Improvement in Screw Propellers for Vessels.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Communicated from abroad by JOSEPH COMMODORE STREET, of 78, Mont-
gomery Street, Boston, Suffolk County, Massachusetts, United States of
America, Physician.]
Improvement in Screw Propellers for Vessels.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings, London W.C. do hereby declare the nature
of this invention and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement :-
This invention relates to improvements in screw propellers and particularly
to that class of screw propellers which revolve within a tube or shield which serves
to confine the water acted upon so as to prevent it from being discharged in any
direction, other than directly astern; and it consists in the novel construction
hereinafter described and illustrated and particularly pointed out in the claims :-
The object of this invention is to provide a propeller which shall be more efficient
than any hitherto in use, and thus to economise power and increase the speed of
which steam vessels are capable.
By all screw propellers hitherto in use water is treated as a substance which may
be displaced and moved with but little expenditure of energy; but it is known that
this assumption is fallacious, and that a large percentage of the power absorbed by
screw propellers is expended in moving the water acted upon in directions other
than those in which energy is most efficiently expended in driving vessels onward.
It is the object of this invention to produce as little movement of the water as
possible and to confine this movement entirely to a sternward direction the direction
in which energy is most efficiently expended in propelling the vessel; and also
to give the water an initial impulse in a rotary or spiral direction prior to its
entrance into the tube.
In the accompanying drawings a
Figure 1 represents a plan view of the improved propeller, showing the same
detached from the hull of the vessel, and with the enclosing tube partially broken
away to show more clearly the construction and arrangement of the parts.
Figure 2 shows the propeller when used as a twin-screw in place on the hull of
the vessel, which is shown bottom up in order that the various parts of the propeller
may be more clearly visible.
Figure 3 shows a side elevation of a modified form of propeller showing the tube
in section.
Figure 4 is an end view, showing one manner of attaching the cylinder to the
vessel; and
Figure 5 is a side elevation of a modified form of cylinder.
Similar letters of reference indicate corresponding parts in the several figures of
the drawing.
A represents the hull of the vessel; B the keel and Ca cross-piece attached to
the end of the keel, which serves as a support for the rear bearings of the screw-
shaft D. E represents the propeller tubes, which are fastened to the hull of the
vessel at each side of the keel, and preferably let into the sides of the keel and also
into the bottom of the vessel, as clearly shown in the end view Figure 4, and
secured in any desired manner, and within which revolve the screws F. The
screws F consist each of a central shaft D, around which is wound the spiral
ribbon flange G, supported from and attached to the shaft D by the spokes H, the
ends of said ribbon being attached in any desired manner to said shaft. The
ribbon G is preferably, but not necessarily, not of uniform diameter, but as shown

page_text: f
commencing at the circumference of the shaft near where the latter passes through
the hull of the vessel, gradually increases in diameter for two or more turns, when
it reaches its greatest diameter, and from there on continues of uniform diameter
throughout its length.
It is to be understood however that the above proportions are not to be rigidly
adhered to but may be varied as deemed desirable. The tube E may be somewhat
shorter than the screw F, the forward portion of the screw being used simply to
start the water in motion gradually and carry it into the tube, where it is acted
upon by the revolving screw and forced astern or, what is the same thing, the
vessel, by the reaction against the main body of water outside the tube, is pushed
ahead. The tube E is made of course of greater diameter than the screw, and
serves, by confining the water, to prevent the escapement of any at the sides, so that
the entire stream is sent directly astern.
As shown in Figure 5 I may form the tube slightly conical and arrange the
same with its larger end forward, the object of which being to give the water
passing therethrough a greater force.
In Figure 2, both screws are shown as of the same kind; that is, left-handed but
they may also be of different kinds, one right-handed and the other left-handed, in
which case they would be revolved in opposite directions.
As shown in Figure 3, I may dispense with the central shaft D when the screw
is to be used on certain craft, such as craft built to attain a high speed the ribbon G
being made of sufficient strength and stiffness as not to require strengthening by a
central shaft, and having its ends formed with a cylindrical portion h, by which the
screw may be supported and operated.
The tube E may be incomplete, being left open longitudinally at the bottom for
from one-third or less to one-half the circumference of the tube, thus forming a
shield as shown in Figure 3.
The screw-shaft may be connected to the engine shaft in any suitable manner,
but I prefer to have the power transmitted from the engine-shaft to the screw-shafts
through gears I which may be bevel gears so that the axis of the screws, and the
tube surrounding the same may be inclined slightly upward from front to rear
or vice versa thus coinciding more nearly with the direction of movement of the
water which rises up under the stern of the vessel to fill the space left by the
forward movement of the vessel.
While this propeller is shown arranged at each side of the keel of the vessel, as a
twin screw, it is not the intention to be confined to such an arrangement, as it
is evident the single screw may be used, in which event the keel would be cut
away, and the screw and its tube arranged thereon, the lines of the vessel being
formed so as to permit a free ingress of water to the tube.
The operation of the screw is as follows:-When the screw is revolved in
the direction opposite to that in which the ribbon is wound around the shaft, water
is given its initial movement and drawn into the tube E by the forward portion of
the screw F, and there is acted upon by the ribbon, which pushes it astern, the
vessel, by the reaction of the moving water against the main body of the water
outside the tube being pushed ahead. The tube or shield E acts to confine the water
and prevent the escape of any at the side, where it would have little if any effect.
It will be observed from the foregoing description of the construction and
arrangement of the screw-propeller that it will work gradually and easily into
the water, which is treated as a semi-solid substance, with comparatively small
resistance, the great number of threads or spiral winding of the ribbon which
compose this screw being adapted to enter and hold the water, as a long screw holds
in wood, and the tube preventing the sidewise escape of the water and the conse-
quent loss of power, the whole body of water entering the tube being forced through
the same to the rear and before it is discharged, and consequently, the whole force
or power of the water is exerted, to move the ship forward.
The screw may be attached to the forward end of the vessel in addition to those
at the rear when great speed is to be obtained, in which case the screws are

page_text: arranged at an incline, the forward end being raised and the rear end depressed, in
order to throw the current of water beneath instead of against the vessel.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. A screw propeller formed of a spiral ribbon provided with suitable supports for
sustaining it in position, and means for imparting rotary movement to said propeller,
substantially as described.
2. A screw propeller formed of a spiral ribbon provided with suitable supports for
sustaining it in position in combination with a shield or casing wholly or partially
enclosing the same, and means for imparting rotary movement to said propeller,
substantially as set forth.
3. A screw propeller formed of a spiral ribbon which gradually increases in
diameter from its forward end for a suitable distance of the length provided with
supports for sustaining it in position, and means for imparting rotary movement to
said propeller, substantially as described.
4. A screw propeller formed of a spiral ribbon which gradually increases in
diameter from its forward end for a suitable distance of the length and continues
therefrom of uniform diameter to its rearward extremity, and suitable supports for
its revolution, substantially as set forth.
5. A screw propeller formed of a spiral ribbon which gradually increases in
diameter from its forward end for a suitable distance of its length, and continues
therefrom of uniform diameter to its rearward extremity in combination with a
shield or casing within which it is adapted to revolve, substantially as described.
6. A screw propeller which gradually increases in diameter from its forward end,
and continues therefrom of equal diameter to its rearward extremity, in combination
with a shield or casing applied to that portion of the propeller which is of equal
diameter, and having its forward portion extending beyond said shield or casing,
and in front thereof, substantially as set forth.
7. The combination, with a screw propeller which gradually increases in
diameter from its forward end for a portion of its length, of a tapering or conical
tube or shield partly enclosing said screw propeller, substantially as described.
8. A screw propeller formed of a spiral ribbon in combination with a covering
and flanking casing or shield provided with an open bottom, substantially as set
forth.
9. A screw propeller formed of a spiral ribbon, a shaft extending through said
ribbon, spokes connecting said ribbon and shaft, and said ribbon having its ends
directly secured to said shaft, in combination with a casing or shield wholly or
partially enclosing said screw, substantially as described.
Dated this 31st day of May 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.