Year: 1888

page_text: Date of Application, 7th Aug., 1888
Specification Accepted, 19th Oct., 1888
RESERVE
We ALEXANDER DEPUY HALL and GEORGE BEATTY SLOAN, both of No. 1916
Stevenson Street San Francisco, in the County of San Francisco, State of California,
in the United States of America Gentleman, 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 that will be more
fully set forth hereinafter and particularly pointed out in the claims.
In the accompanying drawings
Fig. 1 is a side elevation of a screw propeller embodying our improvement.
Fig. 2 is an end elevation of the same.
Fig. 3 is a detail sectional view taken on the line - of Fig. 1.
Fig. 4 is a similar view taken on the line y-y of Fig. 1.
A represents the propeller shaft, which projects rearward from the dead wood of
the stern of the vessel for a suitable distance and has its bearings in the stern post
and in the rudder post in the usual manner.
B represents the blade of the propeller which is spiral in form and makes one
complete revolution on the propeller shaft so that the propeller is perfectly balanced
at all points and is caused to act upon a column of water which is equal to the
diameter of the propeller.
The pitch of the screw blade may be varied to suit the requirements of the case
but we have found by experiment that probably the best results are obtained when
the length of the blade is somewhat in excess of the diameter of the propeller.
The said blade is formed of a number of sectors, C, each of which is cast or
wrought separately and the said sectors are provided at their inner ends with hubs D
which are keyed separately to the shaft.
The opposing edges of the sectors are provided with tongues and grooves and
thereby perfectly tight joints are formed between the sectors thereby making the

page_text: surface of the propeller blade perfectly flush and entire throughout the entire length
and breadth of the blade as will be readily understood.
E represents a spiral flange which is arranged on the outer edge of the propeller
blade, and at right angles thereto, the said flange being disposed in a plane which is
parallel with the axis of the propeller.
The said flange extends forward and rearward beyond the sides of the propeller
blade and in practice the rearward projecting portion is equal to about twice the
width of the forward projection portion thereof.
When the propeller is in operation this flange prevents the water from being
thrown laterally and radially from the propeller and causes the column of water which
is equal to the diameter of the propeller to be forced directly aft in the wake of the
vessel, thereby very materially increasing the power of the propeller and rendering
the same much more serviceable.
We have found in experimental test that with a propeller thus constructed we were
enabled to obtain twenty-five per cent. more power, and effect an economy of ten per
cent. in the fuel over propellers of the ordinary construction.
The flange E is made in sections of suitable length and is adapted to break joints
with the blade sections on the outer edges of the spiral blades and said flange is
provided on its inner side with a pair of inwardly extending radial flanges F, thereby
forming a groove between the side flanges in which the outer ends of the blade
sections are fitted.
Bolts G, are passed through transverse aligned openings made in flanges F and in
the outer ends of the blade sections and serve to secure the flange E firmly to the
spiral blade.
By reason of the said flange, E being arranged in a plane parallel with the axes of
the propeller said flange is enabled to slip through the water without exerting radial
or centrifugal action thereon and without in any manner retarding the motion of the
vessel.
The front projecting portion of the flange, E is of less width than the rear projecting
portion thereof so as to offer as little unnecessary resistance as possible to the rotation
of the propeller when the vessel is advancing and at the same time enable the said
projecting portion of the flange to prevent the water from being dispersed radially
from the propeller when the latter is reversed consequently enabling the vessel to be
stopped or backed in a very short space.
Inasmuch as propellers thus constructed do not disperse the water radially and force
the same rearward in a solid column equal to the diameter of the propeller the same
are well adapted to be used as twins so as to cause no friction, as will be readily
understood.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :
1. A screw propeller having a spiral continuous blade with no openings therein
making one complete revolution and provided at its outer edge with the spiral laterally
extending flange, for the purpose set forth, the said flange being disposed in a plane
parallel with the axis of the propeller, the length of the said blade being in excess of
the diameter of the propeller, substantially as described.
2. The propeller having the continuous spiral blade formed of separable sectors the
said sectors being separately keyed to the propeller shaft, and having their opposing
edges secured together substantially as described.
3. The propeller having the continuous spiral blade forming one complete revolution
the said blade being made of separable sectors the said sectors having their opposing
edges tongued and grooved and thereby adapted to effect tight joints substantially as
described.
4. The combination in a propeller of the spiral blade and the flange E at the outer
edge of the said blade, said flange having the flanges F embracing the opposite sides
of the spiral blade and bolted thereto, substantially as described.

page_text: 5. The propeller having the continuous spiral blade, forming one complete revolution
and the flange E on the outer edge of the blade the said flange being disposed in a
plane parallel with the axis of the propeller and having its rear edge or projecting
portion broader than its forward projecting portion, for the purpose set forth,
substantially as described.
ALEXANDER DEPUY HALL.
GEORGE BEATTY SLOAN.
By Jensen & Son,
77, Chancery Lane, London, W.C.,
Patent Agents.