Dictionary of marine technology

DICTIONARY OF MARINE TECHNOLOGY By CYRIL HUGHES, C.Eng., M.I.Mar.E LLP Limited Legal & Business Publishing Division 69-77 Paul Street London EC2A 4LQ SOUTH EAST ASIA LLP Asia Limited Room 1101, Hollywood Centre 233 Hollywood Road Hong Kong © Cyril Hughes, 1997 First published in Great Britain 1997 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 1-85978-136-5 All rights reserved No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission' of LLP Limited Whilst every effort has been made to ensure that the information contained in this book is correct neither the author nor LLP Limited can accept any responsibility for any errors or omissions or for any consequences resulting therefrom Text set 11 on 13pt Palatino by Selwood Systems, Midsomer Norton Printed in Great Britain by Headway Press Ltd, Reading Preface This dictionary was written to fill a void in the current selection of technical works of this nature and it covers all the many recent developments in the mainly technical side of shipping, although allied subjects have also been included to give the reader a background to the reason for some of the developments Each item included has been carefully researched and a definitive rather than an inconclusive explanation offered in most cases Readers' attention is drawn to other LLP publications, for example the Dictionary of Shipping Terms and The Marine Encyclop~dic Dictionary which give more detailed information on the allied non-technical items included in this work Thanks are extended to all those who contributed to the compilation of the data and special thanks are extended to Claire and David Hughes c.B List of Acronyms and Abbreviations ABS AC AC AC ACV AF AF AFRA AIMS ALERT AMD AMECRC AMRIE AMSA AMVER AP API APS ARPA ARPA ASD ASTM ATOMOS BC BCH vi American Bureau·of Shipping Air Conditioning Alternating Current Anti Corrosive Paint Air Cushion Vehicle Anti Fouling Paint Anti Friction Bearings Average Freight Rate Assessments American Institute of Merchant Shipping Automatic Life-Saving Emergency Radio Transmitter Advanced Multi Hull Designs Australian Maritime Engineering Co-operation Research Centre Alliance of Maritime Interests in Europe Australian Marine Safety Agency Automated Mutual Assistance Vessel Rescue System Aft Perpendicular American Petroleum Institute Advanced Propulsion Systems Advanced Research Projects Agency Automatic Radar Plotting Aids Allowable Stress Design American Society for Testing and Materials Advanced Technology to Optimise ManpowerAboard Ship Bulk Cargo Code Bulk Chemical Code List of Acronyms and Abbreviations BCLU BHP BIMCO BM BSI CA CAD CAES CAP CCA CCAI CESS CFC cn CLT CM CODAD CODELAG CODOC COFR cas COW CO2 CPP CRINE CRIS CRP CRS CSA CSC CSR CST CV CYMERA DC DFT DIN Code of Practise for Safe Loading/Unloading Bulk Carriers Brake Horse Power Baltic and International Maritime Council Bending Moment British Standards Institute Controlled Atmosphere Computer Aided Design Canadian Atmospheric Environment Service· Condition Assessment Programme Chemical Carriers Association Calculated Carbon Aromacity Index Committee for the Elimination of Substandard Ships Chlorofluorocarbon Cetane Indicated Index Contracted and Loaded Tip Propeller Construction Monitoring Combined Diesel and Diesel Combined Diesel Electric and Gas Turbine Combined Diesel or Gas Turbine Certificate of Financial Responsibility Chamber of Shipping Crude Oil Washing Carbon Dioxide Controllable Pitch Propeller Cost Reduction Initiative for the New Era Common Rail Injection System Contra Rotating Propeller Corporate Research for Ships Canada Shipping Act Convention for Safe Containers Continuous Service Rating Centis tokes Calorific Value Cyprus Marine Environmental Protection Association Direct Current Dry Film Thickness Deutsche Industrienormen vii List of Acronyms and Abbreviations DNV DP DR! DSC DSC DWT Det Norske Veritas Dynamic Positioning Direct Reduced Iron Digital Selective Calling Dynamically Supported Craft Deadweight EC ECCTO E MAIL EPA EPIRB ESP ETS EU Engineering Council European Chemical Coastal Tanker Owners Electronic Mail Environmental Protection Agency Emergency Position Indicating Radio Beacon Enhanced Survey Programme Emergency Towing System European Union FDA FEA FEU FOBAS FOC FP FPSO FSA FWPCA Fatigue Design Assessment Finite Element Analysis Forty Foot Equivalent Unit Fuel Oil Bunker Analysis Flag of Convenience Forward Perpendicular Floating Production Storage and Offshore Unit Formal Safety Assessment Federal Water Pollution Control Act GA GESAMP General Average Group of Experts-Scientific Aspects of Marine Pollution Germanischer Lloyd Global Marine Distress and Safety System Greenwich Mean Time Global Positioning System Glass Reinforced Plastic Gross Tonnage GL GMDSS GMT GPS GRP GT H&M HCM HELMEPA HFO HNS viii Hull and Machinery (Policy) Hull Conditioning Monitoring Hellenic Marine Environmental Protection Association Heavy Fuel Oil Hazardous and Noxious Substances List of Acronyms and Abbreviations HP HSC HSS HTS HVF H2S Horse Power High Speed Craft High Sea-Service Speed High Tensile Steel High Viscosity Fuel Hydrogen Sulphide lACS International Association of Classification Societies International Bulk Chemical Code International Bunker Industry Association Integrated Bridge Systems Intercooled and Recuperated (Gas Turbines) International Chamber of Shipping International Electrotechnical Commission Integrated Fire Protection Systems Interim Final Rules International Federation of Ship masters Associations Inert Gas International Gas Code Indicated Horse Power International Load Line Convention International Labour Office Institute of London Underwriters International Marine Dangerous Goods Code International Maritime Organisation International Marine Satellite Organisation International Cargo Owners Association International Association of Independent Tanker Owners International Oil Pollution Prevention Certificate Institute of Petroleum International Parcel Tankers Association Integrated Radio Communication Systems International Shipping Federation International Safety Guide for Oil Tankers and Terminals International Ship Information Database International Safety Management Code International Ship Managers Association International Standards Organisation IBC IBIA IBS ICR ICS lEC IFP IFR IFSMA IG IGC IHP ILLC ILO ILU IMDG IMO INMARSAT INTERCARGO INTERTANKO IOPP IP IPTA IRCS ISF ISGOTT ISID ISM ISMA ISO ix List of Acronyms and Abbreviations IWL International Salvage Union International Transport Workers Federation International Tanker Owners Pollution Federation Institute Warranty Limits JIS Japanese Industrial Standards LASH LBP LCB LDC LLL LNG La Loe LOOP LOT LPG LQS LRFD LRS LSA Lighter Aboard Ship Length Between Perpendiculars Length Breadth Ratio Longitudinal Centre of Buoyancy London Dumping Convention Low Location Lighting Liquid Natural Gas Lubricating Oil Letter of Compliance Louisiana Offshore Oil Port Load On Top Liquid Petroleum Gas Lubricant Quality Scan Load and Resistance Factor Design Concept Lloyd's Register of Shipping Life Saving Appliances MAIB MARAD MARIS MARPOL MARS MCR MEIF MEPC MES MKS MOU MPA MSA MSC MSCR MSIS MTBF Marine Accident Investigation Branch Marine Administration Maritime Information Society Marine Pollution Convention Marine Accident Reporting Scheme Maximum Continuous Rating Mandatory Excess Insurance Facility Marine Environment Protection Committee Marine Evacuation Systems Metre Kilogram Second Memorandum of Understanding Marine Preservation Association Marine Safety Agency Marine Safety Committee Marine Spill Response Corporation Marine Safety Information Systems Mean Time Between Failure ISU ITF ITOPF LIB x List of Acronyms and Abbreviations MTBO MTD Mean Time Between Overhaul Marine Technology Directorate NAABSA NAMAS NAVIC NDT NI NLS NMD NOX NPRM NPSH NRC NRC NSA NTSB NYPE Not Always Afloat But Safely Aground National Measurement Accreditation Service Navigation and Vessel Inspection Circular Non Destructive Testing Nautical Institute Noxious Liquid Substances Norwegian Marine Directorate Nitrogen Oxide Notice of Proposed Rule Making Net Positive Suction Head National Research Council National Response Corporation Norwegian Shipowners Association National Transportation Safety Board New York Produce Exchange OBO OCIMF ODMC OSPREY OSRL OTIS OWS Ore Bulk Oil Carrier Oil Companies International Marine Forum Oil Discharge Monitoring and Control System Measurement Operational Differential Subsidy Organisation for Economic Cooperation and Development Officer of the Watch (Bridge) Oil Pollution Act 1990 Oil Pollution and Preparedness Response and Cooperation Treaty Ocean Swell Power Renewable Energy Oil Spill Response Limited Offshore Tidal Information Systems Oily Water Separator PCB PCC PIRO P&I PLT PMAX P MEAN Polychlorinated Biphenyls Pure Car Carrier Petroleum Institute Response Organisation Protection and Indemnity (Club) Protectively Located Tanks Maximum Pressure Mean Effective Pressure ODS OECD OOW OPA90 OPRC xi List of Acronyms and Abbreviations PREP PROBO PSC PSIX PTI PTO Preparedness for Response Exercise Programme Product Oil Bulk Ore Carrier Port State Control Port State Information Exchange Power Take In Power Take Off QA QMS QRA QS Quality Quality Quality Quality RCD RDF REG NEG RES RINA RINA ROPME Recreational Craft Directive Radio Directional Finder Regulatory Negotiating Committee Rapid Evacuation Systems Registro Italiano Navale Royal Institute of Naval Architects Responsible Organisation for Protection of the Marine Environment Roll On Roll Off RORO SAE SAN SAR SATCOM SATNAV SBT SCM SCR SDC SEA SEMT SERS SES SI SI SIRE SMM SNAME SOlAS xii Assurance Management System Risk Assessment Standards Society of Automotive Engineers Strong Acid Number Search and Rescue Satellite Communication Satellite Navigation Segregated Ballast Tanks Screwshaft Condition Monitoring Selective Catalytic Reduction Selective Digital Calling Ship Event Analysis Societe d'Etudes de Machines Thermiques Ship Emergency Response Services Surface Effect Ship Statutory Instruments Systeme International Ship Inspection Report Shipbuilding Machinery and Marine Technology Exhibition Society of Naval Architects and Marine Engineers Safety of Life at Sea Convention Variable injection timing (VIT) Variable injection timing (VIT) VIT has long been employed by the designers of marine diesel engines in a joint attempt first to enhance specific fuel consumption at part load, and secondly to improve the engine's ability to deal with poorer quality fuel VIT enables the critical period of fuel injection relative to the position of the piston to be varied either by mechanical or electronic means while the engine is running This allows the maximum combustion pressure (P Max) to be maintained at optimum value, a prerequisite in enhancing performance from both a thermal efficiency and combustion efficiency point of view Vee engines The majority of marine diesel engines are built in an inline configuration whereby a single row of cylinders is served by a single crankshaft In a vee engine two banks of cylinders in a V configuration drive a single crankshaft with opposing pistons in each bank usually connected to a common crank throw Veeengines permit higher powers to be developed in a given machinery space volume, and they are popular in small fast ferries and similar craft They are occasionally used on larger ships when a 16 cylinder engine is needed to supply the powering requirements, a cylinder configuration not feasible with an inline engine, mainly because of length restraints, but often employed in vee engines Very large bulk carrier (VLBC) These ships are generally in the 200,000 to 250,000 tonnes deadweight range and are usually purpose built for dedicated trades, typically iron ore or coal to Japan They have not proved to be commercially popular and uncertainty surrounding the future design of bulk carriers, having regard to their loss rate when carrying heavy cargoes, will not improve their chances Very large crude carriers (VLCC) These tankers are in the 250,000 to 300,000 tonnes deadweight range and they have had a somewhat chequered career They were first introduced in the mid-1960s after the first closure of the Suez Canal prompted a move towards larger and larger tankers During the several depressions experienced in the tanker business over recent years many VLCCs bore the brunt of the effect by spending sometimes months at anchor in the Gulf awaiting an upturn in rates More recently VLCCs in the 300,000 tonnes deadweight region, many with double hulls, are being built, probably in anticipation of the large number of aged single hull tankers being seen as candidates for breaking up Very lights (pronounced veery) These are coloured pyrotechnic lights fired from a starter-type of pistol They are used as distress 286 Vibration analysers signals to signify that a ship is in serious difficulties Modern radio techniques have made the use of Very lights more or less obsolete, and they are nowadays only rarely used for distress purposes Vessel response plans (VRP) The VRP is a document required under the US Oil Pollution Act 1990 (OPA90) for all tankers trading in US waters The Federal Government via the United States Coast Guard (USeC) is responsible for the implementation of VRPs, but certain US states have their own requirements which in some cases are different The VRP must contain details of what steps a shipowner will take in the event of an oil spillage occurring on his ship This will include the appointment of an oil spill clean up contractor and a qualified US based individual available on a 24 hours a day basis who would coordinate operations The VRP is completely different from the shipboard oil pollution emergency plan (which see) which is required under regulations issued by the International Maritime Organisation (IMO) Vessel traffic information systems (VTIS) VTISare complementary to traffic separation schemes (which see) and they monitor vessel movements using radar, electronic and computer based techniques They are basically used to ensure that procedures laid down by approved traffic separation schemes are followed and they are particularly useful in high density traffic areas, for example the English Channel and Singapore Straits, which already have VTIS in operation Vibration The most likely cause of vibration aboard ship nowadays is that emanating from excitation forces from the propeller, especially if the clearance between the ship's hull and the propeller is insufficient Main engines were also the source of vibration excitation forces, but in the main these are nowadays taken care of by careful design based on years of experience Main engine sources of vibration in the past include first and second order external moments caused by the rotating masses at engine revolutions and twice engine revolutions respectively These can be taken care of by the provision of moment compensators attached to the engine if thought necessary Guide forces emanating from the engine tend to rock it about its foundations, and this can be overcome by the use of top bracings (which see) Axial vibration of the crankshaft can also lead to vibration and this can be dampened by the use of an axial detuner Vibration analysers These are portable instruments used to detect vibration emanating from rotating machinery aboard ship, for example pumps, fans and compressors The use of such equipment can be accepted as an alternative to dismantling the unit for classification 287 Vibration analysers purposes when due its periodical survey Vibration analysers give the acceptable range of vibration for the unit in question, and they can give early indication of the onset of possible faults developing, for example due to a worn bearing If the results obtained are plotted over a period on a time elapsed basis a clear picture of the units performance will emerge Vibrorig This is a comparatively recent device used aboard bulk carriers to dislodge any cargo that may have become lodged between frames or stiffeners located within the cargo hold spaces Some stevedores use pneumatic jack hammers to dislodge the cargo, and this extreme course of action has led to physical damage to the hull structure in several instances The Vibrorig is a portable device which vibrates the hull structure adjacent to the lodged cargo without causing any physical damage and is reportedly effective with even wet cargoes By locating the topside tank longitudinal stiffeners inside the tanks instead of within the cargo hold greatly reduces the amount of lodged cargo in the holds If it is intended to carry cargo in the topside tanks it is probably better to locate these stiffeners in the hold Victory ships Victory ships were built in comparatively large numbers in US shipyards at the end of and immediately after the Second World War (1939-45) They were built to replace the large number of merchant ships lost during this war and were of a higher standard than the Liberty ships (which see) Victory ships were built with turbine propulsion and were provided with fully automatic watertube boilers with combustion control and they had a speed of around 16 knots compared with the 10 knots or so of the Liberty ship Virtual reality (VR) VR is a computer imaging device giving participants a lifelike perception of direct involvement in whatever scenario is being depicted VR is ideally suited to simulating operating conditions, for example as used in training techniques for aircraft flightdeck and ship navigating or machinery control room procedures In the future VR is considered to be a suitable candidate for ship design and production techniques already adopted in the aircraft industry Visbreaker Is an abbreviation for a viscosity breaker, a piece of equipment used in the oil refining industry Its basic purpose is to extract more light ends from the residual fuel oil emanating from primary refining methods at the refinery The introduction of visbreakers more or less coincided with a deterioration in the quality of residual fuel oil as supplied for use in marine diesel engines Vis- 288 Volatile organic compounds (VOC) breakers use thermal cracking techniques to reduce the heavy fractions into lighter products, therefore obtaining more product from the barrel and a deterioration in the quality of the residuum Viscosity Viscosity is defined as a liquid's ability to resist flow, for example when being pumped through a piping system Hydrocarbons in the form of f11eland lubricating oils have quite dramatic changes in viscosity over a temperature range between zero and 100 degrees centigrade, unlike water which has no significant change in viscosity between these temperatures A typical heavy fuel oil will have a viscosity of around 1400 centistokes at a temperature of 20 degrees centigrade, and at this viscosity cannot be pumped It needs to be heated to around 50 degrees centigrade before it can be pumped and to around 130 degrees centigrade before being burnt in a diesel engine Viscosity index (VI) The VI is used to indicate the change in viscosity that lubricating oils experience with a change in temperature It is a measure of the gradient on a graph plotted between the viscosity of an oil between different temperatures A lubricating oil having the least change in viscosity between these temperatures is considered to be more stable and will have a high VI In the case of lubricating oils operating under large variations in temperature the choice of an oil with a high VI is essential if operating problems are to be avoided Viscotherm A viscotherm is a proprietary device used aboard ships automatically to control the delivered temperature of fuel oil so that its viscosity is at its predetermined value when being burnt in the cylinders of a diesel engine It is important that the correct viscosity is maintained, otherwise both combustion and mechanical problems can arise, the former by incomplete burning of the fuel and the latter by increased resistance on the fuel pump drive gear if the viscosity of the fuel is too high Delivery notes issued by fuel oil suppliers rarely give the correct viscosity of the fuel delivered and the viscotherm ensures that whatever its viscosity it will be burnt in the engine at the correct figure Visual display unit (VDU) A visual display unit (VDU) is sometimes called display screen equipment (DSE) and is the standard means of viewing electron bombardment onto a screen, whether it be a radar, television or electronic chart display They are essentially cathode ray tubes (CRT) tailor-made to suit the equipment it is associated with Volatile organic compounds (VOC) VOCs are the vapours emitted 289 Volatile organic compounds (VOC) from tankers when being loaded at a terminal The release of these vapours contravenes the Clean Air Acts of some countries notably the United States (see Vapour emission control systems) When loading a tanker vaporised cargo is released into the atmosphere through the tank vents, and this can lead to environmental problems especially when terminals are located near densely populated areas The whole subject of VOCs, also gaseous and vapour emissions, are targeted for attention of the International Maritime Organisation (IMO) in the not too distant future Voyage data recorders (VDR) Voyage data recorders have been used in the aircraft industry for many years and are then usually referred to as flight or black box recorders VDRs used in marine applications are generally associated with the recording of stress and acceleration in the main hull girder caused by severe weather conditions or improper cargo loading or ballast practices in the case of stress They are not mandatory, and although the International Maritime Organisation has recommended that they be provided on vulnerable ships, for example bulk carriers, very few have been fitted Voyage hull response analyser A voyage hull response analyser has been developed by Lloyd's Register of Shipping (LRS) to further its investigations into the rather high loss rate of bulk carriers The analyser will use a combination of weather and sea state forecasts provided by meteorological offices en route Recourse to theoretical calculations will also help predict critical paths on a voyage where high levels of hull stress and ship motion are expected to be encountered The analyser is seen as being complementary to the Black box recorder (which see) Wake Wake is defined as the entrained water following behind a ship in which the propeller(s) operate and is caused by the friction between the hull and the adjacent seawater When calculating the percentage slip of a ship there are two methods available, one being the apparent slip which takes into account the ship's speed over the ground, and the other being the true slip which takes into account the wake speed The former method is that normally used by ship's staff who not have the facilities for calculating the wake speed The true slip is preferred by hydrodynamicists, but in practice it is difficult to measure the wake speed and various assumptions are made (See also Wake fraction.) Wake fraction When a ship moves in a forward direction it imparts a forward motion to the seawater due to the friction of the ship's hull 290 Waste disposal The speed of the seawater into the propeller is therefore less than the speed of the ship over the ground This difference in speed is known as the wake fraction and is usually expressed in decimal form, and is used by propeller designers In general terms the higher the block coefficient (which see) of the ship the higher the wake fraction, and it can be estimated by using the expression: wake fraction = 0.5 block coefficient minus 0.05 Wake improvement duct A ship's wake has a somewhat random chaotic motion which can interfere with the efficient working of the propeller In an attempt to improve the situation a wake improvement duct was developed some time ago which smooths out irregularities in the motion of the wake It consists of a fabricated steel structure made in halves and welded to the stern frame immediately in front of the propeller This forms a duct-like shape and it greatly improves the wake pattern, especially on ships with a poor aft end geometry Claims in propulsive efficiency in the order of per cent have been made Ward Leonard system Is an electrical system designed to regulate the speed of motors by varying the voltage Ward Leonard systems were used to control such equipment as electric propulsion motors, steering gear motors and any other electric motors driving equipment requiring sensitive speed control They are generally associated with direct current (DC) systems, and in a modern ship would probably only be used by converting the conventionally used alternating current (AC) into DC current as several cruise liners have recently employed for electric propulsion WcirtsiUidiesel Is a diesel engine manufacturer located at Vassa, Finland, and is well known for its four-stroke (cycle) medium speed diesel engines, referred to as the Vasa design Wartsila was at the forefront of the application of the use of heavy viscosity fuel in its Vasa engines, which are generally of smaller cylinder bore than their main rivals In 1992 Wartsila took over Stork Werkspoor, the Dutch based engine builder, and other diesel engine manufacturers have been absorbed into the Wartsila group More recently Wartsila has taken over New Sulzer Diesel (which see) The current largest output engine from the Wartsila stable is around 18,900 Kilowatts (25,300 Horsepower) Waste disposal Waste disposal from ships is covered by Annex V of the International Maritime Organisation's (lMO) Marine Pollution (MARPOL)Convention which entered into force in 1988.The disposal of waste overboard is now strictly controlled and many ships, for 291 Waste disposal example cruise liners, install waste disposal and processing equipment onboard One such piece of equipment is a compacter which can reduce the size of waste matter by a factor of eight to one and enable it to be stored onboard until port is reached If a shredder is combined with the compacter a reduction factor of around 15 to one can be accomplished Incineration onboard is another technique used to dispose of waste matter, although future legislation relating to emissions from incinerators may restrict this activity Under certain circumstances waste may be placed overboard but not in special sea areas (which see), and plastic material is completely banned from being dumped into the sea Waste heat recovery Waste heat recovery systems aboard ship are generally·associated with exhaust gas schemes (which see) Other waste heat recovery schemes are also used aboard ship, the most common being that used to convert the heat contained in a diesel engine's jacket water system into the production of fresh water by an evaporation process It is also possible to use the heat in the jacket water system to provide accommodation heating by means of a heat exchanger in the ventilation system Jacket water systems are nowadays maintained at a much higher temperature than that used previously and are now around 85 degrees centigrade However too much heat taken away by waste heat recovery systems if carried too far could interfere with system temperatures Waterjets Are the preferred means of propulsion for many of the High Sea-service Speed (HSS)ships now entering service in increasing numbers They consist of a pump-like impeller working in a housing the inlet duct of which is usually mo.unted flush with the bottom of the hull and the outlet at the aft end positioned just above the waterline when at speed and are usually arranged as twin or quadruple units Reversing is accomplished by a system of deflectors and buckets without the need to reverse the prime mover Most waterjets are driven by either gas turbines or high speed diesel engines, and at ships' speeds of 40 knots and above are more efficient than Super-cavitating propellers (which see) from a propulsive point of view, not forgetting that conventional propellers are not suitable at high ship speeds Water mist Water mist (or fog) fire extinguishing systems have recently been introduced into the marine sector following the ban on the use of halon for environmental reasons Water mist systems are somewhat different from conventional water sprinkler (which see) systems in that the water particles are much smaller and therefore 292 Water washing have superior what are called fire knock down qualities They require much smaller water quantities than conventional sprinklers and cause much less damage to equipment and fittings in the surrounding area of a fire In the past many ships which caught fire capsized due to the amount of water used to fight the fire and water mist systems make this less likely Waterplane area coefficient This is a term used by ship designers to demonstrate the ratio between a ship's waterplane area and the product of its length and breadth at the waterline It represents a slightly different approach to that of the Block Coefficient (which see) and invariably has a numerically higher number For example a ship with a Block Coefficient of 0.8 would probably have a Waterplane Area Coefficient of 0.9 Water sprinklers Water sprinkler fire extinguishing systems have only recently been made compulsory on passenger ships, even though their excellent fire extinguishing properties have been well known both in shore based and shipboard applications for many years Sprinkler systems are brought into operation by the bursting of a temperature sensitive bulb arranged in the sprinkler head located in all vulnerable areas throughout the ship This immediately operates an alarm and automatically starts the sprinkler pump, and because of this almost instantaneous action quenches the fire before it has a chance to spread in most instances In the unlikely event of the fire spreading then further bulbs in adjacent areas would be automatically brought into action, thereby containing the risk Watertight doors Watertight doors are vertically or horizontally sliding doors of steel construction and they are used mainly aboard passenger ships to subdivide working spaces beneath the freeboard deck to meet damage stability criteria laid down by the Safety of Life at Sea (SOLAS) Convention They are needed mainly because quick access between the working spaces is necessary at sea so that the essential movement of stores and catering equipment can be carried out They are also used to subdivide the machinery spaces on passenger ships with large compartmental facilities In restricted coastal waters and during periods of poor visibility the watertight doors should be in the closed position The location of local and remote door operating controls and alarms are included in SOLAS regulations Water washing Water washing techniques are used to clean the turbine blades of turbocharger rotors and nozzles while the machines are still running, albeit at part-load output Water is introduced into 293 Water washing the turbocharger gas inlet casing using compressed air, then drained at the lower end of the casing, bringing with it the removed carbon particles The air impeller side of the turbocharger can also be water washed using a light detergent, but special precautions have to be taken to avoid interfering with the cylinder liner lubricating oil film Even air coolers attached to the turbochargers can be water washed in situ, also using a detergent Water washing the tube banks of watertube boilers has also been practised for many years Wave bending moments The hull of a ship in still water conditions is subject to bending moments imposed on it by the distribution of cargo, ballast and other weights, including of course the weight of the ship itself The allowable still water bending moments (SWBM) are regulated by the relevant classification society which approves a loading manual giving these limits which is issued to each ship While at sea especially in rough weather the support of the ship's hull becomes somewhat unpredictable as a result of wave action, and the bending moments are not so easily calculated Classification societies based on their experience therefore apply factors to convert SWBMs into wave bending moments taking into account the sea state and weather conditions expected in the area of operation Wave line theory When ships pass through the water they produce waves due to the reaction of the sea to the motion of the hull The bow wave is the obvious example of this, and as the bow forces its way through the water the bow wave is produced, and emanating from this is a pattern of waves and troughs travelling along each side of the ship and joining together at the stern to form the ship's wake The study of this phenomenon is embraced in the wave line theory, and its effect on propulsive resistance was fully investigated by William Proude in the last century The relationship between wave and frictional resistance at various ship speeds and with various hull forms can all be explained using the wave line theory Wave piercing catamarans (WPC) Wave piercing catamarans are only one of many in the emerging breed of High Sea-service Speed (HSS) ships now entering service in ever increasing numbers The WPC owes its name to the unique bow shape of its twin hulls which are designed to pierce through the waves when the catamaran is at high speed Because of their extremely fine lines WPCs have a tendency to pitch in heavy weather and recent designs have incorporated a central bow to dampen the pitching motion (see also Tricats) Wave piercing propellers 294 Wave or surface piercing propellers are Weather routing used on high speed ships as a means of preventing cavitation, always a problem when high revving propellers are being used Wave piercing propellers allow the suction side of the propeller to be at atmospheric pressure and therefore avoid attack from collapsing vapour bubbles which are not then present They are only used on high speed shallow draught craft operating with their propellers only partially submerged, and therefore have only a very limited application Wave statistics Wave statistics are published on a global basis which divides the sea areas of the world used for commercial shipping activities into over 100 separate sea areas They comprise millions of sets of wind and wave data, in many cases going back over 100 years and they are a useful reference for those involved in the design of ships and offshore structures Wave statistics are available in both book and computerised format Wax Wax is present in both fuel and lubricating oils derived from crude oil sources also containing wax, usually in the form of paraffin wax In the case of fuel oils a high wax content invariably identifies a fuel as having a high pour point (which see) A high wax content in lubricating oils invariably results in the oil having a high floc point (which see) The presence of wax itself is not detrimental to the performance of either fuel or lubricating oils, except that in low temperature operating conditions crystallisation of the wax can take place and interfere with various components within these systems Weak acid number (WAN) This is determined by subtracting the strong acid number (which see) from the total acid number (which see) The numerical value of the WAN when obtained in a laboratory test usually determines the presence of organic acids which are associated with ageing or oxidation of used lubricating oils The WAN is an extremely useful means of determining why a lubricating oil has turned acidic and can help identify the reason Weatherfax Weatherfax or weather facsimile is an international system of transmitting weather reports to ships throughout the world Each ship is provided with a weatherfax receiver having a printing facility included which enables weather patterns showing isobars and barometric pressures to be printed at regular intervals Weatherfax is a useful tool which enables the ship's navigators to take evasive action by setting a course to avoid an approaching severe weather system Weather routing There are several weather routing services available to ships which, for a fee, will advise ships' staff of a recommended 295 Weather routing route to be taken and then give regular updates if the original weather predictions substantially change The service also includes a postvoyage analysis showing the difference between the recommended route and that followed by the ship should this be different Many charterers weather route ships they have on charter and they also can use the service to compare logged weather conditions with those recorded by the weather routing service if there is a disputed performance claim against the ship Web frames These are fabricated steel frames used to support the side shell and various other parts of a ship They are much deeper and of heavier section than standard shell frames (which see) and are used at increased span distances, probably one web frame for every five standard shell frames Web frames are used in vulnerable parts of the ship subject to heavy loading, for example enginerooms and side cargo tanks in oil tankers Weibull shape factor The Weibull shape factor can be used as a threedimensional graphic representation on a flat surface which shows the relationship between three variables in grid form In the case of ships' structures it has been used to illustrate the sensitivity of possible fatigue damage due to stress using a maximum lifetime load approach with a 20-year North Atlantic service period as a basis Welding Welding is now the only method used to join metal component parts of a ship together and it took over from fully and part riveted construction many years ago All welding techniques employed in ship constructioh are approved by the relevant classification society and closely controlled by it Most of the numerous welded seams and connections made during ship construction are nowadays carried out by automatic welding machines, with human intervention needed only at start up and stop Overhead welds are notoriously difficult to perform in a satisfactory manner and modern construction techniques using assembly halls more or less eliminate the need for such welds except for certain block joining seams at the berth It is exceedingly rare for a modern welded connection to fail during the ship's life Welding institute The Welding Institute is a UK organisation based in Cambridge which is at the forefront of research and development into all the numerous types of welding now in general use Not only is electric arc welding included in its activities but also all types of gas welding, and more recently the properties of Laser welding (which see) 296 Williamson turn Wetted surface This refers to the underwater surface of a ship's hull It is an important aspect when considering the resistance of a ship's hull through the water Most of this resistance is made up from friction between the hull and the sea which is a function of the wetted surface Any reduction in the wetted surface area will manifest itself in an improvement in the hydrodynamic performance of the ship This is seen in the performance of semi-planing monohulls (which see) which partially lift out of the water at speed and effectively reduce their wetted surface Whale factory ships Although whaling has been outlawed by many countries certain countries still engage in whaling activities under the guise of research Whales are harpooned by whale catcher ships and then hauled aboard the much larger whale factory ships for processing These factory ships are provided with sophisticated packaging and canning equipment for processing the carcasses and they are at sea for many months during the whale catching season Whirling Whirling is a phenomenon related to a propeller and its associated shafting system aboard ship It is a form of radial vibration occasioned by the incorrect alignment and bearing load distribution of the intermediate shaft and stern tube bearings If such a situation exists in the shaft/propeller system then it is usual for the forward stern tube bearing to be unloaded due mainly to the weight of the propeller being supported by the aft bearing When the system is rotating the unrestrained centrifugal forces in the vicinity of the forward bearing can then result in whirling Realignment of the bearings or adjustment of the height of the main engine can usually cure the problem Whistle The ship's whistle is usually mounted on the funnel, although some ships in addition are provided with a whistle on the foremast Modern whistles are usually activated by compressed air, although steam was previously used for many years and some steam whistles are no doubt still in service The noise generated by a modem whistle is by the rapid oscillation of a diaphragm when acted on by air pressure The tone of a ship's whistle is determined by the size of the ship for easy identification purposes Electric whistles are also available, and those located on the foremast are usually activated by electricity Williamson turn This is a manreuvre attributed to a seafarer of the same name which has proved to be effective when used to rescue a person in a "man overboard" situation Depending on the speed of 297 Williamson turn the ship the helm is placed hard over in the port direction for a specified period of time It is then placed hard over in the starboard direction for another specified period The ship should then return to the position it was in when the "man overboard" manreuvre was initiated Windlass The windlass is a mechanical device located on the focsle and is used to recover the anchors from the seabed before a ship departs from its anchorage The basic design of the windlass has barely changed over the years and normally consists of an electric or hydraulic motor driving a cable lifter so arranged that they engage snugly with the links forming the anchor cables (chains) In order rapidly to lower the anchor clutches are provided to disengage the cable lifters from the drive mechanism Large brakes are also provided with a joint function of adjusting the lowering speed and then securing the anchor cables in their final position Cable stoppers are also incorporated to take the strain in the cables while a ship is riding at anchor and so ease the strain on the brakes Wing in ground effect The wing in ground effect project is a type of futuristic craft which travels just above the surface of the sea at speeds more akin to aircraft than to ships Russian interests have reportedly built and tested such a craft (see Ekranoplans) but details have not yet been made available Other countries are also looking at the wing in ground effect project but it would appear that some time will elapse before the concept is approved for the carriage of fare paying passengers in view of its inherent dangers Workshop Most ships are nowadays provided with a workshop which is equipped with an array of machine tools and other equipment so that the ship's engineers can undertake running repairs Such items as a lathe, drilling machine, valve refurbishing machine, and welding equipment are generally provided More sophisticated equipment can also be provided if the ship's engineers have been trained in its use World Maritime University (WMU) The World Maritime University is an International Maritime Organisation (IMO) project located at Malmo in Sweden and was opened in 1983 Student intake is mainly from developing countries, which rarely have the high academic facilities provided by the WMD Most students have already obtained qualifications leading to appointment of captain or chief engineer in their own countries The WMU offers a fellowship course running for two years and also offers selected candidates an accelerated MSc course 298 Zinc silicate paint Zinc anodes Zinc anodes comprise the standard means of preventing corrosion to a ship's underwater hull and ballast tank steelwork, usually as a secondary method to support the primary paint barrier They consist of blocks of zinc either bolted or welded to the steelwork they are protecting If the paint surface suffers from a breakdown due to mechanical damage or for other reasons then corrosive attack will be concentrated on the area of breakdown The provision of zinc anodes will assume a sacrificial role, leaving the unprotected area free from corrosive attack Zinc anodes are also used in other locations aboard ship, for example sea inlet chests and heat exchanger casings for similar anti-corrosive reasons Zinc silicate paint Zinc silicate paint is an extremely effective paint coating used primarily as an anti-corrosive measure on parts of a ship's structure exposed to corrosive seawater, for example the upper deck and hatch coamings It has also been used on the cell guides and their support structure in the holds of container ships due to its ability to withstand a certain amount of mechanical damage Zinc silicate is also used as a tank coating on chemical tankers, although it does not have the ability to carry the range of cargoes other coatings have and it is not suitable for use with edible oils 299 ... Metre Kilogram Second Memorandum of Understanding Marine Preservation Association Marine Safety Agency Marine Safety Committee Marine Spill Response Corporation Marine Safety Information Systems... Inspection Report Shipbuilding Machinery and Marine Technology Exhibition Society of Naval Architects and Marine Engineers Safety of Life at Sea Convention List of Acronyms and Abbreviations SOPEP SOX... Piercing Catamaran xiv DICTIONARY OF MARINE TECHNOLOGY Ablative paint Ablative or self-polishing paint was especially formulated to be applied to the underwater surfaces of the hulls of those ships employed