The morning call., 1892-08-18
A SHIPS PROPELLER.
The Accidents to Winch tt Is liable and
Breakdowns That Happen.


Brooklyn Eagle.
The propeller of a steamer is compare
lively Insignificant object compared with
the huge body it propels against the COM
blned forces of wave and wind, but thew
come to grief frequently in a variety of
ways. A few days ago the red D steamer
Venezuela, In calm sea, without breath
of wind almost. suddenly lost one blade of
her screw, just as suddenly and with as
little cause or notice as overripe fruit drops
from its parent bough. Around the dry-
docks are numbers of gigantic propel-
lerS, all IN one stage or other of uiIan-
idation. Some are cast in the solid.
that is to say the hub through which the
shaft passes and the fans which extend
from 1t are one solid casting Others are
built. or cast rather, in sections. The hub
is one and each fan or blade is another.
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. Where
one IAN or blade is broken it is easily re-
placed, as the makers retain the models
of all wheels or propellers, as they
are indifferently called, which thew
east. Then the entire wheel is not rem
dered useless. as In the case when a soIidlv
east propeller like the Venezuela's comes to
grief.
1t is extraordinary to see the proportion
OF vessels that arrive having received some
damage TO their prOpellers. Occasionally
damage is done by the shaft racing, as IL is
technically called. That is caused by the
steamship plunging head on into the troug n
OF big sea, and SO elevating the stern and
the propeller that II is completely out of the
water, and, being suddenly rid of the resist
anee. the engines run away, so to speak, lust
as an ordinary engine will do when driving
belt slips or breaks. Occasionally propellers
are broken by striking broken logs or ice and
rarely by striking a whale or large fish. when
q w nr for tI.a Esh - Al,
Is one curious fact always noticeable about
propellers; that is that the extremities of
the blades are eaten away as though bv
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 sup
poseu TO do. Recently screws or propelIers
are made of different combinations of brass
ana other metals, especially for steam
yachts, and are very costly.
short time ago Pierpont MnTgan's Yacht
struck rock in the sound. The force of
the blow smashed one blade clean off,
although fastened on by s or 10 2-inch bolts
secured by massive nuts, and the second
blade was curled up by the blow just like q
sheet Of lead. This wheel was designed by
Beaver Webb. was only three bladed one,
and yet IL cost the comparatively enormous
sum of S2S00. Ii was made of a composition
metal. bright in color. called Mayenese
bronze. In large ocean steamships if the
p.opellerS are not one solid casting 1t is
usual to cover the nuts and bolt points
which fasten the fans to the hub with a
cement. This is so tenacious and becomes
so hard when once set that it rarely breaks
until Its removal becomes necessary, when
1t gives the workmen q hard tussei to re-
move it.