IMPROVEMENTS IN THE SCREW PROPULSION OF VESSELS
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A M and
W Clark of 53 Chancery Lane in the County of Middlesex Fellow of the
Institute of Patent Agents for an Invention of IMPROVEMENTS IN THE
SCREW PROPULSION OF VESSELS Communicated to him from abroad by
John Gartner of Dallas in the County of Dallas and State of Texas, United
States of America
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 4th December 1882.
ALEXANDER MELVILLE CLARK of the firm of A M and W. Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN THE SCREW PROPULSION OF VESSELS." [Communicated to
him from abroad by John Gartner of Dallas in the County of Dallas and State
of Texas, United States of America]
This Invention consists in tandem propellers located in the sides of the vessel
as auxiliary to a single screw or twin screws at the stern; and also in the con-
nection of the propellers at the sides of the vessel with one another and with the
stern propeller so that they will act simultaneously in urging the vessel forward
whereby a largely increased measure of power is practically applied for the
propulsion of the vessel.
The hull is formed at each side with a recess located from say one-quarter to
one-third of the ships length, from the bow, and within these recesses are tandem
screws on a single shaft at each side. The shafts have bearings ahead and abaft
of the screws and extend sternwards through the bulls sufficiently for the appli-
cation of suitable driving gear thereto. The screws at the respective sides may
be made to revolve in opposite directions to balance the side draft.
A simple means of applying power to the auxiliary screw shafts is by connecting
rods from a crank on the shaft of the ordinary stern propeller (which occupies its
usual position) to cranks on the auxiliary screw shafts. The power, may, however,
be applied in any other suitable manner.
By extending the shafts of the auxilary screws across the recesses and supporting
them in bearings at each end, they are enabled to carry two or more screws
according to the length of the recess whereby the hold on the water for propelling
is very largely increased and the recesses are not required to be so deep in the
sides of the vessel for a given area of propelling surface as when single screws are
employed in the sides. By thus reinforcing the power of the ordinary screw or
screws, a greater speed of the vessel is attained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
31st May 1883.
ALEXANDER MELVILLE CLARK of the Firm of A, M, and W, Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN THE SCREW PROPULSION OF VESSELS." A communication to
me from abroad by John Gartner of Dallas in the County of Dallas and State
of Texas, United States of America.
This Invention consists in propellers located in the sides of the vessel as
auxiliary to a single screw or twin screws at the stern, and also in the connection
of the propellers at the sides of the vessel with one another and with the stern
propeller so that they will act simultaneously in urging the vessel forward, by
which means a largely increased measure of power is practically applied for the
propulsion of the vessel and a greater increase of speed is obtained.
The Invention is illustrated in the accompanying drawings in which similar
letters of reference indicate corresponding parts in the two figures. Figure 1 is a
horizontal section of a vessel having tandem propellers in the sides and a single
screw at the stern, and Figure 2 is a side view of the same vessel.
The vessel is formed at each side of its hull with a recess a located from one
quarter to one-third of the ships length astern of the bow, and within these recesses
are the tandem screws b on a single shaft fat each side. The shafts have bearings
upon each side of the screws and extend sternward through the hull sufficiently
for the connecting rods c to be attached for driving the screws. The screws at the
respective sides may be made to revolve in opposite directions to balance the side
draft. d represents the stern screw which is arranged in the usual manner, or
twin screws may be used. • represents the ordinary propeller shaft which extends
along the keel, in the usual manner, to where the power is applied, and the shafts
of the side screws b are connected to it by their rods c as a simple means of
applying the power to them. The power may however be applied in any other
suitable manner.
By extending the shafts f of the auxiliary screws across the recesses a and
supporting them in bearings at each end, they are enabled to carry one, but
preferably two or more screws, according to the length of the recess whereby the
hold on the water for propelling is very largely increased; the recesses are not
required to be so deep in the sides of the vessel for a given area of propelling
surface for tandem screws as when single screws are employed in the sides. By
thus re-inforcing the power of the ordinary screw or screws, a greater speed of the
vessel is accomplished.
By thus arranging propellers in longitudinal recesses in the sides of a vessel and
near the curve of the bow, the shafts being extended through the hull sufficiently
for the application of any approved means of power, they can act as auxiliary to
the stern propellers, or may be worked independently of the stern propeller or of
each other, and may be made to revolve in either direction suitably for the
propulsion or steering of the vessel.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
1 The combination with a vessel having opposite recesses in its sides, of pro-
peller shafts carrying screws located in said recesses and fitted for operation by
suitable mechanism substantially as described.

page_text: 2nd The combination of two propeller shafts each carrying tandem screws, with
a vessel having opposite recesses from about a quarter to a third of the ships
length astern of the bow the said shafts being operated by suitable mechanism,
substantially as described.
3rd Propellers set in recesses in the sides of a vessel and arranged to work
with or independently of the stern propeller, and together or independently
of each other for the propulsion and steering of the vessel, substantially as set
forth.
4th In a boat or vessel the combination with a propeller on each side and one
at the stern of the shafts fe having cranks transversely aligned and connected by
rods c whereby all three propellers will operate synchronously and co-operate in
each movement of the vessel.
In Witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this thirty first day of May, A.D. 1883.
AT D