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For more than a decade wave-in-deck loading on fixed surface piercing offshore structures has been an issue of concern for engineers and researchers dealing with the performance of such structures. Most researchers agree that wave-in-deck loading is of dynamic nature and that the dynamic effects on the structural response are important. However there exists no engineering practice for the determination of load time histories for waves hitting the decks of fixed offshore platforms. This applies to both the time variation and the magnitude of the loading. The main recommendations for wave-in-deck loading are presented with reference to wave tank experiments of a model of the Statfjord A Condeep platform subjected to extreme wave loading. The recommendations for loading from these tests comprise time variation as well as magnitude. These recommendations are used as a basis to suggest a simplified method to estimate wave-in-deck loading on jacket platform decks for which to the difference from Condeep platforms the wave height amplification due to the interaction between the incoming wave and the structure (Swan et al. 1997) is negligible. The resulting 'recipe' for wave-in-deck time histories on North Sea jacket platforms is compared to relevant results previously reported in the literature. The method is categorised as a 'global' approach that is one uses an effective deck area as opposed to a detailed deck model. The method is suggested to be applicable for analyses where a 'rough but reasonable' estimate for wave-in-deck loading is sufficient.

Results are described of a comparative study of icing rate meter (IRM) and load cell measurements based on the analysis of statistical data recorded by SYGIVRE (Hydro-Quebec's real time ice monitoring system) on a 315 kV line at the top of the Mt Belair icing test site. A computer program has been developed to remove temperature and wind speed influence on load cell readings and to improve the conversion from icing rate meter signals to actual icing amount on overhead power line conductors.

On 24 February 1994 the off-shore anchor handling and supply vessel Boa Force sank while deploying anchors from the off-shore construction barge Support Station III about half a mile south of Thevenard Island 11 miles north-west of Onslow Western Australia. Conclusions of the investigation are given.

The acoustic effects of bubbles can have a major impact on hydrographic operations using multibeam sonars and on the quality of the data they produce. It is well-known that bubble sweepdown(bubbles entrained beneath the hull due to high ship speeds or heavy weather) is a significant problem and means to mitigate the effects are sought. The relevant factors associated with naturally occurring bubbles and their effects on acoustics propagation are reviewed. The characteristics of existing multibeam systems in light of these bubble effects are then discussed. Finally some of the bubble measurement devices and techniques are reviewed with an emphasis on what might be implemented for hydrographic multibeam operations.

Engineering critical assessment of offshore pipelines is usually very conservative if standardized single edge notch bend (SENB) specimens are used for the fracture mechanics testing. It is commonly accepted that the fracture toughness is dependent on the geometry constraint at the crack tip. The standardized SENB specimens have a high geometry constraint and give lower bound fracture toughness for all geometries. For circumferential flaws in pipes the single edge notch tension (SENT) specimens is taken more into use to establish more correct fracture toughness for the pipe in question. In this paper the effect of crack depth misalignment and different wall thicknesses in SENT specimens have been studied. In addition the effect of crack depth and internal pressure in pipes have been studied with FE simulations.

AutoFlux is an autonomous system for making direct measurements of the air-sea exchanges of CO2 momentum and heat. Such measurements are usually restricted to short dedicated air-sea interaction cruises on research ships which last only a few weeks. In contrast AutoFlux was recently deployed continuously on the RRS Discovery for two years and is now currently part of a three year measurement programme on the Norwegian weather ship Polarfront. The instrumentation on Polarfront also includes two different wave measurement systems and digital cameras. The various systems are described and initial results presented.

Congress held 18-22 August 1997 in Trondheim Norway. Papers are: Report of committee on environment - Wind wave current and temperature data source Wind and wave hindcasting and forecasting Stochastic modelling and prediction of sea waves and sea states Directional wave spectra Ice environment Marine growth Experimental modelling Influence on design and operation of ships and offshore structures Environmental conditions for reliability assessments Report of committee on loads - Wave loads on ships Wave loads on offshore structures Hydrodynamic impact loads Wind and current loads on ship and offshore structures Probabilistic models for design loads Conclusions and recommendations Report of committee on quasi-static response - Calculation procedures Review of structural design guidelines Offshore structures

The world's largest application of SCR and other low emission technologies in stationary diesel engines are currently being implementated in the CEM power plant in Macau. Based on this project and initial operating results expected during the second half of 2003 as well as pre-project test results engine related aspects of such installation are presented. Aspects and initial operational results of this installation are described including the supplementary modifications introduced to enhance results by simultaneous reduction of emissions of UHC (unburned hydrocarbon) and PM (particulate matter). It is shown that it is possible to reach very low emission levels on low-speed diesel engines with a NOx emission level comparable to the most stringent limits for boiler technology and with elimination of the yellow-brownish plume appearance. On present low-speed engines it is necessary to arrange the SCR process upstream of the engine turbocharger and the project on Macau has shown that this is possible as a retrofit solution despite the complexities that most retrofit situations involve.

Supercavitation is known as the way of viscous drag reduction for the projectiles moving in the liquid phase. In recent works there is distinct investigation between cavitation flow and momentum transfer far away from the cavity surface. However it seems that there is strong connection between overall flow and what takes place in the sheet cavity where a constant pressure distribution is assumed. Furthermore pressure distribution on cavity surface caused due to overall conditions induct non-axisymetric forces and they may need to be investigated. Primarily a description is given how pressure distribution into the cavity can cause separation of the aero boundary layer. Then some approaches are presented by which this probable separation can be controlled.

Existing pipelines should be checked after several years in service so the remaining service life time can be estimated and the decision of re-using can be made. A new convenient method based on on-spot pressure test is developed to check the pipeline safety without interrupting the service. In this method first the corrosion state of the pipeline is estimated on the basis of corrosion test. Next mechanical analysis is performed to determine the corresponding test pressure of all corrosion state cases. Then the on-spot pressure test is performed and the test result is a powerful indication of the safety state of pipeline. An Equivalent Reliability Method (ERM) is used to determine corresponding service pressure which is believed to be safe for continuing service. This method has been used in a pipeline safety assessment of CNOOC. The result showed that the new attempt is pretty reliable economic and convenient.

This paper presents results of experimental investigations concerning the pressure distribution on a yawed cylinder oscillating over a plane bed. The pressure variation with respect to time at a point on the periphery of the cylinder was measured by a single transducer for an experimental run of 48 cycles. Eighteen such points around the cylinder were considered for measurements. The experimental data thus collected were then used to construct pressure fields over the cylinder at various phases of oscillations of the cylinder. Typical results pertaining to the pressure patterns showing the effects of yaw angle and gap between the cylinder and the bed are presented. The applicability of the so-called crossflow principle is examined. The hydrodynamic forces exerted on the yawed cylinder are determined by integration of the circumferential variation of pressure. The effects of the yaw angle and gap ratio on the vortex shedding frequency are investigated.

The International Maritime Community has accepted that a major cause of serious sea accidents lies in corrosion causing deterioration in a ship's structural condition. Therefore shipping authorities and classification societies have decided to become more involved in protection against corrosion of critical structural ship parts such as water ballast tanks and bulk carriers' cargo holds. General regulations currently or soon to be enforced dealing with this issue are defined. Possible developments in the near future are also discussed and the current thinking of Bureau Veritas on this matter is outlined.

This report has been drawn up at the request of the European Economic Community Shipbuilding Liaison Committee. The material gathered has enabled a forecast of medium and long term trends of demand and supply on the world shipbuilding market to be made. Contents include a section on the development of newbuilding demand, including foreseeable development of the volume of international sea-borne trade, estimated development of world shipping tonnage and estimated newbuilding needs of the world merchant fleet up to 1975 and from 1975 to 1980; and a section on the estimated future trend of the world shipbuilding supply, with chapters on forecast development of shipbuilding production capacity, foreseeable trend of newbuilding supply and comparison with expected demand; and conclusions.

In certain waters NOx emission limits require a high degree of NOx reduction in the exhaust gas from oil-fired marine diesel engines and installation of a SCR catalyst is the only solution. However there is limited experience with SCR catalysts for NOx reduction on large marine two-stroke diesel engines. Here experience from SCR installations on large two-stroke engines for power plants are used for forecasting design and operational consequences in case of marine use. The influence from the fuel contained vanadium on development of NOx oxidation rate over time is described as well as the influence on the side effect: oxidation of SO2 to SO3. The SCR besides reducing the NOx emission as required also removes the yellowish and brownish colour of the exhaust gas plume but the SO3 together with H2O after the chimney forms droplets and aerosols that might create a heavy whitish-bluish plume.

Two legs of the Chinese JZ-20 multi-leg platform were instrumented to measure the loads that result from advancing sea ice floes. One leg was equipped with five load panels which allowed the local load and total leg load to be determined. The other leg was strain-gauged providing another estimate of the leg load. In 1990 the loads were measured simultaneously on two legs of the platform providing a unique data set for assessing the resultant load on two legs in comparison to the total load on an individual leg. The simultaneity of the measured ice load on two legs is examined using a representative sample of the load information from each leg.

This paper reports ongoing work on a horizontally submerged tension-moored flexible sheet serving as a wave energy absorber. The device represents a "smart structure" designed for efficient wave energy conversion and would have such advantages as low primary converter costs multiple resonant peaks and ready tunability with reactive loading. The natural response of the sheet is studied analytically and both flexural and membrane effects are modelled. Natural frequency dependence on device length and in-plane applied tension is investigated. Secondary energy conversion is via hydraulic actuators applying point loads and desirable locations for the actuators are identified. Finally the effect of reactive loads on the dynamic response is explored through calculations on the lowest oscillation mode.

On modern vessels both naval and commercial lighting accounts for a significant use of energy. LEDs (light-emitting diodes) will soon be the future of maritime lighting on board all types of vessel. They are already widely used on commercial cruise liners for decorative effects; however this paper serves to prove that LEDs offer substantial through-life cost savings and will reduce vessel fuel consumption. This paper investigates the benefits and savings that can be had from using modern LED lighting to replace conventional fluorescent tungsten and halogen bulbs. Over the last ten years there have been significant advances in LED emitter technology; their light output now rivals halogen bulbs at a third of the energy usage. This can result in significant through-life savings as less fuel has to be used to produce energy to meet the lighting demands. The aim of this paper is to present a high level of analysis of the comparison between different light types that could be used on marine vessels. The model presented is only simple and was produced to enable a quantitative assessment of the required number of lights to be installed in a given ship space.

Hydrographic and Marine Consultants BV (HMC) and MARIN have developed a prototype tool known as the Marine Quality Kit (MQK) which can monitor accelerations velocities and motions at arbitrary locations on floating objects. The maximum allowable values for these parameters are calculated during the design of platforms and the values are translated into environmental conditions. On-site operations are then based on comparisons between actual or forecast conditions and the maximum allowable conditions. Because MQK operates in real-time its on-line information and trend analysis will help to reduce weather downtime. The possible fields of application are listed and the hardware is described. Details of the calculation procedure are given and the software and user- interface is described. A pilot project in which the MQK was used with a cutterdredger is highlighted.

When undertaking lifting operations on offshore platform fallen object accidents possibly occur because of mistakes such as overloading misjudgment and operator error. The main risks come from the crane various types of crane lever or collapsed cranes. As a result objects fall on the deck and onto equipments or the structure itself leading to structural failure or loss of stability or buoyancy. On an offshore jacket platform equipment that may be hit by falling objects includes platform structures in or upon the water equipments on the upper deck and submarine equipment and pipelines. This paper analyses the influence of different impact positions on the platform structure from impact force energy conversion and structural damage. The results show that (1) different boundary conditions have little influence on the impact force or on energy conversion

Estimation of the transformation of wave shoaling and breaking is essential in nearshore hydrodynamics and for the design of coastal structures. Many empirical formulas have been well recognised in the wave transformation on gently sloping beaches. The applicability of previous formulas of wave shoaling and breaking indices for the situation of steep slopes are reported based on comparison with present experimental results. Two steep bottom slopes were examined in the present experiments. It was found that the shoaling distance on steep slope becomes short and the surface waves may be partially reflected from the steep bottom. The coefficient of wave reflection is well related to the surf similarity parameter. The estimations of wave shoaling based on the well-known formula by Shuto (1974) did not conform completely to the experimental results for steep slopes. The empirical formula for the breaking criteria proposed in Goda (1975) was slightly modified for application to the steep beaches. A time-dependent mild-slope equation model finally was adopted to calculate the wave height transformation in the surf zone by introducing the modified breaking index.