolution synthetic aperture sonar.

Sub-modelling is a technique which is most useful when it is necessary to obtain an accurate and detailed solution in a local region of a large model. A new sub-modelling technique is proposed and applied to ship structure analysis in which a bulk barrier is selected. Two types of boundary conditions the first displacement boundary condition and the other stress boundary condition based on the SPR (super-convergent patch recovery) method are applied in sub-modelling analysis and their results are compared. Two computational domains of ship structure for sub-modelling analyses are considered and the accuracy of the sub-modelling analysis is investigated. According to the numerical analysis SPR method improves the stresses along the sub-modelling boundary and the proposed sub-modeling technique gives accurate solutions.

In most foreseen disable submarine situations there are two stages in a rescue: to keep the rescuees alive and to recover them to safety. Keeping the rescuees alive may involve getting ELSS (emergency life support stores) into the submarine as quickly as possible. These stores are delivered in cylindrical pods which are posted through the submarine hatches. Perry Slingsby Systems have designed and manufactured both the ELSS pods and the dedicated ROVs for their delivery. Once a SRV (submarine rescue vehicle) and its support ship are on site the task of recovery can begin. A SRV will have the ability to attach itself to the annulus surrounding the submarine's rescue hatch and to transfer rescuees into an integral chamber. The SRV must be able to accommodate conditions such as severe pitch and roll and poor visibility. In addition the submarine may be partially flooded and the transfer may need to happen at elevated pressure.

Conf held in London 29-30 April 1992 by Ins of Meas. & Cont. Papers are - Combined power and signal Signal on power transfer - an economic and technical alternative Robust underwater acoustic telemetry New initiatives for subsea umbilicals Hydraulic operation of subsurface safety valves in high temperature wells Measurements of parameters affecting direct hydraulic control system response time Corrosion protection of subsea production systems A corrosion monitoring system for subsea application FSM - the electric fingerprint - a novel technique for monitoring corrosion erosion and cracking Current and novel concepts for subsea production and control systems The Emerald Field control and monitoring system ROV intervention - experience and potential Standardization of subsea control systems Development of a computer based control system for the Snorre Subsea production system Kvaerner booster station control system Pressure and temperature transmitters engineered for subsea applications

Conf held 28-29 April 1993 in Aberdeen UK. Papers are - Low cost autonomous subsea water injection systems Low cost subsea systems flexible pipe - the way forward The towed pipeline technique as a means of installing a connected structure Future riser requirements - a low cost solution MANTA - the bottom line subsea production control system Building in cost saving - diver reconnectable umbilical weak link protection system Subsea metering for fiscal allocation and well test applications Flexible pipe materials for aggressive hydrocarbon applications Autonomous control system (SPARCS) for low cost subsea production systems Impacts of weather and climate on the offshore industry Risk management in the oil industry indemnities and insurance

All engineered construction on earth must be carried by some kind of onshore or offshore foundations. For almost 50 years the offshore industry has used driven piled foundations as the main support for offshore production facilities in shallow waters. However in deep waters other foundations options must be designed like suction piles VLAs (vertically loaded anchors) etc. An example is presented of the reliability assessment of suction piles foundation in clay-type soils for deepwater applications. The results of two reliability approaches using suction piles as the foundation system for TLPs (tension leg platforms) under deep waters environmental conditions in the Campeche Bay (Mexico) are compared. The first approach uses the FORM (first-order second moment) reliability method with a suction pile analytical model and the second one uses the MC (Monte Carlo) reliability method with a suction pile Finite Element model. The uncertainties of the loads soils mechanical properties and analytical models were included in the reliability analysis. The results from this study point to important topics for future works.

In the Haven accident (Genoa April 1991) a large amount of the Iranian heavy crude oil cargo sank. Some areas located on the sea bottom were examined to assess the benthic ecosystems affected by the sinking of the burned heavy oil. In 1995 dives were carried out from the bathyscaphe Cyana of Ifremer in three selected bathyal areas in the western part of the Gulf of Genoa. During these dives sediments and tar samples were collected and observations were made about the interactions established between the tar depositions and the benthic and bentho-nektonic fauna. The analyses were carried out to investigate the PAH and n-alkanes concentrations in sediment cores and in samples of a tar deposition and to evaluate genotoxic damage and hepatic tissue alterations in demersal fish species and they show the likely occurrence of the Haven oil residuals acting as a chronic source of pollutants.