IMPROVEMENTS IN PROPELLING AND STEERING SHIPS OR VESSELS, AND APPARATUS THEREFOR."
Year: 1879

page_text: LETTERS PATENT to John Isaac Thornycroft, of the Firm of J. I. Thornycroft
& Co., of Church Wharf, Chiswick, in the County of Middlesex, Steam Yacht
and Launch Builders, for the Invention of "IMPROVEMENTS IN PROPELLING
AND STEERING SHIPS OR VESSELS, AND APPARATUS THEREFOR."
PROVISIONAL SPECIFICATION left by the said John Isaac Thornycroft
at the Office of the Commissioners of Patents on the 3rd April 1879.
JOHN ISAAC THORNYCROFT, of the Firm of J. I. Thornycroft & Co., of Church
Wharf, Chiswick, in the County of Middlesex, Steam Yacht and Launch
Builders. "IMPROVEMENTS IN PROPELLING AND STEERING SHIPS OR VESSELS,
AND APPARATUS THEREFOR.
"
One object of my Invention is the so arranging propelling apparatus that the
cross sectional area of the stream or current or streams or currents of water set in
motion accelerated or projected by the propeller shall be caused to diminish or
contract during the action of the propeller, and a diminished or contracted area
shall be maintained until such moving body of water is joined by another or
induced stream or current or streams or currents.
In carrying out my Invention various kinds of apparatus may be employed for
imparting motion to, accelerating the motion of, or projecting the water.
In one
arrangement I employ a screw propeller constructed with a boss of large diameter
in proportion to the diameter of the propeller. The diameter of the boss at its
widest part may advantageously be for instance about one half the diameter of the
propeller. The boss is of a form diminishing in diameter from the back (where it
is largest) towards the front end to which the water to be acted upon has free
access. Behind the propeller I arrange in line with the boss a body of greater
length than the boss (it may be about two and a half times the length) which
at the end next the boss may advantageously be of like cross section to the back
end of the boss, but has a gradually increasing diameter or width for a short
distance, and afterwards a gradually diminishing diameter or width to its rear-
ward end, which may be a point.
This body is furnished with guide plates or blades for directing the water
projected from the propeller.

page_text: Around the propeller and body behind it I arrange a pipe tube case or hollow
guide of a form diminishing in diameter or width towards its back end in such
manner as to form for the flow of the body of water from the propeller a passage,
channel, or way, whose cross sectional area at any part of its length situate
between some point in rear of the propeller, and the back end or point of discharge
shall be constant, so that the velocity of the water throughout the after portion of
the passage, channel, or way may be uniform. In some cases I utilize the
secondary stream or current or streams or currents induced by the body of
water projected through the pipe, tube, case, or hollow guide to assist in pro-
pelling the vessel as follows:-—
I combine with the pipe, tube, case, or hollow guide already described (which I
will call the main pipe, tube, case, or hollow guide) one or more supplementary
pipes, tubes, cases, or hollow guides of larger diameter or width at their front ends
than at their back ends. Such supplementary pipe, tube, case, or hollow guide
(where one only is used), or the first one (where more than one are used), at its
front and larger end may surround (or it may be slightly behind) the back or
small end of the main pipe, tube, case, or hollow guide, but is sufficiently large to
leave an intermediate opening, passage, or way for water to enter. Where more
than one supplementary pipe, tube, case, or hollow guide are used each may be
arranged in relation to the one in front of it in a similar manner to that above
described with reference to the relative arrangement of the main pipe, tube, case,
or hollow guide, and the first supplementary one. The main pipe, tube, case, or
hollow guide may be made parallel, or not reduced in diameter or width-at its back
end, if one-or-more-supplementary pipes, tubes, cases, or hollow guides be used, as
described, and the main pipe, tube, case, or hollow guide be arranged not to extend
rearward beyond the largest part of the body already mentioned as being arranged
behind the propeller.
Another part of my Invention consists in the application and use of pipes, tubes,
cases, or hollow guides as described in conjunction with a stream, current, or body,
or streams, currents, or bodies of water projected from the vessel by apparatus
arranged therein. In carrying out this part of my Invention the external propeller
and body behind are dispensed with.
Another part of my Invention has for object the steering or changing the course,
position, or direction of motion of vessels fitted with apparatus as described. For
this purpose I so articulate or joint one or more pipes, tubes, passages, or hollow
guides such as described that the same may be moved, turned, or in some cases
swivelled by any suitable apparatus or gear so as to direct the stream or current or
streams or currents passing therethrough in various directions, and thereby to
change the course, position, or direction of motion of the vessel.
As is obvious apparatus according to my Invention may be constructed in
various forms, twin propelling and steering apparatus may be constructed
according thereto, and parts of my improvements herein-above described in com-
bination may be used separately or in conjunction with other apparatus.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Isaac Thornycroft in the Great Seal Patent Office on the
3rd October 1879.
JOHN ISAAC THORNYCROFT, of the Firm of J. I. Thornycroft and Co., of Church
Wharf, Chiswick, in the County of Middlesex, Steam Yacht and Launch
Builders. "IMPROVEMENTS IN PROPELLING AND STEERING SHIPS OR VESSELS,
AND APPARATUS THEREFOR."
One object of my Invention is the Bo arranging propelling apparatus that the
cross sectional area of the stream or current, or streams or currents of water set in
motion, accelerated, or projected by the propeller shall be caused to diminish or
contract during the action of the propeller, and a diminished or contracted area
shall be maintained until such moving body of water is joined by another or induced
stream or current or streams or currents.
In carrying out my Invention various kinds of apparatus may be employed for
imparting motion to, accelerating the motion of, or projecting the water.
In one
arrangement I employ a screw propeller constructed with a boss of large diameter
in proportion to the diameter of the propeller. The diameter of the boss at its
widest part may advantageously be for instance about one half the diameter of the
propeller. The boss is of a form diminishing in diameter from the back (where it
is largest) towards the front end to which the water to be acted upon has free access.
Behind the propeller I arrange in line with the boss a body of greater length than
the boss which at the end next the boss may advantageously be of like cross section
to the back end of the boss, but has a gradually increasing diameter or width for a
short distance, and afterwards a gradually diminishing diameter or width to its
rearward end which may be a point. This body is furnished with guide plates or
blades for gradually deflecting and directing the water projected from the propeller
into a direction approximately parallel with the body axis.
Around the propeller and body behind it I arrange a pipe, tube, case, or hollow
guide of a form diminishing in diameter or width towards its back end in such
manner as to form for the flow of the body of water from the propeller a passage,
channel, or way, whose cross sectional area at any part of its length situate between
some point in rear of the propeller and the back end or point of discharge shall be
constant, so that the velocity of the water throughout the after portion of the
passage, channel, or way may be uniform. In some cases I utilize the secondary
stream or current or streams or currents induced by the body of water projected
through the pipe, tube, case, or hollow guide to assist in propelling the vessel as
follows:-
I combine with the pipe, tube, case, or hollow guide already described (which I
will call the main pipe, tube, case, or hollow guide) one or more supplementary
pipes, tubes, cases, or hollow guides of larger diameter or width at their front ends
than at their back ends. Such supplementary pipe, tube, case, or hollow guide,
(where one only is used) or the first one (where more than one are used) at its front
and larger end may surround (or it may be slightly behind) the back or small end
of the main pipe, tube, case, or hollow guide, but is sufficiently large to leave an
intermediate opening, passage, or way for water to enter. Where more than one
supplementary pipe, tube, case, or hollow guide are used each may be arranged in
relation to the one in front of it in a similar manner to that above described with
reference to the relative arrangement of the main pipe, tube, case, or hollow guide,
and the first supplementary one. The main pipe, tube, case, or hollow guide may
be made parallel or not, reduced in diameter or width at its back end, so long as
the passage or way for the water set in motion, accelerated, or projected by the

page_text: Fig. 1 is a side elevation, partly in longitudinal section of apparatus according
to my Invention, and Fig. 2 is a view of the fore end of the apparatus, that is, as
seen from the left hand of Fig. 1. 1 is a propeller boss of a form diminishing in
diameter from the back la, where it is largest, towards the point end 1b to which
the water to be acted upon has free access. 1° are the propeller blades fixed to and
revolving with the boss 1; 2 is a body (it may be a casting, or built of metallic
plates) arranged behind the propeller boss, and with its axis in line with that of
the propeller. The front end 2 of this body next or adjacent to the propeller boss
is of like-cross section to the back lud 1° of that boss, but has a gradually increasing
diameter up to the part 2b which corresponds in longitudinal position to the
terminations of the guide plates or blades 3 formed with or fixed to the body 2 as
shewn. From 2b the body 2 gradually diminishes in diameter to its rearward end 2°
which is a point. 4 is a pipe tube case, a hollow guide (hereinafter called a pipe)
surrounding nearly the whole of the propeller proper, as well as that portion of the
body 2 which is furnished with guide plates or blades 3. The pipe 4 is of sheet
metal, as thin as is consistent with stability, and its fore and aft edges may with
advantage be rounded or sharpened so as to offer little resistance to the water. The
guide plates or blades 3 are fast to the pipe 4 so that they hold the body 2 in place.
The apparatus is arranged in relation to the vessel so that the boss 1 occupies a
similar position to the boss of a screw propeller as ordinarily employed, and the
pipe 4 is secured to the stern frame or hull of the vessel so that the propeller proper
may rotate freely within the pipe. An additional stay or stays may be provided
from the vessel to the body 2 near the extremity 2° of the said body.
It will be seen that by this arrangement there is formed between the boss 1 and
body 2 and the pipe 4 an annular space, passage, or way of a cross sectional area
which diminishes or contracts gradually from the front end 4 where the
water enters to the back end 4b where the discharge takes place; and the
water set in motion, accelerated, or projected by the propeller is thus caused to
diminish or contract in cross sectional area of stream during the action of the
propeller, and the diminished or contracted area is maintained until the moving
body of water is joined (at the point of discharge) by other water. With apparatus
constructed and arranged as above described with reference to Figs. 1 and 2, I have
obtained results shewing equal efficiency and about double the propelling effect of

page_text: an ordinary three bladed Griffiths' form of propeller, each giving its best result in
efficiency; efficiency being taken as the proportion of useful effect to work expended,
and the diameter of the screw in the pipe of my propelling apparatus being the
same as that of the Griffiths' screw with which it was compared. The Griffiths'
screw was not supplemented by a pipe or by fixed guide plates or blades 3 or by
a body 2, but was used simply as an ordinary screw propeller.
The apparatus may be modified by prolonging the pipe 4, as indicated by dotted
lines at 4 (Fig. 1), the prolongation being of a form diminishing in diameter towards
its back end 4d in such manner as to form for the flow of the body of water from
the propeller a passage, channel, or way whose cross sectional area at any part of
its length situate between the part where the smallest cross sectional area first
obtains (4) and the back or discharging end (44) of the pipe is constant, so that the
velocity of the water throughout the after portion of the annular passage, channel,
or way may be uniform. Instead of forming the body 2 as shewn in full lines, it
may be shorter, for example, as indicated in dotted lines (Fig. 1), or the construction
and shape may be otherwise varied so long as the cross sectional area of the annular
passage be according to the directions hereinbefore contained. The body 2 may be
formed in one with the boss 1 of the propeller, provided the guide plates or blades 3
be fixed independently (say to the pipe 4) and not to the body 2, so as to leave the
body 2 free to rotate with the propeller. Should this construction (which however
I do not recommend) be adopted it will be desirable in some cases (for instance
where the body 2 is of considerable length, as in Fig. 1) to provide an additional
bearing or support at the rear end of the body 2.
Figures 3 and 4 illustrate a method of utilizing the secondary stream or current
or streams or currents induced by the body of water projected through the pipe 4
to assist in propelling the vessel by combining with the pipe 4 a supplementary
pipe 5 of larger diameter at its front end 5ª than at its back end 5b. The front and
larger end of the pipe 5* surrounds the back or small end of the main pipe 4, and
is sufficiently large to leave an intermediate annular opening, passage, or way 6 for
water which enters at 6º. The pipe 5 may be of sheet metal with rounded or sharpened
edges fore and aft, and be connected to the main pipe 4 by webs or connecting
pieces resembling those shewn at 10, 10, in Figs. 5, 6, and 7.
Figures 5, 6, and 7 shew a modification wherein I combine with the propeller
and body 2 a long surrounding main pipe 4 of a diameter diminishing gradually
from the back edges or terminations 3b of the blades 3 to the rear end 4ª of the
main pipe, and a short conical supplementary pipe 5 which is also tapered. The
annular space 6 is of uniform cross sectional area from 3 to 4d. The annular
space 7 between the supplementary pipe 5 and body 2 gradually diminishes slightly
in cross sectional area from immediately in rear of 4ª where it is largest to 7" where
it is smallest. 10, 10, are webs or connecting pieces whereby the supplementary
pipe 5 is secured to the main pipe 4.
Fig. 8 shews a modification in which in conjunction with a main pipe three
supplementary conical pipes 5, 8, and 9 are employed. The main pipe 4 may with
advantage be very slightly coned from 3b towards 4d, its smallest diameter, The
several pipes may be connected together by webs or connecting pieces like those
shewn in Figs. 5, 6, and 7.
The annular space between the body 2 and each of the several conical pipes 5,
8, and 9, gradually diminishes slightly in cross sectional area from the front end
towards the back end of the respective pipe, that is to say, the cross sectional area
of annular space immediately in rear of 4d is larger than at 5ª, the cross sectional
area immediately in rear of 5a is larger than at 8ª, and the cross sectional area
immediately in rear of 8a is larger than at 9a.
Figures 9, 10, and 11 illustrate the application of my Invention to a light
draught vessel for shallow water, Fig. 9 being a side elevation partly in section,
Fig. 10 an end elevation, and Fig. 11 a plan. The hull of the vessel 11 has its
bottom recessed, as shewn at 12, at each side of the keel near the stern. The

page_text: recesses are so formed in the under part of the hull that when the vessel is afloat
the mouths or openings of the recesses shall be below the surface or level of the
water in which the vessel is floating, and the crowns of the recesses considerably
above the said surface or level. The propellers work in the recesses formed as
described, which constitute chambers bounded by or having their lateral parts
composed of portions of the hull of the vessel protruding into the water, so that
the mouths, openings, or lower parts of the chambers are sealed by the water, and
access of air to their interiors is thus prevented. The propelling apparatus I
have shewn is in general arrangement like that illustrated in Figs. 1 and 2 of
my Drawings, differing only in detail, as for example, the propeller shafts 13 in
the present case work in bushed bearings in the bodies 2. Apparatus constructed
with one or more supplementary pipes, as already described, may be used in light
draught vessels of this class, but it will be advantageous where supplementary
pipes are used in light draught vessels to make such pipes of a somewhat flattened
cross section, so as to reduce the cross sectional dimensions in a vertical sense, as
for example, in the manner shewn at 21 and 22 in Figs. 12, 13, and 14, hereinafter
described.
14, 14, are watertight doors in the hull of the vessel above the water line. By
opening these doors access is at once gained to the propellers. Vessels constructed
with only one access or chamber such as above described (it being centrally arranged
near the stern) may be provided with propelling apparatus according to my
Invention.
Figures 12, 13, and 14 shew an arrangement of apparatus according to my Inven-
tion, in which pipes, tubes, cases, or hollow guides are used in conjunction with a
--stream, or current, or body of water projected through the vessel by apparatus
therein, Fig. 12 being a side elevation, Fig. 13 an end view, and Fig. 14 a plan.
15 is a centrifugal pump driven in any suitable manner, as for example, by a
pair of engines 16. This pump takes its supply by the passages 17 (provided at
their outer orifices with suitable grids 18 to prevent choking of the pump by
entry of floating objects) and delivers through nozzle 19, behind and in line with
which are arranged three pipes 20, 21, 22, of somewhat flattened cross sections, and
which cross sections respectively diminish gradually in area from the forward
towards the after ends of the pipes, as clearly shown in the Drawings.
The pipes 20 and 21 are secured to the vessel by flanges, as shewn in Figs. 12
and 13. The pipe 22 is pivotted to 23 to serve as a rudder for steering or changing
the course, position, or direction of motion of the vessel, and is operated by a
tiller 30 fixed to the rudder head 29.
Figs. 15, 16, 17, 18, 19, 20, and 21, shew an arrangement in which propelling
apparatus similar to that herein before described with reference to Figs. 1 and 2 is
modified to serve also for steering or changing the course, position, or direction of
motion of the vessel. For this purpose the pipe 4 is arranged to turn or swivel
round parts or extensions 23 of the upper and lower guide blades 3* formed with or
attached to the body 2. The lower part 23 is formed with a square shaped
extension 24, which enters a corresponding hole or socket in the stern frame 25 of
the vessel; and the upper part 23 is securely attached at 26 to the stern frame of
the vessel.
These details of attachment may however obviously be varied to suit circum-
stances. It will be observed that in order to allow of the turning or swivelling of
the pipe 4, as indicated by dotted lines in Figs. 16 and 17, considerable clearance
is allowed between the interior of the said pipe 4 and the outer extremities of the
propeller blades 1° and guide blades 3.
Figs. 22, 23, 24, 25, 26, and 27, shew an arrangement in which a propeller with
a body 2 in its rear and a surrounding pipe 4 are employed in conjunction with
articulated supplementary pipes 5, 8, 9, and 9*, Fig. 22 being a side elevation,
partly in section, Fig. 23 an end view, shewing the helm over, Fig. 24 a
plan, Fig. 25 a detail sectional view to a larger scale, and Figs. 26 and 27 detail
plans. The ripe 5 is jointed to the pipe 4 at a, a; the pipe 8 is jointed to the

page_text: pipe 5 at b; the pipe 9 is jointed to the pipe 8 at c, the hole in the pipe 8 being
however elongated, as shewn in Figs. 25 and 26.
The pipe 9* is jointed to the pipe at d, d.
The pipe 8 is formed with a lug or projection e at its top part, and with a similar
lug or projection e¹ at its bottom part; the pipe 9* has similar lugs or projections
ff; the pipe 9 is formed with curved slots g, g¹, respectively in its upper and
lower parts; through these slots pass freely suitable pins, which are carried by the
lugs of the pipe 9*, and enter slots in the lugs of the pipe 8; the pipe 9 is rigidly
connected to the rudder head 29 carrying the tiller 30; the pintle 31 turns in a
bracket bearing as shewn; 31* is a pintle carrying a lever 32, the pipe 9 is secured
to this lever by the pins d and c, so that when the tiller is moved the pipe 9 is
moved, and with it the lever 32; 33 is a lever secured to the pipe 5, and able with
it to turn on the upper pin a. The lever 33 is operated by the tiller 30 through
the connection 34. 33* is another lever secured to the pipe 5, and able with it to
turn on the lower pin a.
By the foregoing arrangement if the tiller 30 be moved towards the port side of
the vessel, as shewn in Fig. 24, the pipe 9 is moved about the pintle 31, and
through the pin C moves the outer end of the pipe 8, whose inner end it simul-
taneously moved by the lever 33, as shewn in Figs. 24 and 27. The pipe 9* is
moved by the lugs of the pipe 8. The result is that each successive pipe is moved
through a greater angle than the one preceding it, that is to say, the pipe 8 is
moved through a greater angle than the pipe 5, the pipe 9 is moved through a
greater angle than the pipe 8, and the pipe 9* is moved through a greater angle
than the pipe 9, as shewn in Figs. 23, 24, and 27. If the tiller be moved over
to the starboard side a similar movement to that already described would be
imparted to the pipes towards the port side of the vessel. The number of supple-
mentary pipes employed will depend on circumstances, in some cases less than four
may be employed.
Having described the nature of my said Invention, and explained in what
manner the same is to be or may be performed or carried into practical effect, I
hereby declare that what I consider to be novel and original, and therefore claim
as the Invention secured to me by the herein before in part recited Letters
Patent is,
1. The method, substantially as hereinbefore described, of causing the stream,
current, or body (or streams, currents, or bodies) of water set in motion, accelerated,
or projected by a screw propeller to diminish or contract in cross sectional area during
the passage of such water through the propelling apparatus, and the diminished or
contracted cross sectional area to be maintained until such moving water is dis-
charged into or joined in rear of the screw propeller by other water.
2. The use or employment in combination with a screw propeller and fixed guide
plates or deflectors of a body 2 formed substantially as herein before described, with
a part of larger cross sectional area than the propeller boss, and arranged in relation
to the propeller and fixed guide plates or deflectors, as herein above explained.
3. Constructing and arranging propelling apparatus for ships or vessels, sub-
stantially as herein before described with reference to Figs. 1 and 2 of the accom-
panying Drawings.
4. Constructing and arranging propelling apparatus for ships or vessels, sub-
stantially as hereinbefore described with reference respectively to Figs. 3 and 4, to
Figs. 5, 6, and 7, and to Fig. 8 of the accompanying Drawings.
5. The method, substantially as hereinbefore described, of propelling a vessel by
the use or employment in conjunction with pipes, tubes, cases, or hollow guides,
arranged as described, of a stream, current, or body (or streams, currents, or bodies)
of water projected from the vessel by apparatus arranged therein.
6. Constructing and arranging apparatus for propelling and steering vessels, sub-
stantially as hereinbefore described with reference to Figs. 15 to 21 inclusive of
the accompanying Drawings.

page_text: 7. Constructing and arranging apparatus for propelling and steering vessels, sub-
stantially as hereinbefore described with reference to Figs. 22 to 27 inclusive of
the accompanping Drawings.
In witness whereof, I, the said John Isaac Thornycroft, have hereunto set my
hand and seal, this Third day of October, in the year of our Lord One
thousand eight hundred and seventy nine.
JOHN I. THORNYCROFT. (L.S.)