Steel Ships Their 00 Walt Goog

7/28/2019 Steel Ships Their 00 Walt Goog

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HARLES GRIFFIN & CO ., LTD., PUBLI8HE

inth Edition. Illustrated. Embodying the latest Hoard of Tr.idegult on Tonnage and Freeboard. 7^. 6^.

NOW YOUR OWN SHIP.

y THOMAS WALTON.

The work is of the highest value, and all who go down to the seships should mak selves acquainted with It,"Shipping World

n Large 8vo. Handsome Cloth. Profueelv Illustrated. In Twolutncs, complete in itself and sold separately.

HE DESIGN AND CONSTRUCTION OF SHII

y JOHN HARVARD BILES, LL.D., M.Inst.N.A.

rofessor of Naval Architecture in Glasgow University.

n Large Crown 8vo. Hand.some Cloth. With 131 Illustrations. 6LIi:s:.N'.A.

n lArR Cn^wu jjvo. Hius.-i:.' ."C;i. '>V.-.ii v. I. i^-ri:;ori-i

.*. net.

ECTURES ON THE MARINE STEAM TURBINE.

y JOUX HAUVAKO lULES, LL.l'. >L[:.* N.A.

Tlie bett poimlar work on th nurin sUfaiu tur'.i;ie. ^f^-^h

u Htuuls^mio Cl'^tli. With *2o: I ; >-.i-.i. ^v *5v ?.^.'.

HE THEORY OF THE STEAM TURBINE.

A Treatise on the IMuciiiles of Coustrurri.^n .^f "il: St.?.-. T :;r;. w.-L Hidtori.*al Notes on it> 1>.>-..>: ..., r.

Y ALEXANl^KK .irivt:.

*One of the latest text-tiooki . . . aUo on o( th N;st. T-.-lu^

iXTCESTB Edition, Revised. V{k i-xxiv . :i2, \V;:K _:,.. i \iszTi^. -Hi. net.

A MANUAL OF MARINE ENGINEERING.

omprising the De.


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The mo* ilnl)le handbook of tctmnce on the marine enjine nw i,; ^ ,;-BVC^


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;

5


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^ LIMITED,

ujhfs Un^crvid,)


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REFACE TO FOURTH EDITIOK

A SENSE of gratification and satisfaction has accompanied thabour involvedconsequent upon the exhaustion of three largditions in the preparation of the Fourth Edition of this work

omplete revision and much addition in both matter and illusration have been necessary in order that it maintain its characer of representing the latest practice in mercantile shipbuilding

onsequently, detailed illustrated descriptions of a new systemf longitudinal framing (Isherwood's); latest developments in

he construction of * Turret/ * Trunk/ single-deck, and otheypes of steamers are introduced; while much interesting andseful information, accompanied by numerous diagrams and il

ustrations, relative to both launching and construction of thew Cunard quadruple-screw express turbine steamers * Lusitnia' and ' Mauretania' will be found.

he Author begs to express his thanks and acknowledge his inebtedness to the Cunard Steamship Co., Ltd., Liverpool, foermission to publish the information given in connection withhe afore-mentioned steamers; and to Mr A. G. Hood, Editor ohe Shipbuilder, for the use of the blocks for several very valuble illustrations; also to Messrs S. P. Austin & Son, Ltd., Messrhort Bros., Ltd., and Messrs R. Craggs & Sons, Ltd., for permision to illustrate particular vessels built by them.

he Author also gratefully acknowledges the generous treatment accorded him by his Publishers in respect to the genera

roduction of the work, especially in that the scope of the useulness of the work will not be lessened by any increase of price


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lthough it has been considerably increased in size and its valureatly enhanced by the addition of much new matter and manew illustrations.

HOMAS WALTON.

REFACE TO THE FIRST EDITION

ABKIDGED).

The present volume is, in a large measure, the outcome of thratifying reception with which the smaller work, *Know you

Own Ship,' published in the Nautical Sei^ies, met on its iSrsnd. subsequent editions. The success of that book emboldeneds Author to embark, at the suggestion of the publishers, upon

he preparation of a larger and more important undertaking, thesult of which is now presented to the reader in the hope tha

will be found, not less than the former work, to merit the aproval of that section of the shipbuilding world for whose needhas been specially devised. A sketch of the plan of the book

will be found at the end of this preface; it is therefore unnecesary here to do more than briefly outline the circumstances uner which it has been written. The work has taken four years tomplete, the Author having been unable to devote more thanis leisure hours to its composition. A careful study of somears* duration, carried out in that centre of the steel trade, thleveland district, has afforded the necessary basis for the firs

wo chapters, while the subsequent chapters are the result of thAuthor's daily experience in the profession of ship construction

nd maintenance. The book has been copiously illustrated, ando expense has been spared in the preparation and execution


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f diagrams intended to amplify and elucidate the text. Thesave been placed in close juxtaposition to those portions of th

work to which they refer, the Author conceiving that they wilhus prove more retdily available for purposes of reference thanf they had been published as a separate volume, as is sometime

one in works of this class. The whole - subject has been treatedrom a practical point of view, and the requirements of studentship superintendents, shipbuilders, and marine engineers

ave been carefully studied."

HOMAS WALTON.

LAN OF BOOK.

hapter I. is a condensed description of the processes of thmanufacture of steel and iron, from its crude state in the form o

re, to the finished product in the form of ship plates, forgingsars, etc., particularly noting those constituents of the materia

which are essential to the production of good ship steel or ironnd those which, if in excess, introduce objectionable qualitiento the metal.

hapter 11. treats of the strength and quality of ship steel andron as a result of the proportions in which the various constitunts referred to above are present in the metal, and the particuar processes through which the material passes in the course o

manufacture.

A description is also given of the tests applied in order to defin

ely ascertain both the strength and quality.


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hapter III. explains what is meant by a vessel being ' Classednd the nature of the work of those Societies empowered to asign loadlines.

hapter IV. is a general introduction to the subject of ship con

truction, drawing attention to the principal structural featuresnd the alternative modes in which a vessel may be built.

hapter Y. deals with the various forces which are exerted uponhe hulls of ships, tending to strain them and produce deformaon; and shows also how to estimate the maximum stresses en

ured by the materi^d under the worst of such conditions.

hapter VI. Section /. gives a structural description of the funamental types of vessels known as ' Full Scantling' (one, twond three deck), Spar-Decked, and Awning-Decked vessels; and

modifications of those types.

ection II. describes the construction of typical vessels. Amonhese are:.The Express Steamers 'Lusitania' and *Mauretaniand the * Campania' and *Lucania'; the 'Great Eastern'; an

Ocean Steamship Co.'s cargo steamer; 'Turret,' 'Trunk,' and othr 'Self-Trimming' steamers; a large single-deck steamertringerlcss vessels ; steamers for carrying oil in bulk, framedpon both transverse and longitudinal systems of framing; and

n addition, special arrangements for carrying water ballast foong over-sea voyages.

ection III, describes the Isherwood System of Longitudinaraming.


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hapter VII., which is the largest section of the book, dealn detail with the construction and combination generally ohe various parts which go to make up the whole ship strucureframing, plating, stem frames and rudders, rivetingumping, ventilation, etc., and includes also remarks upo

aunching.

hapter VIII. describes the causes of decay and deteriorationenerally in a vessel, particularly noting those parts especiallable to rapid corrosion, and the best means of combating thauses of such corrosion, and of preserving and maintaining th

tructure in a state of efficiency.

ONTENTS.

HAPTER I. Iron and Steel.

AGES

ron and Steel supersede Wood in ShipbuildingCompositionf Iron and SteelPig Iron, its Nature and ManufactureThlast Fumace CastingsMalleable Cast IronMalleable o

Wrought Iron ; its Nature and ManufactureThe Puddling FuraceQuality and Classification of Wrought IronSteel, it

Nature and CompositionSiemens Steel, ManufacturfBessemer Steel, Manufacture ofBasic SteelCementationteelCase-hardened SteelCrucible SteelSteel Cast

ngsForgings Iron and Steel Sections used in Shipbuildin-18

HAPTER II.


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trength, Quality, and Tests of Steel for Shipbuilding Purposes

Definitions of Im))ortant Terms; Tensile Strength, StressDuctility, Elasticity, Elastic LimitValue of Nick

lFatigueTests of Plates and Angles Remarks upon th

Reduction in Thickness uf Steel PlatesTests for Steel CastngsRiyet TestsTreatment of Plates and Bars in Shipyard 9-25

HAPTER III.

lassification.

urpose for which Classification Societies existSocieties emowered to assign Load LinesGoyemment the suprem

Authority for Assignment of Load Lines, and responsible foeagoing Condition of Vessels leaving British PortsStandardf Strength upon which Load Lines are assignedLoad Lines ohree Deck, Spar Deck, and Awning Deck VesselsGrades olassMaintenance of ClassUnclassed Vessels 26-31

HAPTER IV.

Outline of Principal Features and Alternative Modes of Ship

onstruction.

ransverse and Longitudinal FramingForm and Function oartsButts in Transverse FramingFraming in Double Bot

omsRegulations for increasing the number of Tiers oeamsCompensation for dispensing with Hol

eamsNecessity of thorougli combination of Transverse and


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ongitudinal FramingStructural Value of Shell PlatngAlternative Modes of ConstructionNumerals for Scantngs .... 32-50

HAPTER V. Stress and Strbnqth.

AOB

reliminary.Forc


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f Transverse FramesValue of Stress CalculationCalculationor Position of Neutral Axis and Moment of Inertia of an ActuahipEstimate of Bending Moment for an Actiml Ship^ andtress per square inchValue of Registration Societies thipownerComparison of Stresses on Vessels increasing in

izeFurther Remarks upon the Value of Stress CalculaonsWorking Stress Erections on DeckBoard of Trade Intructions for Comparing the Strength of Vessels for FreeboardurposesDeductionsCalculation to find Nentral Ax

sCalculation of Moment of Inertia of a Vessel when supportedpon Wave Crest at Middle of Length, and thus subject to Hog

ing Stresses 51-106

HAPl'ER VI.

ypes of Vessels. Section L

undamental Types and Modifications of sameRelationetween Deck Erections and DeadweightNo Reduction inreeboard for Excessive Strength in a vessel with Full ScantngsDetermination of Tyi>eThree Deck, One and Two Deck|ar and Awning Deck VesselsIllustration of Principal Scantngs of foregoing typesVessels of Intermediate Gradeetween Three Deck and Spar Deck, and Spar Deck and Awnin

Deck Raised Quarter Deck VesselsMaximum StressPartiaAwning Deck, Shelter Deck, Well Deck, Shade Deck Vessels, et

.. 107-ISI

ection II.


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Description and Illustration of the Princii)al Structuraeatures, etc., of some noted, and also some new, Ty|)es o

Vessels * Lusitania' and ' Mauretania' (including Launchinarticulars) ' CamiKiuia' and *Lucania'Turret SteamrsTrunk SteamersSelf-Trimming Steamers (Priestman's)

antilever-framed Self-Trimming SteamerSome Neweatures in Modem ShipbuildingTypical Steam CollierLargingle

A0S8

Deck SteamerStringerless Type *C* Frame SystemOiteamers Water-ballast Arrangements 132-196

ection III. The Isherwood * System of Longitudinal Framin97-203

HAPTER VII.

Dbtails of Construction.

Rivets and RivetingBatt Straps and Butt LapsKeel Blocknd Launching WaysFrames, Reverse Frames, anloorsBeamsPillars Keelsons an

tringersBulkheadsDecksOutside Shell Plating Stemrames and Rudders Misoellaneous Details: Continuity otrength, Engine and Boiler Space, Masts and Derricks, Panting

Hatches, Deck Houses, Poop and Bridge Front Bulkheads, Tunel and Casings, Breast Hooks, Bilg

KeelsVentilationPumpiugLaunching 204-310


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HAPTER VIIL

Maintbnancb 311-327

ndex 328-332

LATES AND ILLUSTRATIONS.

rontispiece. Royal Mail Quadruple Screw Turbine Expresteamer ' Mauretania.*

IO. PAOK

Section of a Cleveland blast funiace, ...... 7

. Cold bending test, ........ 22

. Hot angle tests, ........ 23

. Hot tee bar tests, ........ 23

. Rivet tests, ......... 25

. Midship section showing trausv(>rKe framing, ..... 83

. ,, showing transverse framing with a cellular double bottom6

. ,, ,, longitudinal and transverse framing with ordinary floors9

. ,, ,, merchant steamer, illustrating tenns, . . .42


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0. two tiers of beams, ...... 43

1. ,, hold beams disiKJUsed with, web frame comiRaisation, 4

2. ,, ,, ,, ,, ,, deep frame compensation, . 46 18. Length betweeneq>endicular8, ...... 48

4. Types of upper deck, spar deck, and awning deck vessels, . . 9

6. Water pressures on variously sliaped objects, .... 55

6. internal and external, ... . . .56

7. Total side pressure, ........ 56

8. Calculation of amount of pressure, ...... 57

9. Pressure upon watertight bulkhead, ...... 59

0. Direction of water pressure upon hull, . . . . .61

1. Tendency to transverse deformation, ...... 62

2. vertical ulonj;ation, ...... 62

3. ,, sag due to deck weights, et


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5. Illustrating alternating excesses of buoyancy and weight inght condition, 65

6. Uniform buoyancy and weight, . . . . . .65

7. Bending moments in ship loaded at fore and after ends, . .7

8. ,, in bar loaded each end, ..... 67

9. Tendency to'hog,* ........ 69

0. 'sag,' 70

1. ,, fracture at ends of bridge, ..... 71

2. buckle . .71 88. 'Stressed* bar, 76

4. Elongation and compression in In^nt b:ir, ..... 79

5. Variation of stresses in bent bar, ...... 80


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0 PAOB

7. 'Moment of inertia.' ..,.,, 83

8. Curve of weight for loaded bar, ..,,. 85


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9. Curve of shearing stresses, ..,..,, 86

0. * Compound Girder,' ........ 87

1. * Equivalent Gii-der,' ........ 87

2. The equivalent girder in application, ...... 88

3. Bending moment in actual ship, ...... 91

4. Section of deep framing, ....... 97

5. Midship section, single deck vessel, . . . . . .110

6. Sectional profile of a rule * two deck' vessel,. . . to face pag11

7. ,, raised quarter deck vessel, . . ,, ,, 111

8. Midship section, three deck shelter deck vessel, . . ,, ,, 115

9. Sectional profile, ,, ,, ,, . . ,, ,, 116

0. Raised quarter deck vessel (outline sketch), . . . . .120

1. Partial awning deck vessel ,, . . . . . 127

2. Shelter deck vessel . . . . .128

3. Well deck vessel ..... 128

4. Three-island steamer . . . . .129


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5. Shade deck vessel ,, . . . . .129

6. Bridge front stiffening, ....... 130

7. Midship section of* Lusitania,' .... to face page 188

8. Elevation and plan, * Mauretania,' illustrating general strucural arrangement,

ofacepa^e 138

9. Profile, 'Lusitania,'showing extent of high-tensile steel platng, . . 134

0. (Plate II.) Stem view of * Mauretania'before launching, . toaepage 136

1. Expansion joint in deck, 'Mauretania,' ..... 136

2. Bulkhead stiffening . . . . .187

3. Stern castings ,, ... tofaeepage 138

4. Bilge keels of'Mauretania'and'Lusitania,' . . . .139

5. Launching of ' Mauretania,* showing Tyne waterway, . . . 140

6. Keel blocks, launching ways, fore and alt cradles oMauretania,' to face page 140

7. Launching diagram of' Mauretania,'. ..... 141


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8. ,, curves ,, ...... 142

9. diagram ,, ...... 143

0-71. (Plate III.) Forward and aftpr cradles of ' Mauretania,*. t

ace page 144

2. Launching triggers, ' Mauretania,' ...... 146

8-74. Starting levers, ' Mauretania,' ...... 146

Plate IV.) Royal Mail Twin Screw Steamer'Lucania,' . to facage 148

5. Sectional profile and plan of' Lucania'and'Campania,' . ,, ,49

6. Midship section ,, . ,, 150

7. Details of hydraulic riveting in upper deck sheer strake, . . 51

8. Sectional profile, ' Great Eastern,' .... tofacepa>ge 152

9. Midship section, ,, . . . . t^ it 153 (Plate V.)'Turret Deck'cargteamer, . . . n 154

0. * Whaleback' steamer, . . . . . . . .155

1. Turret steamer, profile, one deck, .... ixt face page 165

2. ,, ,, midship section, one deck, . . ,i i 156


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3. (Plate VI.) Turret steamer, hold view, ordinary method oonstruction,

ofacepctge 156

4. Turret steamer, profile and deck plan, two decks, . . m f 15

5. ,, ,, midship section, two decks, . . . >> >> 156

6. (Plate VII.) Turret steamer, hold view, 'tween decks, anwidely spaced

ube pillars, ...... to face page 157

7. (Plate VIII.) Turret steamer, hold view, no hold beams, harour deck

WIQ. PAQl

8. (Platr IX.) Turret steamer, hold view, widely spaced steenbe pillan, no

old or harbour deck beams, .... to face page 157

9. (Plate X.) Turret steamer, hold view, widely spaced steeube pillars, no

old beams, harbour deck beams, nor side stringers below lowerame heads, ....... to/aeepage 158

0. (Plate XI.) Turret steamer, hold view, special self-trimminype, bulk-


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eads partially disjwnsed with, .... (Plate XII.) A modern turreteamer,

1. Trunk steamer, profile and deck plan, (Plate XIII.) ' Trunkargo steamer,

2. ,, ,, midship section,

3. Modern trunk steamer, profilo and deck plan,

4. long holds, .

^ If II II II i II

6. ,, ,, ,, niidship section,

7. ,, ,, ,, showing trunk side tanks, .......

3. (Plate XIV.) MKiem trunk steamer, hold view,

Plate XV.) A modem trunk steamer, 99. Self-trimming steamerrofile, ....


01. Cantilever-framed self-trimming steamer, profile and decklans,

02. ,, ,, midship section, .

03. (Plate XVI.) Hold views, cantilever-framed self-trimminteamer,


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04. Profile, some new features in modem shipbuilding, .

05. Midship section, some now features in modern Khijtbuildng,

06. Detail sketches of fig. 104, .

07. Stern arrangement and rudder (fig. 104), (I'late XVII.) Aypical cargo steamer,

08. Steam collier, profile, ......

09. ,, midship section, .... 110-111. Deep brackets supportinatch sides (fig. 108), . 112. Large single deck cargo steamerrofile, 118. ,, M ,f midship section,

14. Section showing arched webs (fig. 112),

15. ,1 n through deck beams (fig. 112),

16. Stringerless tyiKj of cargo steamer, ....

17. Midship section illustrating ' half C' frame system, .

18. ,, }, O 11 II .

19. PersiKictive hold view illustrating * C * ,i ,, .

20. Oil-carrying steamer, elevation and deck plans (engineft),

21. ,, elevation (engines aniidslijs),.


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23. ,, enlarged view of coffenlam,

24. ,, transverse bulkheads, .

25. vertical and horizontal bulkhond stiffoners,

26. ,, ,1 side stringer cut and bracketetl to bulkhead,

27. f, liner and angle connection to shell, 12^. ,, bulkheadner,.

29. Cellular double bottom, ....

30. Side water-ballast tanks, ....

31. Profile steamer with side water-1 kiI lost tanks,

32. Deck plans, steamer ,, ,, i>

33. Midship section, ,, ,, ,, n 184. Profile of oil steamer framen longitudinal system,.


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o. - PAOB

35. Midsliip section of oil steamer framed on longitudinal sysem, to face page 199


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36. through machinery space of oil steamer framed on lonitudinal system, ...... to face page 199

37. Shell e^cpanmon, showing arrangement of longitudinals, ,, 198

38. Showing bracketconnections between longitudinals anulkheads, ,, 199

39. Midj^hipof ordinary cargo steamer framed on longitudinaystem, ,, ,, 200

40. Forms of rivets, ........ 206

41. Ttip rivet, ........ 207

42. Methods of riveting, ........ 208

43. Butt lap and strap


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50. side ,, ..... 221

51. Frame bending, ........ 224

52. bevelling, ........ 224

53. Floor plate, ......... 226

54. at bilge, 287

55. Lugs upon floors for keelson connection, ..... 228

56. Bulb angle frames with lugs for stringer connection, . . . 29

57. Inadvisable method of fitting reversed frame, .... 230 168ulb angle beam with welded knee, .... . . 232

59. ,, bracket, . . . . . .232

60. Side elevation of hatch coaming plate, ..... 234 161-168ulb plate beams, welded knees and brackets, .... 235

64. Beam cut for companion ....... 236

65. Section lhr


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69-177. Pillars, formatitui3 of heads and connections, . . 41-243

78-180. Pillar fcot, fomiiition, ...... 243-244

81-182. Pilkrs, porUMe, . . . . . . .245

83. Centrtt kuelaotis on ordinary floors, ...... 246

84. Intercti^tal contrfl ke


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96. Mode of obtaining Gills'^ work ntbntt% ..... 266

97. Stern fnunf'fnr sin Ljlt^ 8err^w steamer, . ...... 270

98. Stem and rudder frames for single screw steamer, . . to fac

age 271

99. Fitted pintle, ......... 272

00. Solid bearing gudgeons, . . . . . . . 272


Pl.

08. Pintles forged on rudder post, 204. Locking pintle, 206ottom bearing pintle, 206-207. Rudder stoppers, . 208. Conection of struts with stem fr


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18. Cellular double bottom discontinued under boilers,

19. Steel mast, .....

20. Telescopic mast, ....

21. Hinged top mast, ....

22. Derrick upon ventilator, 228. tables on masts, 224. Derick outreaches on mast, . 226. Cast-iron socket for derrick, .

26. Composite deckhouse,

27. Insulation,

28. Ventilators, .

29. Ship's hand pump,

80. Sluice valve, .

81. Mouthpiece for suction pipe; stmm box,

82. Pumping arrangement, 288. Bilge suction valve chest,

84. Diagram showing straight and cambered launching ways86. Launching diagram,

Plate XVIII.) Royal Mail Twin Screw Stanicr * Oceanic,*

86. Plate shoe on bar keel,


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87. Hinged bilge shutters.

TEEL SHIPS.

HAPTER I

tON AND STEEL.

ron and Steel snpersede Wood in ShipbuildingCompositionf Iron and SteelPig Iron, its Nature and ManufactureThlast FurnaceCastingsMalleable Cast IronMalleable o

Wrought Iron; its Nature and ManufactureThe Puddling FuraceQuality and Classification of Wrought IronSteel, it

Nature and CompositionSiemens Steel, ManufacturfBessemer Steel, Manufacture ofBasic SteelCementationteelCase-hardened SteelCrucible SteelSteel CastingsorgingsIron and Steel Sections used in Shipbuilding.

ron and Steel supersede Wood in Shipbuilding.^The day owooden ships has practically gone. Travelling through our mo

em shipbuilding districts, one can scarcely fail to be struck bhe conspicuous absence of this material. Whereas, sixty yeargo, wood was the principal constructive element in shipbuildng, it is now a rare sight indeed to see in this country the hull oseagoing craft being built of this material. Even then it is onlsed in the construction of the smallest types of vessels, or elsnly as a composite part of larger ones.

his great and rapid transformation has all been brought abouy the introduction in shipbuilding, first of iron, and subse

uently of steel. The manufacture of iron has been carried on


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or thousands of years, and great skill evinced in its productionwhile the uses of steel have been understood and appreciated foenturies. It is only since about the year 1860, however, that thatter could be produced in sufficient quantities and of the reuisite quality for its adoption in the construction of ships. Eve

hen it was not until after the year 1880 that steel became exensively employed in the building of ships for the mercantil

marine. At the present time over 99 per cent, of the vessels builn this country are constructed of this material.

While, generally speaking, iron has given place to steel, it wil

e shown more definitely in a subsequent chapter that it stilnds favour for certain purposes on account of important qualies which experience has shown it to possess. Hence, to a limed extent, it is still employed as a constructive element in cer

ain parts of a ship.

t is in Btrengtb, toughness, and malleability, that steel, as nowmana-factured, shows its vast superiority over wood, and thosse^siou of these qualities accounts for its having almost enrely superseded that material in the art of shipbuilding.

While the principal aim of this work is to describe the coiistmcon and the means which may be adopted for the maintenancr preservation of steel ships, it will not be out of place to conveome information respecting the process of the manufacture oteel, particularly noting those constituents of the metal whosresence or absence confers, in a marked degree, the qualitief malleability, ductility, weldability, hardness, softness, brittleess, toughness, cold-shortness and red-shortness and strength


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Although in a steamer the hull is principally composed of mildteel plates and bars, made by the Siemens process* (a proces

which takes its name from Sir William Siemens, the inventor osystem of producing steel which has proved especially suited

o the requirements of ship construction), yet iron, in practicall

very form in which it is known commercially, is employed, togreater or less extent, in the construction and equipment of

hip. We thus find, in addition to mild steel and steel castingshat iron castings, malleable iron plates, bars and forgings arlso employed. The great bulk of plates and angles, bulb-platend bulb-angles, tees, channels, and Z bars, etc., used in ship

uilding, are, however, made of Siemens steeL

o embrace the whole subject of the metallurgy of steel and ironn what must necessarily be a few pages in a work of this kind

would be an utter impossibility. However, notwithstanding thnormous dimensions of the subject, and the complicated pro

esses attending the manufacture of iron and steel, we shall eneavour to convey to the reader unacquainted with the subjecome knowledge of the manufacture, composition, etc., in as inelligible a manner as the brevity of the treatment will permit.

omposition of Iron and SteeL^As is well known, steel and

ron are products of iron ore which is obtained, like all otheminerals, from the earth by mining, and which, after being subected to a course of treatment whereby most of the associatempurities are separated, yields iron or steel according to thature and amount of the foreign elements still remaining inombination with the pure iron in the final product. There ar

many substances whose natures can be easily described by imple definition. Such is not the case, however, with iron an


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teel as they occur commercially. Neither of them are purmetals. Indeed, absolutely pure iron, in addition to the practicampossibility of its production upon a large scale, is worthlesor any industrial purpose. It is to the presence and proportionf the foreign elements or impurities which are introduced o

ound naturally in combination with the pure metal, that thpecial qualities which distinguish the alloys known as cast iron

malleable or

A small proportion of chequer plates, boiler plates, channelstc., is still made from Bessemer steel. (See p. 14.)

wrought iron, and steel from each other, are really due. Iron oren its raw state, contains from about 30 to 70 per cent, of ironccording to the nature of the ore. Pig iron, the result of thrst stage of the manufacture, contains from about 90 to 95 peent, of pure iron ; malleable or wrought iron over 99 per cent.

mild steel ship plates about 99J per cent.; while other varietief hard steel may contain considerably less of the pure metalnd a larger proportion of other elements. It will thus be seenhat while neither iron nor steel are absolutely pure, the assoiated elements, whether metallic or non-metallic, are exceedngly small in proportion to the pure metal, and yet it is to the in

uence of these elements that the vast differences between casron, malleable iron, and steel, as to tenacity, ductility, and maleability, are attributable.

he chief foreign elements found in commercial iron and steere carbon, sulphur^ phospTiorus, manganese, and siliconhough infinitesimally small quantities of other substances maometimes be present Any one of the above substances, if in ex


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ess, may produce a deleterious influence, and confer an unesirable quality on the metal ultimately produced. The mos

mportant of these elements is carbon.

n pig iron, and likewise in cast iron, carbon is found in relat

vely large proportions, reaching sometimes to 5 per cent., andonstituting, as a rule, not less than 3 per cent, of the total. Such

metal may be hard and sometimes exceedingly brittle, or sofnd tough, but these qualities depend less upon the amount oarbon present than upon the condition in which it occurs. Suchron readily melts at a high temperature, and can be moulde

nto various forms. In its crude form it is chiefly used in the prouction of malleable iron and steel.

MaUeaMe or torought iron may contain traces only of carbonnd at the most it rarely contains more than about *12 per cent

At one time it was customary to define wrought iron as, chemic

lly, the purest iron that could be produced for commercial puroses, but with the great improvements which have taken placn recent years in the manufacture of steel, it is outrivalled inhis respect by mild steels produced in the processes introducedy Sir W. Siemens and Sir Henry Bessemer, so that the distincon between wrought iron and mild steel lies more in the mod

f production than in chemical composition. Wrought iron iomparatively soft, malleable, ductile, and tenacious. It is excelently adapted for welding purposes, its malleability increasins the temperature is increased. Fusion is only effected at veryigh temperatures. When heated and* suddenly cooled it retains softness. It may be produced direct from the ore, but is usully made from pig iron.


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MUd Steel contains sometimes as little as '06 to '15 per centf carbon, along with small proportions of other elements. Suchteel is malleable, ductile, and tenacious, and when low in caron and comparatively free from other impurities, it is equal t

wrought iron in its welding qualities. Siemens mild steel ship

lates contain from *12 to '2 per cent.

not more) of carbon. Steel containing over -2 per cent, of caron i not adapted for tlie miinafucture of such plates, beinassage-way8 wher

harp

ngle stiffeners might be dangerous.

\2. A patent section for hatches, combining in efl[icicncy bothhe usual rest iron for liatch covers and moulding.

11

o


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L' 13. Best iron, which is attached to the inside of hatch coamngs to sup[)ort the covers.

4. Bound iron, for pillars, stanchions, etc. This may be soh'd oollow.

HAPTER IL

TBEKGTH, aUALITT, AND TESTS OF STEEL FOB SHIPUILDING FTJBFOSES.

Definitions of Imxiortant Terms ; Tensile Strength, StressDuctility, Elasticity, Elastic LimitValue of Nick

lFatigue^Tests of Plates and AnglesRemarks upon thReduction in Thickness of Steel PlatesTests for Steel CastngsRivet Tests Treatment of Plates and Bars in Shipyard.

Definitions of Important Terms. Having briefly traversed thteps in the process of the manufacture, and DOted the constitunts of iron and steel it is now proposed to inquire into the speial qualities essential for purposes of ship construction, and thests to which the metal is subjected in order to ensure the posession of such qualities.

t is advisable at this stage to clearly understand certain termnd expressions which are constantly recurring in treating thispect of the subject

engQe Strength. ^By the tenacity of steel is meant the proprty of adhesion, and the tensile strength is the measure of th

reatest stretching force, applied in the direction of the length o


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he material, necessary to produce fracture; or, in other wordsis equivalent to the maximum stress required to produce frac

ure, and is usually expressed by the number of tons required toreak a bar one square inch in sectional area. The remarkablenacity of steel is one of its most valuable and important char

cteristics.

tress may be defined as the resistance offered by any materiao deformation caused by the application of an external forcetress is also equal to the intensity of the force which produceeformation, providing that it is not so great as to cause ruptur

r fracture (see also page 75, Chapter V. on * Stress antrength').

Ductility is the property of being permanently elongated by thpplication of a tensile force. This property in steel is well illusrated by the fact that it can be drawn into wire.

lasticity and Elastic Limit. Within certain limits, if a tensilorce be applied to a bar of steel, it will show distinct elongationat immediately upon the removal of this stretching force th

material returns to its original dimensions.

his elastic quality is termed elasticity. Elasticity may also befined as that property whereby, after the metal has been sab

ect to a certain pressure, whether of tension or compressiont a given temperature, it seeks to regain and retain its originaolume and shape. If steel, however, be stressed beyond thimit, permanent elongation, or '^,' takes place. This limit, ooint, at which elasticity ceases, and permanent set or distortioakes place, is called the * elastic limits The elastic strength i


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hus the tensile strength up to the elastic limit. So long as stees not subject to a stress beyond the elastic limit, the elongations directly proportional to the stress, but as soon as the elastimit is passed, the elongation takes place at a more rapid rate. I

will now be clear that in very ductile materials, such as wrough

ron and mild steel, very considerable distortion and elongationeyond the elastic limit may occur before actual fracture takelace.

Most of the harder steels possess less ductility, though theilastic limit and ultimate tensile strength may be greater. It i

bvious to everyone how important these qualities of tenacityuctility, and elasticity must be in such a structure as a shipn a large iron or steel vessel rolling and pitching in a seawaynormous and innumerable stresses are set up in every part ohe structure, and owing to the elasticity of the material, thoughmperceptible to ordinary observation, there is a certain amoun

f give and takeelongation and retractionconstantly goinn, which must somewhat relieve the severity of the stressewhich are experienced by rivets and connections generally

rue, this is not, nor should it be, so serious as to be perceptibleevertheless, knowing what we do of the numerous stresseorne by ships at sea, and also of the elastic quality of iron an

teel, it follows that this actually takes place to a greater or lesegree.

he value of ductility in steel is often manifested in cases of colsion, or fouling, or grounding. Steel plates, in such cases, haveen known to buckle and bend, and to be greatly twisted anistorted, and yet show no signs whatever of rupture.


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mportance of Elastic Limit.In considering the strength oteel for ship construction, important as tensile strength may behe elastic limit is of still greater importance. In fact, in dealng with structures from a purely strength point of view, it ihe elastic limit and not tensile strength which is of foremos

onsideration. And while ductility is of great importance, and imight be possible to stretch the steel in a ship considerably bey

nd the elastic limit but well within the tensile strength, suchermanent elongation, excepting under such exceptional cirumstances as grounding, collision, etc., is decidedly most obectionable, and could only be productive of ultimate disaster. I

an easily be imagined what horrible distortion in the form osteel ship would ensue, if vessels were built to anything aproaching their maximum tensile strength, or even in such

way as to be subject to stresses in excess of the elastic limit.

hus the aim of the designer of ships, bridges, etc., after obtain

ng all

ther necessary qualities and properties, is to get the maximummit of elasticity in the material required for the structure iuuestion.

Nickel. In recent years, oonsiderahle improvement has heenmade in the manu-factare of steel forgings for marine engine

nd also for boiler tubes, by introdacing suitable proportions oickel during the process of manufacture. This has the effect o

ncreasing both the tensile strength and the elastic limit But aickel induces hardness, and is also very costly, it is not used in

he manufacture of steel for ship plates and bars. Nickel in boilr tubes has been found to retard corrosion.


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he tensile strength, ductility, and elasticity of steel are furthencreased by elongation, produced by cold rolling and wirerawing at suitable temperatures. This is amply illustrated inhe case of steel wire. Steel rods drawn into wire will increase a

much as 80 to 100 per cent and over, in tensile strength. So tha

teel wire with a tensile strength of 100 tons per square inch is ommon production, while even this has been greatly exceeded

atigue.Of course, it is clearly understood that where elongtion of the nature just described is carried out, the stretchinorce is applied most gradually. Suddenly applied irregula

tresses, which vary greatly in magnitude, produce what inown as Fatigtte, that is, diminished resistance to rupture. Thirobably accounts for the fracturing of tail-end shafts, which exerience severe jerking strains as the propeller blades strike th

water after emersion in pitching movements. A similar reasonould be found for many other breakages. Such irregular strain

ndoubtedly cause disarrangement in the natural molecular disosition in both iron and steel, and microscopic examinations ouch fractures show the effects of this disturbance.

n ordinary mild ship plate steel the elastic limit ranges at abou0 per cent of the tensile strength. Tempered nickel steel ma

ven have a tensile strength of 45 tons and oyer, with an elastimit of 30 tons, while bard drawn steel wire may reach an elastc limit of 50 tons.

ests.Classification Societies such as Lloyd's, Bureau Veritasnd the British Corporation, agree very closely as to the qualitief iron and steel for shipbuilding purposes, and consequentlheir tests are generally very similar. Samples of the steel ar


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ested at the steel works (under the personal inspection of thociety's surveyors) before the material leaves for the premisef the shipbuilder. These societies require that samples be testerom every charge or cast employed in the manufacture of th

material; and moreover, that the whole operation and proces

f testing be witnessed by their surveyors. If they are satisfiedwith the manner in which the steel stands the various tests im

osed upon it, then every plate, beam, and angle is requiredo be clearly and distinctly stamped by the manufacturer. Thrand upon the steel so tested is as follows:

Lloyd's). H ^^ British Corporation.

nd indicates that a shearing from the plate or bar has satisfactrily passed through the whole of the tests made upon it

When these samples fail to fulfil the test requirementB, thlates or angles from which they were cut are rejected. Thesests are made so as to ascertain and measure the tenacity oensile strength of the steel, its ductility and elasticity, and alss transverse or bending strength. Such tests usually comprisot and cold forge tests, tempering, and, in the case of forgingshe sudden impact caused by either allowing the forging to faln hard ground, or by dropping weights upon the forging. Inesting steel, the classification societies require that strips fromplate, angle, or bulb plate or bar, cut lengthwise or crosswise

hould have an ultimate tensile strength of not less than 28 andot exceeding 32 tons per square inch of section, with an elongaon equal to at least 20 per cent on a Hength of 8 in. before frac


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ure in samples ^ths of an inch and above in thickness, and 16er cent, in samples below this thickness. The loDgation test, i

s scarcely necessary to add, is to ensure ductility, and the limif 32 tons as the maximum tensile strength is to obtain a meta

which is soft, and as workable in the hands of ships' platers and

miths as the best wrought iron. Indeed, where sharp bends arequired, as in garboard strakes for bar keels, and in the plateound the stem and counter and stern frame (boss and oxtelates), steel is greatly to bo preferred to wrought iron, as it cane manipulated with better results.

o easily can steel plates be bent, that it is now a very commonractice with shipbuilders to make the comers of engine andoiler casings and deckhouses with a single plate bent to a raius of 2, 3, or more inches, thus dispensing with the usuaonnecting corner angle bar. Steel plates are also preferable fohe round corners of hatch coamings. So fully recognized is thi

uality in steel, that even where iron is employed for houses oneck, etc., it is a very common practice for shipbuilders to adopteel plates for the bends at the corners, etc

lassification societies also require that steel angles for thrames of vessels, and bulb steel for beams, may have a maxim

m tensile strength of as much as 33 tons per square inch of secon.

trips cut from the plate, angle, or bulb steel, after being heatedo a low cherry red, and cooled in water of 82' Fahr., must standending double round a curve of which the diameter is not morhan three times the thickness of the plate tested. In addition


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amples of plates and bars should be subjected to cold bendinests.

Among the numerous tests adopted, the following may be takens examples.

Mild steel cut into strips of about 1^ in.

n width, should stand being bent cold in a

ydraulic press to a curve the diameter of which

io, 2.Cold Bending does not exceed twice the thickness of thlate

est. (or inner radius of bend equal to thickness

f plate). (See fig. 2.)

)

A plain angle should bend hot as shown in Nos. 2 and 3, fig. 3.


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io. 8.Hot Anglo Teste. A J bar shoald bend hot as shown in

Nos. 2 and 3, fig. 4.

v r

io. 4.Hot Tee Bar Teste.

urning to wrought iron, we find that the classification societieequire that, for vessels classed by them, it must be of good maleable quality, capable of standing a tensile strain of 20 tons pe

quare inch with, and 18 tons across, the grain, and of standingertain hot and cold forge tests.*

Remarks upon the Reduction in Thickness of Steel Plates.

he advantage of mild steel over wrought iron is at once appar

nt. The tensile strength is increased from 40 to 50 per centwhile the metal shows very decided superiority in elasticity an


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uctility. As a natural result, steel ships are lighter in weighhan iron ones, a reduction of about 20 per cent, being usuallllowed by the classification societies in the thickness of steelates and angles, and as a more lightly constructed ship permitf a greater deadweight being carried, and thus increased

reights being earned, the reason for the universal adoption oteel is obvious, and more especially as the price of steel is usully as low as that of iron. But even with so much to recommend, there are still certain minor disadvantages associated with itdoption. This applies to all vessels, but more especially to vermall craft As just noted, a steel vessel with plates and angle

0 per cent, lighter than an iron one is equivalent to the latten strength. (Plates and angles which would be, say, ^^ths thicn an iron vessel, become ^ths in a steel ship.) But apart fromtrength, a certain objection is attached to reducing the thickess of plates. Thickness gives rigidity, and thus in some classef very lightly constructed, steel

Shoald any of the samples tested show signs of failure bracking or breaking in any way, and not falfiUiiig the test reuiremente, the whole of the material represented by suchamples is rejected.

essels, the effect of the water pressure upon the immersed surace is sufficient to ca.use the plating to buckle in between thransverse frames, so that the position of every frame is distincn the outside surface. Severe pressure upon the bows in highpeed vessels makes this objectionable feature even more proounced, and while it may be argued that this may not inflict anerious effects upon the strength, it certainly detracts from thppearance of the hull.


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n some quarters, steel has been sadly abused for its rapid deerioration owing to corrosion. Probably, in some measurehere is truth in such a complaint against the metal. But ihould be remembered that taking the same amount of corosion in two plates of equal strength to, say, Lloyd's require

ments, one of iron and the other of steel, the steel plate wouldnly at first sight appear to be the worse of the two. But then thhinness of the steel plate is entirely against it in forming judg

ment. A -j^th off a plate ^^ths thick would appear more strikinhan ^th off a plate -^ths thick. It seems, therefore, that whilome qualities of steel may^ in some measure, show more sign

f decay than wrought iron, it should also be remembered inudging the results that the steel was probably thinner to begin

with.

ests for Steel Castings. The tests for steel castings in the hullf ships are generally as follows:Cast steel stern frames, rud

ers, steering quadrants, and tillers, must be subjected to perussive, hammering, and mechanical tests, in the presence one of the society's surveyors, so as to ensure the material beinf ductile quality. A tensile test is to be made on a piece takenrom each casting, and the extension on a length of 8 in. is noo be less than 8 per cent., and the tensile strength not less than

8 tons, nor more than about 35 tons, per square inch. A coldending test must also be made corresponding to each tensilest, and the sample must bend cold before fracture through anngle of at least 90. Large stern frames cast in one piece muse allowed to fall on a hard flat ground (excavations being mado take the boss part and other projections) after being raised

hrough an angle of 45**. Stern frames cast in more than oniece, and rudders, must be dropped from a height of from


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o 10 ft, according to the design, shape, and weight of the castng. The casting in such case must subsequently be slung up, an

well hammered with a sledge hammer, not less in weight thanlbs., to satisfy the surveyors that the castings are sound and

without flaws, existing either originally, or developed as the res

lt of the application of the preceding percussive tests.

ivet Tests. An equal tensile strength per square inch of secon is required in rivets as in plates and angles. They should bf special quality, both soft and ductile, and capable of standinhe following tests. One rivet per hundred should be subjected

o a forge test.

Temper Test, The rivet bar should be heated to a low cherred, cooled in water of 82 ahr., and then bent double round urve the diameter of which is equal to the diameter of the bar.

. Forge Tests, To bend cold without fracture as shown in No, fig. 5, a;=diameter of the rivet.

. To bend hot without fracture, as shown in No. 3, fig. 5, so thahough the rivet has been nicked with a chisel at x, no signs oearing are apparent.

. The head to be flattened when hot as shown in No. 4, fig. 5ntil the diameter is two and a half times the diameter at x.

reatment of Plates and Bars in the Shipyard. Even after thteel has been delivered in the shipyard, a hard brittle plate maften be detected in the operation of punching, the plate crack

ng round the rivet hole. The nature of the outer surfaces of th


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unchings also often expose bad material; a cracked crevicedurface, together with a severely torn eJge, point to the same deect. This is specially noticeable in bad iron plates.

n rolling a plate cold, the objectionable feature of cold-short

ess (cold-brittleness) is sometimes discovered, and in the samperation with a heated plate, hot-shortness (hot-brittleness

may be detected.

he manipulation of a plate in the hands of the ships' platermay tend

3 4

ig. 6.Rivet Tests.

o cause deterioration in the quality of the material unless ie subjected to proper treatment. Thus, plates (such as countelates and boss plates round the tail-end shaft) which have beeneverely hammered in order to shape them for their particulaositions on the hull, and are, moreover, probably subjected toeveral heatings and coolings, should be annealed before beinxed in position in the vessel, in order to regain the uniformity

n strength which any such severe processes as hammering andneven cooling destroys.


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imilarly, the severity of the operation of punching the holeor rivets in a steel or iron plate, so destroys the molecular arangement of the material in the neighbourhood of the holehat, in order to regain the original uniformity of strength, thlates should either be annealed after punching, or else th

oles should be rimed out. These features are fully recognized bhe classification societies, and we find that important structuraems in the material, such as stringer plates, sheer strakes, garoard strakes, and all buttstraps when about ^^ths of an inch

n thickness and above, are to be carefully annealed, or else tholes are to be limed after punching.

HAPTKK TIL CLASSIFICATION.

urpose fur which Classification Societies existSocieties emowered to assicrn Load LinesGovernment the Suprem

Authority for Assignment of Load Lines and resjwnsiblo fo

eagoing Condition of Vessels leaving British PortsStandardf Strength upon which I>oad Lines are assignedLoad Linef Three Deck, Spar Deck, and Awning Deck VesselsGrades olassMaintenance of ClassUn-classed Vessels.

urpose for which Classification Societies exist.Al at Lloyd's iphni^e more often used than fully understood, though ever

eaman knows that it conveys an idea of the good quality andeaworthiness of a ship.

uch an expression brings us into contact with a subject of paramount importance, viz., "Classification," and as a largo pro

ortion of seagoing vessels are " classed," and the structuratrength in new vessels and the manner in which such stnictura


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trength has been maintained in old vessels determines the lass " to which they belong, it will be well at the outset to obtainclear idea of this matter of " classification.''

A steel or iron ship is often compared, from the point of view

f strength, to a beam or girder, and in many respects such omparison may fairly be made. When iron or steel girders arsed in the construction of bridges, buildings, etc., a very clospproximation can be made to the nature and amount of theverest stresses which may have to be borne; and thus the neessary strengths and dimensions of these girders can be arrive

t almost entirely by calculation, provided that the quality of thmaterial is thoroughly understood. But when wo come to the acual ship girder, we find ourselves confronted by considerablifficulties and complications, which make the determination ohe scantlings and disposition of the material in order to ensuruflicient strength, a matter which cannot be ascertained purel

y calculation. The innumerable varying and sudden stressewhich are experienced by ships in a seaway, when rolling anitching in light, loaded, or ballast conditions, render absolutelccurate mathematical treatment impossible. However, an aproximaU mathematical calculation can be made which is exeedingly usefuL

LASSIFICATION. ^^

he other factor necessary in arriving at an adequate knowledgf required strength is experience. Thus we find, throughout thistory of iron and steel shipbuilding, continiial changes haveen made in the generally accepted rules, as experience has inicated their necessity.


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All ships are built to carry. Some, as in the case of steam yachtshough two or three hundred feet in length, have little else toear than the owner, his family, a few guests, the crew, bunkeoal, stores, and provisions. Other vessels, such as tramp steamrs, are built to carry cargoes of great specific gravity. Th

ormer are so light that, in order to suflSciently immerse themonsiderable quantities of permanent ballast are usually carriedn the latter, on the other hand, if the holds were entirely filled

with cargo of the nature referred to, the vessels would be almostf not entirely, immersed, and apart from considerations otrength ^assuming them to be able to floatthe question o

tability, with little or no freeboard, would probably be a serioumatter.

he purposes for which ships are built are innumerable, ando build all vessels which are similar in size and proportion, oqual structural strength, regardless of the work they have to do

would be absurd. What is more reasonable and sensible is to enure that each vessel is sufficiently strong to satisfactorily perorm her own work. To introduce as much structural strengthnto a cross-channel passenger steamer which has to carry littllse than passengers, mails, and luggage, besides her own equip

ment, stores, and bunkers, as uito a vessel of equal dimension

which has to carry, say, 1000 or 1500 tons of cargo to any part ohe world, would be foolish in the extreme. Or even in the casf two purely cargo-carrying vessels of identical dimensions, ine is intended to be solely employed in carrying a cargo of greaensity, such as coal, while the other is intended to carry a cargf much less density, such as wool, the one amounting to, say

000 tons, and the other to only about 2000 tons, obviouslywould be absurd to build each of these vessels to exactly th


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ame scantlings, for either the one would be excessively strongr the other dangerously weak. But, as stated, it is necessary thaach vessel should be strong enough to do her own work.

he strength of ships, therefore, should be regulated by thei

roportions and maximum displacements, provided thanough freeboard remains to ensure sufficient stability and ondition of general seaworthiness.

t is clear that to study and tabulate the scantlings for every newhip lies outside the sphere of the shipowner. That shipbuild

rs, by their wide experience, would be vastly more capable odequately dealing with the matter, is true; but then, without xed standard of strength, no two of them would either arrang

heir material alike, or arrive at the same strength in the finshed vessel, even for similar vessels imder similar conditions

Moreover, no such method of ship construction would be eithe

atisfactory or acceptable to imderwriters. From both ownersnd imderwriters' standpoint, standards of strength, both for

maximum displacements and minimum freeboard, are absoutely essential Or in other words, a guarantee is required thahe vessel is strong enough to carry with safety, and without inury to herself when experiencing the various and probable de

mands which may be made upon her strength, a certain loadwhich may not, under any conditions, be exceeded, and alshat her design is such that, with a minimum reserve buoyancy

when properly loaded, she runs no risk of capsizing through decient stability. With this aim in view, there exist several societ

es which, by scientific and mathematical investigation couplewith long experience, have drawn up rules and tables of scant


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ngs suited to all types of cargo and passenger vessels. The besnown of these societies are Lloyd's Roister, the British Cororation, the Bureau Veritas, the Germanischer Lloyd, and th

Norske Veritas. These societies save both shipowners and shipuilders an immense amount of labour and trouble, at the sam

me providing general uniformity in strength, and a satisfactoruarantee of efficiency to the insurance societies for the vesselonstructed under their rules. To carry out this system, the com

mittees of these societies employ considerable numbers of sureyors, whose training and experience have specially fitted themor the work. The quality of the material used in the construc

on, the efficiency of the workmanship, the carrying out of theiocieties' rules and requirements, and the periodical survey fohe renewal or alteration of the " class " of the vessels placed inheir hands, are their sole responsibility.

he Load Line Act of 1890.Before the Load Line Act cam

nto force in the year 1890, the overloading of ships, which wasource of danger from both a structural and stability aspectwas attended with loss of life at sea as well as loss of ships. Th

ecessity for Government interference so impressed itself uponhis country, that the passing of the Load Line Act was the finaesult, by which the Government became supremely responsibl

or the seagoing condition of all British vessels and vessels leavng British ports.

ocieties empowered to assign Load Lines.Hence, while thritish Govenmient has sanctioned Lloyd's Register, the Britishorporation, and Bureau Veritas Classification Societies to asign load lines to vessels classed by them, the Board of Tradtill remains the supreme authority for such assignment. It i


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ertainly true that these societies can build ships to whatevecantlings they please, but it is the work of the Board of Trade tnsure that a maximum load line be fixed strictly in accordanc

with the strength of such vessels, with a reasonable percentagf reserve buoyancy.

tandard of Strength upon which Load Lines are assignedWhile considerable latitude is thus allowed in the disposa

f material in the ship structure, the necessity for a minimumtandard of strength is obvious. This is, moreover, essential inrder that uniformity in the strength of the different types o

essels built be secured, while it does not necessarily follow thaniformity in the modes of construction will be a result. The

tandard of strength laid down for the guidance of all classifiction societies is that embodied hy Lloyd^s Rxdes for the yea885. This gives the minimum structural strength for a minim

m freeboard for all classes of vessels. Any society is at liberto demand greater structural strength in vessels classed by themhan that of the Board of Trade standard, and, naturally, there individually responsible for efficient local strengthening.

ocieties for the classification of vessels are thus at liberty to arange and formulate their own methods of construction, and deermine the scantlings of the material used in ships built to theiarticular classes. With uniformity of strength, uniformity in asigning the freeboard of every class of vessel is secured, since i

must be in accordance with the Freeboard Act of 1890.

o the shipowner this subject of classification is of the greatesmportance. If he wishes to add a new vessel to his fleet, and h


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s desirous of ensuring her being built to the highest class, hnserts a clause in his specification, or in the contract betweenimself and the builders, to the effect that she must be classed00 A1 at Lloyd's, or to the corresponding highest class in anther society.

oad Line of " Three Deck^^ Spar Deck, and Atoning Deck Vesels, There are four principal types of steel vessels consideredn the Board of Trade Freeboard Tables, viz., "Three Deck," Spa

Deck, Awning Deck Vessels, and Sailing Ships. A vessel may beong to the highest class in any one of these types. The " thre

eck" type is the strongest vessel built, and is thus allowed thminimum freeboard, with consequently the maximum immerion, displacement, and carrying power. Awning decked vesselare the lightest type built for over-sea voyages, and conse

uently are required to have the greatest freeboard, with conseuently smaller immersion, displacement, and carrying power

upposing that into such an awning decked vessel more strucural strength than is required by the standard (Lloyd's Rules fo885) is introduced, a comparison would be made between hencreased strength and that required for a spar decked vesselnd a proportionate reduction made in the freeboard. Or, if par decked vessel were built in excess of the standard strength

comparison would be made between her increased strengthnd that of a " three deck " vessel, and a proportionate reducon made in her freeboard also. But as the " three deck" vesseas already a minimum reserve buoyancy, additions of strengtheyond that required by rule would obtain no concessions in th

matter of diminished freeboard.


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Grades of Class.While it is customary for shipownera to havew vessels built to the highest class of their respective types does not follow that such vessels will always maintain thighest class; for example, at intervals of four years, Lloyd's reuire that vessels classed with them should be subject to specia

urveys. These special surveys are designated No. 1, No. 2, No, and No. 4 respectively, and as long as a vessel imuntAimi HeSee page 118 re Modern Awning Deck YeoefaL

HAPTER IV.

OUTLINE OP PRINCIPAL FEATUEES AND ALTBRNATIVBMODES OF SHIP CONSTRUCTION.

ransverse and Longitudinal FramingForm and Function oartsButts in Tmna-verse FramingFraming in Double Bot

omsRegulations for Increasing the Number of Tiers o

eamsComi)ensation for Dispensing with Hold Beams, a SteDeck, Hold Pillars, Side StringersNecessity of Thorough Comination of Transverse and Longitudinal Framing Structura

Value of Shell Plating-Alternative Modes of ConstruconNumerals for Scantlings.

ossibly the knowledge of ship construction possessed by maneaders may be of a very limited character, and in this chapteis simply proposed to briefly enumerate the principal parts in

he structural arrangement of ships, so that the names of sucharts may become familiar, and to give a general idea of thei

unctions. This plan, it is believed, will simplify the course purued in this work, besides curtailing elaboration and explana


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on in the longest division of the book, dealing exclusively withDetails of Consti-uction."

raming.

teel and iron ships are usually built on a combination of twoystems of framing, viz., longitudinal and transverse. (Seongxtudirud System, page 197.)

ongitudinal Framing includes all girder forms of materiawhich run in a fore and aft direction, whose function is to afford

ongitudinal strength.

ransverse Framing embraces all girder forms which cross thongitudinal framework at right angles, affording transverse othwartship strength.

he strongest structure is obtained only when these two systemf framing have been intelligently woven together, the strengthf the one co-operating with the strength of the otherthat is

n relation to the work which, conjointly, they have to do. Whenhis is accomplished, the whole is then covered by a skin, in thorm of " shell plating " and decks, which not only stiffens andtrengthens the skeleton or framework, but adds enormously the total strength of the ship considered as a compound girder.

ransverse Framing. In order to preserve the transverse othwart-

MODES OP SHIP CONSTRUCTION.

3


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hip form of a ship under all the conditions of stress to whichhips are subject in carrying their various loads in smooth and

wave water, a girder or frame is placed at intervals of from 20 t0 or more inches apart, all fore and aft. Fig. 6 gives an examplf the simplest form of transverse framing. Here we have a hal

ection of a comparatively small vessel showmg such a transerse frame, with what are known as ordinary floors. It consistf

ection through frame at AB

miakptl

ectionlhroagh floor at A B

aastfrmA A


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io. 6.Midship Section showing Transverse Framing withOrdinary Floors.

frame bar, a reverse frame bar, a floor plate, a beam, and a pil

ar or stanchion. The efficiency of the complete frame dependpon the thoroughness of the combination of the various part

nto one whole.

rames, The frame bar, in this system of framing, is continuus from the top of the keel to the gunwale, extending from th

op of the keel to the bilge along the lower edge of the floor plato which it is riveted.

Reverse Frames, The reverse bar also extends continuouslrom the

middle of the upper edge of the floor plate on the opposite sido the frame (shown by dotted lines on the section) round thilge, then on to the frame bar to the gunwale, except in thmallest vessels, though the alternate reverse bars do not usully extend to this height.

loor Plates. The floor plate extends from bilge to bilge, eithen one plate, or in two plates butted (joined end to end) altern


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tely on either side of the centre line. The frame and reverse barre riveted to its lower and upper edges respectively, convertng the plate into a girder with top and bottom flanges, whichtrengthen it to resist athwartship buckling. (See fig. 6.)

he height of the bilge ends of the floor plate above the base lins usually about twice the depth of the floor at the middle linf the ship; and at three-quarters the half-breadth out from th

middle line* it should be at least half the depth of the floor platt the middle line.

he advantage of carrying the floor plate round the turn of thilge must be obvious, strengthening what is liable to be a wealace in the framing, especially in very square-bilged ships. Auch a comer, " working " is more liable when the vessel is subect to the severe stresses which are experienced among wavesending to produce alteration in the transverse form.

eams, The beam is a steel or iron bar, uniting (in a singleecked ship) the uppermost extremities of the frame, and preenting, by its own tensile strength and rigidity, the tendency ohe frame heads to open wider apart from each other or to aproach each other when the vessel is subject to stresses conseuent upon loading, or from the pressure of the water upon th

mmersed skin of the ship. Beams thus perform the function ooth struts and ties.

Here, again, much depends upon the efficiency of the means oonnection, and also in thoroughly supporting the angular conection of the beam to the frame. Hence it is necessary to formweb of plating (beam-knee) which should extend at least two


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nd a half or three times the depth of the beam down the frameo which it is securely riveted. We shall refer more fully to this inhapter VII. Owing to the depth of the vessel illustrated in fig, additional transverse support is required to the sides betweehe weather deck and the floors. An additional tier of widel

paced beams is thus introduced.

illars. It is scarcely necessary to say that, the shorter a bar ishe more rigidity does it possess, and also, that the fullest effiiency of any structure whose strength is made up of a numbef parts can only be fully developed when such parts are com

ined in the most perfect maimer so as to cause the entire comination to act as one piece. Hence, in order to develop the fulflSciency of the transverse frame, its several parts must be ed," in order to prevent their acting independently of one anther. Pillars are therefore introduced, uniting the beam at thentre with the floor at the centre. These act both as struts and

es, preserving the

istance relationship of these opposite parts of the structureMoreover, without pillars (or some structural formation equi

alent to pillarssee figs. 87 and 102), any severe crushintress upon the sides of a ship would tend to cause the beam

o spring up at the centre, its great length reducing its rigiditynd resistance to bending; on the other hand, they are neededo support the numerous and varying loads^both stationarys winches, windlasses, etc., and temporary, as deck cargoes

Where the beam is very great, additions pillars, termed quarteillars, are introduced between the centre ones and the sides ohe ship, or else a substitute of some kind is required. Beforeaving, for the present, the subject of hold pillars, it may b


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ointed out, as shown upon pages 166 and 157, figs. 87 and 88nd page 167, fig. 102, and Plates XVI. and XIV., that both holdillars and a tier of hold beams may be entirely or partially disensed with by adopting a system of framing which combine

n its formation all the structural advantages of hold beams and

illars, and moreover preserves a clearer hold space.

utU of Frame and Reverse Frame, Though both the framnd the reverse frame have a break in their lengths at the centrne above the keel, in each case it is intended that the strengthf these bai-s be continuous. To unite these ends by such mean

s will ensure this is therefore necessary. In the case of thrame, this is done by fitting a heel piece (a piece of angle ironbout 3 ft. long, of the same size as the frames), on the oppositide of the floor and covering the butt, and in the case of the reerse bar, by fitting a short covering piece on the opposite side ohe floor also. (See figs. 6 and 9.) These butt-covering bars als

erform other services in the ship structure, as will be shownater.

ransverse Framing in Double Bottoms. The system of so contructing the bottoms of vessels as to make them capable oarrying water for trimming purposes or as ballast has becom

more and more universal during recent years.

he earlier forms of these double bottoms were called M*Intyranks, after the name of the inventor. At first these tanks wero built that the transverse framing was maintained in the usua

way, the inner bottom being formed by laying the plating uponore and aft girders standing on top of the ordinary floors. Inome cases the inner bottom plating extended horizontally ou


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o the ship's side, where it was made watertight by fitting anglollars round the frames. In the most common form of M*Intyrank, however, the tank side in each wing is formed by turninhe inner bottom plating down perpendicularly to the bilge

Here, again, the frame bar was sometimes continuous through

he tank side, or, as it is more usually called, the tank marginlate. But generally the frame bar, especially in vessels now fited with these tanks, is cut at the tank margin plate, and a connuous angle bar fitted, making the connection between th

ank side and the outer shell plating watertight.

he continuity of the transverse frame strength in such cases maintained by connecting the frame legs to the tank side byarge bracket plates.

TEEL SHIPS.

hough M*Intyre tanks are less adopted than formerly, they artill fitted in some cases. Such a tank is illustrated in a midshipection, fig. 100.

he double bottom water-ballast tank now most commonly adpted is that known as the " cellular double bottom." The transerse framing of this system (and longitudinal framing dotteds illustrated in fig. 7.

AnnnlrAar

pperdeeH sowQvptm


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^

kldishowifistkefnmligf md double bottMfnaifog before thgfin

oanuttd

ink aargw pine

dp^


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io, 7,Midship Section showing Transverse Framing in a Vesel with i Cellular Double Hottom, also the Longitudinal Framng (dotted).

xamination of the diagram shows the arrangement of th

ransvene framing to be somewhat interfered with, though, inffect, this modified arrangement is identical in principle withhat previously described for vessels with ordinary floors.

he water-ballast tiiiik extends from margin plate to marginlate, and from the keel to the top of the floors. Here we usuall

nd that a

ontinuous deep plate runs fore and aft through the centre of thank (centre keelson or centre through-plate).

he continuity of the floor plate is necessarily interrupted, buhe continuity of the transverse strength is maintained by conecting the floors to the centre through-plate by means ongles. The floors at the middle line are much deeper than reuired for ordinary floors, thus permitting a good connectionnd somewhat compensating for the break in the continuity ohe frames and reverses. The outer ends or extremities of thoors, called bracket plates, extend to exactly the same height a

n similar ships with ordinary floors. But again, at the bilge, wbserve that, in order to form the outer boimdary of the cellulaottom tank, the floors have to suffer interruption in continuy in order to allow the margin plate to pass continuously fornd aft> and fit hard on to the shell plating. However, by meanf angle connections, and a considerable depth of floor at thilace, a minimum for which \a definitely fixed by each classific


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tion society (margin plate width), a good connection is made the bracket plate, or tank knee as it is sometimes called, and thhape of the floor is preserved to the height prescribed.

n order to ensure the water tightness of the tank at this place

continuous bar is fitted to the lower extremity of the marginlate, to connect it to the outer bottom. This necessitates anothr break in the continuity of the frame bar. The depth of the floolate, however, enables a satisfactory connection to be madetween the transverse framing inside and outside of the tanky means of the bracket plate already mentioned. In exception

l cases the frames have been preserved continuously from keeo gunwale, and the watertightness at the margin plate effectey fitting angle collars round the frames for the whole length ohe tank. The reverse bar is also intercostal between the centreelson and the margin plate, and then again commencing outide the margin plate, is continued along the upper edge of th

racket plate, and up the frame bar to its prescribed height.

n all other respects, the upper framing, beams, pillars, and theionnections are identical with those in the ordinary system preiously referred to in fig. 6.

egulations for increasiiig the Number of Tiers of Beams.Sar, we have only dealt with a small type of vessel requirinut two tiers of beams. As vessels increase in size, however, nonly for convenience and adaptation for carrying cargo, but foeasons of structural strength, more tiers of beams, which mar may not be sheathed with a wood or steel deck, are introuced. If the vessel is classed, these are regulated by the rulef the classification society. Thus, we find that vessels classed a


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loyd's, when over 15 ft. 6 in. from top of keel to top of uppeeck beam at centre, require, in addition to the weather deck, anxtra tier of beams in the hold, which may be widely spacedonvery

enth frame (see fig. 6); and when 24 ft. is exceeded, still anotheer of beams is required.

ompensation for dispensing with Hold Beams. The introducon of an extra tier of beams in a ship of, say, 16 ft. in depth

may, however, prove a source of inconvenience to a shipowne

n the stowage of certain kinds of cargo, and a similar inconvenince may also arise in the introduction of the third tier of beamn a vessel of, say, 25 ft. depth.

n such cases, by modifying the transverse framing, these lowermost tiers of beams could be dispensed with, in the manner il

ustrated later in this chapter. First of all, we observe that thesdditional tiers of beams are required for purposes of strengthWith ships of greater depth, and naturally, we infer, of greate

reiuJth, the increased immersion produces vastly increased exernal water pressures, tending to crush in the bottom and sidef the vessel.

Moreover, the loading of heavy cargo tends to distort the transerse form. Thus additional tiers of beams, supported from keeo uppermost deck by pillars, become necessary, unless a satisactory method of compensation can be provided. This can bone by increasing the strength and rigidity of the transvers

raming, the details of which methods are fully described a littlater.


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ongitudinal Framing. We have already observed that the speial function of transverse framing is to preserve the transversorm, when experiencing the numerous and ever-varyintresses to which ships are subject. In a like manner, and to

much greater extent, especially hi vessels of great length, ther

s the tendency to alter in longitudinal form, as, in their pitchinmovements, they are subject to immense differences and sud

en changes in the buoyant support afforded by the water, ando sudden twisting stresses when crossing skew seas. Moreoveruch stresses may be greatly increased, especially imder certainonditions, by the filling of largo peak or other ballast tanks a

he ends of a vessel, or in stowing very heavy cargo towards thxtremities.

Of what paramount importiince does an efficient arrangemenf longitudinal framing become, will therefore be obvious. Thu

we find that along the bottom, on the bilge, and up the side o

vessel are a number of girders of various forms extending alore and aft, the continuity of whose strength is most rigidlmaintained.

Keelsons and Strimjers, Fig. 8 shows the same section as figwith the longitudinal framing introduced. We may notice tha

ll longitudinal girdera of whatever form, on the bottom of thessel between bilge and bilge, are termed keelsons, and thosn the sides above the bilge, stringers. The name given dependsot so much upon the form of the girder section, as upon th

ocality in which it is placed. The most important keelson girdes that standinj^ upon the top of the floors at the middle linet is composed of a vertical plate with two large angles on th


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op, and two on the bottom, the whole being mounted y)y a thiclate called a rider ptaie.

MODES OF SHIP CONSTRUCTION.

9

his girder is termed the centre keelson, and really forms thackbone of the ship.

n order to prevent the floor plates tripping, that is, inclininither forward or aft, and to afford strength and stifliiess to thhell, it is usual to introduce what is termed an intercostal girder side keelson, so named because it is composed of plates fitte

ntercostally between the floors in a

umnletfar


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io. 8.Midship Section showiDg the Longitudinal and Transerse Framing combined, in a Vessel with Ordinary Floors.

ontinuous line all fore and aft, and connected to them bngles. In very small vessels, somewhat similar plates are fittedwhose height terminates at the upper edge of the floors. Thes

re named wash plates, their function being to prevent any waer which may have drained into the bilges (Jashing from sido side when the vessel rolls. This is also one of the functions o

ide intercostal keelsons. But in larger vessels the plates are car


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ied above the floors between two angles as shown in fig. 8, andhereby oon-

erted into a continuous keelson. Keelsons may be built up in arietj of ways according to the dimensions and proportions o

he vessel. These are more fully dealt with in Chapter VII.

he next girder is on the bilge, and is called a bilge keelsonurther up the vessers side is a small girder, known as a sidtringer (or it may be an upper bilge stringer).

Deck Stringers. At the gunwale, and on the lower tier oeams, are broad continuous plates fitted on the ends of theams. These are deck stringer plates, and form most valuablirders in conjunction with the beams. Wherever a tier of beams fitted, whether a wood or steel deck is, or is not laid, this thicktringer plate is always to be found.

entre Through-Plate. In fig. 7 the longitudinal girders arhown (dotted lines) in conjunction with the transverse framinf the double bottom. Extending continuously down the middlne, and standing on the plate keel, is a deep plate, of the depthf the floors and tank. Indeed, the depth of the floor is regulatedy the depth of this plate, the minimum width of which is fixedy the classification society. Two large angles on the top anottom, mounted by a thick plate forming part of the tank top

make up the combination forming the centre keelson. It is alsonown as the centre through-plate, or centre girder.

ntercostal Keelsons. The next girder is usually intercostal, th

oors being continuous, as a general rule, in merchant vessels


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his is known as a side or intercostal keelson. Its continuity imaintained by connection to the floors by means of angles.

Margin Plate. At the bilge is the tank side, or margin plate, exending continuously fore and aft. This naturally forms an effi

ient bilge keelson, though not known by that name. Above thilge, the arrangement of stringers is similar to that for the ship

with ordinary floors.

Necessity of thorough Combination of Transverse oAid Longitdinal Framing. Even viewed separately, although both th

ransverse and longitudinal framing are absolutely essential fohe work to be done, yet neither could possibly perform its ownuty without the aid of the other. Whenever a longitudinairder crosses a transverse frame, it ought to be carefully andhoroughly connected to it, if necessary, by the aid of smalieces of angle iron, or lugs, as they are often termed. For in

tance, in fig. 8 we find that the centre keelson is riveted to evereverse frame that it crosses on the top of the floors by means os own bottom bars. But in order to get a doubly secure connecon, a short piece of reverse bar (lug piece) is riveted to the othr side of the floor, through the horizontal flanges of which thottom bars of the keelson are riveted also. This same lug form

he covering piece for the reverse frame butt. The same principlf connection is applied to all the other keelsons and stringerwherever practicable.

tructural Value of Shell Plating. When the skin, or shell platng, is worked over this framework, the eflect is an enormouontribution toJijoth


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MODES OF SHIP CONSTRUCTION. 41

ransverse and longitudinal strength by more effectually bindin

ogether the whole structure into a single compound girderuch a mode of construction, where one part is interdependenpon another for the utmost development of its own strengthnd rigidity, must commend itself.

ig. 10 shows the vessel whose framing has been illustrated in

gs. 6 and 8 with the shell plating in addition; and similarly fig1 shows the vessel whose framing has been illustrated in fig. 7with the modification in the framing caused by the hold beam

eing dispensed with and web frames and stringers introduces compensation.

he transverse framing stififens and assists the longitudinalnd the longitudinal stiffens and assists the transverse, in doinach its own work. The whole system of the structural work oship is based upon the principle that unity is strength. Each

f the innumerable parts performs its work in conjunction withhe adjacent parts to which it is closely related, there

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