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The hydrodynamic behaviour of different aft body shapes are described with attention given to pressure distribution water flow direction buttock angle and shape effects. Some general information and thumb rules are given regarding aft hull lines design. The concept of a 'wave damping aftbody' is described. This has the advantage of not having a typical aft crest wave and much smaller wave troughs and transom waves than earlier forms. The design is illustrated with examples ranging from fast ferries to the world's largest Eagle-class cruise liner the Voyager of the Seas and its benefits are briefly outlined.

QinetiQ have been working on the design and analysis of trimaran warships for over 10 years. Details of work carried out to understand the wave-induced loading and consequent structural response of trimaran hulls is presented. The programme of work described has been based on hull forms varying from 12000 to 23000 tonnes displacement. Studies of local prediction finite element analyses and parametric studies to develop draft design rules for trimarans are presented. Load prediction methodologies have been developed based on static balance and 3D potential flow theory and validated against segmented model and full-scale operational trials. Finite element analyses have been carried out to derive an understanding of the load paths within trimaran structures in both the damaged and undamaged condition.

Recently IACS (International Association Classification Societies) adopted the CSR (Common Structural Rules) for Tankers and Bulk Carriers in which the requirement relating to the ultimate strength of the hull girder structure is described. The theoretical background and the results of verification study are neither released nor well summarised. Furthermore the requirement is not described as a form of deterministic formula but only a calculation program is provided whose source code is not disclosed. Here a formula for estimating the ultimate bending strength of the hull girder is proposed. The formula is compared to the results of rigorous non-linear finite element analysis and those of the program which was provided by DnV. For this study the reliability of the non-linear structural analysis procedure was verified by comparing its results with those of the test which was carried out for the large frigate model.

Fibre reinforced plastics have for a long time been used in boats and leisure crafts. In those applications the advantages such as low manufacturing cost and little need for maintenance are obvious and well known. The use of composites in larger vessels have been limited to some very special applications such as naval mine hunters. New production methods have been developed that have reduced the labour hours and the amount of materials needed. The materials have become cheaper and better due to increased volumes. As the knowledge among technicians and engineers has increased the composite technology has matured. Today many universities have education programs specialized in composites. This has helped to raise the acceptance among operators and the general public. Classification societies and governmental organisations have rules and regulations on the use of composites in ships that also include fire requirements. The future looks good for composites in commercial ships and the product range will be expanded from todays high speed ferries and smaller work boats to larger ships and superstructures.

In the practice of engineering design for ships and ocean structures and in many classification rules the Morrison equation approach and the strip method are used and defined to determine motions and loads encountered by floating structure in waves. Considering the complex structure and large-scale for the semi-submersible platform the panel method is used in this computation. For the global and fatigue structural strength analysis of a semi-submersible platform the wave loads of design conditions are calculated by using the 3D boundary element method. The maximum of vertical bending moment torsion moment and horizontal spilt force are determined from a series of design waves with limited period and positions of incident wave crest. The extreme wave loads under the combination of wave parameters and the transfer functions of wave loads are used as the input of hydrodynamic pressure in the 3D FEM analysis process.

The objective of a 12-metre designer is to design an object that can be moved around an America's Cup course so that it will cross the finishing line before its opponent using only propulsion forces provided by wind waves and oceanic currents while conforming to the International Twelve Metre Rule the racing committee's rules the Americas Cup Deed of Gift and Lloyd's requirements for Twelve Metre International Rating Class Yachts. While this appears to be rather a strained definition it is meant to point out that a 12-metre yacht is not a powerboat with sails and without an engine. The wide range of engineering methods used during the design and development of 12-metre yachts is described and it is clarified how data resulting from the use of these tools can contribute to better performance. The strengths and weaknesses of each tool are identified and it is shown that next to hard engineering numbers an artist's touch and experience are still required for designing an outstanding 12-metre yacht.

Class NK rules require that the part of the boiler drum where feed water is introduced be provided with sleeves so that an extreme thermal stress may not occur due to direct contact of cold feed water with the drum. A study is presented for estimating the stress condition of the auxiliary boiler drum around the feed water inlet to find out the probability of direct connection of the feed water inlet pipe with the boiler drum. An analysis for obtaining stress distribution is carried out and the area of maximum stress is located. The study concludes that the direct connection of the feed water inlet pipe with the boiler drum may be possible for a boiler of design steam pressure of less than about 2.0 Mpa.

Nauticus Hull is a ship modelling and analysis package produced by Det Norske Veritas (DNV). It has been designed to improve knowledge transfer both within DNV and between DNV and its customers. It is also aimed at reducing the delivery time for a new ship while maintaining or improving safety. The package employs a concept modelling approach which is described in detail. Concept modelling is a way of describing a structure as an assembly of ship structure elements. It offers significant advantages over most current analysis systems in terms of efficiency and quality control. The implementation of the package in the classification concept is described and particular attention is given to its cost-reducing capabilities with regard to direct calculations. A complete Nauticus system is planned for the future which will be integrated with CAD/CAM and planned maintenance systems.

An Integrated Fatigue Analysis procedure for tankers has been developed by Germanisher Lloyd it is based on an overall finite element model of the type used for global strength and vibration analysis and enables the effects of a range of interacting loading conditions on vessel life to be assessed. Methodology described includes the stress analysis of tanker structures (including the hull girder and secondary structural members) and the scheme for Integrated Fatigue Analysis with detailed design (examples illustrate its application to structures in a double hull tanker): the use of the resultant data in the reliable life prediction of vessel structures the optimisation of design and the compilation and verification of rules and guidelines is discussed.

Some of the twin screw ship experience gained by Lloyd's Register's Technical Investigation Department in the context of their problem solving and research activities is described with numerous practical examples cited to show lessons learnt. First a look is taken at propulsion machinery. Next propulsion hydrodynamics and some of its problems are considered. This is followed by an outline of structural considerations. After this vibration and noise are each discussed in turn. Experience with the solution of vibration and noise problems is also used to support the development of Lloyd's Register's new Provisional Rules for Passenger and Crew Accommodation Comfort. Lastly condition monitoring is looked at with Lloyd's Register's primary interest being to use the techniques to enhance survey procedures so that the necessary levels of safety are gained in the most cost effective way to ship operators.

In this paper the vertical bending moments at the midship section of an FPSO are investigated using state of the art numerical simulation tools in combination with experiments. For the seakeeping tests the extremely high New Year Wave (registered in the North Sea) is generated in the wave tank and motions and structural forces are analyzed at model scale. For validation the results are evaluated deterministically and compared to numerical simulations. The time domain calculation allows to artificially change local wave characteristics. The steepness of the selected rogue wave is varied and the influence on wave induced loads is studied. Lastly a comparison with standard procedures of seakeeping analysis and classification rules is given.

Currently recovering from the decrease in Danube traffic caused by the Serbian war the river fleet of the Romanian operators is facing a new challenge. The new European regulations covering the manoeuvring capabilities for inland waterways vessels as well as the new rules for pollution prevention and noise reduction requires drastic measures to be taken by the ship owners. For the moment the most efficient way to solve the problem is to modernise the existing river pushers by replacing and-or upgrading the propulsion and steering systems. From an engineering point of view the most important task of this project was to evaluate and optimise the manoeuvring characteristics to comply with the requirements. This was solved by combined methods of hydrodynamics finite element method and hydraulic systems calculation. These methods are presented. They were used to investigate and optimise the manoeuvring and steering capabilities of a 30 m river pusher 2x1600 HP.

Sessions 2 - 9. These are Prevention of accidents - manoeuvring simulation and crew training Damage stability rules in relation to ship design Fire protection and life saving at sea Collision and grounding mechanics Oil spill prevention with new ship types Reduced exhaust emission with new engine types and new exhaust gas cleaning systems Noise and vibration control International safety management

This paper describes the design of the floater and the mooring system for a small wind turbine. The engineering basis and the hydrodynamics calculations are described as well as the installation and commissioning sequences. The paper deals with the possibility of having a floating mooring designed so that above the water it appears and acts like a single pole permanent pile. If a permanent piling can be avoided in favour of a floating design the wind turbine could be towed to a boat slip of protective shelter for servicing or when there are severe seas following the same rules of safe practice in protecting small boats and yachts. This paper is concerned with the design basis for a one kilowatt floater.

Electric propulsion has tended to be used where conventional methods of propulsion could not be modified to provide the necessary operational requirements. The design of the power system thruster and propeller selection and thruster and propeller drive selection are considered. Both AC and DC drives are available. Also covered is the electrical distribution system's security reliability and flexibility of operation. The choice of propulsion and power plant is often far from straightforward. Details of the design control systems and electrical systems of 2 such vessels the Iolair and Seagair are given. Because of the introduction of such vessels BP (the operators) have introduced a a set of High Voltage Safety Rules. Future trends in the design of such vessels are noted including the increasing use of superconducting motors for propulsion.

Dynamic positioning (DP) is defined as holding a vessel in position automatically without using physical constraints. This was achieved by using thrustors and was particularly important for N. Sea operations where four-point mooring systems were not applicable. The requirements of modern diving support vessels (DSVs) are outlined and the basic parts of a modern microprocessor controlled DP system are illustrated. The limitations and hazards of DP are discussed as is the achievable accuracy of positioning. The possibility of drift-off and drive-off of divers and bells is outlined. The risk of such an occurrence can be calculated and details are given. Operating rules for DP have been devised by Det Norske Veritas and Lloyds Register. The use of improved reference sensors in the future is discussed and this includes using NAVSAT as a back up aid. Microprocessors will find increasing niches and the importance of training is emphasized.

-A basic AUV (autonomous underwater vehicle) control system such as ACE (an IFREMER control system) is associated with a high-level command part. This high level part is provided with complementary features needed by the initial AUV subsystem namely a language allowing plans modification during their execution and a diagnosis and analysis system. The latter checks continuously the information provided by the sensors in relation to some predefined rules in order to ensure the good working of the AUV within its environment. A brief overview of missions programming languages is given. The language PILOT and its control system suggested for the high level command part are presented. This makes it possible to modify plans during their execution. The control system of PILOT is modular and comprises a basic inference engine. Various solutions for AUV missions' safety and supervision are examined. Finally conclusions are drawn.

The application of modern advanced electronic technology to monitoring and control of ship engines and other mechanical equipment has necessitated new rules from the classification societies to cover the requirements of Unattended Machinery Spaces. The extent of control systems varies from the small and simple logic systems to more complex integrated systems and to the very extensive comprehensive systems the facilities offered by each are described and examples given. Basic equipment necessary for the systems is also described and includes central processor unit display units and the attendant computer languages and programming techniques machinery condition monitoring equipment is also discussed although as yet it is not so widely used. The effect of these electronic systems on the job of the marine engineer is considered throughout.

Conf organized by ICE and held in Glasgow 17-18 October 1990 Papers are Insurance and risk control Risk assessment of offshore fish-farming cages Controls and legal provisions governing offshore fish farm developments Classification society rules for fish farms The interaction between physical and biological processes in coastal and offshore fish farming; an overview Computerised mathematical modelling in the assessment of fish farming sites Some considerations in the structural engineering of sea cages for aquaculture Model testing of a cage system for the offshore environment Model tests with flexible circular floats for fish farming The development of an offshore fish cage Some numerical models for predicting wave conditions around aquaculture sites Current forces on cage net deflection Offshore fish farming platforms; development design construction and operation - the SEACON and SULAN Mariculture; biological and management problems and possible engineering solutions Norwegian research and industrial development of floating structures for salmon fish farming Hydrodynamic and biological factors in the design of sea cages for fish culture

This paper briefly examines the evolution of composite design explores the use of modern techniques to optimize ship structures and reviews current manufacturing methods that allow modern composite structures to be constructed in an efficient cost effective manner. This paper explores details of the structural design and construction of an ABS classed 46m sandwich composite trideck motoryacht and a 41m sandwich composite ferry design as examples of the application of modern composites technology in the building of a "fiberglass ship". Class rules are discussed along with detailed analysis of laminate schedules and laminate requirements for various loaded areas of the structure. Mechanical fastening and the use of high strength adhesives for providing foundations for machinery and equipment and vibration considerations are addressed for Marine Engineering applications. Finite element analysis methods are exercised to exploit further enhancements in vessel design. This paper also provides examples of fabrication details with practical considerations to ensure designs are compatible with normal ship production techniques.