Improvements in Central Screw Steamships.
Year: 1892

page_text: Date of Application, 24th June, 1892
Complete Specification Left, 17th Mar., 1893-Accepted, 24th June, 1893
PROVISIONAL SPECIFICATION.
Improvements in Central Screw Steamships.
I, CHARLES HARRIS of Number Nine Upper North Street Brighton, in the
County of Sussex, out of business or employ, do hereby declare the nature of this
invention to be as follows :-
The object of this invention is to further reduce the length of propeller shafts
in centralised screw steamships, & for which centralised form of propulsion Royal
Letters Patent have been granted to me under number & date, 3787, 3rd March
1891.
For this purpose I depend from the longitudinal centre of the uppermost portion,
or top, of the screw cavity, as fully described in the Complete Specification of
the aforenamed l'atent,-(and from one, or two positions, thereon, according as the
screw propeller is designed to receive a single, or a double bearing), a receptacle,
or chamber, in form akin to the lower portion of the bows of an ordinary boat.
The propeller shaft, passing from the propeller itself, enters the said boat shaped
chamber at the narrow portion thereof which resembles the stem, and which is con-
structed, or built, of the smallest possible width, and extends for a sufficient
downward distance to meet and enclose the propeller shaft.
From such enclosing point it declines in a longitudinal slope, or curve, to the
necessary depth required for the chamber, such depth being not lower than the
rabbet of the keel, at the utmost, in the case of single screws, neither lower than
the normal outline of the ships hull, in the case of twinscrews.
And, (from what I have called the stem portion of the said chamber), the said
receptacle, or chamber, widens its sides apart in the same manner as do the bows
of an ordinary boat, until sufficient width is obtained therein, as, combined with the
depth already described, will provide space for the free revolution or throw of the
crank of the engine driving the propeller.
Dated this 23rd day of June 1892.
CHAS. HAKKIS,
Applicant.
COMPLETE SPECIFICATION.
Improvements in Central Screw Steamships.
I, CHARLES HARRIS of Number 9 Upper North Street, Brighton, in the
County of Sussex, out of business, or employ, 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 :-
The object of this invention is to further reduce the length of propeller shafts
in centralised screw steamships, for which centralised form of propulsion Letters
Patent No. 3787 (A.D. 1891), have been granted to me.
For this purpose I depend from the longitudinal centre of the uppermost portion,
or top of the screw cavity, (as fully described, and depicted, in the Complete
Specification, and drawings of the aforenamed Patent), and from one or two positions
thereon, according as the screw propeller is designed to receive a single, or a double
bearing, a receptacle, or chamber, in form somewhat akin to the bows of an ordinary
boat.
In the drawing, deposited herewith, the invention is shown, as applied to a small
twin-screw boat, 40' 3" (forty feet three inches) in length; by 10' (ten feet) beam,
amid, and driven by a pair of propellers 2' (two feet) in diameter.

page_text: Fig. 1 represents the longitudinal section, or sheer plan; Fig. 2 the half-breadth
plan, and Figs. 3, 4, 5, 6, 7, 8, the transverse half sections at the ordinates U, V,
W, X, Y, Z, drawn through Figs. 1 and 2. The line A, B, C, (Fig. 1) represents
the highest outcut of the screw cavity along the line F, (Fig. 2).
As, in a boat of this miniature size, only an ordinary single bearing would be
needed for each propeller shaft, only one of such aforenamed receptacles, or
chambers, would be required in each screw cavity, as shown on the drawing.
The propeller shaft, passing from the propeller itself, enters the said boat-shaped
receptacle, or chamber, at the narrow portion thereof, which resembles the stem.
This is constructed, or built, at this point, of the smallest possible width, and is
shown in Fig. 7 as it descends, from the top of the screw cavity at B, Fig. 1 at
the ordinate, for a sufficient downward distance to meet and enclose the propeller
shaft as shown in Fig. 6, ordinate X. From such enclosing point it declines, in a
longitudinal slope, curve, or quadrant, D, Fig. 1, to the necessary depth E, Fig. 1,
required for the chamber; such depth being not lower than the rabbet of the
keel at the utmost, in the case of single screws; neither lower than the normal
outline of the ship's hull, on the line F' Fig. 1, in the case of twin-screws.
Aud, (from what I have called the stem portion of the said receptacle, or
chamber), the said receptacle, or chamber, widens its sides apart, as shown at D',
and E¹, Fig. 2, and in Figs. 5, and 4, (ordinates W, and V), in the same manner as
do the bows of an ordinary boat, until sufficient width is obtained therein, as,
combined with the depth, already described, will provide space for the free revolution,
or throw, of the crank of the engine, or engines, driving the propeller; such
diameter of revolution being indicated by the dotted line G, Fig. 4.
The dotted lines A', C1, Figs. 8 and 3, show the commencement, and cessation of
the outcut of the screw cavity at ordinates Z, and U, beyond which lines, fore and
aft, the normal shape of the ship is uninterfered with.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
The invention of a crank receptacle, or chamber, depending from a cavity
formed in the under, or bottom part, of a steamship hull, substantially as described
in this Specification, and shown on the drawings.
Dated this Sixteenth day of March 1893.
CHARLES HARRIS,
Applicant.