Apparatus for Propelling Boats and other Navigable Vessels.
Year: 1889

page_text: Date of Application, 17th Aug., 1889
Complete Specification Left, 16th May, 1890-Accepted, 16th Aug., 1890
PROVISIONAL SPECIFICATION.
Apparatus for Propelling Boats and other Navigable Vessels.
I, HENRY BARCROFT, of The Glen, Newry, in the County of Armagh, Ireland,
Director of the Dundalk and Newry Steam Packet Company, do hereby declare the
nature of this invention to be as follows:-
My invention has for its object the propulsion of a boat, more particularly a canal
boat, in such a way as not to interfere appreciably with the carrying capacity of the
boat, and to do this with a less percentage of loss between the power exerted and that
actually employed in moving the boat than has heretofore been attained. Besides
this general object, the propelling machinery is so constructed that it will manoeuvre
the boat not only in respect to steering without a rudder, but also as regards slowing,
stopping or backing the vessel in connection with the motor or engine, while said engine
or motor may be running without intermission at its normal full speed. The propeller
is adjustable at pleasure whether in respect of diameter or pitch.
The main shaft is not submerged so as to avoid the loss of power inseparable from
a water tight bearing and also the loss which attends the motion of the ordinary
submerged boss through the water.
A special object attained by this invention is that an engine or motor can be
employed under control of a governor running at a constant speed. This is
particularly desirable should the motive power be electricity or an oil engine, as an
engine or a dynamo could run uninterruptedly, subject to the governor, without
regard to the movements of the boat, this obviates the difficulty which has heretofore
attended the employment of oil engines in navigation owing to the difficulty of
restarting them.
The engine or dynamo can be geared to the main shaft by wheels, pitch chain, or
any suitable connection, and may be placed on deck so as not to reduce the available
cargo space of a canal or other boat. This propeller is equally adapted to be set in
motion by treadles and worked by foot power.
According to my invention I provide upon one and the same main shaft situated
above the water level in the longitudinal axis of the vessel, two independent sets of
propeller blades or paddles that are made to rotate in contrary directions, the one set
being for this purpose mounted directly on the shaft while the other set is mounted
on a sleeve rotatable on the shaft, from which it receives motion in the contrary'
direction by any suitable gearing.
The propeller blades or paddles are so arranged that their angular position
relatively to the shaft can be varied at will; thus when the angles formed by both
sets of blades are equal but reversed, it will be seen that the tendency of the one set,
in acting on the water, to move the stern of the boat laterally in one direction will be
counteracted by the tendency of the other set to move the boat in the contrary
direction, and the boat will consequently be propelled straight ahead; if on the other
hand the one set be adjusted to a different angle from the other set, the boat will be
steered to the one side or the other, to an extent dependent upon the amount of
differential action produced. If, on the other hand, the angles of both sets are reduced
or increased simultaneously to the same extent, the speed of the vessel will be varied,
and if their angular positions are simultaneously reversed, the vessel will be propelled
astern.
According to one arrangement for carrying out the above described mode of.
propulsion, I place the main shaft, which for the sake of lightness may be tubular,
above the water line and project it outwards some distance beyond the stern post. The
extreme end may be supported by a bearing, or not, as desired.
At or near the extreme end I attach a boss by any ordinary..means, and into this

page_text: boss I attach two or any other number of arms at right angles to the shaft, preferably
tubular, and preferably screwed into the boss. Within each of these hollow arms
another moves in and out, being clamped at any desired projection by screws or other
ordinary means.
Each of these outer projecting arins may have another working inside, and so
on, in manner of a telescope, but for smaller craft it will suffice to attach a thin
blade or paddle of suitable form by rivets or other means to the second arm. It will
thus be obvious that both the pitch and the diameter can be varied by the position in
which one arm is placed within the other before being clamped.
This arrangement is designed to combine lightness, strength and general con-
venience. The blade may be so twisted in itself in relation to the diameter that the
line travelled in the water would increase in obliqueness towards the boss as in an
ordinary screw.
Between the boss and the stern post another similar pair of paddles are caused to
revolve in an opposite direction, the boss of the second set is fastened to a sleeve which
encircles the main shaft.
A bevel wheel on the main shaft drives a crown bevel which in turn drives a bevel
on the sleeve and thus causes the motion of the sleeve to reverse.
In order to control the boat by slowing stopping or backing I alter the pitch of
each pair of blades equally, and for steering I alter the pitch of each pair in relation
to the other.
By reducing the pitch the boat slows, and continuing the reduction until the pitch
disappears and both blades run in the same plane, the way will be taken off the boat,
although the revolutions of the propellers may continue as before, and by continuing
the circular movement of the arms, pitch will commence in the opposite direction, and
the boat will immediately begin to move astern.
For steering, the pitch of each pair of blades must be varied either independently
or in opposite directions, as the boat's head will turn in the direction of motion of the
pair of blades having the greatest pitch.
To control the pitch of the blades I put on the arms close to the boss a toothed
wheel, the teeth need not extend further than half way round. I cause a rack to
work into these teeth and by pushing or pulling the rack to any desired extent the
wheel will move with it, and cause the arm to make the corresponding part of
a revolution. Or a worm and worm wheel may be employed in place of the
rack and toothed wheel, or the required motion may be obtained by an arrangement
of levers.
In order to work the racks nearest the boat I attach them to a carrier or frame
and this carrier is circular at the end next the boat, the end being turned up to fit
into another carrier making a circular journal. Into this second or inner carrier are
attached two rods, one on either side, actuated by levers and screws which cause it to
move in and out at pleasure.
The carriers to which the rods are attached have only a movement in and out with
the rods or shafts but the outer carrier revolves with the propeller and thus the racks
move in and out during their revolutions whilst the rods which actuate them have no
circular motion.
To control the outer pair of propeller arms a similar contrivance is made use of
but in this case it is necessary to employ an intermediate carrier which revolves with
the sternmost propeller arms.
This carrier has a journal at either end so that while it revolves to the right
the outer one to which the racks are affixed may be revolving to the left or
vice versa.
The rods actuating the outer pair of arms are situated outside the other rods, and
the journal of the carrier to which they are attached is of much larger diameter so
that the operation of the inner rods may take place independently of the outer.
If it should be desired to control the steering only and not the speed, it would
suffice to attach racks to the intermediate carrier, to work into the cog wheels of the
arms of the sternmost propeller, and thus the two carriers for the sternmost

page_text: propellors described before, and also the rods attached thereto, could be dispensed
with.
A rudder may be used if desired, in which case the steering arrangement would
not be needed and if the paddle screw were used as auxiliary to a sailing vessel the
propellers when not in action could be fixed horizontally in the same plane and thus
the propelling machinery being quite free of the water would not in any way hinder
the progress of the vessel.
To actuate the rods or shafts I attach levers at a suitable angle and at a convenient
place.
The levers are actuated by two different screws worked by hand. One causes the
levers to move parallel to each other and thus push the sets of rods or pull them
equally by which means the steering is accomplished. By the other screw I change
the relations of the levers to each other by making them approach or separate from
one another at the ends attached to the rods and thus according to the amount of
opposite motion given to the racks through the pairs of rods the pitch of the blades is
simultaneously lessened or increased, and the speed of the vessel retarded or augmented
in proportion.
In cases where the arms of the propeller blades or paddles are made of considerable
length as compared with their diameter, they may be supported at an intermediate
point of their length when in action by antifriction rollers carried thereby working
against fixed surfaces.
Dated this 17th day of August 1889.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Apparatus for Propelling Boats and other Navigable Vessels.
I, HENRY BARCROFT, of The Glen, Newry, in the County of Armagh, Ireland,
Director of The Dundalk and Newry Steam Packet Company, 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 :-
My Invention has for its object the propulsion of a boat, more particularly a canal
boat in such a way as not to interfere appreciably with the carrying capacity of the
boat, and to do this with a less percentage of loss between the power exerted and that
actually expended in moving the boat than has heretofore been attained.
In addition to this general object I so construct the apparatus that in addition to
propelling the boat it will either both steer and vary stop or reverse the motion
thereof, or will effect the steering of the same only.
The propeller shaft is in all cases arranged on deck or above the waterline, so as to
avoid the loss of power inseparable from watertight bearings, and also the loss which
attends the motion of the ordinary submerged boss through the water.
In carrying out my invention I make use of that system of propulsion in which two
sets of propeller blades mounted on two independent shafts are rotated in contrary
directions the angle of the blades of the one set being the reverse of that of the other,
so that each set counteracts the tendency of the other set to make the boat deviate
from a straight course; and I arrange the two sets in such a manner that either the
angles of the blades of both sets can be simultaneously increased or decreased to the
same extent, or even reversed, whereby an increase or decrease of speed, stopping,
and backing can be effected, or the angle of the one set of blades can be made
to differ from that of the other, whereby the side thrust exercised by the one
set being greater than that of the other, the steering of the boat will be
effected.
With this arrangement the great advantage is obtained that a motor can be
employed under control of a governor, which shall run continuously at a constant
speed in one and the same direction, thus obviating the difficulty heretofore

page_text: experienced in employing motors such as dynamos or oil or gas motor engines,
owing to the difficulty or loss of useful effect in working them at variable speeds, or
stopping and starting them.
The arms carrying the propeller blades are by preference made telescopic, so that
the propeller blades can be accurately adjusted to suit varying water levels according
to the varying draught of the boat.
In order that my invention may be readily understood I will now proceed to
describe by way of example the construction for carrying it into effect, shewn on the
accompanying drawings.
Figs. 1 and 2 of the drawings shew respectively a sectional elevation and a plan of
part of a boat with my before described propelling apparatus applied to it. In this
arrangement the one set of propeller blades A is mounted upon a tubular shaft A¹ and
the other set B is mounted upon a solid or tubular shaft B₁ passing through A¹. The
shaft B is driven by a suitable motor engine through gearing while shaft A' is
driven in the contrary direction by B¹ through the bevel gearing D D and inter-
mediate wheel D¹. The blades of the propellers A and B having opposite angular
positions imparted to them, it will be seen that in driving them at the same speed in
opposite directions, the side thrust exercised by the one set will counteract that
exercised by the other set, and they will propel the boat straight ahead.
The two sets of propeller blades are capable of having their angles varied, either to
the same extent, for slowing, stopping, or backing, or to a different degree so as to
render the side thrust of the one set greater than that of the other and thus effect the
steering of the boat. For this purpose the propellers have combined therewith
mechanism part of which is shewn more clearly to an enlarged scale in longitudinal
section at Fig. 3 in cross sections on line X X at Fig. 4 and in part side view at Fig. 5.
The propeller arms E E F F of the two sets are screwed into their bosses E¹ F¹ by
means of loosely fitting screw threads, so that the arms are free to turn in their boss
through the required angle for bringing the blades either parallel to the plane of
rotation, in which case they have no propelling power, or to the extreme angle on
either side of that position for exercising the greatest propelling power. The partial
rotation of the arms for this purpose is effected as follows.
Upon the shaft A¹ is a sliding frame G and on the shaft B¹ is a sliding frame H,
these frames have toothed racks G¹, H', fixed on them which gear with toothed
pinions or quadrants 1 J fixed on the propeller arms, so that by shifting the frames in
one direction or the other they effect the partial rotation of the arms as described.
The frame G has a collar G2 embracing a circular neck on a piece K capable of
sliding on the shaft A¹ and to which are fixed two rods K¹ passing along parallel to
the shaft and carried in suitable guides K². The frame H has a collar H2 embracing
a circular neck on a piece L capable of sliding on the shaft B' and to which are fixed
the rods L' whose other ends are fixed to a ring L³ fitting a circular neck on a sliding
piece M to which are connected rods M¹ passing along parallel to the rods K₁ and
carried in the guides K³.
To the rods K' are attached bosses N N with which gears the lower end of a double
ended lever O pivotted at O₁ to a screwed nut on a screw spindle P carried by
uprights QQ and fitting with its upper forked end between lugs on a sliding bar R
also carried by the uprights Q Q₁ and screwing with a threaded end into a screw
nut S held in the upright Q and rotatable therein by a hand wheel S'. To the
rods M are attached bosses T T with which gears the lower end of a double ended
lever U pivotted at U₁ to a second screwed nut on the spindle P, and fitting with its
upper forked end between other lugs on the bar R.
The screw threads of the spindle P on which are the nuts of levers OU are of
reversed pitch, and the spindle can be rotated by the hand wheel P¹.
From the above described arrangement it will be seen that if it be desired to
simultaneously alter the pitch or inclination of the blades of both sets of propellers A
and B, for either slowing, stopping or reversing; this can be effected by rotating the
screw spindle P so as to move the nuts carrying the levers O U nearer together or
.farther apart; by this movement the lower ends of the levers, and consequently the

page_text: bosses N T rods K' M' and sliding frames G and H are moved in contrary directions,
thereby also turning the propeller arms E F through equal angles in contrary
directions by means of the racks G' H'. If on the other hand it be desired to alter
the pitch of the one set of blades relatively to the other, so as to steer the boat either
to port or to starboard, this can be effected by rotating the nut S so as to shift the
bar R in one direction or the other, thereby moving the upper ends of the levers OU
simultaneously in the same direction and consequently also shifting the rods K' M'
and sliding frames G H in the same direction, whereby the racks in turning the
propeller arms in the same direction, will cause the pitch of the one set of blades to be
increased and that of the other set decreased.
It will be seen that as the frame G can revolve independently of the piece K, held
by the rods K¹ and as the rods L' which are carried round by the frame G can
revolve independently of the frame H on the one hand and the piece M on the other
hand, the above described actuation of the propeller arms can be effected while the two
sets of propellers are revolving in contrary directions.
Instead of effecting the partial rotation of the propeller arms by racks and pinions
as described, it might obviously be effected by a suitable lever connection between the
slides and arms.
It will be obvious that instead of arranging the above described mechanism so as to
enable the boat to be both steered and slowed stopped or reversed by varying the
angular position of the propeller blades these may be arranged to perform either the
one or the other function alone. Thus for effecting the steering only, the fulcra O¹ U1
of the levers O U may be fixed, and only the upper ends of the levers be actuated as
described.
In this case the slowing, stopping and reversing would be effected by the engine in
the usual manner. If on the other hand the steering is effected by a rudder in the
usual manner, then the upper ends of the lever O U may work on fixed fulcra, and the
points O¹ U be moved by the screw spindle P in the manner described.
The overhanging propeller shafts are supported in bearings on a suitable over-
hanging framing
The propeller arms are made telescopic so that their length can be adjusted
according to the draught of the boat, or to the depth of immersion required for the
blades, the tubular part E F screwed into the boss has for this purpose either a second
tubular part E2 F² sliding in it, in which again slides the tubular or solid stem E³ F³
formed in one with the blade E F4, or the stem of the blade may slide directly in the
tubular part E; by this arrangement both the length of the propeller arm and the
angular position of the blade can be accurately adjusted, as the stem of the blade is
free to turn in the tubular part. The sliding part or parts of the arm can be secured
in the position to which they are adjusted by any suitable known means, a convenient
arrangement being that shewn respectively in elevation and cross section at Figs. 6
and 7. The tubular part E has a slot cut in it through which a key a having a head
at both ends, passes so as to bear against the part E2, the key being held in a strap b
fixed to E, so that on driving the key in one direction the parts E and E³ are firmly
secured together, while on driving the key in the contrary direction, E³ is free to
slide in E.
The propeller blades and gear may be enclosed above water line by a suitable
casing.
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 :-
1. In apparatus for propelling boats, the use of two sets of rotary propeller blades
mounted on shafts above the water line and made to revolve in contrary directions, in
combination with means whereby the angles of the propeller blades can be varied
while in motion in such manner as either to vary, stop or reverse the motion of the
vessel or to steer the same or to perform both functions substantially as herein
described.

page_text: 2. In propelling apparatus such as is referred to in the preceding claim, mounting
the one set of propeller blades upon a tubular shaft through which the shaft carrying
the other set of blades passes, the propeller arms being rotatable in their bosses and
geared by means of toothed pinions or sectors to sliding racks arranged and operated
substantially as described with reference to Figs. 1 to 5 of the drawings so that either
the angles of both sets of blades can be varied simultaneously to the same extent, for
varying the speed of the vessel, or the angle of the one set of blades can be made to
differ from the angle of the other set for the purpose of steering.
3. For the purpose of effecting the partial rotation of the arms of two sets of
propeller blades revolving in contrary directions, the combination of two sliding
frames G H each adapted to effect the partial rotation of one set of the arms,
such frames being connected together and to rods actuating the same by revolvable
connections, substantially as described.
4. In propelling apparatus such as is referred to in the preceding claims, mounting
the propeller blades on telescopic arms so as to enable them to be adjusted according
to the draught of the vessel, means being provided for securing the blades in the
position to which they are adjusted, substantially as herein described.
Dated this 16th day of May 1890.
ABEL & IMRAY,
Agents for the Applicant.