Screw Propellers for Navigable Vessels.
Year: 1893

page_text: Cate of Application, 30th Aug., 1893
Complete Specification Left, 30th May, 1894-Accepted, 30th Aug. 1894
PROVISIONAL SPECIFICATION.
Screw Propellers for Navigable Vessels.
We, GIOVANNI COSTANTI PARINI, of 156, Dale Street, in the City of
Liverpool, Restaurant Proprietor, and PETER DUFF, of 18, Radnor Place,
Birkenhead, in the County of Chester, Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention has reference to screw propellers for navigable vessels, and more
especially to the type of propeller set forth in the Specification of Letters Patent
No. 8825 of 1891. And it has for its chief object to so form, construct, or arrange
the blades of propellers that their action on or in connection with the water shall be
such as to produce useful propulsive effect in passing through it, and that the non-
effective or non-propulsive work, and-what is of greater importance-the, not only
negative, but harmful or retrogressive action, such as commonly happens with
These harmful or retrogressive
propellers of ordinary kind, shall be obviated.
actions include the carrying round of water by and about the roots and lower parts
of the blades of the propeller, and the resultant effect of the thrusting or pushing
forward, through the water, of a large body of water in front of the propeller, and
the lifting or depressing of bodies of water up and down by the propeller when the
vessel is pitching; whilst under the head of useful propulsive effect. comes the
general gripping of the blades of the water throughout its forward edge or part,
the direct discharge of the water astern as solid or unbroken water both at the boss
and throughout the circle circumscribed by the propeller, and its general clean and
efficient working in all directions.
In setting forth the nature of this invention we will describe the improvements
thereunder in connection with a propeller having the improvements set forth in the
aforesaid Specification of Patent 8825 of 1891; as a propeller having this improve-
ment, is the best, so far as we are aware, as regards the construction, form, and
arrangement of blades at the parts towards and about the boss.
A propeller of this kind and provided with the improvements according to this
invention is constructed as follows:-The blades-with the exception of the
triangular parts towards and at the roots of the blades, that is, the parts within the
line lying between the fore-part of the blades at the boss, and a point about one
third the length of the blade at the after or rear edge- -are of any known suitable
pitch or degree of inclination, but-under this invention-of a special form, con-
struction or arrangement, namely, the forward or leading edges of the blades are
carried forward of or project beyond the boss, and thus they lean towards the hull
of the ship; the form or curvature of the blade edges-i.e., leading edges-being
that of an arc or bow. The rear or after edges may, above the points forming the
apices of the triangular portions above referred to, also with advantage be carried
or project forwards. Below these points, the edges of the blades-i.e. the parts
forming the after edges or sides of the triangular portions-may be carried
approximately straight up from the boss, or even may project aft or sternwards of
the boss.
The angle of the blades where they join the boss, that is the root of the blades,
may be about 45°, and they may be carried round the boss at the after or
The two inclinations of
trailing part for about half the circumference thereof.
the after edge of a blade, as just specified, give the propeller a knuckle shape or
formation.
A propeller, constructed as described, has greater width of blade at the root than
is provided by the ordinary form of propeller, and due to this increased width, its

page_text: thickness may be less than that of an ordinary propeller; and so the resistance
offered by the water in the blades passing through it, due to their diminished
thickness, is diminished.
When the ship is in motion, the action of the propeller blades, constructed or
formed as described, is such that solid water is offered to them to grip and act upon,
and this equally over the whole circle in which the propeller revolves; and this
formation or construction directly behind the leading or forward edge is such that
the water is not broken up, churned, carried round, or thrust forward, but is
discharged as solid or unbroken water and giving no vibration; and furthermore
when the ship pitches and the propeller passes vertically up and down through the
water, the formation or construction of the blades prevents vertical pressure,
upwards or downwards, being put upon the blades, the form and inclinations
described being such that the water is thrown off the blades and not lifted up or
pressed or thrust down.
A further feature in connection with the propellers is the provision of an aperture
or apertures of suitable shape and size in alternate blades, to allow water to pass
through, and be discharged on the following blade, thereby tending to give the
water greater solidity, and an improved thrust forward, as well as reducing the
vibration and shock.
It is to be stated that the features of or improvements under this invention may
be used conjointly in propellers, or separately or individually therein.
Dated this 29th day of August 1893.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.
.
Propellers for Navigable vessels.
We, GIOVANNI COSTANTI PARINI, of 156 Dale Street, in the City of
Liverpool, Restaurant Proprietor, and PETER DUFF, of 18 Radnor Place,
Birkenhead, in the County of Chester, Engineer, 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 has reference to screw propellers for navigable vessels, and more
especially to the type of propeller set forth in the Specification of Letters Patent
No. 8825 of 1891. And it has for its chief object to so form, construct, or arrange
the blades of propellers that their action on or in connection with the water shall be
such as to produce useful propulsive effect in passing through it, and that the non-
effective or non-propulsive work, and-what is of greater importance-the, not only
negative, but harmful or retrogressive action, such as commonly happens with
propellers of ordinary kind, shall he obviated. These harmful or retrogressive
actions include the carrying round of water by and about the roots and lower parts
of the blades of the propeller, and the resultant effect of the thrusting or pushing
forward, through the water, of a large body of water in front of the propeller, and
the lifting or depressing of bodies of water up and down by the propeller when the
vessel is pitching; whilst under the head of useful propulsive effect, comes the
general gripping of the blades of the water throughout its forward edge or part,
the direct discharge of the water astern as solid or unbroken water both at the boss
and throughout the circle circumscribed by the propeller, and its general clean and
efficient working in all directions.
In setting forth the nature of this invention we will describe the improvements
thereunder in connection with a propeller having the improvements set forth in the
aforesaid Specification of Patent 8825 of 1891; as a propeller having this improve-
ment, is the best, so far as we are aware, as regards the construction, form, and
arrangement of blades at the parts towards and about the boss.

page_text: A propeller of this kind and provided with the improvements according to this
invention is constructed as follows:-The blades-with the exception of the
triangular parts towards and at the root of the blades, that is, the parts within the
line lying between the fore-part of the blades at the boss, and a point about one
third the length of the blade at the after or rear edge-are of any known suitable
pitch or degree of inclination, but-under this invention-of a special form, con-
struction or arrangement, namely, the forward or leading edges of the blades are
carried forward of or project beyond the boss, and thus they lean towards the hull
of the ship; the form or curvature of the blade edges-i.e., leading edges-being
that of an are or bow. The rear or after edges may, above the points forming the
apices of the triangular portions above referred to, also in some cases be carried
or project forwards. Below these points, the edges of the blades-i.e. the parts
forming the aft edges or sides of the triangular portions-may be carried
approximately straight up from the boss, or even may project aft or sternwards of
the boss.
The angle of the blades where they join the boss, that is the root of the blades,
may be about 45°, and they may be carried round the boss at the after or
trailing part for about half the circumference thereof. The two inclinations of
the after edge of a blade, as just specified, give the propeller a knuckle shape or
formation.
A propeller, constructed as described, has greater width of blade at the root than
is provided by the ordinary form of propeller, and due to this increased width, its
thickness may be less than that of an ordinary propeller, and so the resistance
offered by the water in the blades passing through it, due to their diminished
thickness, is diminished.
When the ship is in motion, the action of the propeller blades, constructed or
formed as described, is such that solid water is offered to them to grip and act upon,
and this equally over the whole circle in which the propeller revolves; and this
formation or construction directly behind the leading or forward edge is such that
the water is not broken up, churned, carried round, or thrust forward, but is
discharged as solid or unbroken water and giving no vibration; and furthermore when
the ship pitches and the propeller passes vertically up and down through the water,
the formation or construction of the blades prevents vertical pressure, upwards or
downwards, being put upon the blades, the form and inclinations described being
such that the water is thrown off the blades and not lifted up or pressed and thrust
down.
A further feature in connection with the propellers is the provision of an aperture
or apertures of suitable shape and size on alternate blades, to allow water to pass
through, and be discharged on the following blade, thereby tending to give the
water greater solidity, and an improved thrust forward as well as reducing the
vibration and shock.
The propeller is illustrated in the annexed drawings, of which Figure 1 is a back
end view, and Figure 2 a side elevation.
Referring to the drawing, a generally designates the blades of the propeller,
whilst b is the boss. The direction of the line of motion, along which the propeller
travels, when on the ship, is that shewn by the arrow c; that is, this arrow
represents the direction of the ship, to which the propeller is fitted, through the
water.
The forward or leading edges of the blades are as above stated, carried or project
forward of the front of the boss, the vertical plane in which the said front lies being
illustrated by the dotted line dd, in Figure 2. Thus the portion of each of the
blades to the left hand of this line is the portion which is carried or projects forward
of the boss, the bulk of this portion being disposed nearer to the tips of the blades
than to the boss.
The dotted line e e shewn in Figure 2, is drawn at the part of the blades, above
and below which the form thereof is different; namely, the portion above it is of
ordinary pitch or inclination, whilst the triangular part below i.e. between such

page_text: lines and the boss, is of a less pitch than the upper part, it being arranged at
about 45° to the axis of the propeller. By the latter portions the water at and
about the boss is prevented from being carried round by the blades when rotating,
as happens with ordinary propellers, and when the ship lifts and falls, the resistance
of the propeller in being forced through the water vertically up and down, is
diminished and the large amount of strain which exists with ordinary propellers, is
thus obviated. By this portion also the direct discharge of water astern is effected
in a solid and unbroken manner.
By the formation of the leading edges of the propeller blades as described, the
gripping of the blades with the water throughout its forward edge or part is
increased, and the whole operation of the propeller is rendered efficient in all
directions.
The upper edges of the blades a are cut away or sloped downwards from the front
to the back; whilst the back edges of the blades are carried slightly aft.
From Figure 1 it will be seen that from the back end of the propeller, the two
formations of blades described give it the appearance of an elbow or bend. The
formation and arrangement of the portion of the blades below the line e e, provides
for the root of the blades at the points of their connection with the boss, being
carried round a suitable portion of the boss; by this, the construction of the
propeller that is connection of the blades and boss,-greater strength is afforded,
and by this means the thickness of the blade at this part will be less than that of
an ordinary propeller, and so the resistance offered to its passage through the
water is diminished.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A screw propeller having the parts of the blades near the boss of an inclination
or pitch less than the normal pitch of the propeller, and the outer parts of such
blades of the normal pitch of the propeller, and their leading edges carried or
projecting forward of the boss; substantially as herein set forth and as illustrated in
the drawings.
Dated th'
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.