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Wave-induced vibrations often referred to as springing and-or whipping increase the fatigue and extreme loading in ship hull girders. Both effects are disregarded in current ship rules. Various numerical codes exist for predicting the wave induced vibrations but so far they are not considered reliable. Another means to investigate the importance of the high frequency response although more resource demanding is to carry out full-scale measurements and-or model tests. Recently full-scale measurements of blunt ships have been carried out by DNV and in this paper one of these ships was considered and tested in a towing tank to evaluate the additional fatigue damage due to the wave-induced vibrations. Different excitation sources may excite the 2-node vertical vibration mode depending on ship design and it is not straightforward to determine which is more important. The relative importance of the excitation mechanisms are investigated by two approaches. The first separates the whipping from springing to illustrate their relative importance based on basic theory in combination with model test results. The linear and second order transfer functions are used in this procedure. The second deals with the effect of the bow design on the additional fatigue damage. Three different bows were tested. The first bow design is identical to the real ship. The second bow design is a simplified version of the first one by removing the bulb and flare. The third bow is fundamentally different from the two former blunt bows. Bow three is sharp pointed with a vertical sharp stemX44934 The effect of bowshape on the seakeeping performance of a fast monohull

Electrical power networks for alternating current are often designed as three-phase systems. An advantage of such systems is the possibility of a balanced power distribution over the three phases. As a consequence the power generator has a continuous load. Furthermore the neutral lead does not carry or barely carries current because the currents through the phases cancel each other out. The situation becomes different when the alternating current is no longer sinusoidal. This occurs when the power demand becomes more pulse shaped. Equipment showing this behaviour includes such office equipment as computers energy-saving lighting power converters commercial appliances such as photocopiers and printers. The use of such equipment is growing also in the maritime market. A characteristic of this equipment though is that the pulses are at fixed-phase shifts with the AC power from the generator. This means that the power system faces significant higher harmonics particularly third and fifth harmonics. An in-depth analysis of pulsed power demand effects on an AC network is reported. The load on the generator is discussed as well as the current in the supposedly neutral wore and branch networks. It concludes on relevant design issues in the light of growing pulsed power demand that would benefit installers and system integrators amongst others.

Marine propulsion shaft alignment using the strain gauge alignment technique is becoming more commonplace as shipyards and owners find the technique is accurate reliable and cost effective. There are a number of advantages of incorporating this technique on slow-speed diesel propulsion shaftlines. Accurate measurements of both the vertical and athwartships loads on the lineshaft and sterntube bearings can be obtained while the shaft is completely assembled. Direct measurement of the shear and bending moment at the thrust shaft flange can also be obtained to ensure the load on the aft-most engine bearing is acceptable. Measurements can usually be obtained within thirty minutes enabling shaft alignment to be evaluated at various loading conditions and machinery temperatures without significantly interfering with operations or production. The strain gauge alignment technique has also been shown to be more accurate and less time consuming thant the traditional method using gap and sag and jack-up load measurements. The strain gauge alignment technique was incorporated into the alignment procedures for the Pure Car Truck Carrier "MV Jean Anne" built by VTHalter Marine Inc. and the first two CV-2600 container vessels built at Ajer Philadelphia Shipyard. This paper describes the measurements and results of the strain gauge alignment technique used for two classes of vessels.

The effect of a finite Froude number on the performance of fully cavitating foils in the vicinity of the free surface is investigated. A solution is obtained using a distribution of Kelvin sources and vortices along the mean line of the foil-cavity system. In this way the correct free-surface conditions on the cavity surfaces and on the water surface are satisfied. The convergence rate is found to be inversely proportional to the number of singularity elements used and this fact can be used to extrapolate the results for higher accuracy. The effect of the Froude number is found to be more important when the cavity length is greater. For example when the cavity length is eight times the chord of a flat foil and the foil submergence equals the chord the lift co-efficient is found to be 21% less at a Froude number of 2.828 compared with the infinite-Froude-number calculation. The cavitation number is found to be 72% less in the same condition. It is also shown that in the range of interest the infinite-Froude-number results can be corrected by a term which is proportional to the inverse-square of the Froude number. Large distortions in the cavity shapes by the Froude-number effect are also predicted by the method. Concluding remarks are presented and further work identified.

The development of spar platforms for offshore gas and oil exploitation and production has been ongoing since Neptune production spar was installed in GOM by Kerr-McGee in 1996. Among those spar concepts put forward by the design companies and institutes the classic spar and truss spar are the most prevalent. The cell spar is a new design and now operated in Texas. For the sake of installation of rigid risers with dry wellhead motions of the spars should be confined in a certain range. Haslum and Faltinsen proposed that the wave frequency response might be reduced in three ways: 1) by increasing the damping of the system; 2) by increasing the natural heave period out of the range of the wave energy; and 3) by further reducing the linear heave excitation forces. An experimental study on the effect of heave plates on the hydrodynamic performances of a cell spar platform is presented. A variation of the cell spar concept whose hard tank still consists of several cylinders (cells) with the same diameter and length but whose lower part is fitted with a truss section and several heave plates is modelled and tested. As the effectiveness of heave plates is crucial to the heave performance different types of heave plates are fitted to the truss structure varying from the number and spacing to the form such as perforated plates to investigate various design aspects of the plates. Experimental results and numerical predictions for the responses of the spar to the wave loading as well as loads and added mass and damping coefficients on the heave plates are presented.

Ship propulsion trials in ice were carried out in the Antarctic in January 1995 during the USCGC Polar Star's mission to re-supply bases along the Antarctic Coast which included extensive icebreaking in McMurdo Sound. This project the measurement of ice loads on a propeller blade of the largest controllable pitch propeller icebreaker in the world is the latest of many collaborative arctic research and development projects over the years between the Canadian and US Coast Guards. The objective of the trials was to measure the ice and propeller interaction loads on one starboard propeller blade and the corresponding propeller shaft of the vessel. A comprehensive analysis of the data was then carried out in order to determine the influence of design operational and environmental parameters upon the nature and magnitude of the ice loads. This paper concentrates on the application of the results to regulations and most importantly to the IACS Unified Requirements supporting the IMO Polar Code.

Symp held in Hamburg 5 - 9 Dec 1977 Papers are Todays great paradox - the wealth of the seas and the shipping crisis Philosophy and safety requirements for land based nuclear installations An NEA confrontation to the safety of nuclear ships The international state of affairs in marine safety Development of a nuclear ship safety philosophy Application of risk assessment to nuclear merchant ship safety Port interface requirements Ship accident studies A mathematical model for the analysis of the protection barrier of nuclear ships Effects of ship casualties on reactor safety and marine reactor design Conclusions from collision examinations for nuclear merchant ships in the Federal Republic of Germany Flooding and sinking of nuclear merchant ships Heat removal from the reactor pressure vessel to the surrounding seawater in case of sinking A role for probabilistic methods in nuclear ship safety Safety studies on loca for N S Mutsu Development of accident event trees and evaluation of safety system failure modes for the nuclear ultra large crude carrier Start up test and technical problems encountered on N S Matsu N S Otto - non destructive retesting (in service inspection) Engineered safety equipment and safety analysis of NCS-80 Handling loss of coolant accidents in the IPWR In service inspection programme for the NCS-80 reactor pressure vessel

Zeke's Island part of the North Carolina National Estuarine Research Reserve is an undeveloped site. The Reserve site is owned by the State of North Carolina and managed by the North Carolina Department of Environment and Natural Resources Division of Coastal Management as part of the Coastal Reserve Program. State statutes and rules allow compatible recreational uses and other activities on the Reserve. Although a fairly pristine and isolated reserve site the Zeke's Island Reserve is located near the communities of Wilmington Carolina Beach and Kure Beach. These communities attract significant numbers of in-state and out-of-state tourists and local residents each year. Many of these tourists and residents choose to recreate on the Zeke's Island Reserve due to its less crowded undeveloped character and nature. The effects of various recreational activities are investigated in a study. Based on the results it is concluded that the passive use of regulatory signs is an effective management tool in regulating visitor behavior within the Zeke's Island Reserve.

In future the electrical power generation on the navy's AES (all-electric ships) will have increased significantly. This will lead to higher short-circuit currents in these ships' power systems. Therefore components carrying the short-circuit currents will be exposed to higher mechanical and thermal stress. The sources of power available to produce fault current into a fault on a ship power system will be limited by the presence of PE (power electronic) converters which can rapidly control current flows. Issues are illustrated that may arise if medium-voltage class FCL (fault current limiters) are introduced on navy type AES (all-electric ship) power systems as well as the modelling of that system for various transient simulation studies. The system is modelled in detail with all power electronic converters in place. Later these complex models are replaced by simpler average load models and validated against the detailed model. A model to represent the FCL in terms of variable impedance is modelled and validated against published data from measurements. Different configurations of FCL placements within the power system are considered and simulation results are presented. The need to consider different operating conditions of the power system and the need to evaluate the protection system setting when FCLs are added are identified. The simulations are carried out in the industry standard transient simulation program PSCAD-EMTDC. Results are presented and conclusions drawn.

DRDC (Defence Research and Development Canada) Atlantic has a number of sonar projects that require the underwater transmission of acoustic energy. Because of potential adverse environmental effects a number of international and Canadian laws as well as DND (Department of National Defence) policies impact on these research activities. Of particular interest for this paper are the Canadian legislation and departmental policies relating to the potential impact of active sonar research sea-tests on marine mammals. The relevant legislation and policies in place to protect the natural environment from undue stress from human activities are sumarised. The emphasis is on legal and policy vehicles that are directed towards the protection of the living marine environment. DRDC activities must adhere to many other Canadian laws both federal and provincial; however only the environmental protection legislation and policies affecting sea-trial activities are discussed.

Conference held 26-27 September 1995 in London UK. Papers are - Britannia - enlarging the operational envelope of an old warrior Structural design of a harsh environment - 4 legged jack-up boat The use of DNV classification systematics as a means of satisfying the NPD requirements to structural strength for a jack-up unit Evaluation of hydrogen assisted cracking resistance of high strength jack-up steels Voyage acceleration climate - a new method to come to realistic design values for ship motions based on the full motion climate for a particular transport Verification of methods for simulation of nonlinear dynamic response of jack-up platforms Systematic model tests on a harsh environment jack-up in elevated condition Effects of non-gaussian waves to the dynamic response of jack-up platforms An introduction to the PFEER regulations Estimation of foundation fixity parameters for a simplified jack-up model Some aspects of the safety of jack-ups on location and during transit

The international climate change negotiations have identified options for countries to achieve their greenhouse gas emissions reduction targets by either contributing to emissions-reducing projects in other countries or through the international exchange of emissions-reduction credits (trading). Such approaches offer significant opportunities to achieve greenhouse gas emissions reductions at lower societal costs than other measures while providing significant additional contributions to environmental protection and sustainable development. Businesses have the ability to play an important role in enabling these 'mechanisms' to function to their maximum potential. The prospects for realising these opportunities will depend on decisions concerning the international operation of the 'mechanisms' and on the manner of implementation of these 'mechanisms' by national governments. These factors will in turn largely determine the role of businesses in the 'mechanisms'. A business perspective on the opportunities issues and barriers surrounding the practical application of these 'mechanisms' is provided through examination of some opportunities to apply them within the petroleum industry and the identification of the issues that must be addressed to enable such commercial applications.

A numerical modelling toolset is described which has been produced to study the survivability implications of a trimaran hullform subjected to non-contact UNDEX (underwater explosion) attack. The validation process carried out on the toolset is discussed and numerical prediction versus experiment comparisons are presented. The shock analyses used a finite element model based on RV Triton scaled up by 3-2 to represent a full-scale trimaran warship. The whipping studies used a 1-25th scale trimaran pipe model based on an indicative trimaran design and also a full-scale beam idealisation of the indicative design with which initial parametric design studies have been performed.

The extreme loading on structures caused by the impact of breaking waves has long been known and has recently been brought into focus again as a result of the occurrence of unexpectedly high or steep waves around both fixed offshore structures and FPSOs. This has prompted work on re-analysis of wave records and on numerical modelling of temporally and spatially extended wave fields in order to investigate whether for example nonlinear effects may increase the probability of occurrence of extreme waves. In this paper consideration is given to wave breaking the geometrical scale of breaking crests and the criteria which determine the type of breaker by reference to selected sources from the literature more-or-less in a qualitative manner

Despite all the new worldwide information about ice-structure interactions locating a fixed structure in the Baltic Sea is in general considered to be costly and hazardous. When discussing suitable locations of offshore wind generators along the coastline of the Baltic Sea the potential of ice loads is essential. Selected data from full-scale measurements of extreme ice pressure on structures in the Baltic Sea are discussed. Simplified empirical design rules are challenged with a proposed method using statistics on ice crushing climate and ice conditions. Indications of strong influence of structure diameter on the effective ice pressure are confirmed by results obtained from other lighthouses in the area. The results can be used in simulating ice-load probabilities for fixed vertical structures with small diameters located in the Baltic Sea.

This paper makes clear the concept of the ecological development policy for the model of the coastal city. The paper shows the general concept of the future development and the ecological development coastal city on Osaka Bay coastal zone based on the various relations of the land and sea in the coastal zone. The paper shows that it is desirable that the new coastal city and social economy is established where sustainable development with the ecosystem is aimed at based on the ecological development of the coastal zone.

A set of experiments performed in a closed-circuit wind tunnel in order to investigate the aerodynamic characteristics of a typical offshore supply boat are presented. The test facility is described along with wind speed measurement simulation of the marine boundary layer force and moment measuring system and data collection and processing system. Results are discussed in terms of Reynolds Number effects the effect of boat heading on the un-iced vessel effect of severe ice accretion accuracy of wind tunnel tests and influence of wind forces on ship dynamics. The results are compared with previous work. Severe ice accretion was found to cause a significant increase on wind loading and to reduce drastically the dynamical stability of the ship.

The principal aim of this paper is to study the dynamic behaviour of offshore platforms subjected to wave loading. A general review of offshore structure wave loading and their effects on offshore structures are presented. A brief review on the basics of Wavelet analysis is also mentioned in this study. The techniques for modeling wave loading in finite element analyses are described and discussed in detail. A series of 3D analyses were carried out using the ABAQUS finite element software to study the effects on the dynamic response of the change in support conditions at the seabed. The effects of wave height wave period and wave velocity on platform behaviour were studied. The results from time history analysis are characterized using Wavelet Analysis in order to obtain the response pattern due to wave loading. These analyses allow the frequency response of the jacket structures to be described in the time domain. These results give a clear view on the response of jacket structure. The important parameters on offshore modeling have also been identified and discussed in this paper.

The character of the current and temperature records from an array of moorings on the San Pedro shelf are discussed briefly. The circulation of the San Pedro shelf is shown to have three major components: low-frequency flows derived from the large-scale oceanography of the southern California Bight; the sea breeze-induced upper-layer flows on the outer shelf; and tidally forced currents. The low frequency (sub-tidal) flow variability observed is discussed (section 2); the effects on the current field of the daily fluctuating winds of the coastal sea-breeze system are considered (section 3); and the semidiurnal surface and internal tide are studied (section 4). These three processes in this order of importance account for most of the observed variability in the current and temperature fields over the eastern part of the San Pedro shelf.

In-service monitoring systems for safe ship navigation can be used for decision support for course and-or speed changes if the on-site directional wave spectrum in combination with the frequency response function(s) is known. Therefore it is interesting to have a method which on the basis of ship response measurements facilitates a continuous update of the directional wave spectrum. Thus the problems related to the fixed position of wave buoys and current meters are overcome. Moreover since the sensor measurements are already inhand from the in-service monitoring system a ship response-based estimation method has no initial cost as opposed to for example wave radar systems not to mention the calibration and maintenance of such systems. Two ship response-based methods for the estimation of onsite directional wave spectra are compared: a non-parametric method based on Bayesian modelling and a parametric method