Improvements in the Construction of Propelling Screws.
Year: 1890

page_text: Date of Application, 20th Jan., 1890
Complete Specification Left, 20th Oct., 1890-Accepted, 22nd Nov., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Propelling Screws.
I, JOHN MOORE of 18 Donegall Quay Belfast in the County of Antrim, Shipowner,
do hereby declare the nature of this invention to be as follows:-
My invention relates to screw propellers for vessels and is designed to overcome
the resistance of the dead water or air that more or less surrounds the inopperative
portions of the ordinary propeller and to accomplish this I place auxiliary blades
constructed as hereinafter described between the larger or main blades of the screw
propeller.
In order to increase the efficiency of these auxiliary blades and enable them the
exert the maximum amount of propelling effort I reduce the diameter of the boss so
dispensing with any superfluous metal and diminishing resistance and displacement
and on this reduced boss I place the small auxiliary blades arranged so that an
augmented propelling effect is obtained near the boss and to further ensure this I
make these auxiliary blades of relatively greater width at the root than the larger
blades and extend them along the boss. These blades may be of differential pitch
and so constructed as to meet varying requirements and so as to enable them
to be applied to both solid propellers and those having adjustable or removable
blades.
To lessen the effect of drag or churning of the water &c. by the large blades I also
construct them in a special manner where they unite with the boss by making the
blades narrow and also thickening them at or near that point so as to obtain strength
and thus giving them the appearance of an oval stem where so narrowed and
thickened.
I do not limit myself to the number of large or small blades which may vary
according to circumstances.
POPPLEWELL & Co.,
17 & 18, Southampton Buildings, Chancery Lane, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Construction of Propelling Screws.
I JOHN MOORE of 18 Donegall Quay Belfast in the County of Antrim, Shipowner
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 my invention is to overcome the resistance of the dead-water or air
that more or less surrounds the inoperative portions of the ordinary propellor and to
accomplish this I place auxiliary blades constructed as hereafter described between the
larger or main blades of the screw propellor.
In the accompanying drawings
Figure 1 shows an end view of my improved propellor having the long blades A A¹
and short blades B B' combined on one boss, and
Figure 2 shows the long blades on one boss and the short blades are indicated by
dotted lines as being on a separate boss placed upon the same line of shafting.
In order to increase the efficiency of these auxilliary blades B B' and enable them
to exert the maximum amount of propelling effort I reduce the diameter of the
boss C so dispensing with any superfluous metal and diminishing resistance and
displacement, and on this reduced boss C I place the small auxilliary blades arranged
Price 6d 1

page_text: so that an augmented propelling effect is obtained near the boss, and to furthur
ensure this I make these auxilliary blades of relatively greater width at the root than
the larger blades and extend them along the boss.
These blades may be of differential pitch and so constructed as to meet varying
requirements so as to enable them to be applied to both solid propellers and those
having adjustable or removable blades.
To lessen the effect of drag or churning of the water by the large blades A A' I
also construct them in a special manner where they unite with the boss by making
the blades narrow and also thickening them at or near that point so as to obtain
strength and thus giving them the appearance of an oval stem where so thickened and
narrowed.
I do not limit myself to the number of blades which may vary according to
circumstances to further the object for which this invention is designed.
The propellers may be placed either at the stern of the vessel amidships or at the
stem or in both stem and stern or at the sides as may be required to meet the
exigencies of river channel or ocean going vessels.
By the means of the combination of long blades and short blades the danger
incurred in a rough sea by the racing of the shaft with the present form of propeller
will be to a great extent obviated if not entirely prevented.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what
I claim is
1st. In screw propellers the combination of long and short blades placed upon the
same boss in the manner and for the purposes herein described and illustrated by
Figure 1 of the accompanying drawings.
2nd. In screw propellers the method and arrangement of blades placed upon separate
bosses in the same line of shafting substantially as described and illustrated by Figure 2
of the accompanying drawings.
3rd. The general arrangement and construction of screw propellers substantially as
described and illustrated herein.
Dated thig 20th dow of October 1800