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Many vessels are lost at sea due to severe weather. Various loss statistics are given. It is advised that route selection based upon historical information and limited forecast data can be very costly. A system called OSR (optimum ship routing) is presented. This increases vessel safety and reduces damage. It is advised that using an OSR service company is far more efficient than a ship's master trying to do it himself using his limited data. OSR selection uses accurate forecasting methods to establish the most effective selection of a pre-departure route and then monitors and advises altering course if necessary once the voyage is underway. Voyage time distance and weather are taken into account. The system improves efficiency and cost-control and can either be shore- based or can be an on-board pc-based fleet tracking system such as the Orion system provided by WNI Oceanroutes.

The past ten years has seen motor yacht construction characterised by increased vessel speed. The evolution of high power density diesels and advanced propulsors such as waterjets and surface-piercing propellers is making all this possible. However new advances in propulsion system technology and the desire for speed can clash with the age-old naval architectural subject of weight control unless precautions are taken. There have been cases where the unexpected weight of a vessel overcomes the capability of the propulsion system to deliver the intended speed. A standard for weight definition and an approach to weight control is presented for modern motor yachts and other craft. This includes a definition of weight and loading conditions for these vessels which can be related to attainable vessel speeds. The weight control plan addresses concept through detailed design construction delivery and service life. The procedure is adaptable to all types of hull structural material. Weight curves developed from regression of previous vessel data are included and cover a variety of pleasure and commercial craft. Examples of the effect of weight control on speed are given. Recommendations for application of the procedures are offered.

The standard structure of flexible pipe for oil and gas applications presents some limitations for ultra deep water applications mainly due to the weight of steel wire reinforcements. Lightweight composite material based on high strength carbon fibre has been selected and tested. The use of such material as tensile armour has been justified by the high tensile resistance and low density of composite armour good fatigue performance in tensile mode of loading and increased diameter and pressure capacity of flexible pipe versus water depth when compared to conventional structures. This present paper gives an overview of the different phases of the development programme conducted to qualify this technology.

Session Reports on Welding and allied processes in maintenance and repair, showing the wide range and variety of the application of welding to maintenance and repair. The papers have been divided into five groups: study of techniques used in repair work, problems raised in repair work by the nature of the base and filler materials and by the properties to be obtained in service, typical examples of the repair of parts of the maintenance of equipment in particular industries, organisation of maintenance and repair work and economical questions relating to the use of welding and allied processes in maintenance and repair work. The fields covered by the papers are small repairs of a great number of various objects, important repair work of a great number of the same or similar objects, and special cases of repair of particularly large cast parts in rolling mills, presses and the like. The problems dealt with include weldability in all its aspects, fatigue, influence of residual stresses and quality control.

Drilling in deep waters has forced a more complete understanding of and appreciation for pore pressures and fracture gradients. Shallow water flow sands perhaps exemplify the most extreme example of how narrow the window between pore pressures and fracture gradients can be. Areas of known SWF (shallow water flows) require careful well planning and the latest technology for pressure monitoring while drilling. The Kestrel well Mississippi is introduced (canyon 632 number 1). Here geologists geophysicists drilling engineers and pressure prediction specialists worked together to design and drill a well that had to contend with SWF sands and narrow margins between pore pressures and fracture gradients. The planning and drilling of the well are described. Maps and graphs appear on pages 5 to 10.

The findings of the 1993 GESAMP report concerning the estimated quantity of oil annually entering the marine environment from various natural and industrial sources particularly shipping are presented and compared with those of previous reports (19901985 1975). Critical discussion pays particular attention to apparent improvements in the environmental performance of ships with regard to operational discharges: special mention is made of the practice of continuously upgrading operational performance on tankers the progress of technical innovation in the world's tanker fleet and inadequate port reception facilities for ship generated residues and wastes. The potential for governments port authorities enforcement agencies and tanker operators to further improve the environmental impact of ships is considered.

In all European countries with shallow coastal waters and strong mean wind speed at the coast the planning and construction of offshore wind farms is on the way. Large parts of the North Sea and the Baltic are under investigation as to whether they are suitable for offshore parks. In this paper it is demonstrated how satellite images taken by spaceborne radar sensors can be used to determine mesoscale wind fields and thus help in the task of planning offshore wind farms. High resolution SAR images acquired by the European remote sensing satellite ERS 2 are presented which show single wind turbines. The derivation of high resolution wind fields from SAR images is explained and comparisons with numerical models are presented.

In all European countries with shallow coastal waters and strong mean wind speed at the coast the planning and construction of offshore wind farms is on the way. Large parts of the North Sea and the Baltic are under investigation as to whether they are suitable for offshore parks. In this paper it is demonstrated how satellite images taken by spaceborne radar sensors can be used to determine mesoscale wind fields and thus help in the task of planning offshore wind farms. High resolution SAR images acquired by the European remote sensing satellite ERS 2 are presented which show single wind turbines. The derivation of high resolution wind fields from SAR images is explained and comparisons with numerical models are presented.

All the wave climate conditions separated into wind wave swell and combined situations their probability and statistics is a part of wave climate. Any of these conditions has a set of it own climatic spectra including extreme ones. For statistical generalization of climatic wave spectra the tools of multivariate statistical analysis is used for each of the classes; the approximation and parameterization offered. The further statistical analysis of spectra parameters carried out in the terms of Markov processes has made it possible to construct the stochastic model of a spectral wave climate. Adjusted approaches do not allow investigating phenomena known as freak (or rogue) waves. The main difference between extreme and freak waves is in their unusual form. Probability of freak wave arising depends on a set of metocean conditions. Some approaches are proposed and described in this paper.

The development of the AME CRC systematic series for yachts has resulted in enhanced knowledge of the effects of various hull parameters on the performance of IMS (International Measurement System) style yachts. Experimental procedures used are explained highlighting sources of errors and their magnitude. Some of the results directly relating to seakeeping predictions and experiments carried out are given. To illustrate the accuracy of results a comparison between the performance predicted from the investigation of prismatic coefficient variation and that calculated from previous Velocity Prediction Program (VPP) results is presented.

Contents comprise of chapters on: Air conditioning for human well-being, Humidity, Ventilation requirements (heat gains and ventilation calculations), Air motion (air velocities for cooling), Ventilation systems (extraction and supply), Air distribution (inlets, extraction, discharge velocities), Fume and dust extraction (hoods, airborne solids), Air cleaning (filters, air sterilisation), Evaporative cooling (methods and types of cooling), Drying, Air heating (heating efficiency, fuel properties, appliances), Airflow measurement (pressure, instruments), Air duct design, System resistance, Fans, Isolation of Noise and Vibration, Hazardous applications and arduous conditions (fire, corrosion), Noise in fan systems (sound, loudness, sound absorbers), Selection of fans, Back draught prevention (shutters and windshields), Electric motors for fan drives. The final chapter comprises of all kinds of useful data.

Two tankers and a floating production storage and offloading (FPSO) vessel the Conkouati have been producing the Yombo Field offshore Congo since June 1991. The FPSO mooring is unusual in that the vessel has a heading fixed by a 12-line spread. Some aspects of the mooring design and its rationale are discussed together with some wind and wave tank test data. The platforms' well streams go directly to the tanker via two pipelines and two flexible risers. Electrical power is generated on the FPSO and transmitted to the platforms via underwater cables. The oil and electric risers are deployed in a "lazy" wave configuration and the rationale behind that choice is discussed. An efficient and rational method for adjusting the mooring line tensions is also presented.

A special modulation format derived from OQPSK (offset quadri-phase shift keying) is applied to digital transmission and a novel practical multichannel receiver architecture is proposed for its demodulation. The receiver is based on the standard adaptive DFE (decision feedback equaliser) which is extended so that both its multichannel feed-forward section and the feedback section operate fractionally spaced. A new decision rule is therefore introduced that exploits the structural properties of this signal type and allows the adaptive filters to be updated twice per symbol. This also enables the receiver to operate in a completely self- recovering or blind manner. To compensate for Doppler effects explicit non-data-aided timing recovery and decision- directed carrier recovery is performed. To demonstrate the performance of the proposed system the receiver is applied to experimental data for acoustic communication in shallow water where the information signal is both emitted by a fixed and a moving source. The modulation format is characterised (section 2). The applied timing recovery scheme is briefly described (section 3). The doubly-fractionally spaced DFE (DFS-DFE) is presented (section 4) where we also derive the decision rule. A short description of the data obtained from an underwater communication experiment is given (section 5). Results of the system’s application to experimental data are presented (section 6).

A common problem in video surveys in very shallow waters is the presence of strong light fluctuations due to sunlight refraction. Refracted sunlight casts fast-moving patterns which can significantly degrade the quality of the acquired data. Motivated by the growing need to improve the quality of shallow water imagery a method is proposed to remove sunlight patterns in video sequences. The method exploits the fact the video sequences allow several observations of the same areas of the seafloor over time. It is based on computing the image difference between a given reference frame and the temporal median of a registered set of neighbouring images. A key observation is that this difference will have two components with separable spectral content. One is related to the illumination field (lower spatial frequencies) and the other to the registration error (higher frequencies). The illumination field recovered by low-pass filtering is used to correct the reference image. In addition to removing the sun-flickering patterns an important advantage of the approach is the ability to preserve the sharpness in corrected image even in the presence of registration inaccuracies. The effectiveness of the method is illustrated in image sets acquired under strong camera motion containing non-rigid benthic structures. The results testify to the good performance and generality of the approach.

Existing simulation methods are not able to determine in detail the wave loads on a complex subsea structure when it is passing through the splash zone. To determine these loads model tests are necessary. Otherwise only simplified formulations or empirical relations for added mass and damping can be used. The iVOF (improved volume of fluid) method presented is a potential candidate for the better numerical prediction of the behaviour of a subsea structure in the splash zone. The iVOF method included in the ComFLOW program is summarised. Then results of simulations with a typical subsea structure in the splash zone are presented. A comparison is made with results of dedicated model tests with the same structure. The comparison gives good insight in the special capabilities of the method. However significant further development and validation is needed before a fully coupled simulation of a subsea structure and its lifting vessel in waves can be carried out. This possibility is also affected by the long simulation times required at the moment. As an intermediate step the method might be used to determine the wave loads and added mass in an uncoupled simulation.

Understanding the spatial and temporal structure of ambient noise is a critical factor for estimating the performance of active and passive sonar systems. This is especially true in warm shallow waters where snapping shrimp dominate the ambient noise spectrum over 6 octaves. A second reason for designing a compact high-frequency data acquisition system is to study dolphin echolocation. A compact high bandwidth (up to 5MSa/s) simultaneous quad channel general-purpose sampling data acquisition system has been developed. It is highly modular and easily reconfigured to suit different acquisition specifications. It permits 3D spatial beamforming on the data collected. Up to four sensors can be connected to the four synchronised input channels allowing the realisations of different arbitrary array configurations. The system is described and some sample data from the dolphin echolocation study is presented. The building blocks of the acquisition system are described together with their possible alternate modules-configuration in respective modules. The performance of the hardware setup used for the echolocation studies is briefly described. The discussion continues with two application examples followed by sample data collected from the dolphin echolocation study. In short the system is a highly modular general-purpose high-speed data recording system that is compact and low cost.

Sea ice thickness is one of the most important parameters for ice engineering problems and climate studies. Apart from IPS (ice profiling sonar) measurements EM (electromagnetic induction) thickness sounding has become an accurate and efficient method for thickness profiling and can be operated on the ice from ships or from structures like lighthouses or oilrigs. However EM sounding is most powerful when operated from helicopters or from fixed-wing aircraft. The accuracy of EM thickness sounding increases with the salinity of the water below the ice. Unfortunately in many key regions for ice-engineering activities the salinity of the water is very low for example in the brackish waters of the Baltic and Caspian Seas. An example of EM thickness measurements in the shallow water of the Bay of Bothnia (northernmost Baltic Sea) is shown using a small helicopter EM sensor and some model results. These demonstrate the particularities of EM sounding in brackish water. It is also shown that accurate ice thickness measurements are still possible with very low salinities of 3 ppt. In addition it is shown by means of model calculation and data that EM ice thickness measurements in shallow water less than 10 m deep are possible with instruments using high frequencies.

It is foreseen that the logistics will be one of the important services in Hong Kong for the next economic evolution. The role of the sea transportation becomes more and more important; it is not only to serve the re-export of the Pearl delta but a key nodal of the sea transportation chain in southeast China. nowadays when the emission from other sources is under control the contribution from marine becomes significant. Currently the local marine emission inventory estimation is following the reference issued in Europe and the United States and no work has been done to verify the accuracy of these approaches in Asian countries. in the last two years preliminary study has been carried out which included a survey of marine activities engine power of vessels and the measurement of ambient pollutants at Tsing Yi area. The result of survey and measurement could show a weak correlation of the concentration of pollutants and the maritime activities globally in Hong Kong region and also locally in Kwai-Tsing region. An alternative method is proposed for estimation of emission inventory using a systematic database of individual engine power of ocean-going container vessels. The result provides additional information on the martime emission to assist and refine the estimation/prediction of the emission inventory of the seagoing container vessels. Furthermore it can assist in the assessment of environmental impact from maritime activities. Better estimation of the marine emission inventory could improve the pollution prediction town planning as well as to enhance theX40694

A behaviour-based scheme for the high-level control of AUVs (autonomous underwater vehicles) is proposed. Two main characteristics are highlighted in the scheme. Firstly behaviour co-ordination is carried out through a hybrid methodology which takes advantage of the robustness and modularity in competitive approaches as well as the optimised trajectories in co-operative ones. Secondly behaviour state- action mapping is learnt by means of RL (reinforcement learning). A continuous Q-learning algorithm implemented with a feed-forward neural network is used. The behaviour- based scheme attempts to fulfill simple missions in which several behaviors (tasks) compete for the vehicle’s control. The feasibility of the scheme is shown with a target following mission designed to be carried out in a pool with the AUV ODIN. Simulation results show the good performance of the hybrid method on behaviour coordination as well as the convergence of the RL-based behaviours. The proposed hybrid co-ordination system is described (section 2). The continuous Q-learning algorithm used for behaviour learning is introduced (section 3). The target following application to test the hybrid co-ordination method is detailed (section 4). Simulation results are presented (section 5). Finally conclusions and future work are presented (section 6).

In offshore construction knowledge about sediment transport dynamics is essential and the quantification of SPM (suspended particulate matter) is of great importance. The Laptev Sea shelf is one of the largest Siberian shelf seas and ice-covered for about nine months a year. In order to use indirect measuring devices for the quantification of SPM concentration on the Laptev Sea shelf optical (turbidity meter) and acoustic (ADCP) (Acoustic Doppler Current Profiler)) backscatter sensors were compared to assess their potential for the investigation of SPM dynamics in an arctic environment. To estimate SPM concentrations from optical backscatter signals these were converted using the linear relation between the backscatter signals and SPM concentrations derived from water samples. By applying the theoretical interaction of sound in the water with SPM the acoustic backscatter signals were transformed adapting a previously established approach. SPM concentrations estimated from the backscattered signals of both sensors showed a close similarity to SPM concentrations obtained from filtered water samples. While the ADCP offers distinct advantages over the turbidity meter in that it allows measurement of the complete concentration profile bottom location and currents co-deployment of both sensors are recommended for improved SPM measurements.