The enterprise. [volume] (Wellington, Ohio) 188?-1899, 1892-11-30
SHIPS PROPELLERS.
They Are Sometimes Disabled by
Trifing Causes.
Special Pains Necessary In Their Manu-
fActure 10 Provide Against Accidents
aud Corrosion from the Action
OF the Water.

The propeller Of q steamer Is an in
significant object compared with the
huge body II propels against the COM
bined forces of wave and wind, but the
Brooklyn Eagle says they come to grief
frequently In variety Of ways. A few
days ago a steamer in calm sea, with
out q breath OF wind almost, suddenly
lost one blade of her screw, just as sud-
denly and with as little cause or notice
as overripe fruit drops from Its parent
bough. Around the dry docks are al
ways numbers of gigantic propellers'
all in one stage or other Of dilapidation.
Some are cast in the solid, that is to
say, the hub through which the shaft
passes and the fans which extend from
II are one solid casting Others are
built, or cast, rather. in sections; the
hub is one and each fan or blade is an
other, which fit into bases made for
them in the hub, where they are screwed
on by huge bolts that are set In the hub
casting. When one fan or blade is
broken It Is easily replaced, rs the
makers retain the models OF all wheels
or propellers, as they are indifferently
called, which they cast Then the en-
tire wheel is not rendered useless, as is
the case when a solidly cast propeller
comes to grief. II is extraordinary to
see the proportion Of vessels that ar
rive having received some damage to
their propellers. Occasionally damage
Is done by the shaft racing, as it is tech
nically called. That is caused by the
steamship plunging head on into the
trough of big sea and so elevating the
stern and the propeller that 1t Is COM
pletely out of water, and being sudden
ly rid of the resistance the engine runs
away, so TO speak, just as an ordinary
engine will do when driving belt slips
off or breaks. Occasionally propellers
are broken by striking floating logs or
ice and rarely by striking whale or
large fish, when II is much the worse
for the fish.
But there is one curious fact always
noticeable about propellers; that is that
the extremities of the blades are eaten
away as though by some corrosive acid.
They are pierced with holes Of greater
or lesser depth, which weaken the points
OF the fans so that they snap off. These
corrosions are said to be caused by the
action Of the water, but It seems strange
that the wearing should take the form
Of honeycombing the metal instead OF
wearing It away smoothly, as the mere
friction of striking the water might be
supposed to do. Recently screws or
propellers are made Of different combi-
nations Of brass and other metals,
especially for steam yachts, and are
very costly. A short time ago yacht
struck a rock in the sound. The force
of the blow smashed one blade clean
off, although fastened on by eight Oh
ten two-inch bolts secured by massive
nuts, and the second blade was curlet
up by the blow Just like a sheet OF lead
This wheel was only q three-bladed one
and yet It cost the com paratively enor
nous sum of twenty-eight hundred dol
lars. It was made Of a composition
metal resembling brass in color, called
Mayanese bronze. In large ocear
steamships, II the propellers are not o.
one solid casting, It is usual 10 covel
the nuts and bolt points which faster
the fans TO the hub with cement. Thii
Is so tenacious and becomes SO harC
when once set that It rarely breaks un
til Its removal becomes necessary, whei
II gives the worlSmen hard tussle Il
remove II.