《内燃机学》课程教学资源（书籍文献）Pounder's Marine Diesel Engines and Gas Turbines，9th ed. - D. Woodyard（B-H, 2009）

POUNDERSMARINE DIESELENGINES AND GASTURBINESDOUG WOODYARDBE

PrefaceMajor developments in two-stroke and four-stroke engine designs for pro-pulsion and auxiliary power drives in the 5 years since the publication of theeighth edition of Pounder'sMarineDieselEngines callforanother update.This ninth edition reflects the generic and specific advances made bymarine engine designers and specialists in support technologies-notably tur-bocharging.fuel treatment,emissions reduction and automation systems-which are driven by: ship designer demands for more compactness and lowerweight; ship-owner demands for higher reliability,serviceability and over-all operational economy; and shipbuilder demands for lower costs and easierinstallationprocedures.A historical perspective logs the nautical milestones over the first centuryofmarinediesel technology,which closed withtheemergenceofelectronicallycontrolled low-speed designs paving the path for future so-called IntelligentEngines'.Development progress with these designs and operating experiencewith the escalating number in service are reported in this new edition.Since the last edition, increasing interest in dual-fuel (DF) and gas enginesfor marine and offshore industry applications is reflected in an expanded chapterThe specification of DF medium-speed diesel machineryfor LNG carrier new-building projects in 2002 marked the ousting of steam turbine propulsionfromits last bastion in commercial shipping. A growing number of these DF-electricinstallations are now entering service, alongside direct-coupled low-speedengine-powered LNG carriers equipped with boil-off gas reliquefaction plantControls on exhaust gas emissionsparticularly nitrogen oxides, sulphuroxidesandsmoke--continue to tighten regionally and internationally,dictatingfurther responses from engine designers exploiting common rail fuel systemsemulsified fuel, direct water injection and charge airhumidification.These andother solutions, including selective catalytic reduction and exhaust gas recircu-lation systems, are detailed in an extended chapter.Also extended is the chapter on fuels, lube oils and the problems of contamination, which includes information on low sulphur fuels, new cylinder andsystem lubricants, and cylinder oil-feed system developments.Marine gas turbines, specified for some cruise ship and fast ferry propulsionprojects from the late 1990s, have seen their competitiveness undermined by risingfuel prices in recent years. The relevant chapter, introduced in the last edition,has been revised to cover design refinements and significant installations.The traditional core of this bookreviews of the current programmes of theleading low-, medium- and high-speed engine designers-has been thoroughlyviupdated.Details of all new designs and major modifications to established models

vii Preface Major developments in two-stroke and four-stroke engine designs for pro￾pulsion and auxiliary power drives in the 5 years since the publication of the eighth edition of Pounder’s Marine Diesel Engines call for another update. This ninth edition reflects the generic and specific advances made by marine engine designers and specialists in support technologies—notably tur￾bocharging, fuel treatment, emissions reduction and automation systems— which are driven by: ship designer demands for more compactness and lower weight; ship-owner demands for higher reliability, serviceability and over￾all operational economy; and shipbuilder demands for lower costs and easier installation procedures. A historical perspective logs the nautical milestones over the first century of marine diesel technology, which closed with the emergence of electronically controlled low-speed designs paving the path for future so-called ‘Intelligent Engines’. Development progress with these designs and operating experience with the escalating number in service are reported in this new edition. Since the last edition, increasing interest in dual-fuel (DF) and gas engines for marine and offshore industry applications is reflected in an expanded chapter. The specification of DF medium-speed diesel machinery for LNG carrier new￾building projects in 2002 marked the ousting of steam turbine propulsion from its last bastion in commercial shipping. A growing number of these DF–electric installations are now entering service, alongside direct-coupled low-speed engine-powered LNG carriers equipped with boil-off gas reliquefaction plant. Controls on exhaust gas emissions—particularly nitrogen oxides, sulphur oxides and smoke—continue to tighten regionally and internationally, dictating further responses from engine designers exploiting common rail fuel systems, emulsified fuel, direct water injection and charge air humidification. These and other solutions, including selective catalytic reduction and exhaust gas recircu￾lation systems, are detailed in an extended chapter. Also extended is the chapter on fuels, lube oils and the problems of con￾tamination, which includes information on low sulphur fuels, new cylinder and system lubricants, and cylinder oil-feed system developments. Marine gas turbines, specified for some cruise ship and fast ferry propulsion projects from the late 1990s, have seen their competitiveness undermined by rising fuel prices in recent years. The relevant chapter, introduced in the last edition, has been revised to cover design refinements and significant installations. The traditional core of this book—reviews of the current programmes of the leading low-, medium- and high-speed engine designers—has been thoroughly updated. Details of all new designs and major modifications to established models

viliPrefaceintroduced since the last edition are provided, along with service experience withthe most popular designs. Technically important engines no longer in productionbut still encountered at sea justify their continued coverage.In preparing the new edition the author expresses again hisgratitude forthegroundwork laid bythe late C.C.Pounder and to the editors of the sixthedition, his late friend and colleague Chris Wilbur and Don Wight (whose con-tributions are respectively acknowledged at the end of sections or chapters byC.T.W. and D.A.W.),In an industry generous for imparting information on new developmentsand facilitating visits, special thanks are again due to MAN Diesel, WartsilaCorporation, Caterpillar Marine Power Systems, ABB Turbo Systems,themajorclassification societies, and the leading marine lube oil groups. Thanks again alsoto my wife Shelley Woodyard for her support and assistance in this project.Finally, the author hopes that this edition, like its predecessors, will con-tinue to provide a useful reference for marine engineers ashore and at sea,enginebuilders and ship operators.DougWoodyard

viii  Preface introduced since the last edition are provided, along with service experience with the most popular designs. Technically important engines no longer in production but still encountered at sea justify their continued coverage. In preparing the new edition the author expresses again his gratitude for the groundwork laid by the late C.C. Pounder and to the editors of the sixth edition, his late friend and colleague Chris Wilbur and Don Wight (whose con￾tributions are respectively acknowledged at the end of sections or chapters by C.T.W. and D.A.W.). In an industry generous for imparting information on new developments and facilitating visits, special thanks are again due to MAN Diesel, Wärtsilä Corporation, Caterpillar Marine Power Systems, ABB Turbo Systems, the major classification societies, and the leading marine lube oil groups. Thanks again also to my wife Shelley Woodyard for her support and assistance in this project. Finally, the author hopes that this edition, like its predecessors, will con￾tinue to provide a useful reference for marine engineers ashore and at sea, enginebuilders and ship operators. Doug Woodyard

Introduction:A Century of DieselProgressClose to a century after the entry into service of Selandia, generallyregardedas the world's first oceangoing motor vessel, the diesel engine enjoys almosttotal dominance in merchant ship propulsion markets. Mainstream sectorshavelongbeen surrendered bythesteam turbine,oustedby low-and medium-speed engines from large container ships,bulk carriers,VLCCs and cruiseliners.Evensteam's last remainingbastion inthe newbuilding lists-theLNGcarrier-has been breached by dual-fuel medium-speed diesel engine designsarranged to burn the cargo boil-off gas as well as by direct-coupled low-speeddiesel engines.The remorseless rise of the diesel engine at the expense of steam recipro-cating and turbine installations was symbolized in 1987 by the steam-to-dieselconversion of Cunard's prestigious cruise liner Queen Elizabeth 2.Her tur-bine and boiler rooms were ignominiously gutted to allow the installation ofa95600kWdiesel-electricplant.The revitalized QE2's propulsion plant was based on nine 9-cylinder L58/64medium-speed four-stroke engines from MAN B&W Diesel which provided alink with thepioneering Selandia:the 1912-built twin-screw7400dwt cargo/passenger shipwas powered bytwoBurmeister&Wain eight-cylinderfour-strokeengines(530mmbore/730mmstroke),eachdeveloping920kWat140rev/min.An important feature was the effective and reliable direct-reversing system.Progress in raising specific output over the intervening 70 years was under-linedbythe580mmbore/640mmstrokedesignspecifiedfortheQE2retrofit:eachcylinderhasamaximumcontinuousratingof1213kW.Selandia was built bythe Burmeister &Wain yard in Copenhagen forDenmark's East Asiatic Companyand,after trials inFebruary1912,success-fully completed a 20000 mile round voyage between the Danish capital andthe Far East (Figure I1).The significance of the propulsion plant was wellappreciated atthetime.Onher first arrival in London,the shipwas inspectedby Sir Winston Churchill, then First Lord of the Admiralty; and Fiona, a sistership delivered four months later by the same yard, so impressed the GermanEmperor that it was immediately arranged for the Hamburg Amerika Lineto buy her.ix

ix Introduction: A Century of Diesel Progress Close to a century after the entry into service of Selandia, generally regarded as the world’s first oceangoing motor vessel, the diesel engine enjoys almost total dominance in merchant ship propulsion markets. Mainstream sectors have long been surrendered by the steam turbine, ousted by low- and medium￾speed engines from large container ships, bulk carriers, VLCCs and cruise liners. Even steam’s last remaining bastion in the newbuilding lists—the LNG carrier—has been breached by dual-fuel medium-speed diesel engine designs arranged to burn the cargo boil-off gas as well as by direct-coupled low-speed diesel engines. The remorseless rise of the diesel engine at the expense of steam recipro￾cating and turbine installations was symbolized in 1987 by the steam-to-diesel conversion of Cunard’s prestigious cruise liner Queen Elizabeth 2. Her tur￾bine and boiler rooms were ignominiously gutted to allow the installation of a 95 600 kW diesel–electric plant. The revitalized QE2’s propulsion plant was based on nine 9-cylinder L58/64 medium-speed four-stroke engines from MAN B&W Diesel which provided a link with the pioneering Selandia: the 1912-built twin-screw 7400dwt cargo/ passenger ship was powered by two Burmeister & Wain eight-cylinder four-stroke engines (530mm bore/ 730mm stroke), each developing 920kW at 140rev/min. An important feature was the effective and reliable direct-reversing system. Progress in raising specific output over the intervening 70 years was under￾lined by the 580mm bore/640mm stroke design specified for the QE2 retrofit: each cylinder has a maximum continuous rating of 1213kW. Selandia was built by the Burmeister & Wain yard in Copenhagen for Denmark’s East Asiatic Company and, after trials in February 1912, success￾fully completed a 20000 mile round voyage between the Danish capital and the Far East (Figure I.1). The significance of the propulsion plant was well appreciated at the time. On her first arrival in London, the ship was inspected by Sir Winston Churchill, then First Lord of the Admiralty; and Fiona, a sister ship delivered four months later by the same yard, so impressed the German Emperor that it was immediately arranged for the Hamburg Amerika Line to buy her

xIntroduction:ACenturyofDiesel ProgressFIGUREI.1OneoftwoBurmeister&WainDM8150Xenginescommissioned(1912)topowerthefirst Selandia (MAN B&WDiesel)Athirdvessel intheseries,Jutlandia,was built byBarclay,Curle,in Scotlandand handed over to East Asiatic in May 1912.The Danish company's ocean-going motor ship fleet numbered 16by1920,the largestbeing the13275dwtAfrikawithtwinsix-cylinderB&Wenginesof740mmbore/1150mmstrokedeveloping a combined 3300kW at 115rev/min. Early steam-to-diesel conver-sionsincludedthree4950dwtvesselsbuilt in1909and repowered in1914/1915bytheB&W Oil EngineCo.of Glasgow, eachwitha single six-cylinder 676mmbore/1000mmstrokeenginedeveloping865kWat110rev/min.Selandia operated successfullyfor almost 30 years (latterly as Norseman)and maintained throughout a fully loaded service speed of 10.5knots beforebeing lost off Japan in 1942.Thepropulsionplantofthe second Selandiawhichenteredservicein1938.demonstratedtheadvancesmadeindieseltechnology since the pioneering installation. The single, double-acting two-stroke,five-cylinder engineofthe8300dwtvessel delivered5370kWat120rev/min: three times the output of the twin-engined machinery powering thepredecessor.Theperformance of Selandiaand other earlymotor shipsstimulated EastAsiatictoswitchcompletelyfromsteamers,anexamplefollowedbymoreandmore owners.In 1914 therewerefewerthan 300diesel-poweredvessels inservice with an aggregatetonnageof 235000grt; a decadelater thefleet hadgrown to some 2000 ships of almost two million gross register tonnage; and by1940thetotal tonnagehad risen to18milliongross registertonnage embracing8000motorships (Figure1.2).Between the two world warsthe proportion of oil-engined tonnage inservice thus expanded from1.3per cent to25per cent of the overall ocean-going fleet.By1939 an estimated 60per centof thetotal tonnage completed in

x Introduction: A Century of Diesel Progress A third vessel in the series, Jutlandia, was built by Barclay, Curle, in Scotland and handed over to East Asiatic in May 1912. The Danish company’s ocean￾going motor ship fleet numbered 16 by 1920, the largest being the 13275dwt Afrika with twin six-cylinder B&W engines of 740mm bore/1150mm stroke developing a combined 3300kW at 115rev/min. Early steam-to-diesel conver￾sions included three 4950dwt vessels built in 1909 and repowered in 1914/1915 by the B&W Oil Engine Co. of Glasgow, each with a single six-cylinder 676mm bore/1000mm stroke engine developing 865kW at 110rev/min. Selandia operated successfully for almost 30 years (latterly as Norseman) and maintained throughout a fully loaded service speed of 10.5 knots before being lost off Japan in 1942. The propulsion plant of the second Selandia, which entered service in 1938, demonstrated the advances made in diesel tech￾nology since the pioneering installation. The single, double-acting two-stroke, five-cylinder engine of the 8300 dwt vessel delivered 5370 kW at 120 rev/ min: three times the output of the twin-engined machinery powering the predecessor. The performance of Selandia and other early motor ships stimulated East Asiatic to switch completely from steamers, an example followed by more and more owners. In 1914 there were fewer than 300 diesel-powered vessels in service with an aggregate tonnage of 235000 grt; a decade later the fleet had grown to some 2000 ships of almost two million gross register tonnage; and by 1940 the total tonnage had risen to 18 million gross register tonnage embracing 8000 motor ships (Figure I.2). Between the two world wars the proportion of oil-engined tonnage in service thus expanded from 1.3 per cent to 25 per cent of the overall ocean￾going fleet. By 1939 an estimated 60 per cent of the total tonnage completed in Figure I.1 One of two Burmeister & Wain DM8150X engines commissioned (1912) to power the first Selandia (MAN B&W Diesel)

Introduction:acenturyofdieselprogressxiFIGUREI.2A20bhpengine built in1898byBurmeister&Wain to drawingssuppliedbyDrDiesel,forexperimentalanddemonstrationpurposes.MANbuiltthefirstdieselengine—a250mmbore/400mmstrokedesign-—in1893worldyardscomprisedmotorships,comparedwithonly4percentin1920(FigureI.3)In outliningthe foundations of the diesel engine'spresent dominanceinshippingotherclaimantstopioneeringfameshouldbementioned.In1903twodiesel-powered vessels entered service in quick succession:the Russian naph-tha carrier Vandal, which was deployed on the Volga, and the French canalboatPetitPierre.Bytheendof 1910therewere34tradingvesselsover30mlong worldwide with diesel propulsion,and an unknown number of naval ves-sels, especially submarines.The earliest seagoing motor vessel was the twin-screw 678 ton Romagna,built in 1910 by Cantieri Navali Riuniti with twin four-cylinder port-scavenged

world yards comprised motor ships, compared with only 4 per cent in 1920 (Figure I.3). In outlining the foundations of the diesel engine’s present dominance in shipping other claimants to pioneering fame should be mentioned. In 1903 two diesel-powered vessels entered service in quick succession: the Russian naph￾tha carrier Vandal, which was deployed on the Volga, and the French canal boat Petit Pierre. By the end of 1910 there were 34 trading vessels over 30m long worldwide with diesel propulsion, and an unknown number of naval ves￾sels, especially submarines. The earliest seagoing motor vessel was the twin-screw 678 ton Romagna, built in 1910 by Cantieri Navali Riuniti with twin four-cylinder port-scavenged Introduction: a century of diesel progress xi Figure I.2 A 20bhp engine built in 1898 by Burmeister & Wain to drawings supplied by Dr Diesel, for experimental and demonstration purposes. MAN built the first diesel engine—a 250mm bore/400mm stroke design—in 1893

xiIntroduction:ACenturyofDieselProgressEvolution of large two-stroke engines50 40ThermalThermal efficiencyefficiency%309200808820 2015 BMEP10 (bar)BMEP5FORORO8Mean piston speecMean8282828856-pistonAspeed2(m/s)1900191019201930194019501960197019801990yearsHeavy fuelBlast injectionAirless injectionDouble-actingTurbocharged two-stroke engineTurbochargirgMechanical supercharging_Valve scavengingOpposed-pistonUniflow-scavenging single exhaustvalveLoop scavengingCross-scavengingFour-stroke engineTwo-stroke engine1900191019201930194019501960197019801990yearsFIGUREI.3Main linesofdevelopmentfordirect-drive low-speedenginestrunkpiston enginessuppliedbySulzer.Each310mmbore/460mmstrokeenginedelivered280kWat250rev/min.Theyear1910 also saw thesingle-screw1179dwt Anglo-SaxontankerVulcanus enter service powered by a 370kw Werkspoor six-cylinder four-stroke crossheadenginewitha 400mm bore/600mmstroke.TheDutch-builtvessel was reportedly the first oceangoing motor ship to receive classificationfrom Lloyd's Register.In1911the SwanHunter-built 2600dwt Great Lakes vesselToiler crossedtheAtlantic withpropulsionbytwo132kW SwedishPolar engines.Krupp'sfirstmarine dieselengines,six-cylinder 450mmbore/800mm stroke unitsdeveloping 920kW at140rev/min apiece,were installed the same year in thetwin-screw 8000dwt tankers Hagen and Loki built for the German subsidiaryoftheStandardOilCo.ofNewJersey

xii Introduction: A Century of Diesel Progress trunk piston engines supplied by Sulzer. Each 310mm bore/460mm stroke engine delivered 280kW at 250 rev/min. The year 1910 also saw the single-screw 1179dwt Anglo-Saxon tanker Vulcanus enter service powered by a 370 kW Werkspoor six-cylinder four￾stroke crosshead engine with a 400mm bore/600mm stroke. The Dutch-built vessel was reportedly the first oceangoing motor ship to receive classification from Lloyd’s Register. In 1911 the Swan Hunter-built 2600 dwt Great Lakes vessel Toiler crossed the Atlantic with propulsion by two 132 kW Swedish Polar engines. Krupp’s first marine diesel engines, six-cylinder 450mm bore/800mm stroke units developing 920kW at 140rev/min apiece, were installed the same year in the twin-screw 8000 dwt tankers Hagen and Loki built for the German subsidiary of the Standard Oil Co. of New Jersey. BMEP (bar) Evolution of large two-stroke engines Thermal efficiency Mean piston speed BMEP Airless injection Double-acting Turbocharged two-stroke engine Mechanical supercharging Valve scavenging Opposed-piston Two-stroke engine Four-stroke engine Cross-scavenging Loop scavenging Uniflow-scavenging single exhaust valve Turbocharging Blast injection Heavy fuel 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 years 50 40 30 20 Thermal efficiency % 8 6 4 2 Mean piston speed (m/s) 20 15 10 5 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 years Figure I.3 Main lines of development for direct-drive low-speed engines

Introduction:acenturyofdieselprogressxiliFIGURE IL.4Twin Sulzer4S47typecross-flow scavenged crosshead engines servedtheMontePenedo,thefirstlargeoceangoingvesselpoweredbytwo-strokeengines(1912).Four long tie-rods secured each cylinder head directly to the bedplate,hold-ingthewholecastironenginestructureincompressionThefollowingyear,afewmonthsafterSelandia,Hamburg-South AmerikaLine's 6500 dwt cargo/passenger ship Monte Penedo entered service as the firstlargeoceangoing vessel powered bytwo-stroke diesel engines.Each of thetwin four-cylinder Sulzer 4S47 crosshead units (470mm bore/680mm stroke)delivered625kWat160rev/min (FiguresI.4-1.6)(Theadoption of the two-stroke cycle by Sulzer in 1905greatly increasedpower output and fostered a more simple engine. Port-scavenging, introduced in1910, eliminated the gas exchange valves in the cylinder cover to create a simplevalveless conceptthatcharacterizedtheSulzertwo-strokeenginefor70years:the

The following year, a few months after Selandia, Hamburg-South Amerika Line’s 6500 dwt cargo/passenger ship Monte Penedo entered service as the first large oceangoing vessel powered by two-stroke diesel engines. Each of the twin four-cylinder Sulzer 4S47 crosshead units (470mm bore/680mm stroke) delivered 625 kW at 160 rev/min (Figures I.4–I.6). (The adoption of the two-stroke cycle by Sulzer in 1905 greatly increased power output and fostered a more simple engine. Port-scavenging, introduced in 1910, eliminated the gas exchange valves in the cylinder cover to create a simple valveless concept that characterized the Sulzer two-stroke engine for 70 years: the Introduction: a century of diesel progress xiii Figure I.4 Twin Sulzer 4S47 type cross-flow scavenged crosshead engines served the Monte Penedo, the first large oceangoing vessel powered by two-stroke engines (1912). Four long tie-rods secured each cylinder head directly to the bedplate, hold￾ing the whole cast iron engine structure in compression

xivIntroduction:ACenturyofDieselProgressFIGUREI.5Oneofthe twoSulzer4S47enginesinstalledintheMontePenedo(1912)FIGURE1.6The6500dwtcargolinerMontePenedo (1912)change to uniflow scavenging only came with the RTA-series engines of 1982because their very long stroke-required for the lower speeds dictated for highpropeller efficiency—was unsuitablefor valveless port scavenging.)Another important delivery in 1912was the 3150dwtFurness Withy cargoship Eavestone, powered by a single four-cylinder Carels two-stroke cross-headenginewitharatingof590kWat95rev/min.The508mmbore/914mmstroke design was built in England under licence by Richardsons Westgarth ofMiddlesbroughThere were,inevitably,somefailures amongthepioneers.For example,apairof Junkers opposed-piston two-stroke engines installed in a 6000dwtHamburg-Amerika Line cargo ship was replaced by triple-expansion steamengines even before the vessel was delivered.The Junkers engines were ofan unusual vertical tandem design, effectively double-acting,with three pairsofcylindersof400mmboreand800mmcombinedstroketoyield735kWat120rev/min.More successfulwasHapag'ssecondmotorship,Secundus

xiv Introduction: A Century of Diesel Progress change to uniflow scavenging only came with the RTA-series engines of 1982 because their very long stroke—required for the lower speeds dictated for high propeller efficiency—was unsuitable for valveless port scavenging.) Another important delivery in 1912 was the 3150dwt Furness Withy cargo ship Eavestone, powered by a single four-cylinder Carels two-stroke cross￾head engine with a rating of 590 kW at 95 rev/min. The 508mm bore/914mm stroke design was built in England under licence by Richardsons Westgarth of Middlesbrough. There were, inevitably, some failures among the pioneers. For example, a pair of Junkers opposed-piston two-stroke engines installed in a 6000 dwt Hamburg-Amerika Line cargo ship was replaced by triple-expansion steam engines even before the vessel was delivered. The Junkers engines were of an unusual vertical tandem design, effectively double-acting, with three pairs of cylinders of 400mm bore and 800mm combined stroke to yield 735 kW at 120 rev/min. More successful was Hapag’s second motor ship, Secundus, Figure I.5 One of the two Sulzer 4S47 engines installed in the Monte Penedo (1912) Figure I.6 The 6500dwt cargo liner Monte Penedo (1912)

Introduction:acenturyofdieselprogressXVdelivered in 1914 with twin Blohm + Voss-MAN four-cylinder two-strokesingle-acting engines, each developing 990kW at 120rev/min.After the First World War diesel engines were specified for increasinglypowerful cargo ship installations and a breakthrough made in large passengervessels. The first geared motor ships appeared in 1921, and in the followingyear the Union Steamship Co. of New Zealand ordered a 17490grt quadruple-screwlinerfromthe UK'sFairfield yard.Thefour Sulzer six-cylinder ST70two-stroke single-acting engines(700mm bore/990mm stroke)developedatotalof 9560kWat127rev/min-farhigherthananycontemporarymotorship-and gave Aorangi a speed of 18 knots when she entered service inDecember1924.Positive experience with these engines and those in other contemporarymotor ships helped to dispel theremaining prejudices against using diesel pro-pulsion in large vessels.Swedish America Line's 18134grt Gripsholm-the first transatlantic die-sel passenger liner-was delivered in 1925; an output of 9930kW was yieldedby a pair of B&W six-cylinder four-stroke double-acting 840mm bore engines(Figure I.7). Soon after, the Union Castle Line ordered the first of its largefleet of motorpassengerliners,headed bythe20000grtCaernarvon Castlepowered by 11000kW Harland & Wolff-B&W double-acting four-strokemachinery.Another power milestone was logged in 1925 when the 30000grt linerAugustuswas specifiedwitha20600kWpropulsionplantbasedonfourMAN six-cylinder double-acting two-stroke engines of 700mm bore/1200 mmstroke.It was now that the double-acting two-stroke engine began to make head-way against the single-acting four-stroke design, which had enjoyed favour upto 1930. Two-stroke designs in single- and double-acting forms, more suitablefor higher outputs, took a strong lead as ships became larger and faster.Biggerbore sizes and an increased number of cylinders were exploited.The 20 000 grtOranje, built in 1939,remained the most powerful merchant motor ship formany years thanks to her three 12-cylinder Sulzer 760mm bore SDT76 single-acting engines aggregating27600kW.The groundwork for large bore engines was laid early on. Sulzer, for exam-ple, in 1912 tested a single-cylinder experimental engine with a 1000mmbore/1100mm stroke (Figure I.8).This two-stroke crossheadtype 1S100design developed up to1470kW at150rev/minand confirmed the effective-ness of Sulzer's valveless cross-scavenging system, paving the way for a rangeof engineswithboresvaryingbetween600mmand820mm.(Itsboresizewasnot exceeded by another Sulzer engine until 1968.)At the end of the 1920s the largest engines were Sulzer five-cylinder900mmboremodels(3420kWat80rev/min)builtunderlicencebyJohnBrown in the UK.These S90 engines were specified for three twin-screwRangitiki-class vessels of 1929

delivered in 1914 with twin Blohm  Voss-MAN four-cylinder two-stroke single-acting engines, each developing 990kW at 120rev/min. After the First World War diesel engines were specified for increasingly powerful cargo ship installations and a breakthrough made in large passenger vessels. The first geared motor ships appeared in 1921, and in the following year the Union Steamship Co. of New Zealand ordered a 17490grt quadruple￾screw liner from the UK’s Fairfield yard. The four Sulzer six-cylinder ST70 two-stroke single-acting engines (700mm bore/990mm stroke) developed a total of 9560 kW at 127 rev/min—far higher than any contemporary motor ship—and gave Aorangi a speed of 18 knots when she entered service in December 1924. Positive experience with these engines and those in other contemporary motor ships helped to dispel the remaining prejudices against using diesel pro￾pulsion in large vessels. Swedish America Line’s 18 134 grt Gripsholm—the first transatlantic die￾sel passenger liner—was delivered in 1925; an output of 9930 kW was yielded by a pair of B&W six-cylinder four-stroke double-acting 840mm bore engines (Figure I.7). Soon after, the Union Castle Line ordered the first of its large fleet of motor passenger liners, headed by the 20000 grt Caernarvon Castle powered by 11000 kW Harland & Wolff-B&W double-acting four-stroke machinery. Another power milestone was logged in 1925 when the 30 000 grt liner Augustus was specified with a 20600kW propulsion plant based on four MAN six-cylinder double-acting two-stroke engines of 700mm bore/1200mm stroke. It was now that the double-acting two-stroke engine began to make head￾way against the single-acting four-stroke design, which had enjoyed favour up to 1930. Two-stroke designs in single- and double-acting forms, more suitable for higher outputs, took a strong lead as ships became larger and faster. Bigger bore sizes and an increased number of cylinders were exploited. The 20 000grt Oranje, built in 1939, remained the most powerful merchant motor ship for many years thanks to her three 12-cylinder Sulzer 760mm bore SDT76 single￾acting engines aggregating 27 600 kW. The groundwork for large bore engines was laid early on. Sulzer, for exam￾ple, in 1912 tested a single-cylinder experimental engine with a 1000mm bore/1100mm stroke (Figure I.8). This two-stroke crosshead type 1S100 design developed up to 1470 kW at 150 rev/min and confirmed the effective￾ness of Sulzer’s valveless cross-scavenging system, paving the way for a range of engines with bores varying between 600mm and 820mm. (Its bore size was not exceeded by another Sulzer engine until 1968.) At the end of the 1920s the largest engines were Sulzer five-cylinder 900mm bore models (3420 kW at 80 rev/min) built under licence by John Brown in the UK. These S90 engines were specified for three twin-screw Rangitiki-class vessels of 1929. Introduction: a century of diesel progress xv