Notes Upon a Marine Engine (1912)
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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.