Screw Propeller.
Year: 1893

page_text: Date of Application, 24th Apr.,
1000
Accepted, 2nd June, 1903
CALC vipprivativ, TAPI
Певерей)
COMPLETE SPECIFICATION.
Screw Propeller.
We ALEXANDER DEPUY HALL Builder, and GEORGE BEATTY SLOAN
Merchant, of No. 158 Golden Gate Avenue, in the City and County of
San Francisco State of California, U.S.A. do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
Our invention relates to an improvement in screw propellers for vessels, and it
consists in the peculiar construction and combination of devices as will be more
fully set forth hereinafter and pointed out in the claims.
Referring to the accompanying drawings for a more complete explanation of
our invention,―
Figure 1 is a side view of our propeller.
Figure 2 is a perspective view of the same.
A is a propeller shaft which projects rearwardly from the deadwood of the stern
of the vessel for a suitable distance, and has its bearings in the stern post and also
in the rudder post.
Upon the shaft is fixed the propeller hub B which may be made in sections
keyed to the shaft or formed in a single continuous piece.
We have found that in practice a long single spiral leaves an open space upon
the opposite side from the blade of considerable length, and our present invention
is an improvement upon that construction.
In our present invention we have shown our propeller blades C made in the form
of continuous spirals of equal diameter from end to end, making one half or
more revolutions each on the propeller shaft, and placed opposite each other upon
the hub so as to form two spiral channels between the blades upon opposite sides
of the hub.
The pitch of the screw blades may be varied to suit the requirements of the
case, either regular or graduated.
By forming our opposed blades with a half revolution around the shaft, we
shorten the extreme length of the propeller one half, and make it practicable to
employ it in the space which is available for that purpose between the stern post
and rudder post of a vessel.
Upon the outer periphery of each blade is fixed a spiral flange E at right
angles thereto, the flange being disposed in a plane parallel with the axis of the
propeller, and extending forward and rearward beyond the sides of the propeller
blade.
By reason of the two interlocked spirals upon opposite sides of the same hub,
this flange, projecting over the channels which are formed between the interlocked
blades of the propeller, produces a partially enclosed channel upon each side of the
hub, each channel being equal in diameter to the distance between the hub and
these flanges from one end to the other.
When the propeller is rotated it acts upon a column of water, the full diameter
of which is equal to the diameter of the propeller. This column is divided into
two bodies, each of which is essentially enclosed in the channel between the blades
upon opposite sides of the shaft, and the propeller, by reason of its double inter-
locked construction of the blades, is more perfectly balanced than when a single
blade is employed making a full revolution around the shaft.
By reason of the blades being made so long as to make a half or more revolu-
tion around the shaft, each channel is practically enclosed between the two blades
from the commencement to the end, and no open unbalanced space is left upon one
side, as in the case of a single blade forming a complete revolution.

page_text: No pounding or jar is noticeable at the highest speed, by reason of the balancing
and steadying action of the double columns of water.
The front edges of the blades and of the ends of the spiral exterior flanges
are beveled or tapered so that they enter the water with the least possible
resistance.
This construction is especially applicable for propellers to run in either direction,
as in double ended boats for ferry and other purposes, as a propeller of this form
will have equal power in either direction, and one of these may be mounted at each
end of the boat, either upon separate shafts, or upon a single shaft continuing from
one end of the boat to the other.
Having now particularly described, and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1st. A screw propeller having the spiral continuous blades of equal diameter
from end to end projecting from opposite sides of the same hub, making each a
full half revolution around the propeller shaft, the rear edge of each blade and
the front edge of the opposite blade, terminating in a radial plane taken through
the axis of the shaft and upon opposite sides thereof, substantially as herein
described.
2nd. A screw propeller having spiral continuous blades of equal diameter from
end to end projecting from opposite sides of the same hub and interlocking with
each other to form continuous channels upon opposite sides of the hub, said
blades making a half revolution around the propeller shaft and having flanges
fixed upon the outer edges of the blade projecting in each direction in a plane
parallel with the axis of the propeller, substantially as herein described.
3rd. A screw propeller having spiral continuous blades of equal diameter
from end to end projecting from opposite sides of the same hub, each forming
a half turn about the propeller shaft with the front edges of the blades
commencing upon opposite sides of the shaft, and the rear edges lying in
radial planes taken through the axis, and intersecting the front edges of the
opposing blades, and flanges fixed to the peripheries of the blades, projecting upon
cach side thereof parallel with the axis of the propeller, substantially as herein
described.
Dated this Seventeenth day of April 1893.