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Two methods Hybrid Wave Model (HWM) and Mode-Coupling Method (MCM) are respectively used to simulate ambient wave kinematics of a Single Degree of Freedom (SDOF) cylindrical structure and in turn to predict wave forces on it by using the Morison equation. The statistics of the simulated results reveal the effects of surface intermittency and nonlinear wave kinematics on the wave forces. It is shown that the combination of surface intermittency and nonlinear wave kinematics greatly increase the wave forces on a bottom fixed cylinder with the increase in the spectral steepness in comparison with the results given by linear wave theory (LWT). Hence both nonlinear wave kinematics and surface intermittency should be considered in predicting the wave forces. It is also shown that their effects depend on the characteristics of sea states. The effects are stronger in sea states of a spectrum of broader band than in a narrow-band spectrum.

The designers of accommodation on ships like the designers of buildings rely heavily on experience and tradition. They have few opportunities to test spaces and fittings as prototypes in use before committing to final construction. They also have little opportunity to know the expectations of users - passengers and crew - and to be able to balance those expectations with the requirements of maintenance staff and ship owners or with engineering and physical environmental constraints. It is suggested that POE (post occupancy evaluation) methods developed for evaluating buildings in use could also be used to evaluate and inform the design of passenger and crew accommodation on ships. POE has been developed and used in architecture during the last 20 years. It is a technique that enables designers to optimise the expectations of all interested parties associated with the building. It is a process of negotiation which can be used to inform the fine-tuning or re-fit of an existing building and provides a sound database about users' expectations for the design of new buildings. It has been used on a wide range of building applications including courthouses retail stores scientific research laboratories banks

Tests with a catalytic converter were carried out on MaK engines within the framework of the CLEAN project. The contaminant components of marine diesel engines are described and the ideas behind reducing emissions are discussed. The Siemens selective catalytic reduction (SCR) system used in the tests is described. The TT-Line ferry newbuilding Nils Dacke was used as a test ship for practical trials of the experimental SCR plant. Besides experience with gas oil operation on the MV Nils Dacke trials were also carried out on the MaK experimental test bed with an engine running on heavy fuel and an SCR catalyzer. Results are discussed and optimisation possibilities for future SCR exhaust gas cleaning plants are outlined.

A recently developed numerical design method for analysis of green sea events and resulting impact loads on deck structures of FPSO's is validated against model test data. Steep irregular wave conditions are considered and numerical time series reconstructions are made using the measured wave as input. A second-order numerical random wave description is combined with standard 3D wave diffraction and related vessel motions to predict the relative wave kinematics. A modified shallow water formulation is applied for the prediction of the propagation on deck and resulting local pressures on the deckhouse are estimated by a similarity solution. Comparisons to the experiments are made for the relative wave amplitudes water propagation on deck and the resulting deck-house loads. Thus selected green sea events are investigated in detail and characteristics identified.

This paper reports on the investigation carried out by British Maritime Technology into the capsize and sinking of the passenger/ freight ferry `Herald of Free Enterprise'. The study concentrated on hydrodynamic aspects of the incident and involved a multidisciplinary approach using computer models physical models and a full-scale trial. Once sufficient water was on the deck stability was lost and the ship heeled and entered a severe turn due to yaw/heel coupling. Centrifugal effects aggravated the heel with the ship ultimately resting on her beam ends.

The aim of this paper is to predict the effects of area closure on fishing effort distributions and the production of benthic communities. Also there is comparison of the effects of observed effort distributions with the effects of uniformly or randomly distributed effort on the same fishing grounds. It is determined how the spatial scale of analysis affects the results. The analyses focus on the response of the international beam trawl fleet to the cod box closure as assessed by satellite monitoring. A look is taken at methods covering study area estimates of trawling disturbance and effects on benthic production. Next results are considered. These are followed by discussion.

The analysis of influence of axial force on the vibration of Euler-Bernoulli beam structures is frequently necessary for modern engineering design. Numerical methods can be used to solve this vibration problem. An efficient method that can be used to develop a solution algorithm for this structural problem is DQEM (the differential quadrature element method). The influence of axial force on the vibration of Euler-Bernoulli beam structures is analysed by DQEM using EDQ (extended differential quadrature). DQEM uses the differential quadrature to discretise the governing differential eigenvalue equation defined on each element the transition conditions defined on the inter-element boundary of two adjacent elements and the boundary conditions of the beam. Numerical results solved by the developed numerical algorithm are presented. The convergence of the developed DQEM analysis model is efficient. The developed analysis technique can be used to solve more structural problems existing in the offshore field.

In the present study effect of draft changes on hydro-elastic response of pontoon type VLFS is investigated mainly focusing on local response wave run-up along the waterline. Three dimensional higher-order boundary element method (Hong et al; 1999 Choi Hong and Choi; 1998) is extended to be able to generally treat hydrodynamic forces of elastic bodies (Newman 1994). Thin plate equation is used for representing elastic behaviours of the structure. Intensive numerical calculations are carried out for box type structures to investigate draft effect on elastic responses as well as hydrodynamic forces on pontoon type VLFS. Main attention is paid to wave run-up along the waterline for various cases of draft scantling.

The icebreaking forces and resistance on the design waterline of a ship advancing in level ice have been studied with simple analytical and numerical models to shed light on the dependency of icebreaking forces on the local angles at the waterline. The influence of compressive membrane stresses in the ice cover were studied as the flexural stresses are reduced which postpones the ice cover failure at the waterline of the advancing ship causing additional resistance. With higher ship speeds the in-plane forces gain further importance as the fluid foundation of the ice cover becomes harder; the development of the flexural stresses but not the membrane stresses are slowed. This breaking mechanism has relevance both to icebreaking resistance and to the ice loads on the ship hull and should be included in numerical models describing the icebreaking process at the waterline.

Experimental observations of a secondary load cycle in the force acting on a vertical cylinder exposed to long and steep waves are considered. A complementary discussion of the occurrence of ringing of models of offshore structures is given. The paper summarizes the occurrence of pronounced higher harmonic forces observed in wave tank experiments in periodic waves the leading transient part of a wave group focussing waves and irregular waves. Results from other scientific groups are collected and compared with the measurements made at the University of Oslo. The paper also includes the main findings of a larger investigation.

The effects of ultra-fine grain microstructure on fracture toughness and fatigue strength in air and artificial seawater are investigated. SUF steel plates have superior fatigue properties both in air and seawater. Especially the shape and depth of corrosion pits formed on the surface of the SUF region in the seawater fatigue test were completely different from those on conventional microstructures. Inner surfaces of corrosion pits on SUF microstructure were smoother than those on conventional microstructure and depth of corrosion pits on SUF microstructure were shallower than those on conventional microstructure. Therefore the fatigue strength Of SUF in seawater is better than that of conventional microstructures.

Understanding the dependence of velocity and attenuation on confining pressure and pore pressure in reservoir sandstones is vital both for extracting subsurface dynamic elastic parameters from seismic data and also for relating laboratory measurements to larger scale lower frequency data. The influence of pore pressure on velocity and attenuation is of obvious interest to the oil industry as the ability to predict overpressure and lithology pre-drill can have significant impact on well costing. Triaxial loading combined with ultrasonic testing is carried out on two Carnarvon Basin reservoir sandstones from the Australian Northwest Shelf. Results are explained and presented graphically.

In modern marine diesel engine operation the tendency is to increase the power the PME (mean effective pressure) and the piston speed while reducing the fuel and lube oil consumption. This has a great impact on cylinder lubricant performance requirements especially in the very large bore and long-stroke crosshead engines. However as pressure increases so lubricant film thickness reduces and the time of exposure to combustion is extended. This increases the probability of adhesive wear and scuffing. In addition as HFO (heavy fuel oils) contain high amounts of sulphur corrosive wear can remain depending on the engine condition. New test methods on pin-on-disc tribometers are developed which can describe adhesive wear

Geomagnetic navigation based on a geomagnetic field model is an autonomous navigation which is very useful for the activity of underwater vessels. Geomagnetic navigation can provide real-time positioning information by matching geomagnetic observation data and geomagnetic background map or LGFM (local geomagnetic field model). A very important factor which restricts the accuracy of geomagnetic navigation is the accuracy of LGFM. The primary difference between local normal geomagnetic field modelling and global geomagnetic field modelling is the number of observation points and the building model methods. Usually polynomial surface method is adopted in building LGFM rather than spherical harmonic analysis because LGFM does not have 3D meaning. Although the polynomial surface method is simple and convenient it is difficult to achieve satisfying model accuracy in actual applications. In order to obtain high-accuracy LGFM to serve underwater geomagnetic navigation two typical surface interpolation methods are studied: SSF (spine surface function) and MSF (multi-surface function). The two methods are described in detail and conclusions and recommendations are drawn.

CBMS (condition-monitoring-based survey) is now available on propeller shaft and bearing metal on board ships under some conditions. However a surveyor must inspect the lubricating surfaces of a diesel engine every 5 years. This can be called a 'time-based survey'. The possibility of using a CMBS for ship diesel engines is investigated. One trial the combination test of an acoustic emission analysis and cylinder drain oil analysis was done on board a sailing ship and the results were reported in 2002 at a marine symposium. The other trial analysing oil containing foreign metal wear particles is considered here. Two foreign metals (cobalt and yttrium) were embedded in piston ring test piece and another foreign metal (barium) in a white metal test piece. PDWT (pin on disk wear tests) were run by a private wear test machine. The first wear test was run for 180 hours under an oil temperature of 160 ºC and a load of 5000 N. The second wear test was run for 97 hours under an oil temperature of 100 ºC and a load 3500 N. The oil in service was analysed by a spectrometric oil analysis program and a ferrography analysis method.

Wave groups a finite run of higher than normal waves are often observed at sea and in the wave records. The wave group phenomena have an important impact on a wide range of ocean and coastal activities and should be taken into account for sophisticated design of deep water and coastal structures. Here the effect of wave grouping on the wave height distribution was investigated on the basis of field data. Field observations were conducted at the Research Station “Shkorpilovtzi” in the Institute of Oceanology - Bulgarian Academy of Sciences. The tendency that wave height distribution becomes wider as the degree of wave grouping is higher is examined. The problem of suitable wave group parameters which can present the influence of wave group structure on probability density function of wave heights is also discussed.

An economical-environmental model for the evaluation of a marine transportation system is proposed. In the model a transportation system is evaluated based on an economical-environmental index. The index is determined by dividing an economical impact by an environmental impact. The economical impact is calculated by multiplying an economical ratio by a weight of economical impact. The environmental impact is calculated by summing up the multiplication of each element of environmental ratio by weight of each element of environmental impact respectively. The economical ratio consists of economic margin and return ratios and business impact. The environmental ratio includes annual volumes of CO2 NOx and SOx emitted per annual cargo capacity. These economical and environmental ratios are determined using technical data including cargo capacity engine power and building cost of a ship. The weights of economical and environmental impacts depend on public opinion. These weights are determined by using the AHP (analytical hierarchy process) model on the basis on public opinion. Using the model a feasibility study on a podded propulsion LNG (liquefied natural gas) tanker is accomplished by comparing it with a conventional one which has been operating for some 20 years.

API Bulletin 2U is the bulletin on Stability Design of Cylindrical Shells. It has provided guidance for the design and analysis of cylindrical shells since its first publication in 1987. The API Bulletin has recently been revised and the second and third editions issued. A brief summary is presented of the changes introduced into the third edition of Bulletin 2U. Firstly it analyses several TLP column designs based on the second edition of Bulletin 2U. Secondly the designs are reviewed based on the third edition of API Bulletin 2U and modified as necessary. Thirdly the designs are further modified to meet the requirements of Det Norske Veritas. The discussion and tables and figures illustrate the sensitivity of various parameters on design and indicate the significance of the design basis on design and product. The buckling stress equations are briefly discussed and a comparative assessment of buckling stresses applicable to different orthotropically stiffened cylindrical shells. The paper then presents several large diameter cylindrical shell designs applicable to TLP columns. These columns are reanalysed using both API Bulletin 2U and DNV recommended design equations to show that in the third edition of Bulletin 2U the designer has the flexibility and information needed to design cylindrical shells that have structural integrity and yet remain cost effective.

Establishing a visual map of a region observed by an onboard camera of a mobile robot is a powerful tool which can be used either for post-mission environment analysis or for on-line navigation. A new approach to image matching based on both entropy and mutual information measures that can correctly carry out association under very low overlap conditions is presented. The method is feature-based working on a list of interest points detected on the acquired images. Unlike the classical SSD-RanSaC method this algorithm is robust to the existence of many similar regions in the images thus enabling situations to be handled where the interest points correspond to local details of a habitat that is dispersed with a regular-like structure across the ocean bottom. This method actually only requires that four corresponding points be detected in the two images being aligned. This allows matching under minimal overlap of the images. The improvement in efficiency of this method when compared to previous techniques relies on explicitly accounting for ambiguities in the association between the templates of the two images thus preventing that useful information be discarded at an early association step.

Many offshore platforms have suffered from significant wave loading on their lower deck and FPSOs (floating production storage and offloading) systems have also suffered topside damage from 'green water' on their decks during storms. However understanding of the wave kinematics such as crest velocities accelerations and overtopping rates for extreme events remains rudimentary. Although the overtopping of shallow water coastal structures has been well studied there have been very few studies on overtopping of a fixed deck in deep water with high wave steepness (i.e. storm conditions). A statistical model is developed to predict wave overtopping of extreme waves on a fixed deck. Here existing theories developed for crest statistics to the problem of wave overtopping are extended; the theoretical model is compared with experimentally determined overtopping probability distributions. Firstly the statistical formulation of the problem is presented and the sensitivity of the derived probability functions to non-linearity and deck clearance is shown. The experimental setup and procedures of the small-scale hydraulic model test are presented. Conditional sampling of the crest heights seaward of the deck produced a normalised probability distribution similar to that of the maximum water level measured on the deck for each over-topping event. A detailed discussion of the model-data comparisons is presented. It is concluded that the model prediction of the exceedance probability of deck overtopping has given very good agreement for large over-topping values.