IMPROVEMENTS IN THE PROPULSION OF SHIPS BY SPECIAL LOCATION OF SCREW PROPELLERS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I JOHN BUCHANAN, of Gourock in the County of Renfrew, North Britain
Gentleman do hereby declare the nature of the said invention for "IMPROVEMENTS
IN THE PROPULSION OF SHIPS BY SPECIAL LOCATION OF SCREW PROPELLERS " to
be as follows:—
This Invention which relates to Improvements in the propulsion of ships by
special location of screw Propellers is applicable to the improved ships described
in the provisional specification of the said John Buchanan N°, 10708 dated
29th July, A.D. 1884, as well as to other ships as ordinarily constructed with
transverse Bulkheada.
The Invention consists in locating the Screw Propellers one on each side of the
keel at or about midships and the lower part of the Midship Compartments formed
by the Bulkheads or equivalent divisions in which each Propeller is placed, is cut
away to allow of the blades of the Propellers to revolve, so that they project into
the water beyond the surface of the ship's bottom.-When a Steam-ship constructed
according to these improvements, is provided with screw propellers, the propeller
abafts are so mounted that they project through an opposite pair of transverse
bulkheads and on each end of such shaft a driving crank is fixed, to which
independent engines are coupled so that in the event of one engine or pair of
engines breaking down the other engine or pair of engines is available for use.
The engines and their boilers are placed in one or more of the compartments
formed by the bulkheads or equivalent divisions.

page_text: COMPLETE SPECIFICATION.
I, JOHN BUCHANAN of Gourock, in the County of Renfrew, North Britain,
Gentleman do hereby declare the nature of the invention for IMPROVEMENTS IN
THE PROPULSION OF SHIPS BY SPECIAL LOCATION OF SCREW PROPELLERS and in
what manner the same is to be performed, to be particularly described and
-ascertained in and-by-the-following statement :—
The Invention, which relates to Improvements-in-the propulsion of ships by
special location of screw propellers, is applicable to the improved ships described-in-
the Specification of the said John Buchanan No. 10708 dated 29th July A.D. 1884,
as well as to other ships as ordinarily, constructed with transverse bulkheads.
The Invention-consists in locating the screw propellers, one on each side of the
keel at or about midships, and the lower part-of-the-midship compartments
formed by the bulkheads or equivalent divisions in which each propeller is placed,
is-cut-away and open to allow of the blades of the propellers to revolve, so that
they project into the water beyond-the-surface of the ship's bottom. When a
steam-ship constructed according to these improvements, is provided with screw
propellers, the propeller shafts are so mounted that they project through an opposite
pair of transverse bulkheads, and on each end of such shaft a driving crank is
fixed, to which cranks independent engines are coupled so that in the ovent of one
engine or pair of engines breaking down the other engine or pair of engines is
available for use. The engines and their boilers are placed in one or more of the
compartments formed by the bulkheads or equivalent divisions.
In order that the said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the drawings hereunto annexed.
Figure 1 is a part side elevation of portion of a ship provided with screw
propellers in accordance with the present Invention.
Figure 2 is a longitudinal section of the same taken on the line AB Figure 3.
Figure 3 is a transverse section of the same, the left hand portion of the said
Figure being taken on the line CD Figure 2, and the right hand portion thereof.
being taken on the line EF Figure 2, ….
In carrying out the present improvements, I locate the two propellers a, one on
each side of the keel c, or about midships, and between the bulkheads d. The
bulkheads d, are cut away at their under edges as shewn at Figure 3, so that the
blades of the propellers a, project out beyond their edges, while the under surface
of the ship's hulle, is correspondingly hollowed at the two sides of the keel c, as
represented at, upon the annexed drawings to admit of the free passage of the
water to and froin the said propellers. The shafts g, of the propellers project
through the bulkheads d, as shown upon the annexed drawings, and at each end of
the said shafts, a driving crank h, is fixed, and to these cranks, independent engines
are coupled so that in the event of one engine or pair of engines breaking down,
the other engine or pair of engines are available for use.
The present improvements are represented upon the annexed drawings as applied
to a ship constructed according to the manner set forth in the hereinbefore men-
tioned Specification, that is to say, to a ship divided lengthwise by the longitudinal

page_text: vertical bulkhead i, so that the propellers a, are rotated at either side of the said
bulkhead i, and the driving cranks h, are coupled to engines independent of each
other, but it is to be understood that the present improvements may be applied to
ships as ordinarily constructed.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed, I declare that what
is claimed is
Improvements in the propulsion of ships by the locating of the screw propellers
thereof at or about midships so that the blades of the said propellers in rotating
project through openings in the bottom of the hull protected on either side by
bulkheads or their equivalents all substantially as and for the purposes hereinbefore
Bet forth with reference to the annexed drawings,