MENTS IN SCREW PROPELLERS, AND IN THE CONSTRUCTION OF VESSELS RELATING THERETO
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Robert Moore Steele at the Office of
the Commissioners of Patents on the 17th September 1881.
ROBERT MOORE STEELE, of Hampstead, in the County of Middlesex. IMPROVE
MENTS IN SCREW PROPELLERS, AND IN THE CONSTRUCTION OF VESSELS RELATING
THERETO."
"
My Invention is designed to render more practicable and economical the use of
screw propellers with large bosses, and to improve those of usual construction by
the combination therewith of a certain device hereinafter specified; and further to
modify the construction of the after part of vessels to be fitted with same, in order
to give adequate structural strength for its support and advantage in steering.
My said device, hereinafter termed a propeller run, consists of a fixed structure
or run in axial line with the propeller, and of approximately similar diameter to its
boss at the points of proximity.
This propeller run is constructed on such tapering lines, conical or otherwise, as
shall approximately follow those of the submerged after part of the vessel, and
have a diminishing transverse section forming an easy exit without "suck" behind
the propeller boss, and shall thus enable the use of a large boss with its well known
concomitant advantages. Forward of the boss my propeller run forms or contains
the shaft tube, and where of large diameter it may be carried well forward into the
after body of the vessel, thus causing the complete junction of the stream lines
from the run of the vessel to take place abaft of the propeller, and permitting
portion of the propeller's revolution to take effect on water running more or less
parallel to its axis. The spiral current of water induced by the revolving blades
of the propeller swirls round my propeller run as a core, and thus is directed in
the axial line of the vessel with greater force than is now possible.
a
Vessels to be fitted with my propeller run are constructed with an overhanging
stern and lengthened keel adequately strengthened, bearing one or more stern posts
for the direct support of my propeller run.
The space above and below may be filled up or left open. In the former case
ports above and below may be pierced or the structure may be recessed, so that the
spiral current induced by the moving propeller blades may swirl round iny
propeller run or round a portion of it as a core; this is also the case where an

page_text: open construction is adopted. In some cases, especially where it is of large size,
the propeller run may be further supported by stanchions.
The end of the propeller run nearest to the boss may be made hollow and open
towards the boss, access being made through a manhole in its external surface;
or it may have one or more openings cut in such manner as to admit of the
inner circumference of the boss or the after bearing of the shaft being reached. In
relation to some spherical constructions of boss I may form my propeller run with
rounded shoulders towards the boss, and may further provide removable pieces to
bring it close up to the said boss where required.
The situation of the rudder at a distance from the propeller allows of increased
advantage in steering.
My propeller run may with advantage be fitted as an adjunct to propeller bosses
of usual construction when their size is great, in order to prevent suction and to
afford a core round which the spiral current induced by the blades of the moving
propeller may swirl.
In some cases, especially in the last named, it may be desirable to recess the
rudder, so as to admit of a long taper without placing the rudder so far astern, as
consequent upon the construction hereinbefore specified.
My propeller run is applicable to twin propellers. In this case I afford support
by stanchions, similar to those now used for the support of the exposed shaft tubes;
or I fill in the open space thus left, and form a supporting structure similar in
character to that specified in relation to vessels driven by a single propeller.