Year: 1888

page_text: Date of Application, 11th Jan., 1888
Complete Specification Left, 11th Oct., 1888
Complete Specification Accepted, 14th Dec., 1888
We THOMAS WILLIAM SCOTT, .of 7, Elverson Road, St. Johns, Deptford, in the
County of Kent, Carpenter, FREDERICK BILLINGS of St. Mary Cray in the County of
Kent, Gentleman, and FREDERICK ABBOTT DURNFORD of 39 Harvard Road Lewisham
also in the County of Kent, Plasterer, do hereby declare the nature of this invention
to be as follows:-
This invention has for object improvements in ships. or vessels propelled by
screws whereby greater speed is obtained than hitherto from a given engine power.
According to our invention we.place the propeller at the bow end of the vessel and
in a chamber formed at the bottom thereof, passages being formed from the rear end
of the chamber to allow of the water passing from the propeller.
Our invention also consists in providing the edges of screw propeller blades with
a web or flange for the purpose of lessening the centrifugal action of the scrow on
the water.
TL 11th low of Ton 1888
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to Vessels Propelled by Screws.
We, THOMAS WILLIAM SCOTT, of 7, Elverson Road, St. Johns', Deptford, in the
County of Kent, Carpenter, FREDERICK BILLINGS, of St. Mary Cray in the County
of Kent, Gentleman, and FREDERICK ABBOTT DURNFORD, of 39, Harvard Road,
Lewisham, in the County of Kent, Plasterer, 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:-
This invention has for object improvements in ships or vessels propelled by screws.
The cause of slip in the propellers of screw-vessels as at present constructed must
be attributed to the following causes, viz. :
The propeller is placed at the stern of the vessel and when rotating practically forms
a disc, the diameter of which represents the whole surface which is available for
propelling purposes and this disc can only act upon a quantity of water which, when
compared with the area of displacement of the vessel, is exceedingly small. When
the propeller is in motion a great centrifugal action takes place, whereby a largo
amount of power is wasted which ought properly to be employed in assisting the
progress of the vessel.
The propeller has also a tendency to create a vortex in front of it.
As the vessel is supported by the water underneath it, this water, as the vessel
passes over it, rushes towards the vortex between the propeller and the dead wood of.
the vessel. This water, known as dead water, meets the propeller blades at about the
same angle as the angle of their pitch and, although it obviously requires a great
amount of power to produce this dead water, it does not assist the progress of the
vessel.
Now the object of this invention is to prevent slip in screw-propellers and to obtain
greater speed than hitherto from a given engine power and with a given area of
displacement, greater buoyancy of the vessel and greater stability and amount of
storage room.
1
According to this invention, we place the propeller at the bow end of the vessel and
in a chamber formed at the bottom thereof, passages being formed from the rear end
of the chamber to allow of the water passing from the propeller.
The invention also consists in providing the edges of screw propeller blades with
a web or flange for the purpose of lessening the centrifugal action of the screw
on the water.
In order to enable the invention to be fully understood, we will describe how it may
be carried into practice by reference to the accompanying drawing, in which
Figure 1 is a side elevation partly in section of the hull of a steam vessel with the
improvements applied thereto.
Figures 2 and
are views of the underside and bows of the same.

page_text: Figure 4 is a longitudinal section drawn to an enlarged scale of part of the screw
propeller which we use for propelling the said vessel.
Similar reference letters indicate similar parts throughout the drawing.
a is the screw propeller and b the chamber for receiving the same, the said chamber
being placed at the bottom of the bow end of the vessel as shown clearly in
figures 1, 2, and 3.
The screw propeller a is shewn formed of several convolutions of a single thread or
helix and is mounted on a shaft c supported in bearings d, d. It will be obvious
however that several propeller blades having one or any required number of convolu-
tions can be employed on one shaft. Also that more than one shaft, each having a
propeller or propellers, can be employed placed side by side.
By this means we increase the effective area of the propellers and therefore obtain
an increase of propelling power against the resistance of immersed midship section as
a larger body of water is acted on at each revolution.
e, e are the passages for allowing the water acted upon by the screw propoller a to
pass away easily.
The water thrown back by the propeller or propellers is to a great extent forced
underneath the vessel thereby increasing the buoyancy of the latter and the water
flowing through the rearwardly extending passages and out through the after ends of
the same tends to keep the vessel on an even keel in rough weather.
The amount of space available for storage purposes will be considerably greater
than in an ordinary screw-vessel inasmuch as that the usual alley necessary for the
screw shafts of such vessels is dispensed with and the engine can be placed close to
the propeller, a long screw shaft being no longer required.
The propeller, being entirely submerged, is protected from shots, torpedoes, ropes,
floating wreckage, or substances on the surface of the water.
The propeller having a tendency to continually form a vacuum, the vessel is
practically forced to follow in its wake. The propeller will tend to keep rising swolls
down at the bow of the vessel and will therefore reduce the swells in the wake of the
vessel.
Further by the propeller being placed under the bow of the vessel and in a
chamber as described the centrifugal action of the same is almost entirely
prevented.
The power of the water flowing through the passages e, e can be utilized for
causing water to circulate through the condenser, (thus rendering the use of circu-
lating pumps unnecessary) for fire-extinguishing purposes, for filling tanks, for
sanitary purposes, for washing decks, and for other purposes for which sea water can
be used or for driving an electric light motor.
Butterfly valves can advantageously be placed in the passages e, e so that by
closing one or the other of them the vessel can be steered in case the rudder should
become disabled; or, when the vessel is full under weigh, it can be turned round in a
very small compass.
fis the web or flange with which we provide the edges of screw propellers for
the purpose of lessening the centrifugal action of the said propellers on the water.
The said web or flange is arranged at an opposite angle to that of the pitch of
the screw so as to produce a centripetal action of the propeller blades and hold the
body of water in proximity thereto. By reason of this tendency of the propeller
blades to retain and act upon a larger body of water than is the case with propellers
as heretofore constructed and by reason of the water entering or meeting the propeller
in a line with the axis of the shaft we obtain a direct pull upon the water the power
of which pull is proportionate to the power developed by the engines. The screw in
fact works as if it were in a nut.
We have shown the web or flange f applied to the edge of a propeller such as we
propose to employ at the bow end of a vessel as hereinbefore described and this will
enable its application to the edges of other propellers to be well understood without
further illustration.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
こ
(1.) Arranging ships' propellers at the bow end of the vessel in a chamber adapted
for that purpose passages being formed from the rear end of the chamber to allow
of water passing from the propeller or propellers, substantially as hereinbefore
described.
(2.) Providing the edges of screw propeller blades with a web or flange, substan-
tially as and for the purpose herein before described. .
(3.) The improved vessel herein before described and illustrated in figures 1 to 3 of
the accompanying drawing.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicants.