Improvement relative to the Position of Screw Propellers for Propelling Ships.
Year: 1893

page_text: Date of Application, 29th June, 1893
Complete Specification Left, 19th Feb., 1894-Accepted, 24th Mar., 1894
PROVISIONAL SPECIFICATION.
Improvement relative to the Position of Screw Propellers for
Propelling Ships.
ALEXANDER WINGATE MILLER Merchant 79 West Nile Street Glasgow,
ALEXANDER MUNRO Coach Builder 7 Walker Street Glasgow, JOHN MILLS
Engineer 60 Dunard Street Glasgow, do hereby declare the nature of this invention
to be as follows:-
The propeller is placed behind the rudder sufficiently low so that the projecting
end of stern tube shall be below the rudder. The centre of the shaft to be a
sufficient distance above the keel so that when a two bladed propeller is fixed on
the end of the shaft while the blades are in a horizontal position no part of the
propeller shall be lower than the keel and while the shaft revolves each blade in
its turn will drop lower than the keel.
Dated this 28th day of June 1893
ALEC. W. MILLER.
A. MUNRO.
JOHN MILLS.
COMPLETE SPECIFICATION.
Improvement relative to the Position of Screw Propellers for
Propelling Ships.
ALEXANDER WINGATE MILLER, Merchant, Seventy nine, West Nile Street,
Glasgow, ALEXANDER MUNRO, Coachbuilder, Seven, Walker Street, Glasgow,
JOHN MILLS, Engineer, Sixty, Dunard Street, Glasgow, 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 relates to the propulsion of ships and it has for its object to
increase the speed by placing the propeller behind the rudder, and in a position
sufficiently low down to enable the projecting end of the stern tube to be located
below the rudder.
On the drawing annexed Figs. 1 and 2 show a ship with our invention applied
thereto.
On the drawing a is the rudder, 6 the ordinary four bladed propeller and ca
second, preferably two bladed propeller, located below the rudder. d is the
projecting end of the stern tube of the second propeller.
The shaft of the second propeller, is, as shown, located at such a distance above
the keel, that, when a two bladed propeller is fixed on the end of the shaft and its
blades are in a horizontal position no part of the propeller will be below the level
of the keel, and, when the shaft revolves, each blade will in its turn, drop lower
than the keel.
The stern tube d is, as shown, made to project backwards to a distance sufficient
to ensure that the blades of the propeller c shall clear the rudder when revolving.
When the ship is in shallow water it may be propelled by the propeller b and the
propeller c be stopped and its blades turned to the horizontal position as shown at
Fig. 2.
It is not necessary with vessels which always sail in deep water to use the
ordinary propeller b.

page_text: As the propeller c always works in dense and undisturbed water it is much more
effective than the ordinary propeller.
The propeller may have three or four blades if so desired.
The shaft of the propeller c is preferably arranged on an incline from the stern
tube forward so as to give clearance for cranks or machinery.
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
consider novel and desire to claim is :-
1. In a ship or boat a propeller having two or more blades and located behind
the rudder, substantially as and for the advantage set forth.
2. A ship or boat made with a stern tube for the propeller shaft which projects
out underneath the rudder at or about the end of the keel, substantially as herein-
before described with reference to the drawing annexed.
Dated this 15th day of February 1894
ALEC. W. MILLER.
ALEXANDER MUNRO.
JOHN MILLS.
ALEC. W. MILLER.
ALEXANDER MUNRO.
JOHN MILLS.