Search our collections

Sea Surface Temperature (SST) is required by operational ocean and atmospheric forecasting systems to constrain the modelled upper ocean circulation thermal structure for exchange of energy between the ocean and atmosphere and for validation of model output. The Global Ocean Data Assimilation Experiment (GODAE) is an international collaboration for ocean forecasting activities which in 2002 initiated a GODAE High Resolution SST Pilot Project (GHRSST-PP) to address an emerging need for more accurate high resolution sea surface temperature (SST) products. GHRSST coordinates the harmonisation of a wide variety of SST data streams from satellite and in situ sources that are shared indexed processed quality controlled analyzed and documented within a Regional/Global Task Sharing (R/GTS) framework implemented in an internationally distributed manner. GHRSST-PP data management teams continue to refine the data management structures to provide a functional system that conforms to international and federal directives. The GHRSST-PP International Project Office jointly funded by the European Space Agency and Met Office UK continues to manage the international co-ordination of the project. This paper reviews the progress of the GHRSST-PP highlighting achievements that have been fundamental to the success of the pilot project. The current status of the follow on Group for High Resolution SST (GHRSST) is presented which aims to pull through the pilot project successes into a sustainable system for SST.

The LNG industry is growing at a rapid pace and medium- to long-term forecasts predict a shortage of LNG supply in a few years' time. With the huge amount of stranded gas fields and associated gas the introduction of offshore LNG production or as it is often referred to the FLNG (floating LNG) can reduce the gap between supply and demand. The FLNG is a floating ship-shaped vessel that can produce LNG condensate and LPG from stranded and-or associated gas fields offshore. FLEX LNG has four hulls on order and has an EPCIC contract for the topsides of the first vessel. The final design is neither an evolution from the LNG shipping industry not the Offshore Oil & Gas industry nor is it a marinisation of a land-based liquefaction plant but rather it is a dedicated unit combining the best of these industries. This paper describes the design process and the resulting basic design. Particularly the generic character of the design is described and the adaptability to serve a large range of gas fields with all kinds of project- and client-specific requirements and conditions. The paper helps both engineers and project developers to consider floating LNG production for a given offshore or onshore gas field.

In ship structures the strength of rectangular plate elements is extremely important for the overall strength of the ship. The possibility of using panel models equivalent to single rectangular plate models under in-plane compression loads was investigated in order to allow future studies about isolated effects on plates. The strength of panels composed of three and five plates connected transversely and loaded along the longitudinal direction is considered. First a comparison between the strength of panels having asymmetric imperfections and of single plates is made which allows the ability of the single plate to properly simulate the panel strength to be evaluated. Following this the results obtained for a panel model having symmetric imperfections are compared with the results of the asymmetric imperfections. The asymmetrical and symmetrical models of the panel give respectively the lowest and highest strengths possible (imperfections in adjacent plates with different amplitudes have 'in between' strengths) allowing limits to the variation of the strength to be established. The results show that using a single plate can be conservative or non-conservative depending of the plate slenderness and shape of initial deflections. It is concluded that for design purposes it will in general be enough to consider assemblies of three plates as the results for five plate assemblies are not much different

The current major design practice for permanent taut mooring systems leads to large suction installed piles suitable for very soft clays that are common in West Africa. These suction piles are expensive to build and to install requiring a large installation vessel with significant deck space and lifting capacity. For these reasons SBM has undertaken a large R and D program to develop a plate anchor called the VELPA (vertically loaded plate anchor). This is pushed to target-known depth by a new installation tool called the Pyrodriver developed by the sister company IHC Hydrohammer. Extensive Laboratory centrifuge and onshore tests have first been carried out with the VELPA. Three full scale VELPAs (4 8 & 12 m squared) have been made and tested offshore West Africa in a water depth of about 450 m. The testing is described. After this the Pyrodriver is described. This is a tool to push an anchor into the seabed. There is no need for a large diameter umbilical or hoses from surface to Pyrodriver. The fuel in the Pyrodriver is based on nitrocellulose in pellets and is a very slow burning propellant. This also makes it relatively safe to transport because it will never detonate. Water is the main component of the reaction mass.

Acoustic surveys are used in 20 stock assessments within the ICES community and almost all as relative indices of abundance. The North Sea herring acoustic survey started in 1979. In this paper the precision of the survey is estimated using data at ICES statistical-rectangle level from 1989 to 2001 and bootstrap-resampling methods modified by geostatistical estimates of the spatial autocorrelation. Similar techniques are applied to the larvae Methot and trawl surveys that provide the other data on North Sea herring. The comparison of survey performance is also examined using the bootstrap estimates of abundance to give 1000 simulated assessments of North Sea herring using the integrated catch-at-age (ICA) method. The results of these analyses are compared and the weighting of the various indices within the assessment is investigated. A weighting method is presented that provides a more precise method for estimating the stock. The more precise assessments are compared for retrospective pattern. An assessment is proposed which provides the most precise stock estimates with the best retrospective pattern. The importance of the acoustic survey and its contribution to the assessment in relation to the other indices is discussed.

The book is based on 'Practical Yacht Construction' by C.J. Watts but is a revision due to the changes covering the whole field of yacht construction. It uses the original framework. Chapters 1 and 2 cover construction of keel, hull, decks and other parts but includes glues for main structural members and of plywood for decks, changes in metal fastenings etc. Chapter 3 covers engine seating, anchor arrangements, davits, cavils, stern chocks or archboards. Chapter 4 covers masts and rigging, with changes from gaff rig to the more efficient Bermudan rig and the introduction of aluminium masts, stainless steel standard rigging etc. Chapter 5 covers joinery work, plumbing, heaters, steering, ventilation, electric equipment and auxiliary propulsion. Lighter, more efficient joinery, better plumbing systems, plastic piping and improved ventilation have been introduced. Chapter 6 covers Thames tonnage, inside ballast, general arrangement, winches, pulpits and other fittings. Chapter 7 deals with the emergence of the glass-reinforced plastic hull, covering materials, moulds, methods of construction and notes from Lloyd's Rules repairs. The final chapter covers the introduction of special ship building alloys and a comparison with more traditional steel or timber construction.

13rd International Marine Systems Design Conf held Pittsburgh 8-10 June 1988 Papers are The subcavitating/supercavitating hybrid propeller An advanced method for design of optimal ducted propellers behind bodies of revolution Optimal hull forms for fishing vessels A knowledge-based system architecture for control of underwater vehicles Roll reduction by rudder control An integrated rig management system for a semisubmersible floating production vessel Computer aided navigation system (CANSY-II) Evaluation of impact loads associated with flare slamming Surface effect ship loads; lessons learnt and their implications for other advanced marine vehicles Advanced ship structural design and maintenance Methods of incorporating design for production considerations into concept design investigations Achieving customer and marketing orientation in marine transport system design Incorporating a seakeeping capability in a computer aided preliminary design system Hull form design - only a matter of the computer ? The components of the propulsive efficiency of ships in relation to the design procedure Design conception and CAE/CAD of hull form Direct curve and surface manipulation for hull form design Intelligent computer aid in marine design and ocean engineering Ship synthesis model morphology Teaching design for students of marine technology Operational aspects in ship design; the case of the roll on/roll off vessel The productive experience of 3D CAD/CAM techniques applied to ship design and construction A new concept for neat fit ship propulsion

Marginal fields must have every economic factor working in their favour to justify any development. This typically requires the operating companies to accept a higher risk standard for the field development decision. If a major company has numerous development opportunities then there is little incentive to develop a marginal field. However operators that are opportunity limited are more willing to accept the calculated development risks of a marginal field. Any development needs to closely examine every cost aspect. Marginal field profitability is frequently controlled more by the commercial arrangements than by technology issues. Examples include: transportation tariffs host facility processing tariffs chemical costs and well intervention services. Close attention to the commercial arrangements and continued technology progress to find more reliable less costly ways of operating marginal deepwater fields will provide field development opportunities well into the future. A process is presented developed by DeepStar to identify technology that has good economic impact on ultra-deepwater marginal reservoirs. This is accomplished with a life-cycle economic analysis which incorporates the new technology and compares the analysis results to a benchmarked field development cost estimate based upon current technologies. The 12 Operators within DeepStar selected 3 representative small tie-back type reservoirs from West Africa and the Gulf Of Mexico and established conventional technology development scenarios for eachX44045

A knowledge-based software package that allows a "quick look" assessment of the economics and risk profile of small oilfields in the Central and Northern North Sea has been developed. The system employs a cost database and cost adjustment algorithms that were calibrated using data from the Thelma Gryphon Fife and Eider Fields as well as cash flow analysis and simulation procedures. It can integrate and analyse the impact of reservoir and production characteristics costs and economic factors on the development decision thereby allowing the most efficient production system to be selected. The economics of the development can be continually assessed as additional data become available making the system a useful management tool. Three production system configurations can be considered: an unmanned wellhead platform tied back to a third- party platform for fluid processing and export a floating production storage and offloading (FPSO) system exporting oil to a shuttle tanker and gas via a tie-in to an existing pipeline and a group of subsea wells tied back to a third-party platform for fluid processing and export.

There is currently a strong market demand for competitively priced large and fast ferries. One of the major considerations in the structural design of larger fast vessels is construction weight savings. The use of high tensile steels aluminium alloys and composites would be an effective means of meeting this requirement. Presently many fast ferries are constructed of aluminium alloys mainly due to the weight savings possible good corrosion resistance and good producibility. In order to reduce structural weight and fabrications costs shipyards have used large extruded sections and prefabricated panels. Although the use of these extruded sections and prefabricated panels has reduced weld distortions and fabrication cost such use is somewhat less effective in reducing structural weight. A new concept for the design and construction of weight-critical vessels such as large fast ferries is presented. A hypothetical fast catamaran ferry of 80 m length is designed as a case study. The design of a vessel focuses on the use of aluminium sandwich panels for some or all of the main hull structural strength members. The local strength of aluminium honeycomb sandwich panels under axial compression bending and crushing loads is studied both theoretically and experimentally. The advantages and disadvantages of sandwich panel designs in terms of the strength to weight ratio and fabrication costs are discussed. A comparison of the aluminium sandwich panel concept with the conventional single skin stiffened panel design approach for hull de100605

The common rail fuel injection system for marine diesel engines can meet the demands for simultaneous reduction of exhaust emissions and fuel consumption. The key techniques of common rail fuel injection system have to be studied in detail. Virtual prototyping is becoming a common practice due to time and cost constrains in diesel engine field industry. The key techniques of common rail fuel injection system for marine diesel engine by use of simulation and test research are presented. The common rail system comprises a low-pressure part composed of fuel tank with pre-filter the supply pump fuel filter and low pressure fuel lines as well as a high pressure part consisting of high-pressure pump with PRV (pressure regulator valve) common rail injectors and ECU and sensors to control these components. Based on the theory of 1D compressible fluid flow dynamics and 2D multi-parts body dynamics a simulation model was established by HYDSIM software. The model with consideration of the effect of leakage from plunger couples and needle couples and the body's elastic deformation etc can calculate the pressure in the hydraulic volumes and the lines the lift of needle and control piston the injection volumes

NAVOCEANO (the Naval Oceanographic office) runs WAM (wave model) and STWAVE (steady-state spectral wave mode) in many areas throughout the world. Nearly 60 different areas need to be run two times a day and around 90 graphical products are produced and displayed on the Web. To help operational modellers set up and maintain the model-run stream a web-based GUI has been devised. The prototype GUI is described together with the lessons learned from that experience. Recent improvements in WAM-run stream allow such a GUI to be created in a logical manner. First these recent improvements are reviewed and it is shown how they allow easier interface with a GUI. The GUI itself uses a number of free packages including the Linux operating system the Apache web server the MySQL database server and the Generic Mapping Tools. The GUI contains a number of distinct tables corresponding to distinct model objects. Examples of objects include WAM models WAM graphics and WAM output spectra. Each object has a distinct set of associated widgets associated constraints and associated routines used to construct the model object.

This book presents a comprehensive review of the current state of adaptive analysis in engineering computation. In chapter 1 adaptive analysis methods such as h, p and hp-versions are described in detail for the finite and boundary element methods. Chapter 2 deals with adaptive finite element techniques for three-dimensional Navier-Stokes equations and other transient problems. In Chapter 3, adaptivity through mesh movements is considered rather than the usual localised mesh refinement techniques. Application to aeronautical problems such as inviscid flow around an aerofoil are presented to demonstrate the versatility of the proposed method. Chapter 4 deals with adaptive finite element method for transient compressible flow problems. The application of adaptive finite element method for phase change problems is described in Chapter 5. In chapter 6, adaptive solution strategies for nonlinear finite element analysis are presented. Particular attention has been paid to computationally intensive operations such as updating the stiffness matrices, decomposition, bisection and line search algorithms. Parallel computation and solution procedures for linear elliptic partial differential systems are presented in Chapter 7, using the finite element method based on automatically unstructured grids. Finally, the application of boundary and finite element methods to three-dimensional problems of acoustic scattering is presented in Chapter 8.

Over the past 10 years there has been a tremendous increase in research and development of UWA (underwater acoustic) communication systems. The desired high data rates are in contrast to the transmission conditions induced by the underwater acoustic telemetry channel which is band-limited and reverberant thus posing many obstacles to reliable high-speed digital communications. Therefore combating time-varying multi-path induced by the transmission channel - especially the horizontal shallow water acoustic channel - is considered the most challenging task. A completely unsupervised receiver concept based on non-data-aided timing recovery blind multi-channel equalisation and carrier phase recovery is proposed. The core of the receiver is an adaptive super-exponential algorithm for multi-channel fractionally spaced blind equalisation. In the noise-free case over-sampling the received signal in space or time leads to a rank-deficient covariance matrix of the corresponding vector process. This seems to be the major obstacle towards a multi-channel adaptive super-exponential algorithm. In the absence of additive noise the optimal multi-channel equaliser setting can also be found as the solution to a suitably chosen quadratic cost function. In the presence of a moderate amount of noise minimisation of the same cost function should result in an equaliser setting close to the optimal one. The optimisation however can now be carried out recursively using a stabilised RLS algorithm. Experimental results with underwater acoustic communication data show good performance of the suggesControl No

SAR (synthetic aperture sonar) is a technique for high-resolution range-independent imaging. After MOCOMP (motion compensation) has been carried out SAS image quality is ultimately limited by the ability of auto-focus algorithms to correct for blur caused by medium fluctuations. Conventional approaches to this two-stage problem use navigation systems typically based around an INS (inertial navigation system) and DVL (Doppler velocity log) to remove the bulk motion error. Auto-focus techniques are then applied to provide the final image sharpening. Both require expensive equipment suffer from the accumulation of integration errors over time and do not provide ground truth information. Here an alternative approach is presented in an attempt to overcome these limitations using a portable 'active beacon' deployed on the seabed. Simulations of this system have been promising and practical problems have been identified and solved through various pool and marina tests. The operation is explained and it is shown how the beacon can be used to estimate sonar velocity and sway over a wide extent. This is followed by results and discussion from recent sea trials using the sway and velocity estimates to improve image quality.

Thousands of kilometres of pipeline lie directly on the seabed or in shallow trenches. Operators are required to carry out frequent inspections of these pipelines either visually or by using sidescan sonar. The application of new developments in sonar signal processing and advances in computing power have resulted in the development of an automated sidescan sonar pipeline inspection system. Pipeline localisation and tracking is controlled by a computer model that provides a graphic real-time display of the pipeline height relative to the seabed and a visual representation of the incident sonar beam. The computer algorithm used for automatically measuring pipeline span heights is described and one method for compensating distortions found with the sidescan sonar beam width and tracking angle during typical survey operations is addressed. Analysis parameters input to the sonar system control the type and frequency of features automatically generated during survey operations. Limitations of the automated analysis to calculate measurements of span height and extent of pipeline burial are discussed when in-situ conditions deviate from the input analysis model. Automatic survey operations using ROTVs (remotely operated towed vehicles) are discussed using illustrative case histories in which ROTV position and steering controls are guided by the automated system using sonar incident reflections from the pipeline and seabed. The major benefits derived from using an automated sidescan sonar pipeline inspection system include better data quality improved survey efficiency and an overall reductionX25011 An automated system for weld sampling and defect removal

GLARE is a new aerospace structural material composed of alternating, bonded layers of aluminium alloy and glass fibre reinforced plastic. The results of an experimental study are presented here concerning mechanical fatigue testing of GLARE structural specimens in conditions relevant to the acoustic fatigue problem. Endurance testing of 35 GLARE Tee-coupons under simulated random acoustic loading has been carried out and resonance frequency, damping loss factor, and strain response of the specimens have been experimentally determined. CFRP specimens have also been tested to provide a benchmark against which to compare the properties of GLARE. FE analysis of the coupons has also been carried out to support the experimental work and the theoretical results have been compared with the experimental data. Damage mechanisms have been observed and fatigue data established. Using these experimental data, surface strain versus number of cycles to failure curves have been established. In particular, this work has assessed the behaviour of GLARE in bending and has highlighted the importance of the lay-up sequence for the ‘‘fibre bridging effect’’ on crack propagation to be effective.

As offshore operations move to deeper water more geologically complex and geohazard prone areas are encountered. This has increased the demand for geohazard assessment. Proper assessment requires a suite of complementary tools for in situ sampling and testing. These tools are rapidly improving in terms of technology and robustness. The focus here is on the FPWS (Fugro Water Sampler) an improved downhole tool to sample pore water and has in situ at water depths of as great as 3000 m. The samples are kept pressurised during retrieval to detect has in the soil. The features of FPWS are described. These include optional add-ons for in situ pore pressure and temperature measurements within a single deployment round and for real-time monitoring of sampling and testing. The FPWS is attached to a new WISON EP system which provides the thrust to push the tool in the ground with a maximum stroke of 4.5 m. The analyses of gas in soil have been significantly improved by the addition of a tracer to the filter water. The dilution of the tracer is a measure for the dilution of pore water by filter water during sampling. The dilution is applied to determine the in situ pore water salinity. The quality of the measurements from the in situ pore water samples has been validated by independent measurements from pressure (core) samples.

Oil in produced water has traditionally been determined using a reference method based on Freon-113 extraction followed by IR (infrared) quantification. However when Freon-113 was phased out OSPAR (the Oslo-Paris Commission) agreed that Tetrachloroethylene (Perklone or TTCE) should be used as a Freon replacement. Since then there have been concerns over health and safety of the solvent and the use of Perklone in the analysis of oil-in-water has been limited despite its analytical suitability. In 2000 the ISO 9377-2 method for the determination of hydrocarbons in water was made available. A number of studies to establish its suitability as a reference method for the determination of oil in produced water were carried out and the ISO method was subsequently modified to become the new reference method to be implemented from 01 January 2007. While there may be a new reference method it has been recognised that there is a need for alternative oil-in-water analysis and monitoring methods for the determination of oil in produced water. This is because the new reference method is not ideally suited for offshore applications. Some of these new methods have already reached trial stage or have been accepted for reporting. Also recognised is the need for using alternative oil-in-water monitoring methods. A number of studies have been carried out by the industry to identify alternative technologies. An overview of alternative oil-in-water analysis and monitoring technologies available is presented together with some examination of search efforts made to identify Freon replacement solX19123

Protection of coastal environments is a vital issue in many countries. Marine structures (such as seawalls caissons etc.) have been used to protect residents from the action of ocean waves. However marine structures may be damaged by two kinds of failure. Firstly structural failure caused by the wave forces acting on the structures. Secondly wave-induced seabed instability (such as liquefaction and scour) in the vicinity of the structure. The velocity and bottom shear stress distribution within the wave bottom boundary layer have a direct relationship with the quantity of sediment transport rate. Thus a better understanding of wave bottom boundary is important for coastal engineers involved in the design of coastal structures. The FLDV (fiber laser Doppler velocimeter) system is applied to measure the velocity profile outside and inside standing wave boundary. The characteristics of flow fields in the potential region and bottom boundary layer of finite amplitude standing waves are investigated experimentally for Ursell number ranging from 1.21 to 50.59. FLDV is used for quantitative measurement. According to linear standing wave theory the nodes and anti-nodes are fixed points in the space of wave field and the nodes just locate at the still wave level. However these specific points are found not to be fixed in the wave field due to tiny period differences of incident waves generated by a precise wave maker. Therefore spatial distributions of the highest lowest and mean water levels in finite amplitude standing waves were measured first. The positions of the maximum and minimum (mean) wave-heights were thenX30592