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The American shad Alosa sapidissima is the largest member of the herring family and is found in the Atlantic Ocean along the East Coast of the United States and Canada. Shad are an anadromous fish species meaning that they spend most of their life at sea but migrate into rivers to spawn. Historically both the Delaware and Susquehanna Rivers were major producers of American shad on the US Atlantic coast. However significant environmental problems led to the virtual extirpation of American shad in the Susquehanna River and a severe population reduction in the Delaware River stock. These problems are detailed together with the solutions implemented to address the problems. The successful results are outlined.

Some information on modelling safety of ships in damaged conditions at the preliminary design stage is presented by using an alternative performance-orientated risk-based method. The performance-orientated risk-based method of assessing safety of ships including modelling is briefly discussed. Some examples of safety assessment for two container ships using the proposed method are presented. The method uses the performance-orientated risk-based approach. The elements of safety case and FSA (formal safety assessment) methodologies are incorporated within the method. The hazard identification scenario development ship hydromechanics analysis risk estimation and risk control options are combined. In this respect the method is a risk-based design method as it integrates the systematic risk analysis in the design process with the reduction of risk embedded as a design objective. The method may be implemented as a design for safety method (including safe operation) or salvage-orientated method.

North Sea regulatory regimes in the UK Norway Denmark and the Netherlands are described and compared. The various descriptions and demonstrations required may be placed in a single document structure covering safety environment and asset risk assessment. Considerable cost savings can be made from a unified approach. The safety case framework is based on acceptance criteria most importantly for individual and group risk. The different states require a formalised Safety Management System (SMS) but the technical requirements for risk assessment are similar. Examples of two analysis styles are given: a quantitative approach applied to blowout hazards and a qualitative approach applied to failure mode and effect analysis (FMEA) of a ballast system.

Conf held in Aberdeen UK 1-3 April 1992. Papers are - Risk analysis of offshore installations - a decade of experience and prospects for the future Risk assessment and the control of industrial major accident hazards - experience with CIMAH Offshore safety cases - a comparison with onshore CIMAH safety cases The use of risk analyses in petroleum activities on the Norwegian Continental Shelf Consequences of gas explosion experiments and FLACS simulations Assessing ways to reduce effects from fire and explosion The EER system - paralysis by analysis or paralysis through lack of it Consequence assessment of offshore structures: the development and application of "chaos" Risk criteria and the role of cost benefit analysis The role of human factors within risk studies Developments in environmental risk assessment Future directions for offshore risk analysis The role of the project forwarder in the offshore supply industry

The actual challenge for the requalification of existing offshore structures through a rational process of reassessment leads to state the importance of Risk Based Inspection methodology. This paper points out the inspection results modelling and their contribution to decision aid tools. The study of the impact of through cracks on structural integrity of jacket platforms is still a challenge. The detection of large cracks is first addressed. In order to minimize inspections and maintenance costs all the available data from inspection results such as probability of detection and probability of false alarm must be addressed as well as the probability of crack presence. This can be achieved by the use of the decision theory. These capabilities of Non Destructive Testing give a first input for the risk study. A cost function is suggested to introduce this modelling into a risk analysis and is devoted to help rank the NDT tools. The case of large through-wall cracks is specifically addressed.

The Rocky Flowline project is reviewed from preliminary design to installation with special emphasis given to fabricating and reeling insulated pipe-in-pipe flowlines. The design and installation of 21000 feet of dual-insulated flowline in 1785 feet deep water is highlighted. Validation testing of the components was carried out to optimise the design. Details of the final design are given for the carrier pipe jacket pipe bulkheads insulation and centralisers. Critical installation tasks are listed and discussed as follows: fabrication of the pipe-in-pipe strings welding and inspection of the bulkheads reeling the dual pipelines dual pipeline J-tube pull termination of simultaneously laid dual pipelines on a common sled. The project represents a number of world firsts and the lessons learnt are listed.

The application of modern methods of non-linear dynamics to the study of the non-linear roll motion equation started during the late seventies and is now used to give design indications for safer and more seaworthy ships. To obtain reliable results by applying the modern methods of Non-Linear dynamics a realistic mathematical model of ship motions is needed. When considering the general approach to capsising i.e. including broaching and parametric resonance other degrees of freedom have to be included in addition to roll motion. In particular the coupling of roll motion with other motions in the transversal plane heave and sway is analysed employing a parameter identification technique used to discuss the goodness-of-fit of different mathematical models to the experimental data and to obtain values for the coefficients. The results of a series of tests on the scale model of a small ro-ro in beam waves are presented. Three different initial metacentric heights are tested within the same displacement.

These Rules cover materials, design principles, design loads, longitudinal strength, shell structures, decks, bottom structures, framing system, deck beams and supporting deck structures, watertight bulkheads, tank structures, stem and sternframe structures, rudder and manoeuvring arrangement, strengthening for navigation in ice, superstructure and deckhouses, hatchways, equipment, welded joints, fatigue strength, hull outfit, structural fire protection on board seagoing ships, strengthenings for heavy cargo, bulk carriers, ore carriers, oil tankers, tugs, passenger ships, special purpose ships, subdivision and damage stability of cargo ships, supply vessels, ships for sheltered water service, barges and pontoons, dredgers, strengthening against collisions, special requirements for in-water surveys, and corrosion protection.

In deepwater operations the survivability of the wellhead system and conductor casing during a drive-off or drift-off with the riser connected to the BOP (i.e. failure of the LMRP to release) has been of concern to drilling engineers for several years. FEA results are used to draw conclusions about casing and wellhead design for DP operations. A methodology for selecting casing and wellhead equipment for deepwater DP operations is defined. Major factors that influence bending moments and stresses generated on the wellhead and conductor casing as a result of a drive-off or drift-off are identified. The first yield point versus the most likely point of failure in the riser-wellhead-casing system in a drive-off or drift-off event is examined. The validity of previously used design criteria for conductor casing and wellhead connectors in deepwater DP applications is examined.

The demand for marine HSVs (high-speed vehicles) brings with it the need for safe and reliable machinery systems. The classification requirements and processes that have been developed in this area are described. The assessment of safety and dependability of such machinery and their control systems in this area is addressed with reference to compliance with codes and standards. Some features that are related to the safe and reliable operation of aeronautical systems are discussed. An analysis of 'fail safe' for different situations where speed of response may be critical to the safety of the vehicle is also presented. Although the safety and dependability of marine machinery in HSVs depend on a number of factors all of these need to be considered from a holistic point of view and not separately to ensure that the machinery installation in a marine HSV is both safe and dependable.

TLP and Spar technology as applied to floating production applications is dealt with. In particular safety considerations as related to classification and certification requirements are addressed. This covers hull structures marine systems production facilities and the relevant mooring systems for each platform type from design approval on through construction installation and ultimately the ongoing maintainenance of the platform to acceptable standards throughout its operating life. The experience of the American Bureau of Shipping with these platforms will be used in supporting the practical application of classification and regulatory standards to ensure safe operations and concluding that use of such standards in conjunction with an experienced classification society provides a substantial benefit to companies utilizing these technologies.

The subject is concerned with safety management of High Speed Craft (HSC) and how the safety can be assessed in place of the traditional prescriptive regulatory approach. The paper begins by highlighting the background to the development of high speed craft and the goal of the HSC operator. Importance of safety to HSC is then outlined following a brief discussion on the methods of treating the safety of HSC. A new methodology called the Generic Management System (GMS) approach is given and its application illustrated by examining the safety of an HSC. The main conclusion shows that it is essential to adopt an alternative to the prescriptive regulatory approach to assess safety and the Generic Management System approach has proved to be a powerful and flexible method for assessing safety of novel craft.

The salinity distribution in the ocean is just one manifestation of the global hydrological cycle which also involves ice and snow terrestrial water storage the atmosphere and the biosphere. Through its role in determining seawater density salinity (along with temperature) has a direct effect on ocean circulation at all scales. The World Ocean Circulation Experiment (WOCE) was initiated in the mid 1980s aiming to complete a survey of the world ocean from top to bottom. In 2000 the ongoing Argos project began as a result of the plan to deploy a large number of profiling floats over the globe to collect conductivity-temperature-depth (CTD) data to 2000 m and report the measurements in real time to global data centers. A look is taken at motivation and history followed by float technology/salinity and the quality of Argo salinity data. After this consideration is given to large-scale salinity yesterday and today.

FPBP (fast polar back-projection) is a variant of the FFBP (fast-factored back-projection) algorithm originally developed for ultra-wideband airborne SAR (synthetic aperture radar) but since applied with success to SAS (synthetic aperture sonar). The FPBP and FFBP algorithms are outlined comparing computation time and memory requirements for the two methods. Processing time comparisons with a standard FFT-based method are also given. Since FFBP and FPBP are both approximation methods computation time also depends on the preset approximation error which particularly affects azimuth side-lobe level. This is an opportunity to review speed and accuracy estimates made in previous literature. However reduction in computation time is not the decisive advantage of these time-domain methods. The difference from the FFT-based methods lies in the flexibility with which non-linear platform trajectories wide swaths wide bandwidths and multi-element sonar arrays can be handled. It is also straightforward to obtain a set of intermediate physical aperture images for auto-positioning purposes.

The Warfighting Support Centre Regional Analysis Division of the Naval Oceanographic Office supports the warfighter by generating map and text products that exploit remotely sensed data for information in the littoral zone. SAGE (the satellite analysis and geographic exploitation) database and tools were developed to enable imagery analysts to extract store and manipulate image-derived features in a GIS (geographic information system) environment. The application links Earth Resources Data Analysis Systems Imagine with an Environmental Systems Research Institute Librarian database. SAGE enables previously stored features to be extracted from the database and overlaid on more recent imagery for a one-to-one comparison. This procedure can be performed in minutes rather than hours or days and consequently can provide more thorough analysis to the warfighter. During the development of SAGE a methodology was set up to identify and define attributes for each feature type. When possible GIS attribute standards were implemented so features could be shared between different branches of the Office as well as the DoD (Department of Defence) community. Attributes such as image date image type and other image and text-derived information enable these features to be of greater use to the analyst and future customers. SAGE development is described and conclusions are drawn.

A field program has been initiated for satellite ocean colour product validation. The objectives of the validation project are:- to establish a high-quality observational time series dedicated to satellite ocean colour product validation at Martha's Vineyard Coastal Observatory (MVCO) to quantify major uncertainty sources in satellite ocean colour retrievals and understand temporal and spatial variability of these uncertainties to explore coastal validation approaches and to improve satellite ocean colour products in this coastal region. This paper describes the MVCO ocean colour validation program and presents a preliminary validation of marine and atmospheric products from the ocean colour sensor MODIS on the platform AQUA using in-situ automatic above-water radiance measurement system (SeaPRISM) measurements collected from 2004 to 2005.

Prediction of active sonar performance in bistatic application requires the knowledge of 3D properties of sea surface and bottom scatterings that govern reverberation. In order to acquire 3D properties of sea surface and bottom scatterings in shallow water low frequency bistatic reverberation is measured in the East China Sea. An inversion method is applied to the estimate of parameters in sea surface and bottom scattering functions. By using the estimated parameters sea surface and bottom scattering strengths are derived as functions of grazing angle and azimthal angle. The result obtained shows high scattering strength in the vicinity of the direction of specular reflection and little dependency of scattering strength on scattering azimuthal angle except around forward direction in each case of sea surface and bottom scatterings.

The scenarios addressed concern Britain's coastline and in particular the length from just north of the Humber clockwise to Portland Bill. This is the soft coastline of southern England made up of chalk and clay cliffs with sand and shingle beaches. It is a coastline that has been under attack by the sea since it was formed and it is still under constant attack today. As a coastline it is almost totally artificial due to man's defence of it against this attack. The scenarios centre on the role of the dredging industry that has over the last quarter century become very involved in coastal defence work. The object is to try to forecast possible scenarios 25 years hence and see what effect a guiding hand today might bring. The current situation and towards 2025 is considered.

The design of the surface-controlled sub-surface safety valve (SCSSV) system for the Shasta and Mustique subsea satellite wells in the Gulf of Mexico is discussed. The design challenges were typical of deepwater subsea completions and included high operating pressures and reliability. The emphasis on reliability resulted in the selection of tandem rod-piston non-equalising flapper-type valves with selective lock-open capability and in-line hydraulic control line filters. The extent to which the control system pressure had to be elevated above shut-in pressure was not fully appreciated initially. In addition time constraints meant that the control umbilicals had to be ordered before final hydraulic analyses could be performed. Ultimately however the control systems for both Mustique and Shasta allowed the high-pressure circuits for the SCSSVs to be operated below the working pressures of the umbilicals although the relief valves had to be set slightly higher than the working pressures. This highlighted the need for early attention to be given to the SCSSV system.

A seabed-following method for an under-actuated AUV (autonomous underwater vehicle) navigating in unknown environment is presented. The proposed method is used to generate a trajectory which minimises the error between the actual and the ideal path (defined by the seabed shape) and which also respects the dynamic constraints of the Taipan Vehicle. The paper is comprised of three sections. Firstly the theoretical aspects of the construction of such trajectories are discussed and it is explained how the constraints of the vehicle have been translated into equations. The selected interpolation functions are described and detailed description of the algorithm is given. Secondly a commentary is given on the results obtained with the hydrodynamic simulator of the Taipan vehicle. Thirdly the realisation of electro-acoustic sensors is described and the experimental results obtained during the first tests of our acquisition system is presented.