Notes Upon a Marine Engine (1912)

INSTITUTE OF MARINE ENGINEERS

INCORPORATED

Session 1912-1913

Vol. XXIV.

PAPER OF TRANSACTIONS No. CXCI.

Notes upon a Marine Engine

B y Mr . W. VEYSEY LANG (Member of Council .)

Read Monday, March 4th, 1912.

C h a i r m a n : Mr. JOHN McLAREN (Member of Council) .

ADJOURNED DISCUSSION : Monday, March 18th, 1912.

In taking for my subject “ Notes upon a Marine Engine,” I am merely writing down those memoranda and mental notes th at have from time to time occurred in my experiences, either from observation or adoption, and whilst no one of them may be new or original, their very summary within the limits of a single paper may be of interest to some and possibly of instruction to others.

When I read a Paper on February 15, 1909, upon “ Some Details of a Cargo Steamer,” some of the younger members present expressed themselves as unable to join in the discussion on what, to them, appeared to be a paper on shipbuilding.

I maintain that any structure of iron or steel comes under the head of subjects an engineer should be more or less conversant with, and any one of which his training should enable him to take an interest in and, if necessary, to master the details of. However, this present is, in particular, directed to the engine department. For myself I esteem an ounce of practical experience—from any source—above the proverbial pound of theory—from anywhere !

As upon the former occasion, I take as my subject the ordinary marine engine of a cargo steamer, having engines developing —at sea—(say) from 1,000 to 2,000 I.H.P., and a builder’s “usual specification”; which, in itself, whilst providing the main essentials required for the propulsion of a steamer of given size, will contain not an “extra” of any importance unless it be some “speciality" of the engine builders themselves. In fact, the engine which a builder will put forward in a low quotation, or for a “spec” ship, will be devoid of much that the marine engineer desires. They will, for instance, probably lack cylinder liners—except (generally) in the H.P. cylinder rings in piston valves; any other than plain Ramsbottom rings in pistons; provision for wear and tear and turning down of

rods and reboring of cylinders, etc. ; white metal in eccentric

straps, guide shoes, etc. ; loose liners in thrust ; metallic

packing of any description ; cylinder lagging (under the clead-

ing) ; ballast pump of sufficient capacity ; pipes of ample

size—especially for tank-filling and suction ; economical

arrangements in connexion with steam exhaust and pump

pipes ; oil tank capacity ; outfit and equipment.

Design.—To most of us—-marine engineers—it lies to do with what is in being and not to the design of engines. To the whole design of a modern engine one must go back over many years of trial, experiment and perfecting of things formerly crude or in actual error. But to the details we may bring our every-day experience, and particularly our past experience and th at of others, to bear, and so doing to still improve and simplify.

By such small and simple (in themselves) details has the modern marine engine evolved from the less reliable and more diversified engine of years ago. It is very much to be noted how greatly have the varied types of (say) twenty years ago become so nearly alike in pattern, design and efficiency. Twenty years ago one could tell at a glance the build or make of a job : the undertype condenser ; the position of cylinders ; the differing design of cylinder tops ; square versus rounded, and solid versus built cranks ; various ideas in lagging, jacketting and expansion ; and last, but not least, those patents in valve gears, cranks, motions, etc., which most of you will remember.

General Description.—We are, of course, only considering the ordinary triple expansion, inverted, surface condensing marine type engines. One of the first items is usually “class,” and but few (if any) engines of the powers named are built in the United Kingdom other than under the survey of some one of the Classification Societies, and, for all practical purposes, their respective rules are similar or identical as to scantlings, and vary but slightly in detail. Only in Board of Trade Rules do we come, occasionally, upon some abnormal requirement in comparison with Society rules, such as crank shafts, spare gear, etc., and in the case of boilers with thickness of shell plates.

Size of Cylinders.—Ratios of cylinders this paper does

not enter into, but the practice of the last twenty years seems

to have standardized the cylinder ratios of some established

engine builders, although, for the same size of H.P. cylinder,

the other cylinder diameters vary with different builders’

practice, and there does not seem to be a fixed, efficient or economical

standard arrived at in regard to cylinder ratio, for the

same initial steam pressure, th at one would have thought the

experience of years would have established. As to whether a

ratio of 24 • 39 • 64 is better or otherwise than 24 • 40 • 66 is

not easy to say without bringing into view design, areas,

clearances, valve operation, etc., but the fact remains th at in

practice two identical engines—by different builders—will

give varying results, and this sometimes most unaccountably.

Some engines balance their power equally between the three

cylinders, others again will not balance at all, or if balanced—

compulsorily, so to speak—reduce the revolutions by so doing.

I have in mind two sets of engines by the same builders—

one = 2 4 - 4 0 - 6 6 and the other 25 • 44 ■ 73. Neither of these

engines will divide the power equally between the throe cylinders—at

least, not without a reduction of revolutions, and an

unsteady running engine—by as much as 100 H.P. more or

less, and to secure the maximum of revolutions at a stated

consumption and with an easy-rumiing engine, the powers may

even work out at a greater divergence.

Siz e o f E n g in e s is naturally based upon requirements of

the shipbuilder and the expectations of the shipowner. I use

the word “ expectation ” advisedly, as the average sea speed

is so often disappointing. In an inquiry for engine power for a

given length, breadth, and depth, displacement and co-efficient,

it is surprising how nearly several engine builders will give

their proposed sizes. As a m atter of fact, the engine powers

usually fitted for a given speed are—in most cases—beyond

the power of the boilers supplied to produce steam for. I think

in many cases, if not in most cases of the cargo steamer class, a

smaller engine and a size larger boiler—or boilers—would be a,

great improvement upon “ usual ” practice. I have proved this

in some five or six cases by lining down the H.P. cylinder from

(say) 24 in. to 22J in., or from 27 in. to 25 in., and the result

has been a decided economy in fuel and a not proportionate

loss in speed. Indeed, in two of the first-named instances—

together with finer pitched propellers—the speed has increased.

Cylinder Liners .—In most cases, in the sizes of engines

under notice, the H.P. cylinder is fitted with a liner. In a few

cases the M.P. also is so fitted, and never, or rarely, in L.P.

cylinder. Liners in both the H.P. and M.P. are most essential,

in the L.P. negligible. It stands to reason th at a cylinder

casting—however good the metal—must be suitable for easily

machining its various bores and faces, and the same metal in

all three would vary in wear owing to the difference in steam

temperatures, and the different tension of the respective piston

springs are naturally less pliant in the small than in the larger

diameters. The ideal cylinder liner is one th at a file will

hardly touch for hardness, and with good sound metal a face

is soon formed th at the wear of years will have but little effect

upon. The cylinder liner should undoubtedly be harder than

the piston rings.

Cylinders should be bell-mouthed, or recessed, both at top

and bottom, and, personally, I think it is important that the

piston rings should overrun the cylinder wall at either end of

the stroke and so prevent “ ridging.” Needless to say, with very narrow rings it is important that the clearance—or any over (or under) lining-up of the rod—should not permit of such

rings over-running and springing into the ports, but with the

ordinary clearances, and widths of rings, this should be impossible.

I consider th at, in any case or under any circumstance

of need, it should always be safe to lower the piston

(complete with its rings), to the bottom of the cylinder.

Cl e a r a n c e .—It is important that cylinder clearances should

be ample for due allowances of wear and tear, cover joints,

etc., say, \ in. at bottom and \ in. at top for a 24 in. H.P.

cylinder job, but I certainly think th at clearances of ljin . and

| in.—such as I have found—are excessive. Clearance marks

should be always well cut and distinct, and there should never

be any doubt as to the position of the piston in relation to its

working space at each end of the stroke.

Cylinder Lagging.—In the “ good old days ” of compounds,

the steam jacket was familiar to those of us who were at sea

twenty years ago. The “ cleading ” then was chiefly teak or

mahogany, brass bound, and packed with hair felt. To-day,

planished steel sheeting is the usual lagging, and in many cases

there is no non-conducting material or packing other than

Nature supplies. W ith the high temperature of modern pressures

hair felt seems to burn to dust, and asbestos sheets but

inadequately fill up the uneven spaces. There is nothing like

a good mortar non-conducting composition put on when the

cylinders are under steam, either in the shop or on board, and

the steel sheets put on afterwards. It is im portant such lagging

should be allowed to dry out before sheets are screwed up,

otherwise they will rust badly from the moisture. One little

“ extra ” is well worth incurring—viz., brass instead of steel

snapheaded screws to secure the sheets. In any future removal

such (steel or iron) screws are almost of a certainty rusted in,

and break, with considerable extra trouble or cost of drilling

out, whilst brass screws usually come out all right, or are otherwise

easily drilled into with a breast brace.

P is t o n R in g s.— The types of these are legion, and each

(as per maker’s catalogue) is better than the other. It would

be invidious on my part to name any one, but the main feature

in a piston or steam packing ring is suitability of metal. For

this reason alone the rings of a bona-fide piston ring maker

often gives far better results than those of the engine-builder28 NOTES UPON A MARINE ENGINE

or repairer ; for in the one case specially suitable metal only is

used, and in the other case it must partake of the quality being

run down for other castings. The cylinder wall or liner should

be hard and the rings of lesser hardness, otherwise the cylinder

bore wears badly, and in time—sometimes in a very short time—

requires reboring, which is costly and necessitates a new piston

or rings in any case. On the other hand, if the rings wear they

are renewable. Piston rings which rely upon outward pressure

by inclined surfaces are more theoretical than practical in

action. Such surfaces soon become clogged and fail to act.

Rings which are set out by steam or water pressure cannot

possibly give an equal pressure during the stroke, and barrelling

ensues. Strong ('’springs, exerting considerable outward pressure,

cause great friction and loss of power, as well as abnormal

wear of the cylinder wall. In the old days of the f) or coach

spring, I have seen them put in with a crow-bar and hand

hammer. For the plain, flat L.P. ring I prefer volute springs

to the D type. A truly bored cylinder and a truly turned ring

do not require much internal force to keep them in proper and

efficient contact. The less of steel spring about a high tem perature

steam piston the better. It is the simplicity of the

Ramsbottom ring th at has made it so popular. I have seen

illustrations of composite packing rings th at would have been

more successful as a Christmas puzzle than as a contrivance for

use on ship board. Piston valve rings would seem to require

more consideration than cylinder packing rings, and the choice

is more limited, for the conditions are stringent ; still there are

types which satisfactorily fill the requirements. Just one

remark relevant to this subject : Don’t take too much notice

of the lists of “ Users ” you see in pamphlets and catalogues—-

nor in the lists of other manufacturers, for that m atter—for they

are often most misleading. Some time ago, in a piston ring

list I received, I happened to notice the name of the firm I

represented as “ users of ” or “ ships fitted with ” this type.

I wrote at once and pointed out th at no such make of ring

existed in the fleet. I duly received a semi-apologetic reply,

excusing the error on the ground th at some twenty-four years

previously one set of rings had actually been supplied to a

steamer whose name has long been amongst the absent ones.

If you send an order for a sample file or a gallon of some

composition, you will get a firm’s name into such lists, and you

may be misled into thinking some engineer or superintendentNOTES UPON A MARINE ENGINE 29

you personally know uses it or believes in it. Not long ago an

agent assured me their speciality was fitted throughout a certain

fleet. A few weeks later another agent assured me that

their speciality was replacing all the other in the same fleet.

Sh a f t in g.— The present classification rules appear to supply

and apply to marine propulsion sufficient and ample strength

in shafting. Formerly there was an undoubted weakness in

the tail shaft, but the last revision of rules appears to have

remedied any such defect. It is well to remember th at such

rules are for the minimum diameters of crank, thrust, tunnel,

and propeller shafting ; and it is for the owner—or his representative—to

add to same for wear and tear and emergencies.

It is no uncommon thing for a shaft piece to be found so badly

scored or cut in the way of its journal as to require turning up

in the lathe, and if such truing up would materially reduce the

diameter it means condemnation, i.e., a new shaft piece,

either whole or part, as the case may be. But if the specification

says th at the crank and thrust shafts are to be (say) an

J in. over classification rule, and the tunnel shafting swelled

(say) I in. in way of bearings, then you protect against such

happenings. The length of crank journals and pins are

governed by the length of engine centres, and are usually as

short as possible. Increased diameter will, to some degree,

make up for a more desirable length, and in this respect the

crank pin is frequently found to be, and most desirable it

should be, a J in. larger diameter than the journal ends. As the

crank pin is in the nature of a ‘ carrier,” and not in torsion as

the journal ends are, it is permissible to bore the webbs more

for the pin ends than for the shaft ends. I firmly believe in

dowelling all built shafting. In some cases th at have come

under my notice—and one in particular—the crank shafting

having been running badly has been taken out, bolted together,

and put into the lathe. I have found such to be from in. to as

great as ^ in. out of truth, due to “ twist ” in the shrunk webbs.

The case I particularly remember showed no trace of slackness

or of movement in the webb eyes, but it was soon found th at

no dowels existed, and upon inquiry the builders wrote th at

they did not fit dowels unless by special request. N.B.—This

was some years ago, and I believe they always dowel now !

It stands to reason th at however carefully a webb is shrunk

011 to a shaft end, the striking of a propeller blade upon a3 0 NOTES UPON A MARINE ENGINE

submerged obstruction, or a quay wall or pile, is more than mere

friction can stand, and such a shock will start a shrunk end

th at no steady rotary strain would seem to affect.

Mostly dowels are plain turned pins driven in by hammer or

hydraulic, but I prefer a piece of screwed boiler stay to any

driven pin, for the former will work out if there is the lightest

slackness, but the other remains. The old style of male and

female coupling faces is rarely seen now, and are of no service

in point of strength and a great trouble when overhauling.

Coupling faces should, however, be hollowed at their centre part,

say, a in. recess the diameter of the shaft body. Wherever

a step takes place the fillet should be well rounded, not squared.

It is remarkable the weakness a square comer or recess develops

during the stress of work. I am inclined to think the frequent

fracture at the top of a tail shaft cone is often due to the

squaring down at this point. A rounding could quite well be

left in.

Continuous liners on tail shaft are now very common, and

certainly meet, to a great extent, the defects of the two-liner

shaft, but the all-important thing is to make a water-tight joint

at the propeller recess. The usual india-rubber ring is quite

satisfactory, but if omitted, or damaged in fitting, or a misfit,

trouble is sure to ensue if salt water gets to the shaft. W ith two

liner shafts, 9 in. to 12 in. of water-tight lapping at the inner

ends is a perfect protection, always assuming it is properly and

tightly applied and is not damaged in putting out the shaft—

a very common occurrence.

I think all continuous liner Tail shafts should have the fact

stamped in J in. letters, circumferentially, at both the outer

and inner ends of the liner—always open to view—then, if

Lloyd’s would grant the concession the British Corporation

allow, viz., tri-annual survey instead of bi-annual (as in the

case of two-liner shafts), then owners would receive some encouragement

to fit the more expensive continuous liner propeller

shaft.

One thing is very desirable in a continuous liner shaft, viz.

that the outer surface, within the tube, be reduced a good sixteenth

between the bearing parts. Also the after part, running

in the bush, should be in. less diameter than the forward

end.

I had a case in dock quite recently, where it took two to

three days to draw the shaft, due to a hard scale having formedNOTES UPON A MARINE ENGINE 3 i

between wearing parts upon a quite parallel liner, and in which

we had to use chemicals to dissolve the scale. As regards

recessing the liner internally between bearing parts, before

shrinking on, I see no objection to this, but think such recess

should be pumped up hard with a suitable composition.

T h r u s t .—This all-important bearing takes and transmits

to the ship all the effort of boilers and engines.

It often gets less attention in design, surface, quality of

wearing metal, and consideration at sea than it deserves.

Too often the area of surface or number of rings are on

the scant side, and a hot and unreliable bearing results.

Many thrust bearings, without water or cooling arrangement,

would hardly run at all, and I have known thrusts—in spite

of water bath—which always ran, and probably are still running,

very close to a dangerous temperature. A surface which

is running hotter than the hand can bear it is much too hot

for safety.

Personally, I like a good solid thrust carriage with heavy

horse-shoes bolted down on both sides, and capable of slight

adjustment by screws at both ends. The wearing faces to be

loo.se white metal shoes, say J in. thick, carried on brass studs

and adjustable by liners, when required. Well designed, and

with water circulation arranged in the shoes, such a thrust

will give no anxiety or trouble. The common type of side

(screwed) bars with nut adjustment is a good deal better in

theory than practice, for when required to be adjusted the

nuts are usually fast on the side bars, and the slightest turn

of a nut—upon an J in. or yf; in. pitch screw—means more

or less unequal adjustment.

For existing thrust blocks not fitted with cooling arrangement,

25 or 30 ft. of heavy f in. or in. lead water-piping rove

or coiled in the oil bath, the one end being jointed to end of

cooling pipe or cock and other led to bilge, will greatly reduce

the temperature of the oil bath.

T h e r m o m e t e r .—For thrusts, in particular, there is nothing

to equal a thermometer kept in the bath for reference as to

temperature. In fact, where sufficiently large hand holes are

arranged in main bearing top halves a 10 in. copper thermometer

would be a better indicator—when “ feeling ” round—than3 2 NOTES UPON A MARINE ENGINE

a dirty and greasy hand. A thermometer is much more

sensitive than one’s hand, especially a horny h an d !

St e r n T u b e s .—I have tried oil-retaining devices with unsatisfactory

results. They may be all right for small shafting,

or where vessels are running in regular trades and dry docking

periodically ; but I can with good reason advise against such

arrangement where steamers are trading to out-of-the-way

places or where dry dockings are costly. There are patents

in skeleton stern tubes, but it seems to me that a tube with a

U middle section and a bolted cover within the peak space and

between the wearing bushes would be an easy way of examination

of shafts between liners, and such an examination might

be accepted for classification, provided the outer ends were,

at the same time, available for inspection.

I have tried solidified oil in stern tubes, a circulating oil

arrangement and forced lubrication, but not one of them has

shown any economical results. In any case a tail shaft has

to come in every two years, and if the lignum vitae bush is

worn down it is not an expensive renewal, and sea water is a

cheap lubricant.

W h it e M e t a l .—It seems to me that white metal may comprise

any alloy of lead, zinc, tin, copper and antimony. I

gather from the behaviour of some white metals th at the per

centage must be quite 90 of lead. I don’t think any white metal

is worth the name, or the use, in marine work unless it is mainly

composed of tin. I am no expert in this matter, but I have

found from experience that a white metal with less than 75 to

78 per cent, of tin is too soft for heavy shafting and spues out.

The higher grade metals on the market are an even higher

per cent, than named, and including Navy practice. For top

halves in main bearings a lower quantity might be used, but

for bottom main bearing blocks the best should be used, for

lifting and relining shafting is an expensive job. For tunnel

carriages it is usual to melt up the scrap of the crank shaft

metalling. Wherever a stern or after bush is of white metal,

the best quality is cheapest in the end. In one case I had, an

after bush wore very badly, and upon request the builders

stated that it contained 40 per cent, of tin. I replaced that

bush by one of 85 per cent., which has run well for some years.

As the casting (alone) of such a bush is worth over £100, oneNOTES UPON A MARINE ENGINE 3 3

does not want to renew very often. One thing seems certain,

th at any zinc alloy—either in white metal mixtures subject to

saltwater action, or in salt water condenser tubes—will pit and

honeycomb. A high grade white metal with a Navy percentage

of tin ought to last in a main bearing twelve to eighteen years

without renewals. Some of the others don’t, and won’t run

beyond the first survey, and most of the builders’ (own) white

metal mixtures come in for renewal on the second survey.

Oil w a y s.—These form a small item, but have an important

bearing upon the cool working of an engine. I had thought

to make a few diagrams, but it would be a big undertaking to

illustrate every design one has seen or could think of. One

important thing should be avoided, viz. cutting an oilway

across the crown of a brass. This is equivalent to nicking a

piece of metal to break it, and is sure to result, sooner or later,

in broken top or bottom end brasses or halves. In the white

metalling of main bearing and bottom end bearings I have

noticed that some engine builders make no provision for

oil pockets or recesses at the sides, and in some cases the

edges are straight across and even dropped at either side !

This is a most wasteful arrangement, and simply acts as a

scraper to carry away the oil which should be retained within

the working part as far as possible. On the other hand,

recesses in bottom halves, having neither inlet or outlet, get

filled with dirt and grit which in time will harden and score

the journal. There are all sorts of oiling devices, but the one

th at fails not and is the most effective is the hand of the

careful engineer.

Co n d e n s e r s .—As far as I have had cause to investigate, I

have generally found sufficient cooling surface in the ordinary

main condenser, and usually the air and circulating pump

diameters (although sometimes on the small side) calculated

to give a moderate vacuum. But in several cases th at have

come under my notice the vacuum was by no means satisfactory.

In one case, in particular, in a 1,600 I.H .P. job, the

actual surface was on the excess side, the air and circulating

pumps, although rather small, of sufficient capacity to deal

with the steam under normal conditions, yet the vacuum was

never obtainable, at the first, over 23-23^- in. at sea. This

was a three flow condenser. Eventually, by trial and experiment

consisting of taking out tubes to admit of a better steam34 NOTES UPON A MARINE ENGINE

circulation, fitting of steam baffles and, most effective of all,

the diversion of a portion of the initial circulating water from

the first to the third flow by a 4 in. pipe from the bottom to

the top of one water end, the vacuum is now easily maintained

at 25-26 in.

I mention this case to emphasize the importance of proper

and proportionate circulation, both of water and steam respectively.

In several cases I have found improvement by

taking out sufficient tubes (and plugging holes in plates) to

form a V or W steam way in the top, and also, sometimes, in

the bottom nest of tubes. I am aware of many claims for improved

types of condensers having fewer tubes and an increased

circulation, but if overworked, tubes must necessarily come

sooner to renewal. In regard to condenser tubes I consider

it all-important they should be free from any admixture of

zinc, which, in conjunction with sea water, sets up an electric

battery and consequent corrosion. From a simple test with a

Leclanche cell I found that the E.M.F. varied for different

metals as follows :—

Z inc . . . . . 1 1 T ool steel ^

A lu m in iu m . . . - f t C opper a b o u t J.

L e a d . . . . j Iro n

M u n tz m e ta l . .a b o u t J

It therefore stands to reason that with one element of cast iron

(and especially if in the decomposed or rotten condition so frequently

found to exist in the water ends), or the presence of

coal or ash, and the other element an easily corroded metal,

you have, with sea water as the exciting element, a nice little,

electric battery.

It is very desirable to plaster the sides and bottom of the

water ends with portland cement, and if the cast-iron doors

were coated, when dry, with bituminous enamel or other preservative,

we might get less trouble with our condenser tu bes!

As regards ferrules, there is much to be said for both wood

and brass screw ferrules. Properly seasoned wood ferrules,

a correct fit, will last as long as the condenser is likely to run

without requiring cleaning. Screw ferrules badly packed (as

they too often are) give continual trouble until repacked, and

it should be borne in mind th at it costs more in the first instance,

and from 50 per cent, to 100 per cent, extra in both

time and cost to draw and clean tubes and repack a screw ferrule

condenser,NOTES UPON A MARINE ENGINE 3 5

Pumps.—In these we have the most important adjuncts of

the marine engine. I am only referring to the main pumps

worked direct from the levers ! As to which engine the pumps

should be dr iven off seems more or less a question of choice or

arrangement. In the days of compounds undoubtedly the

L.P. (of two engines) would be the proper engine to fit such

auxiliaries to, as in the event of a breakdown the L.P. crank

must work, if any a t all. In these triple days we think less

of total breakdowns ! Still, one can conceive, even to-day, of

the easy possibility of a breakdown in which the L.P. engine

would be the sole stand-by for the ship’s propulsion, and in

th at event it would be all-important th at the pumps could

fulfil their functions. Some builders fit the levers on the

M.P. engine. Some I have seen with two sets of levers and

pumps on both engines.

Of the wear and tear and the thump and rattle of pumps

worked by and through the agency of levers, most of us have

experience of. There is much in design and arrangement, and

especially in detail, th at upon the whole, more or less, depends

the efficiency and smooth working of these parts.

A ir Vessels.-—Nothing in the arrangement of pumps can give

such relief to undue strains as the proper size and position of

these. An air vessel, to be in any sense efficient, should be

placed immediately adjacent to or forming an integral part

directly to or upon the pump delivery chest. Unless the

volume of water per stroke is delivered directly into the space

th at is, or forms, the expansion box or air vessel, it is more or

less inoperative.

An air vessel upon the F.P. pipe line, or indeed even close to

the delivery chest, is more or less out of action, for water is

non-compressive, and the shock once entering the narrow orifice

of the pipe line might as well continue its course to the

boiler for all the substantial good an air vessel in the pipe line

can do. On the other hand, an air vessel receiving direct

the full charge of the pump absorbs within its own compressive

air the solid body of non-compressive water, and upon the

suction stroke the air reaction causes and maintains a regular

flow of feed water.

W ith properly arranged air vessel of suitable capacity there

should be little or no “ shock ” from a pump. As a simple

illustration the spring top of a lavatory basin, of the ordinary

type, is usually subject to water shock when released, and which

E3 6 NOTES UPON A MARINE ENGINE

I have known to break joints at some distance away in the

same supply. Instead of connecting such a tap direct to the

end of the pipe, try running the pipe a foot longer, in the vertical

direction, and a branch or wiped joint to the side of the

supply; an air vessel results, and I think you would find the

cure complete.

In some cases a similar arrangement, viz. an air vessel,

is very beneficial on the suction side of a pump ; but as

far as my experience goes this would only be applicable to a

cold water pump, and where the suction pipe line was long or

restricted in area. In such a case the air vessel acts as a displacement

vessel, and creates a constant flow in the pipe line,

and by so doing reserves a ready charge for the return lift

stroke. One thing I consider an air vessel on the pipe line

beneficial for, viz. if placed on its highest point and vertical

to its top side, it forms an air trap ; with a I in. cock on top and

a pipe led back to the hot well, a lot of air will be led away from

the boiler feed. N .B .—The same effect applies if a cock and

pipe is fitted to the top of a feed filter or heater.

A ir P u m ps.—In conjunction with pumps in general, I should

like to make special remark upon air pump buckets. I have

had three cases before me within the past three or four years

of air pump buckets breaking when working under normal

conditions at sea. In one case the chief reported that the fibre

valves were found to have swelled over a £th, and attributed

the accident to this account, which, upon measurement, showed

th at this swelling had reduced the lift and inlet area of the

valves, and probably upon an extra roll of the vessel had

overcharged the foot valve. In another case the valves were

of the Kinghorn type. The third case has recently happened,

and I have not yet any data to hand as to valve lifts.

It seems to me very important th at the area of valve orifice

in the bucket and also in the head valves should be substantially

increasing, both in number or surface, and lift, from the

foot to the head valve inlets or discharges, and th at valves

should be non-absorbent.

T a n k E x a m in a t io n .—There is one item of interest th at I

omitted in my former paper, but which will not be out of

place in this one as relative to the pumping arrangement in a

steamer. I refer to the examination of damage, cementing,NOTES UPON A MARINE ENGINE 3 7

pipes or strums, throughout the ship under any circumstances.

In the majority of cases builders now carry the tank spaces

before and abaft the machinery space, some two frame spaces

within same, thus enabling manhole doors, on each side,

available for inspection without regard to any cargo in the

holds. Also a manhole or two is sometimes found in the tunnel

floor. But these, if fitted, do not enable access to be made to

all double bottom tanks.

In recent steamers I have specified for a manhole fitted,

on each side, in the bottom of the No. 1 bulkhead, with

stud-bolted plate doors on the fore side, thus permitting of

access from the F. peak to the No. 1 tank, for examination.

In the case of subdivided (fore and aft) tanks, the manholes

within the tunnel—which can only give access to one side

[N.B.—The tunnel is not in the centre of the ship by the width

of passage way on one side of the shaft coupling]—a bolted plate

manhole can be fitted in the division plate immediately under

or nearly adjacent to the tank top manhole.

By such means the double bottom space can be entered with

holds full of cargo, and after grounding or stranding, examination

made—provided of course th at the tanks can be pumped

out, or are dry.

T a n k Su c t io n P i p e.—In the previous paper mentioned, I

showed how drop suction pipes can be fitted on tank tops—

particularly within the machinery space—having the flange

above instead of on the underside of tank tops, thus enabling a

suction pipe to be withdrawn, with the tank full, for purpose

of cleaning or clearing.

I have known cases, and they often occur, where suction

ends become choked and tanks cannot be pumped out, when

such an arrangement would permit of same being easily dealt

with.

D r a in a g e is an im portant item. W ater lying in any bottom

space, or in a steam loop, is both troublesome and a source of

danger.

A good drain should always be arranged on the boiler side

of main, or any important auxiliary steam stop valve, also on

top side of the steam stop valves of auxiliary pumps, and

other engines, especially Dynamo Engines.

Additional to the usual main cylinder and steam chest drain3 8 NOTES UPON A MARINE ENGINE

cocks or valves, it is a very simple and beneficial arrangement

to have (say) a | in. drain cock—preferably of the gland packed

type, fitted with a cleaning plug—at the bottom of each steam

chest, with union, and copper pipe led to hot well.

When at sea these can be regulated just to carry off the water

which accumulates, and this prevents the danger of a sudden

roll causing a body of water to surge into the cylinder.

N.B.—It is much to be preferred that all such drains should

lead into a funnel, preferably of a substantial cast-iron cuplike

shape, say a good quart size, instead of direct to hot well, as

by this means the amount of drainage is visible. The same

applies to all pump air or snifting valves, which, fitted with

a funnel and pipe led through floor to bilge, fulfil their functions,

visible to sight, without making the wet mess one so often

associates with the backs of engines at sea.

For priming feed pumps, and to prevent the formation, in

working, of a steam expansion in the top of the pump barrel,

a drain cock (close up under the stuffing box) and pipe led

direct to condenser will remove all troubles, and can be left

open, or partly open, at sea.

V a l v e s .—Dealing first with main H.P. slide valves, I

hold fast by the good old D valve, for normal purposes.

My experience of piston valves is that they do not compare

with D valves in either economy or upkeep. In engines of

similar size the consumption is higher with the piston than with

the flat valve. I cannot see how a solid block piston valve,

however accurately turned and fitted, can be tight under working

conditions, for, under heat, the chamber must expand more

than the block, and where rings are fitted the wear is considerable,

and reboring and new rings only a matter of time.

In my experience jobs running at 200 lbs. boiler pressure

with D valves the faces are excellent, and after ten years are

in first-class order : Also the sheaves, and the straps have

only very occasionally had new white metal fitted.

For any or all auxiliaries, especially the steering engine, I

would taboo the piston valve as wasteful in steam.

Steering gears, in particular, are a source of great waste of

steam, and continual reboring and renewal of the control

valve or chamber liner, when of the piston type.

With the D valve there is neither waste nor renewal. This

is merely my opinion after twenty years’ observation.NOTES UPON A MARINE ENGINE 39

There is a type of J) valve fitted with a saddle upon its back

which practically removes the pressure. I have not seen it in

main engines, but they are fitted upon pumps and auxiliary

engines by some makers.

Coming to pump valves, I have found that for air pumps,

feed and bilge, ballast and donkey pumps, metallic disc valves

are far and away the best.

The only I.R. valve that one is still held to is in the Ch. pump,

and that is due to the engine builder, in the majority of cases,

arranging for vertical faces, and in such position a disc valve is

not a success, for even if held to the grid face by springs, the

oval wear upon the stud is too great. If builders will alter

their design and give us horizontal valve seats we shall soon be

clear, in conjunction with metallic packing, of rubber and all

its imitations.

I recall a substitute for rubber valves th at I was at sea with

twenty years ago, viz. a sewn canvas valve, and which, in an

air pump, gave us no trouble, but I have not heard of its use

for some years past.

For tank chest and other cold water ffat valves, a good

leather face takes some beating, and will outlast modern rubber

anyway.

R o d s.—Piston rods and valve spindles should certainly be

allowed a substantial margin for truing up or turning down in

the lathe, say, a J in. or jk in. at least on a 6 in. and 4 in. rod respectively.

As these parts are subject to wear and scoring, it is

very unfair to the owner if the scantling is so bare and the

design of cone such, that turning down is not practicable and

renewal the only alternative. Yet one ofttimes finds a cone

without any shoulder or provision for any wear.

P a c k in g.—Probably no part of engine detail comes so

prominently before the junior engineer on his first introduction

to marine service as this item. His first job will most probably

be to pack a gland. A methodical junior will quickly possess

himself of a nicely-constructed packing box—very much after

the style of a housemaid’s box of requisites—and therein will

be found, and ready for instant use, a packing knife, two or

three drawers and packing sticks, a pot of tallow and black-

lead or graphite, a lump of waste, and some assorted pieces of

packing and jointing: Some sail twine and lamp cotton will

complete a little kit always ready for emergencies.4o NOTES UPON A MARINE ENGINE

There are frequently too many sizes of packing to order, and

often quite unnecessarily so. A typical job wiU have, say :•—-

I f packing in the piston rods,

I f „ ,, „ valve rods,

1 „ ,, ,, tail rods,

I » » >» bilge pumps,

J ,, „ „ feed pumps,

f „ ,, „ circulating pumps,

i » ,, „ air pumps,

whilst in the builder’s ballast and feed pumps, reversing or

turning engines, tank valves and other similar parts, the sizes

will vary from £ down to §, and the depths of stuffing boxes

from a capacity of 7 or 8 turns down to 3.

Now the sizes of stuffing boxes must bear a relation to the

size of rod working therein, but a little thought would easily

reduce the packing on the main engine rods to two sizes and

upon the pumps to one size throughout, and in'the auxiliaries

to (say) two sizes. By so doing shop drawings, gauges, and

the glands themselves become standardized, and men soon come

to learn and retain in memory sucli sizes, whereas great

variety compels ceaseless reference to drawings, and infinite

loss in so doing.

Soft Packing, as it is usually termed in contra-distinction to

metallic, is now made and sold in such variety that to name

any one would be invidious ; the more so, that by a careful

perusal (if ever you have time to do so) of any maker’s pam phlet,

he invariably sets forth the fact that his is the only reliable,

economical packing on the market, and thereafter follows

a long list of patrons, past, present and future.

Many of the older packings still hold their own amongst the

new-comers, and probably will continue to do so, but it is a

fact—almost remarkable were it not so common—that the

packing which suits one job may not, and often does not, suit

another—even a sister ship.

In the recent rubber boom one could not but deprecate the

way in which all classes of packing—non-rubber packings—■

were advanced in harm ony; and one result of this abnormal

advance (in an always large item of upkeep) set one looking

around for substitutes. I am pleased to say the result has

been a great decrease in packing account, despite rubber booms

and prices.

Metallic Packing has been given a great fillip by the inNOTES UPON A MARINE ENGINE 41

creased cost of soft packing. Instead of metallic packing

only in the H.P. engine, many are now fitting it throughout the

three engines and in the main feed pump. Some of the builders

metallic packing of the old ring type—of brass or white metal,

or both—are giving excellent results, and there are some old-

established firms supplying excellent and reliable metallic

packing at prices from 20s. to 30s. per inch.

Such packing compares well in price with the heavy high

pressure (soft) packings at 3s. 6(1. to 4s. 6cl. lb., many of which

are heavily loaded with white metal or hardened lead.

As for the higher price metallic packings—with a complicated

system of cod pieces and spiral springs—at prices running

up to nearly £5 per inch of diameter, I have found—■

from experience—more satisfaction in the older and simpler

type I have referred to.

Hemp packings—of genuine quality—I have found excellent

for feed pumps. Fibrous metallic packing—if of genuine

white metal, with a good percentage of tin—are of service in

small rods and for boiler m ountings; for pump rams and

large rods I have not found it successful, nor for steel rods

exposed to the weather, or which are subject to rust or pitting.

P l a t fo r m s.—Just a word on platforms to illustrate a point

generally overlooked by most of us. Some time ago I appointed

a young fellow as third of a steamer, who had had a few months

previous sea experience.

However, the next day I received a letter of resignation

from him, with a hand sketch attached, in which he pointed

out and showed on the sketch in figures, that as his height was

5 ft. 7 \ in. and the height between the middle grating and

underside of cylinders only 4 ft. 11 in., he did not consider it

would be safe for him to go in the ship ! I regret I have mislaid

that letter, but the facts are as stated, and were quite seriously

held by this youth. If I ever come across that letter it

shall be framed and presented to the Library of this Institute.

N.B.'—Of course, the obvious thing would be to build engines

to suit engineers, but as things are we have to make engineers

suit the job.

L a d d e r s , H a n d r a il s a n d Sp l a s h P l a t e s .—W hat a lot

there is in these three little items alone to make a job comfortable

and convenient down below, and how often one or the4 2 NOTES UPON A MARINE ENGINE

other or all are more or less lacking or inefficient! If those

who designed these things had to go with them upon the rolling

deep, they would often be better arranged. Ease of access,

safety in getting around, and cleanliness about the engines

are factors to be cai’efully considered in every case.

P a t e n t s .—I might just say, “ The fewer the better.”

Unfortunately, a few things, especially amongst the little

items, which would really be useful in themselves, are so loaded

up with “ Royalties ” that they become extinct. Royalties

of £1 per inch are prohibitive, as are high percentages, and a

small cock or valve weighing fib. in brass can never be worth

the 15s. I have known asked for it. In fact, the saving that

many patents may effect, or are stated to effect, is more frequently

counterbalanced by the capital value of first cost plus

the expense of upkeep.

B o il e r s a n d A u x il ia r ie s .—Can find no place in this paper,

and are worthy a place to themselves.

I n t e r c h a n g e a b il it y o f P a r t s.

—I consider in the design o r

specification of a marine engine that prominence to this desirable

arrangement should be given. Shipowners don’t want to

incur more expense than is necessary, nor is it desirable to

have any surplus gear about that is not more or less requisite

for ordinary deep sea voyages ; but obviously, if one thing will

fit three engines then one spare does for either.

In many cases the H.P. valve spindle is different in length

to the others, and air and circulating rods are more frequently

divergent than alike. Feed and bilge pump rams are usually

of varying diameters, and glands are too often of all sizes and

depths on the same engine or pumps,

Crank shafts are now usually alike and interchangeable,

as they should be, and likewise piston rods (unless in the

case of a tail rod) and valve spindles should be alike in every

respect. Air and circulating pump rods can be made interchangeable—and

are so with several makers who standardize—

whilst feed and bilge rams may always be so. These last are

the most likely of all to break or need renewal, and if a spare

does for either, or a bilge ram can be fitted in place of a feed

ram, then obviously the engineer at sea has a reserve that

averts trouble and possible disaster.NOTES UPON A MARINE ENGINE 43

P la n s a n d D a t a .—To every new job the builder usually

supplies some information, or will do so when desired. Some

builders supply to the chief engineer a sheet of particulars of

the principal dimensions and sizes of cylinders and pumps,

valves and packing. Sometimes plans are supplied, but not

always.

The information that should be supplied by an engine builder

to a steamer’s engine department, per chief engineer, is :—

A tank-piping plan,

A bilge-piping plan (either together or separately).

A cylinder section, showing pistons.

Shafting plan.

Tail shaft and propeller.

Boiler plan (sectional).

All above should be fully-dimensioned working drawings,

same as sent into the shops. He should also be supplied

with all data re sizes required for ordering, valves, packing

; condenser and boiler tube (sizes), diameters of rods and

stuffing-boxes, and depth of latter. Leads and cut-off of main

valves ; sketch of a M.B. firebar, etc. Trammels should be

supplied to the engineer of piston clearances and valve settings,

also a step gauge of crank shafting. Templates should be arranged

for, either to be put aboard, or sent to, or held for

owners, or to their instructions, of—

Propeller (cone) template, with key-seat gauge.

Propeller coupling template.

N.B.—Laths of valve and port faces are very useful to have

aboard ship and for reference.

Trammels of furnaces, with the diameters noted and marked.

Trammels of cylinders.

To the owners or their superintendents’ office the following

tracings or blue prints of working drawings will prove of the

greatest possible convenience, and are more or less indispensable

to the engineer in charge of a fleet, from the units of which

come letters and wires requiring instant reference to data or

drawings. Of these I consider the following necessary :—

Plans and data similar to those supplied to the ship (as

above).

Trial trip data.

Steam piping arrangement.

Detailed tracings (blue prints) of condenser, pumps, cylinders,

shafts, connecting rods and valve spindles.44 NOTES UPON A MARINE ENGINE

N.B.—A general arrangement drawing is sometimes useful,

but it depends upon scale, size and detail shown. As a rule

a G.A. does not give much information.

Spa r e G e a r .— The spare gear required by the Classification

Societies, say Lloyd’s for instance, is as follows for an ordinary

cai'go steamer’s o u tfit:—

2 co n n ectin g ro d o r p isto n to p -en d b o lts a n d n u ts.

2 co n n ectin g ro d b o tto m e n d .bolts a n d n u ts.

2 m a in b e arin g bo lts.

1 se t co upling bolts.

1 se t feed a n d bilge p u m p valves.

1 se t p isto n sp rin g , w here co m m o n sp rin g s a re used.

A q u a n tity of a sso rte d b o lts a n d n u ts.

I ro n of v ario u s sizes.

N.B.—These last two items are somewhat ambiguous, and

the guarantee engineer, unless he keeps his eyes and hands on

the alert, is likely to go away rather unprepared for trouble.

Needless to say, a good sharp and intelligent engineer will

not leave the engine builder’s sheerlegs without most of what

he wants, although a careful scrutiny of the engine store-room

would probably prove abortive.

To the above Lloyd’s recommend the following additional

items to guard against trouble when trading to distant ports :—

1. S p are c ra n k sh a ft.

2. „ p ro p eller sh a ft.

3. ,, p ro p eller, or full se t of b lad es (b u ilt propeller).

4. ,, s te rn b u sh or lig. v itie lin in g fo r b ush.

5. 1 p a ir co n n ectin g ro d brasses.

6. 1 p a ir c ro ssh ead brasses.

7. 1 se t lin k brasses.

8. 1 eccen tric s tra p com plete.

9. 1 a ir p u m p rod.

10. 1 c irc u la tin g p u m p rod.

11. 1 H .P . v alv e spindle.

12. 1 L .P . v alv e spindle.

13. 1 se t ch eck valves.

14. 6 c y lin d er cover b o lts.

15. 6 ju n k rin g b o lts.

16. 4 v a lv e c h est cover bolts.

17. 2 do zen bo iler tu b es.

18. 3 do zen co n d en ser tu b es.

19. 1 c y lin d er escape v a lv e a n d sp rin g .

20. 1 s e t sa fe ty v a lv e sprin g s.

Of these 1 consider items 1, 4, 7 and 8 are hardly reNOTES UPON A MARINE ENGINE 45

quired In the ordinary tram p steamer. Items 9-10 and

11-12 could be halved if the respective parts were designed for

interchangeability, and item 20 should hardly be necessary in a

two, three, or moi’e boiler job, say, two spare main boiler

safety valve springs should suffice.

Additional to any of the above items I usually specify or

order—-

12 ju n k rin g b o lts, or stu d s, w ith n u ts.

6 cy lin d er a n d (or) ste a m c h est d itto .

2 P .K . g lan d stu d s a n d n u ts.

2 V .S. g lan d stu d s a n d n u ts.

£ se t p u m p g lan d stu d s.

2 eccen tric sh eav e b o lts a n d c o tta rs .

2 eccen tric sh eav e k e y s (sh aft).

2 eccen tric s tra p b o lts (lugs).

2 eccen tric s tra p stu d s (rod feet).

1 tu rn in g w heel sh a ft key.

2 tu rn in g w heel b o lts a n d n u ts.

A sp a re sp rin g fo r e ac h size of sp rin g o n th e jo b .

S p are se t of H .P . p isto n rin g s, if c o m m o n ty p e , o r su ita b le sp a re

p a rts if p a te n t rings.

Sufficient w h ite m e ta l to ru n u p a b o tto m en d , w ith m eltin g p o t a n d

ladle. A C .I. cone fo r th e a b o v e p u rp o se.

12 zinc p la te stu d s a n d n u ts.

6 boiler screw ed sta y s a n d n u ts.

2 s te rn g la n d stu d s a n d n u ts.

2 m an h o le d o o r stu d s a n d n u ts.

S p are stu d s a n d n u ts (asso rted ).

S p are fireb ars, as re q u ire d fo r p ro sp e ctiv e tra d e .

S p are fu rn ac e a n d d o o r baffles (w ith b o lts a n d n u ts) as re q u ire d fo r

p ro sp e ctiv e tra d e .

Som e sp a re w ire ch ain s screw s a n d co n n ecto rs fro m th e engine te le g

ra p h fittin g s.

S p are v alv es a n d sp rin g s fo r w a te r en d s of d u p le x p u m p s.

F ire b a r p a tte rn s .

P.S.—Of course, all necessary spare valves, packing, tin,

Muntz metal, etc., for liners will be ordered in the first store

list. '•1

Further, to the above I am now inclined to’ include an air

pump bucket complete for the reason I mentioned under the

head of air pump. l*

The Board of Trade requirements for spare gear under a

passenger certificate seems to comprise nearly another engine,

except for bedplate condenser and columns.

N.B.—A spare propeller shaft should always be complete46 NOTES UPON A MARINE ENGINE

with fitted key and nut and tail pin. As to the original spare

shaft, it should have been fitted and holes rhymered in the shop.

A spare shaft supplied at any subsequent date should have the

holes rough drilled, and a rhymer and set of coupling bolts accompany

same. This often saves time and expense in a dry dock,

and in the case of a breakdown would be indispensable.

T ools.—This important item may well come under the heading

of engine details. The ordinary British cargo steamer is

chiefly remarkable for the lack of working gear. The German

vessel usually has a veritable little workshop, well equipped.

The builders usually supply a set of spanners to suit the principal

nuts, and sometimes a set of light or gland spanners. Needless

to say, a set of really good heavy spanners is required for

all large nuts, whether standard or otherwise, and there should

be light spanners additional for top and bottom ends, and a set

of thin ones for glands. A “ star ” spanner for top and bottom

ends and main bearings, having a short lug, is most useful;

whilst claw or box spanners for air and circulating pumps,

stud nuts, piston junk ring bolts or nuts, and other such

recessed fittings are indispensable, although more often

omitted than supplied.

How often will you find a turn-screw key for cylinder face

cheese-headed screws, or for screw condenser ferrules, in the

tool-store of a new job ?

Chain blocks is another item sadly neglected. The average

builder puts aboard either a Warrick screw or set of Weston

chain blocks for the heavy lifts. The one is slow and cumbersome,

and the other takes “ all hands ” to its fall side. In these

days of cheap and serviceable worm-geared blocks there is no

excuse for hindering work in port, and doubling the stoppage

time at sea when some mishap occurs for the sake of good gear

which, once supplied, need no replenishing. In these days of

frequent surveys, it is most helpful and economical to be able

to have all the top covers off and slung at one time. To do

this a set each of 40, 30, and 20 cwt. blocks will suffice, whilst

a set of 10 cwt. is most useful on the pumps. For bottom ends,

a double or treble rope set of blocks requires quite a gang of

firemen to heave upon, whilst a pah of 5 cwt. chain blocks

will easily and steadily lift or lower a heavy bottom end.

Anything that economizes labour in these days is welcome. In

addition to the usual hand tools, the engineers are greatlyNOTES UPON A MARINE ENGINE 47

assisted in maintaining the machinery in an efficient condition,

and minimizing repairs, if supplied with W hitworth stocks

and dies (with 3 taps to each size) up to, say, 1] in. ; gas

dies and taps {, §, |, f, and brass dies, §, | ; as these,

in addition to tapping and screwing for iron and copper piping,

are indispensable for chain studding and boiler repairs. A

valve reseater can be supplied for £4 10s. Od. to £6 10s. 0d.,

and enables high pressure valves and faces to be kept in order.

Gas tongs to take studs and pipes up to 2 in. are invaluable,

and if any winch pipes are of iron, a size to take them

should be on board.

I was going to ignore the indicator as being too obvious a

part of an engine outfit, but when so many are wanting,

one is tempted to ask the simple question, Why ? Indicator

gear is fitted on any first-class job ; one naturally looks for, and

expects to find, the Indicator.

Before I conclude this subject I will just mention a lathe.

On most foreign ships (German, in particular) you will find one ;

on the British, No. I have got so far as a powerful double

geared hand-drilling machine on all the steamers under my

care, but the difficulty of space and a suitable tool are matters

that hinder in regard to a lathe. My idea of the ideal ship’s

lathe is one that will take in, in length between centres, a feed

or bilge pump ram, and to swing in the gap a main valve

spindle crosshead. A or 8 in. lathe would do it, and the tail

end of a valve spindle can be carried in a steady block by a

bracket on or through the bulkhead.

N.B.—The wearing part of a V.S. will be shorter to turn up

than the length of a pump ram. Length—-too much length—

would be both a difficulty as to space and a needless extra

expense. The two parts 1 name are those most requiring truing

up of the larger parts. The face-plate of this lathe should swing

an H.P. piston ring, and for the size centre I name, a deep gap

would be necessary to take in, say, 24—25 in. ring for a 1 \ in.

or a 26-28 in. ring for an 8 | in. lathe.

Leading screw and change wheels for cutting threads would

be indispensable, but neither separate self-act nor a self-acting

cross traverse to the saddle are necessary. A good compound

rest and a set of tools would complete the tool. For the drive,

I consider a counter shaft with the usual cone and belt drive

and brackets to carry same on a bulkhead would be necessary,

but the “ driven ” pulley on counter-shaft should be rope grooved4 8 NOTES UPON A MARINE ENGINE

with a clutch, the whole power driven from a grooved pulley

on rotary pump or reversing engine. 1

A foot attachment would be of no use for such a lathe, but

hand power could and should be applicable by a hand wheel on

a bracket bolted to the bulkhead and easily turned by a man.

Such a lathe, with dog-chuck, steady rest and faceplate, would

enable engineers to keep their details in good order, and suitable

castings for neck and gland bushes could be ordered on the

store list, or cast from white metal pigs. The lathe I have outlined,

plain and substantial, should be obtainable, complete, for

under £50, if made as a speciality.

My experience of engineers in general is, that given good

tools and gear, they are both anxious and willing to do all in

their power to keep their jobs in good order, and without unnecessary

expense being incurred ashore. As a m atter of fact,

the average overhaul by shore labour generally gives the marine

engineer plenty to do for the ensuing voyage, remaking joints,

readjusting, etc., and the more care and attention an engineer

devotes to the machinery under his charge, the less he likes

the repair gang undoing his work and adjustment.

Finally.—To the ordinary marine engineer lies not the duty

of design and theory ; all he can, or is called upon to, do, is to

make the very best of the machinery he is put in charge of.

Briefly, th at all lies between two extremes, the coal bunker

and the propeller, the former to conserve and the latter to accelerate.

All that comes between is detail, of saving, adjustment,

care and attention to every part.

Common sense and practical application of workshop practice,

and the experience which service at sea alone can give,

coupled with the tactful handling of men and, perhaps most

important of all, a keen sense of duty both to perform and to

inspire, are the qualities to win esteem, confidence, and character

; in the doing of such the Marine Engineer elevates himself

and his profession, as well as his status as an engineer officer in the

Mercantile Marine.NOTES UPON A MARINE ENGINE 49

DISCUSSION.

Mr. W. McLaren : I did not think I was to be called on

first to criticize Mr. Lang’s paper, but certainly he has given

us a variety of subjects to deal with ; from the marine engine

to those which particularly concern the furnisher or store

dealer. Not having copies of the paper, I will deal with the

question which is freshest in my mind, th at of tools. I do not

know who is to blame ; but the German seems to get all the

money he asks for in this respect ; whereas in this country

it seems that everything is to be cut out where it is possible to

do so. One builder cuts his price against another and, of

course, sometimes the competition is not very fair. But it is

possible that, by giving a certain class of engine room equipment,

they may save in the end. Under the British flag I

have never seen any of the ships fitted up as the telegraph

ships a re ; with an engineers’ shop complete. Some are

fitted rather extravagantly ; no doubt they were fitted when

cable laying was rather more remunerative than it is to-day ;

but at any rate they set a good example of what might be

done. It is a credit to the British engineer that he is able to go

through the trial stages with the tools he has ; and he has

saved a large amount of expense as compared with what the

German engineers get put on board. That is not to infer that

he should not get as many tools as the ship can conveniently

carry and is likely to need in case of breakdowns. As regards

the tackle, the present system of chain blocks is very

convenient and rapid as compared with the old style ; but I

should like to know what drift one would give. A 5 ft. drift is

rather difficult to get ; while with the 10 ft., 15 ft. or 20 ft.

drift it would lose any advantages it might have over the rope

block. I do not say the rope block would be quicker ; but

in some respects it beats the chain block. If you have a dry

platform it is all right—I am speaking of the Weston blocks ;

but with some of the worm gear blocks or pulleys the chain is

always in the same continuou - line. W ith regard to cylinder

liners and piston rings, I am inclined to think th at every

cylinder ought to have a finer, whatever the pattern and

whatever care is taken of them. After the castings have

come from the foundry and gone through the different

machines, then is the testing time. Shrinking generally

occurs around the necks of stuffing boxes and at those par-50 NOTES UPON A MARINE ENGINE

particular parts where there has been a drag on the metal.

Then there is always the question of testing for leakage.

W ith regard to white metal ; I certainly agree with Mr. Lang

that we should have a reliable metal. le a n remember on one

occasion being for eleven hours on my knees dealing with a

white metal on the main bearings. That particular kind of

metal was supposed not to run ; but it did run that time. The

whole staff were twenty-three hours. It was a case of putting

her astern and picking out what we could get. There was the

question of tools to be considered. There were a few of the

square files drawn out about 9" drawn right down to about

one-eighth of an inch so that we could get them between the

shaft and the metal block where the white metal flowed in.

W ith regard to the crankshaft. I am inclined to accept the contention

th at the power should develop along the shaft. I

cannot say that I agree with Mr. Lang on the question of i)

slide valves. I prefer the piston valve for the high pressures,

and I have found that the block with no ring at all is good

enough. W hat loss there is you are making up as you go

along until you come to the condenser end. Some makers

differ a great deal in regard to the ratios of the cylinders. 1

believe in getting the fullest power out of the engines with the

boilers “ easy,” or with plenty capacity. The question ot tail

shafts should certainly be one of quality of metal, and nickel

steel has produced a good tail shaft. If the liner overruns

the whole length of the stern bush it must be an advantage.

For the thrust bearings no one will deny that surface is the

first consideration. As to lubrication, that is left to individual

ideas. There are various systems of lubricating the tail

shaft on the market. I would certainly accept the experience

of the white metal instead of lignum vitae fitted in the stern

tube. I will pass over the question of the condenser ; I

think it is reasonable to have a fair circulation either for the

feed or circulating water. As to the packing of the tubes without

the ferrules, it generally means an all night, or two days

and a night to get the condenser out of the way. The packing

nowadays is generally done rapidly and gives a satisfactory

job. I should think there will be very few of ths old

wood ferrules fitted now.

Mr. J . G. H a w th o r n : I do not think it will be out of place

for me to say that during the whole course of the Institute’sNOTES UPON A MARINE ENGINE 5i

existence, I have not had the pleasure of listening to a more

practical paper ;—a paper so full of useful hints to young seagoing

engineers. It is full of the kind of information not

obtained from text-books, but only obtained from hard and

strenuous experience. When we hear Mr. Lang discourse

on such subjects as sizes of cylinders, shafting, boiler, etc.,

and hear him state why sometimes the boilers are too

small for engines, engines too big for boilers, etc., we cannot

help feeling th at the hints he gives must be of great value to

our younger men especially. W ith your kind permission and

Mr. Lang’s, I would like to supplement his remarks with a

few “ rules of thumb ” outside of theoretical design. As in

the design and building up of all structures it is necessary to

have a foundation, I will take the fire-grate area as the course

of foundation bricks upon which to build the boiler. As the

power of the engine depends upon the consumption of coal,

taking natural draught, we can burn with facility 16 to 20

lb. per square foot of fire grate per hour, and as the length

of marine furnaces is limited to about 6 ft., thus it follows

th at consumption is proportional to width of fire grate. Taking

then 16 lb. per sq. ft., and the length as 6 ft., a good approximation

is 1 ton of coal per foot width of furnaces. Thus

an engineer joining a strange ship could arrive at an approximation

of the consumption by allowing 1 ton of coal per foot

width of fire grate. If we allow 1-6 lb. of coal per I.H .P.

per hour, then 16 1-6 = 10, or there should be 10 H.P. developed

in the engine for every sq. ft. of fire grate. There should

be, say, 30 sq. ft. of heating surface to 1 sq. ft. of fire grate,

and, allowing the tube surface to be 80 per cent, of the total

heating surface, this gives 24 sq. ft. of tube surface to 1 sq.

ft. of fire grate. Upon this assumption a good rougli and

ready rule is to say 2 tubes for every 1 in. diameter of f urn aces.

The diameter of the funnel should be the square root of the

width of all the furnaces connected with i t ; thus 12 furnaces

3 ft. 6 in. in width ; diameter of funnel V12 x 3 5 = 6 in. 6 ft.

W ith regard to the size of cylinders ; if we take the limit of

compound working at 90 lb., and then take the ratio of H.P.

to L.P. as 1: 4, then for every 10 lb. increase of pressure,

increase this ratio by -4, or increase the ratio by 1 for every

25 lb. pressure. This would give for 115 lb., 1 : 5 ; for 140

lb., 1 : 6 ; 165 lb., 1 : 7 ; 190 lb., 1 : 8, taking the limit of

triple expansion at 180 lb. With respect to the shafting, if52 NOTES UPON A MARINE ENGINE

we take the cube root of the horse power and increase it by

10 per cent., it should equal very approximately the diameter

of the crankshaft; this is presuming the revolutions are at

about 65 and the stress per sq. in. not to exceed 9,000 to 10,000

lb., engines running in full link. I would commend Mr.

Lang’s paper to all our younger members more particularly.

Mr. F. M. T im pson : We are much indebted to Mr. Lang

for his very comprehensive paper. Most of his remarks are certainly

based on very sound practice, although perhaps his

experience with the D slide valve is happier than th at of

many other members. With regard to metallic packings, Mr.

Lang evidently does not believe in the use of the spring type,

and, although I carry no brief for such, I have known them

run for ten years without the slightest trouble, and I think

that, with commonsense attention, they give as good results

as others. A point th at has not been mentioned is the question

of relief valves on cylinders, etc., which I do not think have

the attention they should have, and are often much overloaded,

thus courting disaster in the event of excess of pressure or

collection of water.

Mr. W. W a lk er : We have to thank Mr. Lang very

heartily for the amount of m atter put into this paper. I

cannot agree with him, however, with regard to the piston

valve. There is nothing more disagreeable at sea than the

sound like the braying of a donkey which is sometimes the

result of the ordinary D slide valve on the high pressure

cylinder. Perhaps Mr. Lang has found a suitable lubricant

to get over the difficulty. Of course that is quite independent

of the noise made, and which indicates a great amount of

friction which ought to be eliminated. Like Mr. McLaren, I think

that if there is a slight loss with the piston valve it will be

taken up with the intermediate or low pressure cylinder. Mr.

Timpson referred to the question of relief valves. I once

had an experience with a broken cylinder and the first question

asked the engineer was “ Did the relief valves lift ? ”

“ No,” he said, “ I left them in exactly the same position as

the makers left them.” The makers had left them screwed

down and the engineer went on the assumption that they

had been properly set. Engineers should realize that relief

valves should be set only a few lbs. higher than the initial

pressure in the cylinder, so as to lift quite freefy when required.NOTES UPON A MARINE ENGINE 53

W ith regard to drainage from the various cylinders, I take

it Mr. Lang means the drainage from the cylinders as well

as the valve chests.

Mr. Lang : It is only an extra cock to the bottom of the

steam chest.

Mr. W a lk er : I know Mr. Lang is aware th at a great many

accidents have arisen from the wrong drainage of the cylinders.

Builders have made most serious blunders in leading the drains

to the wrong places. In my opinion all drain delivery should

be visible. One other point deserves attention, although

perhaps it does not apply so much to the builders as to

those who have been running the plant for some time.

I once took charge of a ship and the first intimation I received

from the donkeyman was th at they had never been abfe to

run the donkey with any degree of efficiency. I tried the lift

of the suction and delivery valves and found same to be

about |" . I reduced it to and i\", and the donkey

worked excellently. I have every sympathy with Mr. Lang’s

idea of having a lathe on board ship, but I should also like

to ask a question, as it would only be in rare cases where a

big plant would be required : would it justify the expense ?

In all the years of my sea-going experience, I do not think

I ever once felt the necessity of having a lathe on board,

and personally, if I were an owner, I do no think I would

be inclined to give my consent for such an expenditure.

It was agreed, on the proposal of Mr. H a w th o rn , seconded

by Mr. N ew a ll, th at the discussion be adjourned.

Mr. Lang stated that he would reply to the various points

raised in opening the discussion at the adjourned meeting.

A hearty vote of thanks was accorded to Mr. Lang on the

proposal of Mr. T im pso n, seconded by Mr. McL a r e n .

ADJOURNED DISCUSSION

Held Monday, March 18, 1912.

Ch a ir m a n : Mb . F. M. T IM PS OX (M e m b e r o p Co u n c il ).

Ch a irm a n : We are met to-night as arranged, for the

adjourned discussion on Mr. Veysey Lang’s paper “ Notes upon

a Marine Engine,” and I am sure you will all regret that Mr,54 NOTES UPON A MARINE ENGINE

Lang is unable to be with us as he has had to go to the Continent.

He has sent a reply to the previous discussion, which

I will now ask our Hon. Secretary to read :—

I am extremely obliged by your kindly reception of my paper.

In fact, I am surprised th at so homely a subject, so casually

treated as an hour’s reading necessarily enforces, should have

brought forth any enthusiasm ; but it proves to me th at you

also take an interest and some delight, I trust, in the details

of our interesting profession. New tips and workshop hints

are experienced every day, and at sea as frequently. I am

glad to have roused some opposition in my subjects ; without

learning the other side one can be but ill informed, and perfection

is only obtained by the obliteration of faults. I trust,

however, I have not given the impression that I am one-sided

in my views or prejudiced against this or th at arrangement

or fitting. I but endeavoured to show that the weight of my

personal experience inclined to such preference. Flat versus

Piston Valves has probably been a controversial point from early

days. In point of fact, the majority of H.P. main engine valves

are doubtless of the piston type, yet on the other hand the

M.P. and L.P. valves remain—in most cases—of the D type,

which seems to prove th at the D valve is favourite in itself,

but not considered suitable in the H.P. of the modern 160-180

lb. steam pressure. Thus I consider it is all a question of suitable

metal, whether a flat valve (or any other for that matter)

runs well or not upon its face. There are some engine builders,

and one firm in particular, who believe in the flat valve and

fit same in practically all cases up to 180 lbs. These valves

are without any relief arrangement except to order, but above

180 lbs. they are usually fitted. The relief valve takes off a

considerable proportion of the total load, but not all. As I

mentioned to one inquirer, I have known them to be found out

of order and the D valve taking full load at 200 lbs. Yet

there was no abnormal wear and tear, although there was

certainly extra strain thrown upon the valve gear.

W hat I particularly want to emphasize is that it is the quality

of metal in wearing surfaces that matters. In the case of

the firm I refer to, and with whose jobs I have had long experience,

I believe the cylinder face is cast vertically—a solid

slab with a big head or “ git ” and this ensures even metal

throughout. The whole is then heavily machined and the

ports milled out. Naturally, if you cast a cylinder face, withNOTES UPON A MARINE ENGINE 55

the ports cored in, you get cross sections of metal with blow

holes and hard places. It is all very well to say th at steam

which passed the H.P. valve is used up in the three cylinders.

The im portant thing is th at the H.P. valve should govern

consumption, both of coal and steam, and unless this cylinder

is doing its work economically there is no chance whatever of

the other two correcting or balancing initial waste.

As regards any noise from H.P. D Valves as suggested by

Mr. Walker, we have all doubtless had some experience of a

“ squeaky ” valve, but I must say mine was in the days of

compounds ; and I have not heard same in a triple.

Again, I say it all depends upon the metal in the wearing

surfaces, and the cylinder face should be harder than the valve.

Undoubtedly some lubrication is necessary to a D valve, but

it need not exceed from a half to three-quarter pint of oil for

the twenty-four hours if the lubrication is positive, viz. forced.

I don’t think this quantity of oil does any harm if soda is used

in the boilers to neutralize grease. Mr. Wm. McLaren mentioned

the “ drift ” of chain blocks. As a m atter of fact, the

usual length of chain allowed for in stocked sizes is 10 ft.

drift or lift. As regards his remark re Tail Shafts, I am under

the impression that nickel steel is only used on high grade engines

and in the Navy. Ingot steel is generally used in ordinary

shafting. Mr. Hawthorn gives us some interesting data, and

I was happy to see that my paper had touched some of the

hidden springs of his extensive experiences.

In regard to piston rods, valve rods, etc., it would be very

convenient and establish a closer standard in scantlings if

classification rules gave a formula for these as for shafting.

We might then look in vain for such divergence in sizes as now

exists on similar size engines by various builders. One gives

a 6J in. rod and another a 7^ in. for the same size of cylinder.

Chairm an : Mr. Lang apparently agrees with what is

common practice in regard to the use of the piston valve on

the H.P. engine. The piston valve on the intermediate is

certainly not so common, and several cases have come under

my notice where the intermediate valves gave a great deal of

trouble. I think Mr. Walker had some remarks to make on

this subject on the occasion of the last discussion.

Mr. W . W a l k e r : In his paper Mr. Lang put forward a

plea for the D valve irrespective of pressure, but evidently56 NOTES UPON A MARINE ENGINE

he has made an exception now in favour of the piston valve

in the H.P. cylinder. I heartily agree with his remarks as

to the quality of metal. There is no doubt if you do not get

a proper mixture for cast iron—and this applies to every working

surface—it will not be satisfactory in regard to standing

the heat and wear and tear. My own experience with slide

valves was th at they gave great trouble in overcoming the

difficulty, not only of wear and tear, but of squeaking. Certainly

lubrication reduced it to a great extent, but there is

an enormous pressure behind the valve forcing it on to the

face, irrespective of the pressure from the inside relieving it,

and unless the slide valve is balanced there is enormous wear

and tear on the surface, and consequently friction to a greater

extent on the ordinary valve gear. If slide valves are used

there should be sufficient bearing surface, and also sufficient

grooves on the surfaces to allow whatever lubricant is used

to get thoroughly between the faces.

Chairm an : Mr. Lang remarks th at balanced shde valves

have never been a great success. In some of the earlier jobs

I have seen balanced shde valves with different methods and

none were satisfactory. W ith regard to lubrication, about

eighteen months ago one of our members had great difficulty

with an intermediate shde valve, and he had filled up the

recess with a mixture of graphite and plaster of paris. It

seems a very curious mixture, but he said it had helped him

a great deal.

Mr. A. H. L ed g er : W ith regard to the type of valve used.

I t should not be forgotten, th at though the intermediate

pressure is now equal to the H.P. pressure of former days,

the intermediate valve has the great advantage of being a

double-ported one. I might mention a case of interest to

engineers, concerning an old compound job. The H.P. valves

(twin-screw) had a compensation back and a balancing piston

on top, but had a stroke of II in. ahead and 14 in. astern ;

and without constant attention to the impermeators, these

valves were sure to give trouble.

I have met engineers who say th at no set of engines require

internal lubrication. Well, an engineer went in charge of

this job and would use no oil. Upon arrival at Colombo the

faces of these valves, phosphor bronze I | in. thick, were found

completely stripped off, the pieces lying at the bottom of theNOTES UPON A MARINE ENGINE 57

chambers. These faces had oil grooves in them with openings

to the steam to lessen the friction. I am not advocating

internal lubrication at all, but this job would not run without,

in fact was the exception to the rule th at the engineer must

always be provided for.

Chairm an : Mr. Lang remarks upon the sizes of piston

rods, and L think there is certainly some ground for standardizing

in this direction. As far as I remember, the sizes were

apparently taken from the old compound engine, and in some

of the earlier triple expansion engines the rods were much

smaller than those of the present day. In one vessel I know

some of the rods had to be renewed after eighteen months’ service

I think the standardization of rods would be an advantage.

Mr. G. W. N ew a ll : I think the earlier practice regarding

the size of the connecting rod was largely due to the material

used instead of mild steel. The materials of the present day

are much better ; the surfaces are better and the poundage

per square inch is more sustained. Mr. Lang makes some

comment upon the sizes of packing, and I think he is quite

right there. The question is whether so many sizes of packing

are necessary ; I do not think they are. The author has reduced

the number to seven, and I think they might be reduced

still further. In fact, the store list could be halved if you

could halve the sizes of the stuffing boxes. There are so many

different draughtsmen doing the work ; one puts J in. and

another | in. instead of making them both the same size as

they might very well be, and should be always proportionate

to the diameter of the rod.

Mr. 1). R. D ilw o r th H arrison : We already lose so much

horse power unavoidably th at it is desirable to save wherever

possible, and I think th at where the piston valve is kept in

decent order and is overhauled occasionally, it is just as efficient

as the slide valve. There was an interesting series of

papers and discussions in The Engineer a week or two ago on

this subject, and of course there were very diverse views

expressed, but the consensus of opinion was th at the piston

valve was more economical. There seemed to be the impression

th at the slide valve must tend to warp by reason of the

high temperature. As to the point of cylinder clearance I

agree with Mr. Lang that in many cases this is much more58 NOTES UPON A MARINE ENGINE

than is necessary. When an engine is designed to run economically

at full power, the greater the clearance, the less economy

will there be at average speeds. This is an important point,

as very few cargo vessels utilize their full power constantly.

Drainage is important, so far as it goes, because where there

is a chance of the water settling it militates against economy.

I do not altogether agree with him in his remarks on condensers.

He proposes painting over the cast-iron part of the condenser

as a remedy for condenser trouble ; but I consider the cast

iron itself exerts a protective influence over the tubes. In

an interesting paper by Rear-Admiral Corner some time ago,

he mentions the case of a condenser which came under his

notice. It was an old type with the water outside the tubes.

This condenser ran for many years without the slightest

trouble and then, unfortunately, the vessel ran ashore. When

they got off, the condenser was more or less filled with sand.

They took out the tubes, scraped the cast iron and painted

with red lead. It was re-tubed and sent away again, and in

a very short time the tubes went one after another. They

brought the ship back and re-tubed her condenser, and while

re-tubing scraped off all the red lead paint, and they had no

further trouble. The particles of iron oxide swept into the

tubes from time to time may cause corrosion, but I do not

think this a serious m atter. One method of preserving the

tubes that seems to be favoured is by placing blocks of aluminium

or alumin-alloy in the water ends of tube plates, and

electrically connected thereto. The aluminium is eaten away

and the tubes are protected to a considerable extent. As

to the ordinary screwed ferrules, they are very cumbersome,

and one cannot hope th at when a man puts in about 2,000 on

each side of a condenser, they are all going to be water-tight.

I think this trouble is got over by the tapered ferrule. These

are very handy to put in and make a very good job. Being

also easily removed, retubing a condenser takes only a fraction

of the time absorbed by the older method. As to the piston

valves on steering engines, of course a good many companies

have abstract sheets on which the engineer enters the amount

of coal said to be used by the steering engine. The figures

given are generally conventional, and according to office

requirements, but a glance at the atmospheric exhaust of a

ship working into port will give a fair idea how far hah a

ton of coal will go in twenty-four hours. The difficulty ofNOTES UPON A MARINE ENGINE 59

keeping steam on the half ton per day usually allowed is too

great. W ith regard to the circulating rubber valves, they

are quite efficient, and I have not found them troublesome

when properly fitted.

Chairm an : W ith regard to painting the cast-iron portion

of the condenser, I think Mr. Lang merely intends th at to

apply to the water spaces, and in my experience I have seen

painting done with great advantage. In some instances,

in painting the condensers for the first time, the metal has

been found to be very soft, in fact, a considerable amount of

surface had to be scraped away before coming to the sohd

metal. If carefully done, I have known it to last for two

or three years, and the water boxes to be in much the same

condition as when originally painted. W ith regard to the

india-rubber circulating pump valves, I believe a great many

are broken by reason of them being sprung and abrading

the inside edges, thus tending to split them. Most of the

valves break away from the centre, due probably to the holes

being made too small.

Mr. N ew a ll : Regarding the latter part of your statement,

of course many people will have the name stamped on the

rubber, th at is to say, the words “ air pum p,” “ circulating

pump,” etc., put on. Other manufacturers object, because

this makes initial cracks where the stamp is inserted. I t is

best to have the valve straight from the mould instead of

having anything stamped on at all.

Mr. R. H. P in n : W ith regard to the use of cast iron, I

know of a firm which is experimenting with two classes of

cast iron, and they have succeeded so far in the way of pumps

and valves, running cast-iron valves against cast-iron faces

without any lubrication.

Chairm a n : Is there any noise ?

Mr. P in n : There is no noise and no lubrication required.

I do not know how far they have gone, but they have been

experimenting for a long time. Of course th at is with ordinary

steam ; I do not know how it would work with highly superheated

steam.6o NOTES UPON A MARINE ENGINE

Mr. -Tas. A damson : Mr. Lang raises the question of the

ratios of cylinders. We had a paper on the ratios of cylinders

and the distribution of power by one of our late members,

Mr. I). MacMillian, and at that meeting I put forward a table

showing the different ratios for compound engines. I see

Mr. Lang gives the ratios 24 : 40 : 66 and 24 : 39 : 64. I do

not know why makers should differ so much, or whether

they are coming nearer one another; but the list, which I

made in 1891, was a very long one, and showed the ratios and

areas of the cylinders for triple and compound engines at th at

date. Another point th at is worthy of being discussed is

the question of nominal horse power. I am surprised th at

the Board of Trade has not made some regulation on the

subject, as it is left largely in the hands of the maker to call

the engine whatever horse power he likes. In the new regulations

for certificates, the same horse power, 99, is given, without

any exact definition of what nominal horse power is. W ith

regard to the slide valve, some years ago we had a discussion

on the subject and several of our members had experienced

very serious trouble in connection with grooving and undue

wearing. Incidentally, we were shown a picture of Church’s

slide valve, which certainly eliminated the trouble experienced

in the compound engine H.P. slide valves. I have seen

such a slide valve wearing, in the course of an outward

voyage, right down until a spare one had to be put in at the

other end. The introduction of Church’s slide valve with

the new D slide valve worked excellently. I think the general

practice is th at the H.P. valve is a piston valve. We

have had some most baffling experiences with condenser tubes.

A fortnight or three weeks ago one of our members spoke of

an experience he had with condenser tubes and asked if the

waters of India had a deteriorating effect upon the tubes.

I said I knew of a steamer running regularly for over twenty

years and no condenser trouble was experienced excepting a

voyage now and again, when the ends of the tubes were found

to be wasted. Many reasons have been assigned as the cause

of the trouble ; but I do not know th at we are any nearer

the real cause, which leads to condenser tubes corroding more

on one voyage than another. In the navy, for many years

past, zinc plates are attached in the water spaces ; I did not

know aluminium was used. Some use Swedish iron, others

mild steel, with a view to eliminate the cause of corrosion of-NOTES UPON A MARINE ENGINE 61

the tubes. W ith regard to circulating pump valves, I think

it is largely a question of price. Some years ago I knew

of cases where trouble was experienced, but during the last

few years the circulating pump valves in such cases have run

for two years without renewal, and I attribute it to the better

quality and higher initial cost resulting in economy in the

long run. Mr. Lang refers to the main boilers. I do not

know if he also refers to donkey boilers, but at one time it

was commonly said th at the donkey boiler then supplied could

not keep ah the winches going, with the result th at there was

much friction and serious disabilities on the part of the stevedores,

from which their successors are reaping advantage,

as I think modern practice has put on 50 per cent, at least to

the donkey boilers, because it is quite manifest th at the cargo

must be loaded and discharged with as great expedition as

possible, and if the donkey boiler is not able for its work, the

stevedore and the owner both suffer. I quite agree with Mr.

Lang th at it is a mistake to put in a full powered engine and

a small boiler; I think, however, the modem tendency is with

wisdom to give ample boiler power. I know of one case where,

fortunately, one boiler could be dispensed with for the whole

voyage, and had it been otherwise the ship might have been

laid up for a time to get all the boilers running, resulting in the

capital represented by the vessel lying idle. W ith reference

to drains, I heard of a peculiar experience in which there was

great knocking in the cylinders, evidently due to water, but

they kept the drains open and still the trouble continued.

Ultimately it was found th at the inner casing was carried up

about 9 in. and the drain had been put upon the inside instead

of the outside. The water collected round about the casing,

which held the body of water. A hole was bored into this

chamber to let the water through into the d rain ; this cured

the evil. I was looking round a small passenger steamer

recently, and in going down the engine-room ladder, I pointed

out an angle iron running out from the bulkhead so close to

the ladder th at the first stranger coming down would be almost

certain to get his fingers injured. Attention to these small

details is good, so also is it in connection with the general and

specific comfort of the engine-room staff and accommodation.

Chairm an : WTe all regret Mr. Lang has not been able to

be with us. He fully intended to be here, but was prevented62 NOTES UPON A MARINE ENGINE

through force of circumstances, but a report of the discussion

will be sent on to him.

A vote of thanks was accorded to Mr. Lang for his paper

on the proposal of Mr. W a lk er , seconded by Mr. L e d g e r.

The meeting closed with a vote of thanks to the Chairman,

on the proposal of Mr. N ew a ll.