AUXILIARY SPECIALTY COURSE SEAMANSHIP

(AUXSEA)

STUDENT STUDY GUIDE

PUBLISHED FOR EDUCATIONAL PURPOSES ONLY

COMDTPUB P16794.42

;;,kffff'MCommandantU.S. Coast Guard

21 @ Second Street S.W.Washington, DC 20593-0001Staf f Symbol : G-NAB-1P h o n e : ( 2 O 2 ) 2 5 7 - L o o L

COMDTPUB PL6794 .42

I 5 APR 1992

COMMANDANT PUBLICATION P16794.42

Subj : Auxi l iary Specia l ty Course Seamanship (AUXSEA); StudentStudy Guide

1. P_UBPOSE. This publication is intended for use as the studentstudy guide for the Auxil- iary Specialty Course inSeamanship. I t is published for instructional- purposes onlyand is not po l icy mater ia l .

2. DIRECTIVES AFFECT_E_D_. The Auxil iary Operational SpecialtyCourse, Student Workbook, CG AUX 498-2(74) , is canceled.

3. DISCUSSION. This publ icat ion conta ins inst ruct ionalin format ion regard ing Coast Guard Auxi l iary Seamanship.Major rev is ions in th is new edi t ion j -nc lude:

a. New chapter on anchoring techniques which reviews theproper safety procedures for anchoring and clearing afouled anchor.

b. New chapter on duties and manners which reviews thedutj-es expected of the deck hand, radio watchstander,navigator, engineer, J-ookcut, hel-msman, and towingwa tch .

c. Redesigned and expanded topics on terminology, boatconstruct ion mater ia ls , and steer ing gear types.

d. Revised chapter on internal combustion engines,i nc lud ing i n fo rma t ion on i nboard -ou tboa rds ( I /O ' s ) .

A

B

D

E

F

u

H

DISTRIBUTION - 5P1Pe. 130

a b d e o h J K m n o p q u w x v z

NON-SrANDARDDlsrRlBUTloN: See page 2.

COMDTPUB PL67694 .42

15 APR 19sZ4. ACTION. Distr ict Commanders shall insure that this

publication is used as a resource for Auxil iary training andthat al l Auxil iary instructors and teaching assistants areaware of this publication and become thoroughly famil iarwi th i ts contents .

/QA,rxW. J . ECKERChief , 0f f jce of Navlgai lon Safety

i r :C I j l tCr ' , r , ,e1, Scrv ices

Nonstandard Distribution

Auxil iary National BoardAuxil iary Department ChiefsAuxi l iary Past Nat ionaL Commodores

TABLE OF CONTE}MS

TNTRODUCTION

CIIAPTER 1-TENMINOLOGY, BOAT CONSIRUTTION MATERIALS AIID STEERINGGEARTYPES

INTRODUCTION.......... .,......... l-lFIBERGLASS BOATS.... ...,...... 1-lwooD BoATs ...................., ............,............ t-5

ALUMINUM ,.......1.7FABRIC 0nflatables) ................ l-8TypEs oF STEERINC $YSTEMS .......,....... l-8CHAPM.AN Piloting Seamanship and Small Boat Handling

EdyEditions ;....................Chap1er onNautical TermsIater Editions ...Section I Chapter I and Abbreviations and Acronyms; Section 8, Appcndices

Pagoiv

STUDY QUESfiONS

CHAPTDN, 2 - BOAT MNNTENANCE

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CHAPTER 4 * MARLINSPIIG SEAMANSHIP

TNTRODUCTTON .......,........TYPES OFROPE

NanualLineSynthetic Line ...,...,.......Wire Rope

CARE OF LINESLINE USAGE, KNOTS, HITCHES, BENDS, AI.{D SPLICES ...................-........,.

"DippingfteEye-. SquareKnot.........,...,

BowlineHalf HitchClove HitchTimberHitchRolliogHitchSheet Bend/Becket Bcnd ..*.....,....

SAICINGShort SpliceEye Splice

STOWINGLINECHAPMAN Piloting Seananship and Smail Boat Handling

Early Editions ......Chaper on Marlinespikc SeamanshipLater Editions Section 3, Chapter 13

STUDY QT.IESTTONS .. 4-r2

CHAPTEN. 5 _ BOAT IIANDLING

INTRODUCTION 5.ISTUDYOUTLINE 5-I

4-l4,14-l4-l+3u34-54-54-54-6M4-74r74.84-94.94-94-104-l I

Basic Principles of Boat HandlingDock Lines and Their UseLanding at aPierGetting Clear of a BerthManzuver at Slips in tigbt QuartersHandling Twin Screw Boats

CHAPMANPilotingSearnanship and SmallBoatHandlingEatly Editiom, Chapter onPower Cruiscr Seamanship

Iator Editionsn Section 3, Chapte{ 9STUDYQUESTTONS 54

CIIAPTEB 6 * H0AVY WEATIIER

INTRODUCTION 6.IwrNDwAy8s.................... 6.rSTORMTIDE WAVES 63SEISMIC WAVES G4TIDALWAVE$ 64SWELLS 6.4suRF............ MWAKES 65cRoss sEAs ............ 6sTI{B ETFECT OF WIND AND CURRENT ON MANEUVERING................... 65HEAVYWEATIIEROPERATION 6.8TrrE SEAANCHOR(DROGUE)..................... 69

6 l lCIIAPMAN Piloting Searnanship and Small Boat Handling

Early Editions ....,..Section on Boat Handling Under Adverse Conditions

Later Editions .,. ., - :.. ".:- ::::1" ::.T.:13: :::.T:1 ::g#ffiHHJ1TSTUDYQT]ESTIONS GI3

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CIIAFTER 7 - ASSISTANCE TO BOATS IN DISTRESS AND DAMAGD CONTROL

INTRODUCTrON....,..... 7.1RIGIITING A CAPSIZED SAILBOA.T 7.1REFLOATINGASTRANDEDVESSEL 7AAPPROACHINGABURNINGVESSEL 7.5FrRE FIGInING............. 7.5PLUGGINGAI{DPATCHING ....,.I".r....r.,... 7.6D8WAT8RrNG................. ?-10CHAPMAN Piloting, Seamanship and Small Boat Handling

Early Editions ,.....Section sn Stranding, Assisting and Towing and on Emergency

LaterEditions................-:.:::::::.T.::::::.:.:.:::::::.:::::.::5ffiJfffiffisrIJDy QUESTIONS.................. .............r!.,....

CTIAPTER 8. NAVIGATION RI]LES

7-13

INTRODUCTIONSTUDYOUTLINENAVIGATION RULES: LIGHTS AND DAY SHAPES

Tho U. S' Inland RrlttIntehationil Rules of the Road

STUDYQUESTTONS

CHAPTER 9- AIICEORING

INTRODUCTION ....,......... ..................STUDY OUTLIM

CHAPMAN Piloting Seamanshipond Small Boat llandlingEarly Edritions, Chaptor onNavigation RulesLater Editioq$! Section 3, Chapters 7 and I

8.18-1

9.19-1

l0-llG.ll0-3

AtchoringGround TacklsAnchoring Te,chniquesPermanent Moorings

CHAPMAN Piloting Seamanshipand Small Boat IlandlingEarly Editions, Chapto on AnchoringLater Editiong Section 3, Chapter 12

STUDY QUESTIONS ...............-. %3

CHAPTER TO-DUTIES AI\ID MAI\INERS

INTRODUCTIONDUTIESMANNERSPOLLUTIONCOURTESY BOARDING A COAST GUARD VESSELSTUDYQUESTIONS

104lc.510{

l lt

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This Page Left Intentionally Blank

Reverse of Page iii

CHAPEER 1

TEnMtNOI.ocy, BOf[ CONSIRUCIITOD| lrATERflxJ, AIID grEERnrG CEAR lrpEs

MTRODUCrIq}!. This chapter provides overall lnforrnation onf f ima tex ia1sused fo rboa tbu i1d ing . I t g i vessomeo f theadvarltages and disadvantages of, each. Students are also introduced tosome of the "Nautical Terms" associated wlth seamanship. Fina}lythere is a review of corunon steering systems. The readS-ng materialfor this l-esson can be found In the fol lowing pages of this chapterand in designated portions of Cna4tril Pil.gttllgt, FeaoanqLlip ?tl4.,FTet+Boat EandlinE, In the earlier editions of CIIAPMAN, the naterial is in#

m6- cEapEer on l{auti.cal lerma. fn the later editionsr the material isin Sectl,onI

sed upon these readings,

Today's prospective boat ewner has nany boat building materials tochoose f rom. I t 's a far cry f rom yesteryearr when pract ica l ly a l l 'boats were built from one material-wood. Now, there ls woodrfibergrlass, aluminun, steel, fero-cement, plus many combinations ofthese, For instance, yoo can see f iberglass hulls with wooden decks,lnteriors, and deck houses. The same is true for aL1 of the othermater ia l$ .

You don't need the desire to be a boat builder to learn more about boatbuilding. The more you know about how boats are buil t and whatmaterials are used to build them' the bet,ter you wil l be able to sel-ecta boat and then to maintain her year after year. This lesson wil lintroduce you to sofite of the boat building materlals In use today andw111 explain the, steering systems you wil l f ind in nearly aL1powerboats.

FIBEF€LaSS=,BgryS. I letrs begin l^t i th f iberglass. Today, f j .berglassf f i po1 i zes theboa tbu i1d ing1ndus t r y .Th i swasno talways so. The use of, fiberElass is a relativel,y new innovation and hason1y, within the last few decades, come to replace wood as the primaryboat building material. The reason f iberglass has become so popuJ.aris due to the fact that i t is so easily maintained. Thousands of boatolrners have discovered to their delight that, taking care of afibergJ-ass boat is far easler than maintaining its wooden counterpart,A J.ook at f i t t ing-out yards in the spring is proof enough. Owners ofwooden boats spend hour upon hour getting them ready for launching,Owners of fiberglass boats find that much Jess maintenance-time isrequired.

But then again, f iberg lass is not exact ly a mirac le mater ia l e i ther . I trequiree proper care and, contxary to what many people think, rreedspainting periodical ly.

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The word fiberglass doesn't really define the material. It is more exactly plastic reinforced withfiberglass. The British use a more accurate description - CRP, which stands for glass reinforcedplastic. A fiberglass hull, then, is composed of shands and layers of fiberglass saturaled withiesin. This constuction can be compared with that of reinforced concrete. The fiberglass strartdssompare to the steel rods and the resin compares to ttre cement.

Just as with any other kind of boat building material, there ate good fiberglass boats and badfiberglass boats. There are ilulny ways to use fiberglass in building a boat and, predictably,there are firrr supporters of each of these,

Fiberglass itsel{ the reinforcingmaterial, comes in four differertt forms-mat,cloth, wovon roving, and choppedstrands (frgure 1-1). Mat is a mass ofrandomly chopped fiberglass fibers thatare either bonded together with resin ormechanically stitched together. It is used asa primary reinforcsrnent for the hull and thedeck ofa boat.

It is also used to reinforce joints and toprovide a waterproof banier. Fiberglasscloth is just what the rurme implies. it isan opeq square weave with strandsgoing in trivo directions only. It is used asThe four primary types of a primaryreinforcoment for hulls and decks, andcommonly used as a reinforcemenl fotthesurface coat (called the gel coat). Wovett

Figure l-I.-The four primarytypes of fiberglass reinforcemetrts.

FiberglassMat

FiberglassCloth

- n t\ \ v A - .

,fr?5Ry}\rU

iW-/4ti{t*-o-q l f i l i l h '

Chopped StandsWoven Roven

roving is almost exactly like cloth but it has a heavier weave, It is used as a primaryreinforcement for hulls and decks. Chopped shands are just that, fiberglass that has been choppedinto very srnall pieces.

The two basic types of resin rxed in boat constuction are polyester and epoxy. Polyester resinsare most commonly fouud. They are versatile, easy to handle, and have a relatively low cosLEpoxy resins are stronger than polyesters, but then, they are more expensive. They are also verydifficult to work with.

t-2

There are many substances conmonly actded to boat building resi-ns.Some are used to harden the resin. Others are used to control thecuring t irne of the resins. Stif t others are used to make the resinfire retardant since untreated f iberglass laninates are extremelyflanmable. Resins that have addit ives to rnake thern f ire retardantwi l l d isco lor , smoke, and char in the presence of heato but wi l lnot break in to f lame.

There are various steps which must be fol- lowed to build afiberglass huII, oE any f iberglass part for that matter. First aplug must be nade. This is a nale nold that looks exactly l ike thefinished product. I t can be made of wood, plaster, or almost anyother naterial, and is often rnade very f ightly and cheaply to cutdown on costs. The pluq is used to make a cavity mold, also knownaS a female mold. I t too may be made of wood, p laster , or o thermaterials. } lany t ines i t is made of f iberglass. The cavity rnoldis used to rnake the f inished hutl, much in the same way that a panis used to bake a cake. There are two ways to use a cavity mold inbui ld ing a f iberg lass hul l . One is the hand- Iayup process, and theother i ; the chopped-strand process. Sometimes a combination ofthe t$ to is used. In the hand- Iayup process, f i rs t the gel coat isappl ied to the ins ide of the mold, which wi l l g ive the boat i tscotor anO i ts f in ish sur face. Next a layer of f iberg lass c lo th istaiO down on the gel coat and bonded to i t with resin. This layerof c lo th acts as a re in forcement . Af ter th is , combinat ions ofcloth, mat, \doven roving, and sornetimes chopped strands are addedin successive layers unt i l the desi red th ickness of the huI I isobta ined. How the f iberg lass mater ia ls are combined has a lo t to dowi tn how st rong and durable the hul l w i t l be-

In the chopped-strand process, 9el coat is f irst applied to theins ide of the cav i ty no ld. Then a gun, which is fed wi th res in andfiberglass strands, in one operation chops the strands and ruixesthem wi th res ins. The mixture is sprayed over the gel coat .Handling the gun requires a great amount of ski l l so as to get aneven layer of f iberg lass mixed wi th res in over the gel coat . Anyrn iscalcu lat ions wi l l resul t in a hul l that is th ic lc in sone p lacesand th in in others, someth ing that wi l l produce a ter r ib ly weakboa t .

Af ter the basic f ibergtass huLl has been bui l t i t is s t rengthenedwitn st i f feners and other members. Then the rest of the boat isadded such as the declcs, the cabins, the superst ructure, e tc .

Another nay to make a f iberglass huII is to use the matched diernethod. Matched d ies are noth ing more than male and female molds,usual ly made of meta l , that are c lamped together wi th a laminatebetween. By applying the correct amount of pressure and heat, thehult is made uniform throughout.

l - -3

Sti l l another construct ion nethod is cal led sandwich construct ion.r t consists of a core nater ia l , usuar ly wood, such as balsa, thatis sandwiched on ei ther s ide by layers of f iberglass inpregnatedwith resin. ottrer core materials that are soietirnes

-used are

foaned plastics or plywood. Sandwich construction provides a boattfat_ is very strong and buoyant. There is one diawback though.Should the laninate become cracked, noisture can enter and stirtdry rot in the wooden core. This can cause a najor problern. (seef igure t -2 . )

BArSA n63rerA55tAh,{lNAIEOR oTt-lE<

@MATE€IAUFigurc 1-2.-Srndwich construction. Thc fiberglrs lamina& can bc madc up of rny combinrtion of mrt. doth,

or roving. Ulral ly only the cutsidc of thc hoctformed in thir manncr'u f inichcd with gcl coal

The advantages of f iberglass boat construction are many. Fiberglassby its very nature. is irnpervious to narine borers, shipworns; androt . S ince the f ibergJ-ass hul l does not have any seams as such(af ter a1 l i t is . ? one-p iece hurr ) there cannot be any reaksthrough seams or jo in ts . The co lor can be molded in to f iberg lass,so for a few years, a t least , tbe hul t need not be painted.

Don' t be foo led, however , the bot toms of f iberg lass boats are s t i l la f fected by 'qar ine growths and barnacles. r t is wise, then, to coatthe bot tom wi th ant i fou l ing paint .

Fiberglass boats can be extremely strong. This is true even thoughthey have very I i t t Ie f ran ing. This is not to say there are noweak f iberg lass boats, though. The qual i ty o f the engineer ing thatgoes in to any k ind of a boat d i rect ly a f fects how st iong that boatw i l l be .

Another advantage of f iberg lass is that i t can be molded in toal rnost any shape, nak ing i t very easy for the boat des igner . r tshould be noted, however , that f la t sur faces are not exact ly idealfor f ibergrass boats. Frat sur faces, when used, are norrnar lyre- in forced wi th some other type of nater ia l .

One of the d isadvantages of f iberg lass as a boat bu i ld ing mater ia lis that i t is heavier than water . F iberg lass does not haveinherent buoyancy. fn other words, a f iberg lass boat f i l led wi thwa te r w i l l s i nk , un less i t has bu i l t - i n f l o ta t i on . Such f l o ta t i onis usual ly prov ided by us ing a i r tanks, s tyrofoam, balsa wood, oFo the r ve ry l i gh t rua te r i a l s .

L -4

Another disadvantage of f iberglass boats is that they are usuallyvery heavy. In f iberglass, strength and weight are related.Though it is hard to mal

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Hull rnd d.ck plrnking,nrlingt and oth.rfinirrgr

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The principal considerations inselecting wood for boat buildingare strength, decay resistance,and avai lab i l i ty . Thesecondary,but s t i l l impor tant ,propert ies of woods that affecttheir selection for buitding areworkab i I i t y and w i t e rabsorption.

One o f t he b i gges tconsiderations of wood for boatbui ld ing is how i t wi I I endure.The effect of decay, marineborers, weather ing, heat , e tc . ,makes the difference betweengood wood and bad wood. Howt'rood stands up to decay is animportant factor. Decay-causingfungus plants gradually reducewood to a punky or crunblingmass .

Fungi that cause decay thrive indanp condit ions caused by freshbrater rather than salt water.Wood used in boats, that is notproper ly vent i la ted, a l lowingthe danpness to evaporate, wiIIalmost surely be attacked bydecay. More on this in lessontwo.

Sof twood of a l l wood species isIow in decay res is tance.Hardwood varies considerably indecay resistance according tothe type of wood. Only a fewtypes of wood are rated high inthis property. Hardwood of suchspecies as douglas f i r , cedar ,rnahogany, southern ye l low p ine,western larch, and whi te oak, isusual ly c lass i f ied as moderatein decay resistance andgenera l ly g ives good serv iceunder nold condi t ions of decay.

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1 - 6

STEEL. There are two metals that are most cornmonly used to buildboats, s tee l and a luminurn. Steel has been used in the past , and inthe present , too, for that mat ter , for fa i r ly large boats andyachts, whi le a luminum has been used for large and smal l craf t .For instance, a luminum accounts for the najor i ty o f canoes and johnboats bui l t today.

There are several advantages to steel construction. The mainadvantage is that steel, on a strength-to-weight ratio is strongerthan f iberg lass, wood, or a luminurn. I t ra tes h igh in res is tance toinpact , s t i f fness, abras ion res is tance, and fa t igue res is tance. AhuI I made of s tee l wi l l be l ighter than a hul l o f equal s t rengthmade of another boat bu i ld ing mater ia l .

Another advantage for s tee l const ruct ion deals wi th noise. Steel ,a lurn inum, and f iberg lass have been accused of be ing noisyrnater ia ls ; that is , they conduct no ise more readi ly than wood.Though th is is cer ta in ly t rue, s tee l , however , is less noisy thanaI I mater ia l except wood.

The f ina l advantage is res is tance to f i re . Steel and a luminuro aremore f i re res is tant than other mater ia ls . A s teel huI l wi l l s t i l lbe af loat a f ter a f i re that would have dest royed her f iberg lass orwood counterparts. This does not mean, however, that the non-steeIpar ts of a s teel boat wi l l be f i re-sh ie lded by the s teel . To the-ontrary, a steel boat can be gutted just as quickly, leaving justt he hu l l .

A potent ia l d isadvantage of s tee l for boats is i ts qu ickdeter iorat ion wi thout proper maintenance. A s teel huI I that hasnot been protected correctly fron corrosion can turn into a sorrymess within a short period of t ine. Boat owners who tend toneglect the i r boats would do bet ter wi th a f iberg lass boat .

ALttllINI'Ir{. Like steel, there are many advantages to aluminurnconstruction. One of the prinary advantages of aluminum as a boatbui ld ing mater ia l is i ts l iqht weight . This is why you see somany snit l boats made of alurninum. A canoe, which is required tobe very l ight is ideal ly su i ted for a luminun construct ion.

Another advantage is a luminum, I ike s teel and f iberg lass, isinpervious to narine borers. I t must, however, I ike the others, bepainted with a botton paint to reduce the growth of marine plantson the botton. It is irnportant to remember that aluninu:n and thecopper in botton paint are dissirni lar netals, and when in contactwi t l each other wi t f set up the process of e lect ro lys is . Unless youput a layer or two of non-metal l ic paint between the hull and thetottorn paint, your aluminum wit l be corroded in short order-Alurninun hulIs ind superstructures above the waterl ine need not bepainted at al l - alurninum does not oxidize to the extent of steel.

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one d isadvantage of aruminum is that i t is a very good heatconductor. Aluninum hulls tend to sweat considerably because ofth is . Another d isadvantage is that a lurn inum has a fa i r ly lownel t ing point . rn the presence of a f i re wi th in tense heat ,a luminum wi l l mer t more readi ly than wi l l s tee l . Anotherd isadvantage is that i t is no isy. r t is so noisy that i f the hul lo f an a luminurn boat is not specia l ly t reated against no ise, i t w i l lconduct sounds unheard of in boats buil t of other materials. Tosit in an outboard-motor-powered, non-sound-darnpened alurninum boatbeing operated at high speed can be deafening.

FABRTG (rnf la tab les) . A c lass of boats gain ing increasedpopular i ty is the in f la tab les. They have been around for long t inebut on ly s tar ted to gain ut i l i ty dur ing and af ter I {W I I .

These boats have a wide range of uses frorn the l ight single p1y forp lay to the many layered laminates used for running rapids andheavy ocean use.

Use of many of the synthet ic rnater ia ls , inc lud ing one that is nowused for bu l le t proof vests , enable the bui lders to fabr icate forext reme toughness. As in other mater iars , a wide range of des ignis now being produced inc lud ing large boats wi th inboard enginesand r i g id hu l l s w i th t remendous seakeep ing ab i l i t i es . Thesequal i t ies make them valuable for such dut ies as board i rg, rescue inheavy seas, and where the requi rement is for maximum buoyancy andsha l l ow d ra f t .

There are severa l advantages of fabr ic boats over other boats. Oneis the ease of t ranspor t both in the def la ted and in f la tedcond i t i on . f n f l a t i ons may be accomp l i shed by CO, bo t t l es , bu tgenera l ly is done wi th an a i r punp. The mater iars are tough andw i th reasonab le ca re these boa ts w i r r ras t a rong t ime . They donot rust , b l is ter , or have dry- rot , and storage and haul out can beeas ie r t han boa ts made o f o the r ma te r ia l s .

TYPES OF STBEEING SYSTEI{S. Basical ly, there are six differenttypes of s teer ing systems in use on p leasure boats today. Some ofthem are fa i r ly s imple, requi r ing few gears or pu l leys, but o thersare ext remely complex and employ scores of moving par ts . Here arethe s i x :

1 , T i l l e r2 . D rum and cab le3 . Sp rocke t and cha in

4 . Rack and p in ion5. Gear and shaf t6 . Hyd rauJ - i c

The t i l ler system is the ear l iest type of s teer ing arrangement , andthe s inp les t , f t i s s t i t l used w ide l y on sa i l boa ts , bu t has foundIimited use for powerboats. Just about the only powerboats st i l lus ing t i l l e r s a re sma l l l aunches . T i l l e r s a re easy to hand le andhave no compl icated gears or pu l leys. A t i l ler s teer ing systern isnoth ing more than a hor izonta l p iece of wood or neta l that isattached to the head of the rudder stock.

1 -8

Ti l lers are predorn inant ly usedin sa i lboats. The naind i sadvan tage o f a t i l l e r i s t ha ti t takes up too much room in thecockp i t o f a boa t . And , o fcou rse , a t i l l e r i n a l a rge boa thas very I i t t le mechanica ladvan tage . (See f i g . 1 -3 . )

The drum and cable systen isprobably the next sinplests teer ing system. f t is nade upof a drurn connected to as tee r ing whee l . A cab le i sbound around the drun. The twoends o f t he cab le , a f te r pass ingthrough pul leys, are at tached tothe t i ] l e r o r rudder quadran t .When the wheel is tuned, oneside of the cable is wound uP onthe drurn while the other side isunwound. This is t ransmi t tedthrough the pulleys to rudderquadran t o r - t i l I e r ; t he boa twi I I turn to the r ight or thelef t , depending on which waY thewhee l i s t u rned . (See f i q . 1 -4 . )

Actual ly , the sprocket and chainsystem is noth ing more than avar ia t ion of the drum and cablesystem. Instead of a drum, asprocket is used; and instead ofa cable, a cha j .n ' comPat ib lew i th the sp rocke t , i s used .Operat ion of the s teer ing sYstemis ident ica l to the drum andcable sYstem

The rack and p in ion s tee r ingsystem is becoming more and morepopu la r , because i t t akes uPless room than the three tYPesdescr ibed above and g ives theboat operator nore sensi t ives tee r i ng . (See f i g . 1 -5 . ) Thesteer ing wheel has a smal Ip in ion gea r a t t he end o f t hes tee r ing whee l sha f t . Th i s

Figurc 1.3.-A tillcr rtecring ,yrtrm.

p in ion gea r engages a rack ,wnicn is a f la t , ra ther than round, gear . At tached to the rack isa cab1e , wh ich i s i n a condu i t . Th i s cab le i s a t tached

Figurc 14.-Thc drum rnd flcxible cablc rtocring ryrtom. Ths cabler can bc rfiadred to r tittor or rudderquadrrnt.

Figun 1-S.-Thc rrck and pinion (purh-pulll

rtecring Jystem.

Tru.ER

F,Lt:Y

51FSRtNe

l _ -9

at the other end to the rudder assembly. There is no need forpulleys in this system and the cabre Can go up, down, and aroundaccording to the layout of the boat" when the pinion gear turnsand engages the rack, the cabre is pushed or pulled, ac6ordinq iowhich way the steering wheel is turned. The cable iransmits €fr ispush or pull to the rudder assenbly, which in turn translates i tin to r ight or le f t rudder .

The gear and shaf t s teer ing systern is se ldom found on smal l boats.rt is found more often on large craft, usually commercial boats.At the end of the s teer inq wheel i -s a bevel dr iv ing gear , whichengages another gear that is connected to a shaf t . The shaf t ,sornet imes ut i l iz ing universal jo in ts , t ravels f rom the s teer ingwheel to the rudder, where its notion is transrated by a worm gear,a bevef gear , or cables and purreys, to ref t or r igh l rudder :

Hydraulic steering systems are sini lar to automotive powersteer ing. This type of system is be ing found on an incre ls ingnumber of recreat ional vessels . They use hydraul ic f lu id that i ;purnped through a system to actuate the rudder. The steering wheelis connected to a pump with valves. l{hen the wheel is turn6d, thepump pushes f lu id through the appropr ia te va lves in to hydraul icl ines that carry the f lu id to the actuat ing cy l inder . rn thecy l i nde r , t he mo t ion o f t he f l u id i s t rans la tea i n to te f t o r r i gh trudder by a l inkage to the rudder head.

1 - L 0

STUDY QUESTIONS

l - . A f iberg lass hu l l i s composed o f

2. L is t the four types of f iberg lass re in forc ing rnater ia ls :

saturated with .

t _ .

2 .

3 .

4 .

3. The two types of res ins used in f iberg lass construct ion are

and

4. There are many substances added to boat bu i ld ing res ins. They

are used toand to

5. A rnale rno ld is known as a

6. A f emale rnold is known as a

7. The hand- layup and chopped-st rand processes are used in

A .

g. In the hand- Iayup and chopped-st rand processes, the

is appl ied to the ins ide of the rnold f i rs t -

g . In the matched-d ie method the

are clamped together with

10. What core mater ia ls are used in sandwich construct ion?

l t_ . L is t the advantages of f iberg lass-bui l t boats.

t - L L

12. L is t the d isadvantages of f iberg lass-bui l t boats.

13. What are the two genera l c lasses of wood?

L4. What are the pr inc ipa l considerat ions in the se lect ion of

various types of wood for boat building?

l -5. L is t the advantages of s tee l for boat bu i ld ing.

16. The d isadvantage o f s tee l fo r boat bu i ld ing is

17. Why rnust you put a layer of nonmeta l l ic pa int between the

hult of an aluminum boat and a layer of copper bottom paint?

18. L is t the advantages of a luminum for boat bu i ld ing.

19. L is t the d isadvantages of a luminum for boat bu i ld ing.

20 . The s i x t ypes o f s tee r ing sys tems a re :

1 .

2 .

3 .

4 .

6 .

t-L2

21. The simplest steering system is the

22. The cuve or sweep of the deck of a vessel whe.n viewed from the side is tlre

23, The outward cruvature of the sides of the boat near the bow that is used to keepthe deck drier is called the

24. What are the three basic shapes of thE bottom of a boat?

25. What is the diftrence between a displacement and planing huln

26. In wood boa constnrcdon, the plank attached starting at the gunwale is the

27. What is the differcnce betwe€n a trunk cabin and a raised deck cabin?

28. What re limber holes and what purpose do they senre?

29. The use of two or more materials in the hull of a vessel is known ascons8uction.

30 The portion of the extotior hull at the waterline is called thp

cH2

top.

r-13

31, The spoke of a steering wheel that is vertical when the rudder is exacfly centeredis the _spoke.

32. The vertical distance betweeu the waterline and gunwale is _.

33. Desctibe the characteristics of the followiug sailboat qpes:

Catboat

34. The gross tonnage of a vessel is

Sloop

Ketch

Yawl

cH2l -14

CHAPTER 2

BOAT IIAII'TENAIICE

IIflrRODUCTION. The study questions at the end of the lesson arebased on the readings in this chapter and not on any outsideread ings .

HAULfNG OtIf. Hauling out t ine is one of the nost important t inesto ensure the proper maintenance of your boat. To most boaters,however , haul ing out s ignals the end of the boat ing Season, andmaintenance is put as ide unt i l the f i t t j "ng out per iod just beforethe boat is launched in the spr ing. That a t t i tude is dangerous,since it can mean more work later. Many of the maintenance choresyou night face in the spring can be handled when the boat is hauledout, or can even be prevented if the job is handled correctly atthe beginning. What you do when you haul your boat, and how you goabout Aoing i t , can mean the d i f ference between a wel l -na inta inedboat and a poor ly rna inta ined boat , regard less of your in tent ions.

When you haul your boat, whether the job is done by you or at ayard, the f i rs t th ing to consider is the proper b lock ing of thehul l . Boats should be s tored upr ight , though d inghies, canoes, andother small craft can be stored upside down provided they arecovered adequately. Upright boats must be blocked correctly. Theweight o f the boat should rest on the keel , which should i tse l frest on b locks to a l low vent i la t ion of the bot tom of the keel .Blocks should be spaced about every f ive feet along the keel andshould be high enough so that you can get to the bottom of the keelto per form your maintenance chores. When you b loc l . tp your boat ,t ry to get the water l ine as level as poss ib le ; th is wi l l preventthe boat f rom being subjected to s t ra ins she htas not des igned tohandle. Do not a l low the weight o f the boat to rest on the shor ingthat you wi I I have to use to hold the boat upr ight ; th is shor ing isin ten-ded only as la tera l suppor ts , s ince excessive s t ra ins on thesides and bottom of the hull could do severe damage to thest ructura l s t rength of the boat .

The procedures to fo l low i f you wi l l be s tor ing your boat on at ra i ier are the same. The boat should rest on her keel ; the s idesuppor ts of the t ra i ler should only keep the boat upr ight . .Becer ta in to b lock up the tongue of the t ra i ler so that the boat wiL lbe l eve l a t he r wa te r l i ne .

Af ter the boat is b locked up, the real lay ing-up procedure begins.It is here boats are neglected. Too many boat onners see theirboats hauled up on shore at th is s tage and assume that a l l work onher has ceased unt i l the fo l lowing spr ing.

2-1,

rmnediatery af ter the boat is haured, crean the bot ton of ar lgrowths and nar ine l i fe . r f you wai t to do the job, a l l thatgrowth on the bottorn wil l dry up and harden l ike cement. In shortorder, i t wil l seem as if that ness has become a permanent part ofthe hul l . At the same t ime, wash the ent i re hul l down wi tn f reshwater , inc lud ing decks and superst ructure. This is especia l lyimpor tant i f you are going to s tore the boat under cover , u" thafal l and winter rains wil l then have no chance to wash away al l thesal twater that can becorne crusted on every sur face.

LAYING ttP. When laying up the boat, there are several inportants teps that must be taken.

Dra in, and i f necessary, winter ize your water systen wi th non- tox icRV an t i f r eeze .

F i l I t he fue l t anks and use a fueL s tab i l i z i ng compound . Th i s w i I Iprevent the format ion of varn ish in the fue l system and a id inreducing water condensat ion in the tanks.

Dra in the b i tge. Leave the dra in prug out , but s tow i t where youcan f i nd i t be fo re l aunch ing . r f you don , t have a d ra in i n t nebottom of your boat, pump out as much as you can and then spongedry the res t .

change the eng ine o i l and f i l t e r and then l ay up the eng ineaccord ing to the speci f icat ions of the par t icu la i engine that youa re us ing ; each manu fac tu re r has i ns t ruc t i ons tha t upp ly to i t =machinery. This usual ly involves a t t foggingrr procedure-wnich coatsthe cy l i nde r wa l l s w i th o i l t o p reven t co r roJ ion .

Remove the bat tery and store i t in a rocat ion not subject tof reez ing . The ba t te ry shou ld be checked pe r iod i ca l l y andmainta ined in a fu l ty charged state dur ing s torage.

Go through the ent i re boat and remove arr the per ishables youf ind. Don' t be faced wi th return ing to your boat in the spr ingd iscove r ing a l i nge r ing odo r tha t w i I I no t go away ,

r f you have a hold ing tank, f lush i t out wi th f resh water andapprop r ia te non - tox i c RV an t i f r eeze . Remove a l r l i qu ids i nboa t t ha t m igh t f reeze .

Remove a l l " c l o thes , bedd ing , ma t t resses , r i f e j acke ts , e t c . , andc lean them be fo re s to r i ng i n a c lean ven t i l a ted , d ry p lace .

Take ou t eve ry th ing tha t i s movab le , i nc lud ing a I l t hose i t ens tha tare l ikery aspects for thef t , such as the compass, nav igat iontoo l s , r ad io te l ephone , oa rs , e t c .

Af ter a l l o f th is gear is out o f the boat , wash down the in ter ior ,i nc lud ing the cockp i t a rea , l ocke rs , and fo repeak . Remove thefLoo r -boa rds and l eave them o f f t o a l l ow the b i l ge to ven t i l a te .I f t he boa t i s t o be cove red , l eave the eng ine cove r o f f .

canand

addthe

2 -2

Your boat is now ready to be covered. f f you are going to keep theboat in a shed, so much the better. But i f not, the best bet is tocover the boat wi th a tarp or p last ic . Whatever you use, be surethat the boat is venti lated. Leave spaces around the covering toa l l ow a i r t o c i r cu la te . Th i s w i I I p reven t condensa t i on , wh ich w i l lresult in dry rot andr/or a foul sroell . I t night be a good idea tobui ld a l iqht f ramework over the boat , i f i t is large, to suppor tthe covering. PVC pipe makes an easily constructed framework.

Now check over the cover ing for secur i ty . Make cer ta in that i t ison t iqhtly and that aII t ie-downs are knotted securely. Go overeach i t ress point , and i f there is any doubt in your mind aboutwhether i t w i l l ho ld, then i t w i l l not . Check for p laces wherechafe n ight occur , and put chaf ing gear in p laces where i t isca l led for . Bungee cords are good for mainta in ing tens ion on thecove r .

Check the boa t pe r iod i ca l l y du r ing he r l ayup pe r iod , espec ia l l yaf ter s torms (before, too, for that rnat ter ) . I f you leave the boatin a storage yard, make sure that sornebody nearby has your

telephone nurnber so that you can be contacted in an emergency.

BOTTOU pArNTS. Moored boats suffer from a common problen-thef"r,, f :-. ,q of their bottoms by marine growths over a period of t ine.The tyb" of these growths and the sever i ty o f the i r presence

depenal on local condi t ions. Some areas of the country seem topronote more mar ine growths than others, but no mat ter thelocat ion, a t least some organisms wi l l becone at tached to a boat 'sbot tom over the course of the boat ing season.

Mar ine growth takes two forms: vegetable and animal L i fe . Thoughbo th t ypes can be found ove r a l l pa r t s o f a boa t ' s hu l l , t hegenerai tendency is for vegetable growths to congregate around thewater l ine and ani rna l growths to spread over the l -ower par ts of thehuI I . Vegetable growtn inc ludes weeds, a lgae, and fungi . Animalg rowths i r i c l ude ba rnac les , m inu te she l l f i sh , and worms ( i n t rop i ca lc l ima tes ) .

Two th ings can happen to a wooden huI I that is unprotected andat tacked by mar ine growths. The bui ld-up of p lant l i fe on the

bottorn can become so great that the performance of the boat isgreat ly reduced. The boat wi I I become s luggish and her speed wi l l

6" q . " i t ly reduced. The at tack of an imal growth can resul t in the

weaiening and perhaps even the dest ruct ion of the huI I . Th is is

especia l iy t rue of mlr ine borers that are found in t rop ica l waters.

Boats of materials other than wood are not threatened by borers and

worms ; f i be rg lass , f e r ro -cemen t , a lum inum, and s tee l boa ts a re

irnpervious to tnis type of growth. But contrary to sorne beliefs,

th ly can st i l l be - i t tacked

by vegetable growth and must bep ro tec ted as ca re fu l l y as wooden hu l I s .

2 -3

rn years past, the sorution to the probrem was to sheath hurlbottoms with copper. Sailors discovered that, although copper doesnot corrode much in the presence of sea water, i t constantly givesoff soluble poisonous salts when inmersed in salt water. ihesesar ts , dS they wash of f the sur face of the copper , e f fect ive lyprevent the adhesion of weeds, sherlf ish, and worms to the hurr.

Today, boaters use modern bottom paints that perform the samefunction as copper sheathing. These paints ki l I marine growths inthei r ear ly s tages, prevent ing a bui ld-up of vegetat ion ind aninall i fe on the bottour. The principle of these paints is the same asfor the copper sheathing-a constant solution of poisonous matters(prinari ly copper and mercury) is given off by the paint. i larinegrowths are thus discouraged by what is in effect an antisepticf i lrn on the bottom of the boat.

one d i f f icu l ty o f bot torn paint is that i t is far less permanentthan ord inary mar ine paint . The paint is d issolv ing in the water ,so that a t the end of a boat ing season, there wi l l be very t i t t leleft. Most bottom paints sold today rnust be applied annually forth is very reason. But when choosing between paint ing the bot tomonce a year , or scraping growths of f the bot torn per iod ica l ly , mostboaters wise ly choose the former.

Another problern caused by bottorn paint is galvanic action, whichw i l l be d i scussed l a te r on i n t h i s l esson . Pa in t s tha t con ta inmercury and/or copper react with certain other metals in such a waythat the meta ls can be corroded. For instance, a wooden boat thathas fer rous fasteni -ngs, such as i ron, wi I I soon have no fasteningsa t a l l i f i t i s pa in ted w i th a copper bo t tom pa in t . Th i s i s onereason why you don' t hear much about i ron boat na i ls these days.Even galvanized fer rous fastenings can deter iorate under copperpaint i f onry a t iny n ick is made in the z inc coat ing. specia lsac r i f i c i a l z i nc anodes he lp p reven t ga l van ic ac t i on (as d i scussedlater) and should not be painted.

when buying and appry ing bot tom paint , be ext remery carefur . Readthe laber and tark i t over wi th your paint dearer . l , ta tch thebot tom paint to your boat . Consider the other rneta ls in your boatthat wi I I be in f luenced by the paint i for instance, the meta l inthe skeg , s t ru t , p rope l l e r , sha f t , r udder p in t l es and gudgeons ,etc . Manufacturers have developed many d i f ferent bot ton paints formany d i f f e ren t cond i t i ons . Odds a re tha t you w i l l f i nd one tha t i si dea l l y su i t ed to you r boa t .

DRY ROT. Dry rot is one of the ev i ls that face owners of woodenboats. I t is always Iurking about, ready to str ike when and whereyou l eas t expec t i t . f f you have i t and cu re i t , i t o f t enreappears just after you have convinced yourself that i t is qonefo r good .

2 -4

Dry rot is a nisnomer, as this type of rot only can take hold inthe presence of wetness or dampness. It is caused by a fungrus thatthrives on fresh water. Saltwater seems to discourage dry rot,though it , wiII not necessari ly cure i t once it has taken hold.

Usual ly the f i rs t ind icat ion of dry rot is i ts snel l . I t has arnusty, moldy odor. Once you have snelled dry rot you wil l probablynever forget i t . You are snell ing the worl< of the fungus thatattacks the f ibers of the wood and reduces it to a soft ' powdery,spongy, weak ness.

If you suspect dry rot, thef i rs t p laces to look are dark,danp places. Check out areaswhere fresh water, in the formof ra in or condensat ion, canenter . Some of the nore l ike lYp laces a re : i n t he b i l ge ,especia l ly the garboard s t rakes;in the f loors i in the Plankingaround and behind the frames; atthe top and bottom of theframes; between the deck beansand the deck; under the deck;under the coaning and betweenthe coaming and the deck; in thetransom where it meets thebottom and the sides.

gdr.b.d @ra-a

Figun 2'1.4ommon lnrlt whcrc dry rot drrivcr

Thc tranroor d $c bil6 ir alro I gtctt collcstor of

nRlxtrg-/tE.r6 a1pft4o- fR^rts'

st Br.(.t. GfEcoLLY6!6crs{8t€

Look in a l l o f the above praces, t t t '

and any other l ikelY locationsas weI I . But don ' t conf ine your inspect ion to s ight a lone. Getout your knife, or a spike, and start probing. Dig around for softspots that are easy to penetrate and disintegrate easily. Younight have to remove various parts of your boat to get atsuipicious areas, and even get your hands dirty, but the searchruust be done if you want your boat to last- (See f ig. 2-L-)

After you have found dry rot, i t nust be renoved. The fungus wil lspread l ike wildf ire i f i t is not checked, and merely soaking itwi tn a preservat ive, o ! someth ing you th ink n ight k i l l i t , is noteneugh. Cut out the affected wood innediat€IY, and.get as nuch oneither side of the rot as you can. By cutt ing back into good wood,you are providing for a margin of error. There is no way to tel li f tne fungus has spread from the obviously rotten section or not.

There is a preparation on the market that is said to help you soJ.vethe dry rot problem without cutt i .ng out the affected wood. Peoplewho have used thi-s material have had good results for the mostpar t , and i t is cer ta in ly wor th invest igat ing.

2-5

The rnost effective way to l ick the dry rot problem is to prevent i tfrom gett in.g in your boat in the f irst place. The best way ofdoing this is to keep fresh water out and stop it from collecting.This neans naking sure that hatches are t ight, decks are wellcaurked, f i t t ings are bedded in conpound, etc. rf fresh watercan't get into your boat, then you have nothing to worry about.But you must also be certain that fresh water can also get out ofyour boat. Condensation can form inside the boat and cause dry rotas easily as can rainwater frorn without. Make sure your boat iswe l l ven t i l a ted a t a I I t imes .

Another way to prevent dry rot is to appty wood preservative to aIIunpainted and unvarnished surfaces. There are many preservativeson the market today that are effective, though nothing wil l offeryou total protection. onry by being constantly on your guard canyou keep dry rot out of a wooden boat.

GALVAI{IC ACTION. The process of electrolysis is based on thepr inc ip le that two d iss in i rar metars, when praced in sar t water(or non-pure f resh-water) , generate e lect r ic i ty by a chemicarprocess. This is garvanic act ion. Galvanic act ion is thepr inc ip le behind the funct ion ing of a dry-ce l l bat tery . I t is a lsothe pr ime e lement in the dest ruct ion of meta ls in a boat .

The corrosion of metals by electrochernical action is something al lboaters must be concerned wi th . Unless carefu l a t tent ion is pa idto the types of rnetars that go into a boat, the fastenings,f i t t ings, and even the huI I o f meta l boats can quick ly deter iorateand crumbre away. Though galvanic action is a probrem facedpr imar i ly by boats used in sa l t water , f resh-water boaters cannotbe totarry ignorant of the probrern. Not al l fresh water ischemical ly pure, and even water that is ever so s l ight ly brack ishcan set ga lvanic act ion in to mot ion.

Galvanic act ion as boaters know i t , takes p lace when two d iss in i larmetals that are electr ical ly connected are immersed in non-chemical ly-pure water . The meta ls actual ly don ' t even have to bein the water; corrosion can take place when the metals areconnected only by danp wood. By galvanic action, one metal of thetwo is corroded at the expense of the other.

what exact ry is a d iss imi lar neta l? To make i t . easy on thoseboaters who are not chemical engineers, the fol lowing Electrolyt icTable prov ides the answer. Meta ls are rated as being r tmost noblet lor f l Ieast noble. r f Current wi l t f low f ron the less noble to themore nobre meta l i in the process, the less noble meta l wi l l bedestroyed.

2-6

fn the tab le, the nost noblemetals are at the top, and theIeast noble meta ls are at thebot tom. In other words, n ickeltogether with aluminum in non-pure water wil l produce anelect r ica l current that wi I leventually result in thedestruction of the alurninum.

Galvanic act ion is ins id ious.It takes place when you leastexpect i t . For instance, i f youuse copper botton paint on thehuII of an aluminun boat, thecopper in the paint wil l corrodethe alurninum in the hull . Theonly bray you can prevent this,assuruing that you must use acopper ant i - fou l ing paint , is toput a layer ofnon-ruetal l ic paint between thetwo. But even then, you must becertain that the coverage of thenonneta l l ic pa int is absolute.The sl ightest exposure of thealuninum below can result inga l van ic ac t i on .

ord inary ye l low brass, conposedof z inc and copper , carr ies theseeds of i ts own destruction insal t water . over a per iod of t ine, the galvanic act ion in , Sdy, abrass screw, wiII erode the zinc, Ieaving a spongry mass of copper.For that reason, brass screws, brass sea cocks, and va lves areuseless in sa l t water .

What can you do? lilost boats require many types of netal f ordiverse purposes. For instance, a boat that has a bronze propellerand an iron rudder needs protection or the rudder wil l be quicklydestroyed. The answer is to add a third metal to the process.This th i rd meta l is known as a sacr i f ic ia l rneta l i t is sacr i f icedto save the other two. To protect the iron rudder, a block of zincor other rnetaL less noble than iron can be attached to the rudder.What happens then is the zinc, not the iron, sets up a current withthe bronze propel ler , which is most noble, and is i tse l f dest royed.Thus the iron rudder is protected. The bronze propeller, since iti s mos t nob le , t akes ca re o f i t se l f .

THE ELECTROLYTIC TASLE

Mrranry

Monrl

Nickcl

Eronzr {rillcon}

Copprr

Eras lrtdl

Sron:r {dunrlruml

Gun mrol

Brut lyrllow)

Bron:r (phqhor)

Tin

L..d

Stacl (rtainlorl

I ron

Strl (mildl

Aluminum

Crdmium

Galwnizrd iroo tnd cta.l

Zirc

Megrniwn

Th. illtalr clot togath.r in thir t$h can bo tnrdto{adr.r. Mrtali frr ap.n clnnot. For insoncr. brooza rndcoppar crn bc urcd togcthr; alqminum and copprr crnnot.

2 -7

Note: when us ing sacr i f ic iar metars on your boat , be cer ta in toreplace then per iod ica l ry . r f you do not , you wi l l be foo led byyour ohtn craf t iness the sacr i f ic ia l neta l wi l l conplete ly erode,Ieav ing you wi th the or ig ina l two meta ls , which wi l l imrnediate ly goto work on each other . Remember, do not pa int over the z incsr or -e lse they wi l l not work.

ELEqIROLYTfC ACTfON. Electrolyt ic action is an electrochemicalprocess s in i lar to galvanic act ion. When an e lect r ica l currentfrom an independent source, such as a battery, passes through arle lect ro ly t ic f ru id , such as sea water , metar wi l l be dest royed. r fa stray current from some source on a boat (or adjacent boat)passes through a meta l hurr f i t t ing, for instance, in to the sea,meta l wi I I be t ransferred f ron the hul l f i t t ing. Eventual ly i twil l be eroded. Uetal wiII not be transferred, however, where thecurrent re-enters the boat .

The so lut ion to the problern of e lect ro ly t ic act ion is to e l i rn inatestray electr ical currents from the power sources in your boat. Inrnost boats, the problen centers around the battery. Make sure thatthe negative pole of the battery rather than the posit ive pole isgrounded to the engine. This should be done because current f lowsfrom posi t ive to negat ive. Thus, current s t ray ing f rom theposit ive side of the battery wiII re-enter the boat through thepropel ler shaf t , which is , o f course, connected to the engine. Assaid prev ious ly , meta l t ransfer wi l l not take p lace at the point o fent ry of an e lect r ica l current .

In addi t ion, to prevent other s t ray currents in your boat , checkal1 other electr ical equipment. l , lake sure that everything isproper ly grounded and secure.

Figure 2-2.-The essential parts of the shaft train.

TIIE SHAFT TRArN ( f igure 2-2) .The shaft train of an inboardmar ine engine insta l la t ion isthe nachinery that transmits thepohrer of the engine inside theboat to the propeller outsidethe boat . f t is made up, innost inboard boats, of the shaftlog, the shaf t , the s t rut , thestrut bearing, and thepropel ler . The except ion toth is type of insta l la t ion are V-dr ives and hydraul ic dr ives.

The shaf t is most usual ly acont inuous p iece that is a t tached to the engine by a coupl ing onone end and to the propel ler a t the other end. However , i f forsome reason the shaf t cannot go in a s t ra ight l ine i t n ight have auniversal jo in t to aI low for the change in d i rect ion. Most shaf tstoday a re rnade o f b ronze , mone l , oF s ta in less s tee l .

2-8

The shaft nust eventually 90through the bottom of the hull .To do th is , i t passes through ashaft 1og. At the inboard endof the shaft log there is astuf f ing box. This is s i rn i larto the packing gland in a waterfaucet. This combination of theshaft 1og and stuff ing boxprevents water from entering theboat through the shaft hole.The stuffing box surrounds theshaft and holds r ings of packingmater ia l . These r ings aresqueezed t ightty around theshaft by a ttglandtr or rrgland

nutrr. Water can come up intothe shaft log from the bottorn,but is prevented from enteringthe boat by the packing materialin the s tuf f ing box. The shaf tIog and stuff ing box are usuaIIYmade of bronze. The Packingmater ia l is made of a specia lf l ex ib le na te r i a l .

0t AiloI{UIfl.Arf0

sruffil6BOI

tigre 2-3. Typicaf stuffing bor.

Check the s tuf f ing box per iod ica l ly , but don ' t be a larmed i f thereis a sl ight drip of water coning frorn i t . l ,{ost stuff ing boxes relyon a srnall amount of water gett ing through to work properly.Usually t ightening down on the gland nut, which squeezes thepacking mater ia l more, wi l l contro l the amount of dr ip . I f youhave a leak, however, and no amount of t ightening of the nut stopsi t , then you wi l l probably have to rep lace the pack ing rnater ia l .This is a sirnple process that amounts to nothing more than backingoff the gland nut and wrapping new packing material around theshaf t ins ide the s tuf f ing box.

Once through the hull , the shaft goes through the strut. The strutis an appendage attached to the botton of the boat that acts as asupport and bearing for the shaft. There are many types of strutsin use today, nost with only one arm but sone with two or three.

The strut must always be securely bolted to the bottom of the boatand must be r ig id . I f i t is not , the shaf t wi l l be able to wobble 'the bearing night be ruined, the shaft rnight bend, and you wil l atIeast get a considerable anount of vibration in your boat. As thestrut, shaft, and strut bearing are underwater, the bearing rel ieson water for lubrication. Bearings in the old days were almostalways made of l ignum vitae wood, but now they are.usually nade ofrubber or micarta. Many of then have grooves cut in then to al lowfor a continuous f low of water inside. The bearing rnust be checked

2-9

per iod i ca l l ybear ing goes,

At the end of the shaf t is the propel ler , which comes in nany s izes

and shapes. eiopellers diffe-r i ; diarneter, pitch, direction of

iotation, shaft-n^ofe size, and the nunber of blades. The dianeter

of a propeller is simply the diameter of the circle defined by the

tips tf -tne

turning bfaaes. The pitch of the propeller is the

.ngt" of the blades; to engineers, i t is the distance the propeller

wouta move ahead after one revolution. The number of blades for apropeller can go fron two on up. Most powerboats use a three-

b laded proPel ler .

The selection of a propeller is beyond the scope of this lesson.

It is appropriately in the realrrn of naval architects, that many

calcuta€ions and considerations must be applied to arrive at the

r ight propel ler for the r ight boat .

your main concern about the propeller is whether i t wil l stay on

the shaft. Because most propellers must operate in forward and

reverse, a lock nut must be used to keep it on t-he shaft ' Uost

instal lat ions use a nut backed by a janb nut combined with a key-

Whatever your boat uses, check i t out per iod ica l ly to ensure that

it is secure. The last thing you want to do is lose your

p rope l l e r .

to be certain that i t is in good condit ion. If thethe shaft can be damaged.

2 - L O

STT'DY QUESTIONS

l-. What is the proper way to block up a hul l?

2. Why shouldn't you al low the weight of the boat to rest on

the shor ing?

3. List the lay-up chores that must be done after the boat ishau led ou t .

4 . What is the purpose of a l lowing the boat to vent i la te when

i t is layed up?

5. The two types of marine growth are and

6. What are the two things that can happen to a wooden boat that

is not protected against marine growths?

7. How does copper protect a boat 's hu l l?

8. t lhat should you consider when select ing a bot ton paint

for your boat?

9. What causes dry rot?

10. A f i rst indicat ion of drY rot is

2-Lt

l -1. Lj-st some of the places to look for dry rot in a wooden boat.

L2. When dry rot is found, i t must be

L3. How can you prevent dry rot?

14. What is the difference between galvanic action and

elect ro ly t ic act ion?

15 . Cur ren t w i l t f l ow f rom the metal to the

meta l dur ing galvanic act ion.

16. What is the pr inc ip le of us ing a sacr i f ic ia l meta l to min in ize

the ef fect o f ga lvanic act ion?

17. How can you prevent e lect ro ly t ic act ion?

18. The shaf t t ra in is made uP of

f

, and

19. How does the s tuf f ing box work?

20. The st rut bear ing re l ies on for lubr icat ion.

21. What is used to keep the propel ler on the shaf t?

2 -L2

CHAPTER 3

TNTERNAL CPI{BUSTIOI'I ENGTNES

ffflfRODUCTIOX. The study questions at the end of the chapter arebased on the readings in this chapter and not on any outsideread ing .

RECIPROCATfNG ENGINES. The internal combustion engines (diesel andgasol ine engines) , wi th which most boaters work, are nachines thatchange, or convert, heat energry into work by burning fuel in aconbustion chamber. Since the pistons in diesel and gasolineengi-nes use an up-and-down notion, they are classif ied asrec iprocat ing engines.

IGNITION PRIXCIPLES. The gasoline and diesel engines differpr inc ipa l ly in the method of ign i t ing the fue l .

Gasoline Engines. Gasoline engines uses a spark ignit ion systemand are referred to as an SPARK fGNITION ENGINE. The fuel andai r for the engine is rn ixed in the carburetor (or a in ject ionchamber i f fue l in jectors are used) . This mixture is drawn in tothe cy l inders where i t is compressed and ign i ted by an e lect r icspark from the spark plugs.

Diesel Engines. The d iesel engine takes in atmospher ic a i r ,compresses it , and then injects the fuel into the combustionspace. The heat generated by compress ion of the a i r ign i tes thefuel. Hence it is referred to as a COI{PRESSION IGNfTION EIIGINE.Diesel engines used in boats look very much l ike the gasol ineengine. They have fue l in jectors in p lace of a carburetor , andthe l ines leading to the ry I inders carry fue l o i l instead of ane lec t r i c cu r ren t .

OPERATING CYCLE. AII reciprocating engines have a definite cycleof operat ion. I t is necessary to atonize the fue l , 9et i t in to thecy l inders, burn i t , and d ispose of the gases of combust ion. AI Ireciprocating internal cornbustion engines operate on either a 2-s t roke or a 4-s t roke cyc le. A s t roke is a s ing le up or downmovement of the piston, or the distance a piston moves betweenl in i ts o f t ravel . Each p is ton executes two st rokes for eachrevolution of the crankshaft. The number of piston strokesoccurr ing dur ing any one ser ies of operat ions (cyc le) is l in i ted toeither two or four, depending upon the design of the engine.

FOUR STROKE CYCLB engines are used in most automobiles. Eachpiston goes through four strokes and the crankshaft makes tworevolut ions to cornplete one cyc le. In th is case, each p is ton isdelivering polrer during one stroke in four, or there is one polrers t roke for each two revolut ions of the crankshaf t .

3 - t

rxru!l

t

FiEue 3-1. Ibe Porr StrokeGasoline Brqine.

Let us use one cyc le of a gasol ine engine totrace its operation through the four strokestha t make up a cyc le . (See F igu re 3 -1 . )First there is the fNTAKE STROKE. The intakevalve is open and the exhaust valve isclosed. The piston moves down, drawing amixture of a i r and gasol ine in to the cy l inderthrough the open valve. This is shown in 1.

Next is the COI,IPRESSfON STROKE. Both theintake and exhaust valves are closed andduring this stroke and the piston startsrnoving upward ( i l lus t rat ion 2) . The a i r lgasmixture which entered the cyl inder during theintake stroke is conpressed into the smallspace above the p is ton. The vo lume of th isair may be reduced to less than A/B of whati t was at the beginning of the s t roke.

The h igh pressure which is a resul t o f th isgreat reduct ion in vo lume creates a h igh lyexplos ive mixture. V lhen the p is ton reachesthe top of the compress ion s t roke, the sparkplug in the cy l inder receives h igh vo l tagefrom the d is t r ibutor . This creates a sparkwhich ign i tes the a i r lgas mixture.

During the POWER SIROKE, which follows theigni t ion, the in le t and exhaust va lves areboth closed. The increase in ternperatureresul t ing f ron the burn ing fue l great lyincreases the pressure on top of the p is ton.This increased pressure forces the p is tondownward and rotates the crankshaf t . Th is isthe only stroke in which power is furnishedto the crankshaf t by the p is ton.( f l l u s t r a t i on 3 )

The last stroke of the cycle is the EXIIAUSTSIROKE ( i l lust rat ion 4) . The exhaust va lveis open and the in take va lve remains c losed.The piston moves upward, forcing the burnedgases out of the combustion chamber throughthe exhaust va lve. This s t roke is fo l lowedimmediate ly by the in take s t roke of the nextcyc le, and the sequence of events cont inues.

3

3 -2

The 4-st roke cyc le d iesel engine operates on the same nechanica l ,or operat ional , cyc le as the gasol ine engine. fn the d iesel engine,the coropression ratio is nuch higher than in the gasoline engine.This is necessary to increase the heat generated by the compressionof the air in the compression stroke. The fuel is injected intothe cylinder at the top of the compression stroke where it isignited by the heat.

TI|O-STROKE-CYCLE diesel engines are widelyused. Although some gasoline engines operateon the 2-stroke cycle, their use is l initedprincipally to outboard motors. Every secondstroke of a 2-stroke-cycle engine is a POWBRSTROKE. The strokes between are CII{PRESiSIOXSTROKES. The intake and exhaust functionstake place rapidly at the botton of eachpoerer stroke. With this arrangement there isone power stroke for each revolution of thecrankshaft, or twice as many as in a 4-strokecyc le engine. ( See Figrure 3-2 . )

The cy l inder of a 2-s t roke-cycIe d ieselengine has an exhaust valve but no intakevalve. The air enters the combustion chanberthrough ports (openings) in the cyl inderwall. These ports are uncovered by thepiston as i t nears the botton of each stroke.( I l l us t ra t i on L )

When the piston moves upward on thecompression stroke, the exhaust valve isclosed and the intake ports are covered.( f l lust rat ion 2) The p is ton compresses theair trapped in the cornhustion chamber. Atthe top of the stroke, fuel is f irst sprayedinto the cyl inder and then ignited by the hotcompressed a i r .

I l lustration 3 shows the downward notion ofthe piston on the power stroke. The exhaustva lve is s t i l l c losed and the increasedpressure, resul t ing f ron the burn ing fue l ,forces the piston downward, and rotates thecrankshaf t .

As the piston nears the bottom of the powerstroke, it uncovers the intake ports and theexhaust va lves open. ( I l lust rat ion 4) A i rdelivered under pressure by a blower (airpunp) forces air in through the intake ports,and the burned gases are carried out throughthe exhaust va lve.

a

Figre 3-2. ne fi,o StrokeDiesel hgine.

IIi

iiII

3 -3

This scavenging operat ion takes p lace a lmost instant ly andcorresponds to the intake and exhaust strokes of the 4-strokecyc1e .

On the compression stroke, the exhaust valves are closed, theintake ports are covered, and the air is trapped in the cyl inder.The r is ing p is ton compresses the a i r and heats i t ad iabat ica l ly , orwithout a loss or gain of heat. By the t ine the piston reaches thetop of the stroke, the volume of the eombustion chamber has beengreatly reduced. The relation between the volune of the cornbustionchamber with the piston at the bottom of the stoke, and the volumeof the cornbustion chanber with the piston at the top of the stokeis ca l }ed the compress ion rat io . Cornpress ing the a i r toapproximately one-sixteenth of i ts original volurne representing acompress ion rat io of L6 to L. Gasol ine engines operate atcompression ratios between 4 to L and 8 to I, but the compressionrat ios of d iesels range between 72 to 1 and 16 to L.

As the compression ratio is increased, the r ise in the temperatureof the a i r in the cy l inder increases. For example, wi th acompression ratio of 14 to 1", the ternperature wil l be sl ightly overIOOO' F. This means that on the cornpress ion s t roke of a d ieselengine the a i r is heated to about 1000" F. At th is temperature,the fue l begins to burn when i t is in jected in to the cy l inder .

You might expect a 2-s t roke-cyc1e d iesel engine to develop twice asmuch power as a 4-st roke cyc le engine; however , such is not thecase because approx imate ly 10 to L4 percent o f the engine 's poweris requi red to dr ive the b lower. Never theless, 2-s t roke-cyc lediesel - engines g ive excel lent serv ice.

PPWEB_SISTEU. The Power System of the engine transmits polder fromthe cyl inders to the drive shaft. The pohrer system includes thecy l inders and p is tons, the connect ing rods, and the crankshaf t .

The cy l inders of most nar ine engines are cast in a s ing le b lock.Each cy l inder is l - ined wi th a specia l hardened a l loy i ron s leeve toreduce wear .

The p is tons are at tached to the crankshaf t by connect ing rods,which transrnit power from the pistons to the crankshaft. The rodsare jo ined to the p is tons by p is ton p ins (wr is t p ins) and areconnected to the crankshaf t by bear ings (see f igure 3-3) . A sealis prov ided between each p is ton and the p is ton wal l . Th is seal isaccompl ished by p is ton r ings in grooves in the p is ton wal l . As thepis ton moves up and down, the r ings press against the cy l inderwal l , thus prevent ing the a i r or gases (dur ing the exhaust s t roke)f rom passing down in to the crankcase and the o i l f rom work ing uppast the p is ton.

3 -4

€---0--_-€--

tigre 3-3. Pistonand onnectinq rod parts.

The crankshaft is a device usedto change the reciprocating notionof the piston and the connectingrods into rotary motion needed todrive such iterns as reductiongea rs , p rope l l e r sha f t s ,generator- alternator, and punps.There are many conmon applicationsof th is pr inc ip le ; the t readle ofan o1d- fashioned sewing machineand the up-and-down notion of yourIegs on the pedals of a b icyc le.Figure 3-4 shows the crankshaftaction of a sewing nachine treadleand band wheel. this arrangenentcan also be used to change rotaryto reciprocating motion. Duringthree of the strokes of a 4-stroke-cycle engine, the rotarymotion of the crankshaft is novingthe piston up and down.

Valve Mechanisms. The valvesare opened by the action of acanshaft, driven by the crankshaftthrough a t ra in of gears.

corrPREssroflPSTOil ilG:;

PE;TOil Pir

Plttttr Pil c^P

SANO,, WHEE L

Air Pilot Trainint, Bcrt A. Shields

Fi5rn 94.-Tht cnnkrhrft rction of rtroedh rnd brndwhccl.

E.-/(\\

E;lt

aE

CONNECTING

3 -5

Figure 3-5 Si rnple Camshaf t and ValveMechani . sm

The camshaf t is a long steelshaft that extends the length ofthe engine and carries one or norecams for each cyLinder . The shaf tis cy l indr ica l , but the cans areirregular in shape (see f igure 3-5 ) . Each cam i s pa r t l y c i r cu la rin outl ine but carries a LOBE( HIJUP ) which gives it an egg-shaped appearance. The circularpart of the can is cal led the CAI{FLAT. The canshaft is designed tochange rotary to interrnittentreciprocating motion. A tappetriding on the rotating cam isI i f ted each t ine the lobe comesaround.

On sone types of engines, thecamshaf t is i-ocated near thecrankshaf t " In these designs theact ion of the cam ro l ler istransnitted to the rocker ar:rn by apush rod. In other engines, thevalves are inverted and arelocated in recesses at the side ofthe cy l inders. with thisarrangenent, the valve stems nayride directly on the cams or theymay be separated by a short steelshaf t ca l led a TAPPET. Thisarrangement is shown in above.

The camshaft must be t ined with the crankshaft so that the lobeswi l l open the va lves in each cy l inder at the correct instant in theoperat ing cyc le. In the 2-st roke cyc le the exhaust va lves areopened for only a short t ine, at the botton of the pohter stroke, topern i t the burned gases to escape. Since the cyc le is cornpleted inone revolut ion, the camshaf t ro tates at the same speed as thecrankshaf t .

The 4-st roke-cyc le engine has an in take and an exhaust va lve inevery cy l inder , each of thern operated by a separate can. Theintake va lve is he ld open dur ing the in take s t roke, and the exhaustva lve opened dur ing the exhaust s t roke. Both are opened and c losedseveral degrees of crankshaft travel before and after the top andbot ton of the p is ton t ravel . S ince two revolut ions of thecrankshaf t are necessary to conplete a 4-s t roke cyc le, the canshaf tof these engines turns one hal f the speed of the crankshaf t .

3 -6

Air Svstern. In the 4-st roke cyc le engine, the a i r enters thecy l inders through the in take va lve. As each p is ton goes down onthe intake stroke, the volume of the conbustion charnber increasesand the pressure decreases. The normal atmospher ic pressure thenforces the a i r in to the cy l inder through the in take vaIve.

The 2-st roke cyc le engine does not go through an in take s t roke.The air enters through intake ports, uncovered when the pistonapproaches the bottom of the polder stroke. Since the exhaustvi lves open as the intake ports are being uncovered, the incomingai r forces the burned gas out through the exhaust va lves and f i l lsthe cy l inder wi th a supply of f resh a i r . On large Z-st roke cyc lediesel engines, b lowers must be prov ided to force a i r in to thecy l i nde rs .

Lubricating Systen. TheIubr icat ion system is a v i ta lpa r t o f an i n te rna lcombust ion engine. I f thelub r i ca t i ng sys tem shou ldfa i l no t on l y w i l l t he eng ines top , bu t a I1 o f t he pa r t sare l ike ly to be darnagedbeyond repa i r .

The I ub r i ca t i ng sys ten Fde l i ve rs o i l t o t he nov ingpar ts of the engine to reducef r i c t i on and ass i s t i nkeeping them cool . Mostd iese l and gaso l i ne eng inesare equipped wi th a pressurelubr icat ing system thatde l i ve rs the o i l unde rpressure to the bear ings andbush ings , and a l so l ub r i ca testhe gea rs and cy l i nde r wa l1s .The o i l usua l l y reaches thebear ings through Passagesdr i l led in the f rarnework andthe c ranksha f t o f t he eng ine .The lubr icat ing systern of a a

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I I ltr^tl atq,rxo lTlatrll r.O C.n.tl

syster of an inboard engine.

t yp i ca l 4 -s t roke cyc leinboard engine is shown inf i gu re 3 -6 "

Many methods of lubr icat ingthe i nd i v idua l pa r t s o f eachtype o f eng ine a re i n use i nthe d i f f e ren t eng ine mode ls .

tl. oft ?^ral. lcrttx4tt tult |rT^rtl. ?rllgrrt oL tu.2.. v^tvlJtatlJrc lal-|lti orl |tt^xtlc ort. cE-ar

Pigure 3-6. m€ Lubrication

3 -7

The oi l is delivered by the gear-type oi l punp. This pump takessuction through a screen fron an oi l pan or sump. Frorn the punp,the oi l is forced through the oi l strainer and the oi l cooler intothe o i l nani fo ld in the cy l inder b lock. This nani fo ld extends thelength of the engine and serves as a passage and reservoir fromwhich the oi l is fed to the nain crank-shaft bearings and one endof the hollow carnshaft. Host noving parts and bearings areIubricated by oi l . drawn fron these two sources. The cyl inder wallsand the teeth of many of the gears are lubricated by oi l spraythrown off the rotating crankshaft. After the oi l has served itspurpose, i t drains back to the sump to be used over again.

Constant oi} pressure, throughout a wide range of engine speeds, isnaintained by the pressure rel ief valve that a1lows the excess oi lto f low back into the sump. AII of the oi l from the punp passesthrough the strainer and cooler, unless they are clogged or the oi lis cold and heavy. In such cases, the bypass valve is forced openand the o i l f lows d i rect ly to the engine. Par t o f the o i l fed tothe engine is returned through the f i l ter, which removes f lakes ofureta l , carbon par t ic les, and other inpur i t ies.

The oi l pressure in the l ine }eading fron the purnp to the engine isindicated on a pressure gage. A ternperature gage in the returnIine provides an indirect nethod for indicating variat ions in theternperature of the engine parts. Any abnormal drop in pressure orrise in ternperature should be investigated at once. It isadvisable to stop the engine unti l the trouble has been located andcorrected.

The oi1 should be changed according to the manufacturer'sspeci f icat ions. This is par t icu lar ly t rue for d iesel engines.

Cooling System. Marine

tlrFg?^lrqlt€

engines are equipped with awater-cooling systen to carryarday the excess heat producedin the engine cy l inders. Thewater is circulated throughwater jackets in the cy l inderwalls and passages thatsurround the valves in thecy l i nde r head . Thelubr icat ing o i l acts incool ing the p is tons andcy l i nde r wa l l s .

E i ther f resh water or seawater nay be used forcool ing. fn some engines thesea water is c i rcu latedthrough the engine and thendischarged overboard.

or'.F ^{POa'gl O,€IF^EFOat€D

cn acr Frao

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cn dr{rro

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r^tt nr^SltoaCA.q

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Figrte 3-7. Tte bboard c{ohDg syster

3 -8

In other types of engines, f resh water is c i rcu lated through theengine and then through a heat exchanger. Sea water is purnpedthrough this exchanger and cools the fresh water. An advantage ofthe fresh-water systern is that i t keeps the water passages cleaner,avoids the corrosive effects of sea water, and thus provides bettercoo l i ng .

Electr ical Systen. The electr ical systero of most inboard enginesconsists of the fanil iar generatorr/alternator, and electr ic motorthat serves as a starter, a suitable battery, and the necessarywiring. The generator/alternator keeps the battery charged andprovides current for l ights and other equiproent. The charging rateof the generator/alternator is control led by a voltage regulator,and a cut-out is provided to keep the battery from dischargingthrough the alternator/generator at low speed. When the starterbutton is pressed the starter bendix gear engages with the teeth onthe f lywheel and turns the engine over . Diesel engines genera l lyrequi re double the bat tery capaci ty of gasol ine engines. Somelarge d iesel engines are s tar ted wi th compressed a i r or a snal laux i l iary gasol ine engine.

Diese1 Enqines. Fiqure3-8 shows the componentsfound in the typicald iese l eng ine . Thepower, a i r , lubr icat ing,cool ing and e lect r ica lsysterns are general ly asdescribed above. Asstated ear l ier , thed iese l eng ine i s aCompress ion fgn i t i onengine. The fue l systemof the d iese l eng ine i sd i f ferent f rom thatfound wi tn gasol ineeng ines .

The fuel punp draws thefuel o i l f ron the tankthrough a pr i rnary f i l terand del ivers i t to thein jector through thesecondary f i l ter . Theout le t l ine carr ies theexcess fue l o i l f ron thein jector back to thefuel tank. In someins ta l l a t i ons a t rans fe rpunp i s i ns ta l l edbetween the tank and thep r imary f i l t e r .

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Figrre 3-8. Corpnents of tbe diesei engine.

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A diesel engine wi l l not operate ef f ic ient ly un less c lean fue l isdelivered to the injector. As the fuel oiL is punped into the fueltanks, i t should be strained through a f ine- nesn screen. Thelarger part icles of the solids suspended in the fuel are trapped inthe pr imary screen. The secondary f i l ter separates the

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part icles of _foreign natter that pass through tne prinary f i l terscreen. The f ina l f i l ter ing takes p lace wi th in the in jectdr . l tostf i l ters have a drain plug for removing the water, sludge, and otherfore ign mat ter . The f i r ter shourd be dra ined once ; d .y , or asspeci f ied in the manufacturerrs technica l manual .

There are many nethods of fuel injection and just as many types ofin jectors . one is the r run i t in jector ' r system. The i i jectorconsis ts bas ica l ly o f a smal l cy l inder and a p lunger , and e i tendsthrough the cyl inder head to the combustion chamber. A cam,located on the camshaft adjacent to the cam that operates theexhaust valves, acts through a rocker arm and lowers the plunger atthe correct instant in the operat ing cyc le. when the in jectorprunger is depressed, i t sgui r ts , oF in jects , a f ine spray o i fuerinto the cyl inder, through srnall holes in the nozzLe. The smoothoperation of the engine depends to a large extent on the accuracywith which the plungers inject the same amount of fuel into eachconbustion charnber. The amount of fuel injected into the cyl inderson each stroke is control led by rotating the plungers or a unitin jector . The throt t le , which regulates the speed of the engine,is connected to the injectors through a portable l inkage. Changingthe thrott le sett ing rotates the plungers and varies €he anount oifue l in jected in to the cy l inders on each st roke.

Another system is ca l l the r rcommon ra i r t system. This is mostcomroonly used in engines other then General Motors. Instead of apunp being located at each cyl inder in a separate unit, there isone pump for a l l in jectors. This systern has one drawback. I f a i rgets into the systen it nust be purged. This usuarry is done byloosening the snal l de l ivery tube at the cy l inder and ro l l inq theengine over with the starter unti l the air is purged and only fuelcomes out . Per formance of the r rcommon ra i l t ! system is genera l ly asgood as with the rrunit injectortr system. Caution should be usedbefore naking any adjustments to e i ther system. ser ious andexpensive damage can occur frorn irnproper adjustnents.

GASOLTNE ENGTNES. Most inboard engines are a 4-stroke cycleengine. Two-st roke cyc le gasol ine engines are used pr inc ipa l ly todr ive outboard motorboats, motorcyc les, and rnodel a i rp lanes. Thepower, a i r , lubr icat ing, cool ing and e lect r ica l systerns aregenera l ly as descr ibed above. The pr inc ipa l d i f ference between thegasol ine and the d iesel engines is that the gasol ine engine has acarburetor and an ign i t ion system. rn addi t ion, the gasol ineengine has a lower conpress ion rat io than the d ieser engine. Atyp ica l mar ine gasol ine engine has a compress ion rat io of about 7to L, compared to an approx imate rat io of 16 to 1, even 20 to l , insone d iese l eng ines .

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Induct ion System. This system draws gasol ine f rom the fuel tankand air from the atrnosphere, mixes then, and delivers the mixtureto the cyl inders. f t consists of the fuel tank, the fuel punp, thecarburetor, and the necessary fuel l ines and air passages.Flexible tubing carries the fuel from the tank to the carburetor,while the intake nanifold carries the fuel-air mixture fron thecarburetor to the indiv idual cyl inders.

The FUEL PUlilP comrnonly used ongaso l i ne eng ines i s s l i gh t l ydifferent from any of the purnpsdiscussed la ter on in th ist ra in ing course. In somerespects th is is l ike the o ld-fashioned water punp, wi th thep is ton rep laced by a f l ex ib led iaphragrn. This d iaphragrm,which forms the bottom of thepunp charnber, is composed ofsevera l layers of t reated c lo thheld between two meta l d isks.(See f i gu re 3 -9 )

tiEre 3-9. I scieHtic draring of agsoline eDgine fuel pnp.

The diaphragrm is actuated by the rocker arm, which rides on theeccentr ic . However , the par ts are connected in such a way that thediaphragrn can be pul led downward only . An eccentr ic is mere ly ac i rcuLar-shaped cam that is mounted of f -center on i ts shaf t andwobbles up and down as it rotates" The diaphragrm is raised by theact ion of the spr ing t .hat pu ishes against i ts under sur face. Anintet and an out le t -check va lve permi ts the fue l to f low throughthe punp chamber in one d i rect ion only .

When the engine is running, the eccentric acts through the rockerarn to lower the diaphragrm against the spring pressure. This drawsa charge of fr:el into the pump chamber through the inlet checkvalve. Dur ing the next ha l f - revolut ion of the eccentr ic , thespring pushes the diaphragrm upward and forces the fuel out of thepunp chamber, through the out le t check va lve, in to the l ine leadingLo the carburetor . The pump wi t l cont inue to del iver fue l as longas the force of the spring is able to overcome the pressure in thecarburetor fue l l ine.

Frorn th is descr ip t ion, i t can be seen that the cam act ion of theeccentric merely moves the diaphragrn downward and compresses thespr ing, whi le the actual pumping is done by the spr ing .as thepiessure on i t is re leased. The pressure which the punp mainta insin the fue l l ine depends on the s t rength of the d iaphragrn spr ing.As the pressure bui lds up, a point is reached where the spr ing wi I Ibe strong enough to l i f t the diaphragn only part of the htay. l{henno fue l is be ing taken in to the carburetor , the d iaphragm wi l lremain in the lowest pos i t ion and the punp wi l l not de l iver anyfue l .

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The CARBURETOR is a device usedfor sending a f ine spray of fue linto a ruoving stream of air onits way to the intake valves ofthe cy l inders. The spray isswept a long, vapor ized, andAk Hqm nixia ( as ; gai) , with the

6orrvrlvr noving air. The carburetor isdesigned to naintain the samenourt nixture ratio over a wide range

vrntwi Cbrta of engine speeds. The UIXTTIREvcnr'd RATIO is the number of pounds of

air nixed with each pound oflhrorrtrEorty gasoline vapor. A RICH l,lIxTttRE'

is one in which the percentageThronrrvrhn of gasoline vapor is high, while

a LEAN MIXTTIRE contains a lowpercentage of gasol ine vapor .Gasol ine engines nonnal lyoperate best on a mixture ratioof about 12 to 1. A carburetor

tigre 3-10. I scberatic ftaring of a consists of several principalfloat-type carbrrretor. parts, each of them perf onning

risure 3-r.o). rhese units are the t=t".:? $:S::i"I"iHtttil.(ff;idring systems, and the throttre and choke varves. A throttLeconnected to the thrott le valve controls the engine speed, andadjustrnents are provided for regutating the ial ing ipeed andn ix tu re .

The FLOAT rnaintains a constant fuel level in the f loat chanber byregulat ing the f low of gasor ine through a needle va1ve. As morefuel enters the chamber, the f loat r ises and c loses the va lve.Whi le the engine is running, the f loat a l lows gasol ine to enter thef loat chamber at the same rate as i t is be ing used by the engine.A constant fue l pressure is rna inta ined on the needle va lve by thefuel punp.

The MAIN JET SYSTEM consis ts of the d ischarge nozz le located in theventur i -shaped a i r passage or throat o f the carburetor . Ares t r i c t i on , ca l l ed a me te r ing j e t , i s l oca ted i n t he passage tha tcarr ies the fue l f rom the f loat chanber to the nozz le. fhe nainai r -b leed perru i ts a i r to pass in to the d isc