The Cambria freeman. [volume] (Ebensburg, Pa.) 1867-1938, 1892-11-25
SHIPS PROPELLERS.
They Are Sometimes Disabled by
1riling Causes
Special Pains Necessary In Their Manu-
I.cture Provide Against Accidents
and Corrosion from the Action
of the Water.

The propeller of steamer is an in
significant object compared with the
huge body it propcls against the COM
bincd forces of wave and wind, but the
brooklyn Eagle says they come to grief
frequently in variety of ways. y few
days ago steamer in calm sea, with
out a breath of wind almost, suddenly
lost one blade of her screw, just as sud
denly and with as little cause or notice
aS ovcrripc fruit drops from its parent
bough. Around the dry docks are al
ways numbers of gigantic propcllers,
all in one stage or other of dilapidation.
Some are east in the solid, that Il Ia
say, the hub through which the shaft
passes and the fans which extend from
il are one solid casting. Others are
built, or east. rather. in sections; the
hub i one and each fan or blade IL an
other, which tit into bases made for
them IN the hub, where they are screwed
on by huge bolts that are set in the hub
casting. Nhen one fan or blade Is
broken il Is easily replaced, as the
makers retain the models of all wheels
or propcllers. as they are inditfcrcntly
called. which they east. Then the en-
tire wheel iS not rendered useless. aS IL
he ease when splidly east propeller
comes To- grief 1t i extraordinary u
see the proportion of vessels that ar
rive having received some damage 10
their propcllcrS- Occasionally damage
il done by the shaft racing, a. II Is tech
nically called. That is caused 10y the
steamship plunging head on into the
trough of Il big sea and 80 elevating the
stern and the propeller that il Il com
pletcly ont of water, and being sudden
" rid of the resistance the engine runs
away. 50 To speak, just aS an ordinary
engine will do when "A driving belt slips
off or breaks. Occasionally propellers
are broken 10y striking floating logs or
ice and rarely by striking whale or
large fish, when it is much the worse
for the fish.
But there is one curious fact always
noticeable about propcllerS: that il that
the extremities of the blades are eaten
away as though 10y some corrosive acid
They are pierced with holes of greater
or lesser depth. which weaken the points
of the fans - that they snap off. These
corrosions are sand Ia be caused 10y the
action of ~ water. but il seems strange
that the N.caring should take the form
Of honcycombing the metal instead of
wearing it away smoothly. As the mere
supposed To do. Recently screws or
prupelIcrS are made of different combi-
nations of brass and other metals,
especially for steam yachts. and are
very costly. 4 short time ago Il yacht
struck a rock in the sound. The force
of the blow smashed one blade clean
Off, although fastened ON by eight or
ten two-in, II bolts secured 10y massive
nuts, and the second blade was curled
up 10y the blow just like sheet Of lead.
This wheel was only u three-bladed one,
and yet il cost the com paratively enor-
nous sum of twcnty-eight hundred dol
lars. II was made of "A composition
metal resembling brass in color, called
Manganese bronze. In large ocean
steamships, Il the propellers are not of
one solid casting, it is usual To cover
the nuts and bolt points which fasten
the fans to the hub with a cement This
il 50 tenacious and becomes 81 hard
when once set that il rarely breaks un-
til its removal becomes necessary. when
il gives the worimen "A hard tusSle to
remove. IL