The Savannah morning news. (Savannah, Ga.) 1900-current, 1900-06-16
PROPELLER SHAFTS.
The Achilles Heel of Modern Ships.
The Engineers Post of Danger


Shipping Gazette" recently that the
breakdown of the transport Persia serves
10 call public attention prominently to
a subject which has for some time past
been engaging serious notice in the ship
ping world
For twas ever thus-a condition of
things in public policy or a great indus
try may exist for many years of the ut
most nenace to the well being of vast
number of people, yet the voices Of the
warmers go forth necessarily into ire
sponsiVe silence.
At length there comes a day when, by
means of a great disaster Gn the Persia's
case most happily. just avertedD, the le
thargic monster we call the Public wakes
up, turns himself, and demands that
something be done.
Now. the subject of the leader in ques-
ton was the breaking of propeller
shafts. an accident which, if it befalis
a huge modern steamship in midocean,
leaves her just a log upon the sea. In
few cases does il end in serious damage
TO the vessel, but the amount of public
anxiety and the loss in hard cash it
causes are enormous.
Few. inde7d, of the travelling public are
aware how large a number of these acct
dents occur The committee of Lords
Register recently compiled list of some
of the accidents to shafts of steamers
amounting to a complete breakdown,
which they circulated among those in
terested in the subject, inviting sugges-
lions and observat tons. 1t must have
come as a STARTER to many to find that
during the first half of the present year
no less than seventy-four steamships.
the great majority of which were of
large size, suffered this serious disaster.
OF course there is a goodly minority
among newspaper readers who know
exactly what is meant by steamer
breaking her shaft but for the benefit
of the majority who do not know it may
be necessary, in order to show how the
accids mt is brought about, to give a few
words of explanation as simply as may
be. Nearly all steamships have their
engines at a considerable distance from
the propeller, the four bladed and three
bladed screw, which according as it is
turned, thrusts the hull forward or draws
IL backward.
The connection between the engines and
the propeller is made by means Of a solid
cylinder of steel passing through bear
inss lined with gun metal generally. and
kept cool by a stream of water flowing
over them outside and a liberal supply
of some lubricant, usually tallow, inside.
Now 1t does not need much wit to I'M
derstand that the twisting stress upon
these long shafts of steel is at all times
very great needing them to be OF the
most fawless composition, in order that
they shall be dependable.
Such is the care taken in their manufac-
ture that 1t may safely be said that if they
were only subjected to the steady, equahle
strain of the engines upon them there
would scarcely ever be case of shaft frac-
ture heard of. But such a state of things
is unthinkable at sea. Out on the ocean
the frequent occurrences of gales of wind
and consequent heavy seas brings about
such an alteration of the conditions of
service of the shaft that il is marvellous
how few relatively of these accidents do
occur
When even the heavily laden steamship,
with her propeller so far beneath the sur
face of the sea to be out of sight, meets
with a heavy gale ahead, ra sing a suc-
cession of confronting waves. she must Of
necessity pitch and dive tremendously.
And in so doing it is inevitable that she
will occasionally lift her propeller out of
water suddenly, while the full drive of
the engines is being exerted upon it, What
that means to every part of the machin-
cry can only be imagined by a layman
"a non-engineer). The sudden leap from
the solid resistance of the water into thu
non-resistance of the air is a change Of
condition so great that not even the most
cunningly devised governor" can do more
than to attempt to modify its severity.
1t is instantly followed by return to
the former strain with a wrench th1t
seems sufficient to strip the mighty blades
of metal from the propeller as If they
were feathers in a shuttlecock. The gov
ernor'' mentioned comes to the relief of
the sorely tried mechanism by automa ical
ly shutting off the supply of steam with
the cessation of plunges into its proper
element But the changes are so instanta-
neous, the pressures are sd enormous. that
a tiny flaw, a slight weakness, is almost
sure to be fatal Perhaps not in that gale,
but in the next.
And If this be so in loaded steamer.
how much more is 1t so in a light one.
Experts are at one in considering that
from this cause alone, although there are
others that cannot now be touched upon,
an underoaded steamer is quite as I'M
eeaworthy as an overloaded one. How Of
ten does one pass large steamship COM
ing down Channel bound oversee and no.
tice that even In the smoothest water
nearly half of her propeller is idly beating
the air. Just little head sea gets up
and the vessels engines, shaft and pro
peller are Immediately subjected to
succession OF shocks that make their es-
cape from damage almost a miracle
Then 1t 10 that the engineers lot, never
a light one, becomes truly terrible IN It's
burden He knows in his innefmost fbers
all that Is going OH, the potentialities
of disaster IN every plunge of the ships
stern, from its high poise on the back
Of the sea down into the weltering valley
between-knows, too. what lies before him
and his trusty helpers If the shaft should
break, If the engines should go to smash.
No warrior IN the deadly breach ever
showed more perfect courage or reached
higher plane OF self-sacrifice than does the
marine engineer, and that not as a mere
episode of his calling. but almost contin-
ually. What apparent miracles have been
wrought by these sons of steel at the call
of duty and under the most terrible cir
cumstances we need an engineers roll of
Ia NTua VNNNh IA w
recognition OF their worth could possibly
add TO the fidelity and heroism continually
manifested by them.
One word, in conclusion, on an unfavor-
able comparison which has been drawn
between memo war and merchant steam
ers unfavorabe to the latter on account
of the almost complete Immunity from
shaft breakage of the former. The com
parison is unfair and should never have
been made. THE loading of a warship is
almost a fixed quantity.
This has perhaps more to do with smart
fracture than aught else