IMPROVEMENTS IN THE PROPULSION AND CONSTRUCTION OF SHIPS AND VESSELS."
Year: 1881

page_text: LETTERS PATENT to William Coppin, junior, of Sackville Street, Londonderry,
Ireland, for an Invention of "IMPROVEMENTS IN THE PROPULSION AND
CONSTRUCTION OF SHIPS AND VESSELS."
PROVISIONAL SPECIFICATION left by the said William Coppin at the Office
of the Commissioners of Patents on the 7th July 1881.
WILLIAM COPPIN, junior, of Sackville Street, Londonderry, Ireland. " IMPROVE-
MENTS IN THE PROPULSION AND CONSTRUCTION OF SHIPS AND VESSELS."
This Invention has for its object improvements in the propulsion and construction
of ships and vessels.
At the present time the methods of propulsion in actual use are two, viz., by
paddle wheel and by screw. The first method is dependent upon the surface water
for the resistance, which enables the propeller to exercise its thrust upon the
vessel, and as this resistance is of a yielding nature much of the power is necessarily
uselessly expended.
The screw propellor operates under better conditions in this respect, but being
applied in the stern of the ship it operates in disturbed water which is filling in
after the ship has passed through, and the flow of which is divided by the keel
and stern post. Besides, when one single screw is employed, as is usual, the safety
of the vessel is dependent on this one instrument, which experience shews to be
very liable to injury and not repairable at sea; there is inoreover a decided
objection to using twin screws.
Now, according to my Invention, I so arrange that the propeller will operate
exclusively upon the deep solid water at the bottom of the vessel. I can use pro-
pellers either of the wheel class with the axis lying transversely to the vessel, or
propellers of the screw or inclined blade class, which have the axis longitudinally
of the vessel, but usually I prefer the former.
I form two separate chambers in the bottom of the vessel, and large enough to
contain either wheel or screw propeller. The chamber is open at the bottom, and

page_text: I keep it charged with compressed air by air compression pumps, so that I can
maintain the water level within it to what I require for the proper working of the
propeller. If I use wheels I so place them that the outer edges of the iron floats
descend to the full draft of water.
I use the wheels or screws as propellers either in line across the ship or place
one forward of the other, so that the openings in the bottom may not affect the
strength of the ship, one propeller being on the port and the other on the star-
board side of the bottom of the ship. The propellers are to be driven by separate
engines. The water is allowed to rise in the chambers to the height which best
suits the propeller, say, so that its wheel floats are just immersed.
Sometimes I employ in these air supplied chambers inclined blade propellers on
longitudinal axis, or there may be screws immersed only for a small portion of
their outside diameter, so that the boss and axis remain well out of the water at
all times. In the present ships the boss is a great obstruction. Any repairs that
may be required to the propeller can be done on the voyage without placing
the ship in dock. All and every part employed in this new mode of propulsion
can be come at without docking.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Coppin in the Great Seal Patent Office on the 6th January
1882.
WILLIAM COPPIN, junior, of Sackville Street, Londonderry, Ireland. " IMPROVE-
MENTS IN THE PROPULSION AND CONSTRUCTION OF SHIPS AND VESSELS."
This Invention has for its object improvements in the propulsion and construction
of ships and vessels.
At the present time the methods of propulsion in actual use are two, viz., by
paddle wheel and by screw. The first method is dependent upon the surface
water for the resistance, which enables the propellor to exercise its thrust upon
the vessel, and as this resistance is of a yielding nature much of the power is
necessarily uselessly expended.
•
The screw propellor operates under better conditions in this respect, but being
applied in the stern of the ship it operates in disturbed water which is filling in
after the ship has passed through, and the flow of which is divided by the keel and
stern post. Besides, when one single screw is employed, as is usual, the safety of
the vessel is dependent on this one instrument, which experience shews to be very
liable to injury and not repairable at sea; there is moreover a decided objection to
using twin screws.
Now, according to my Invention, I so arrange that the propellor will operate
exclusively upon the deep solid water at the bottom of the vessel. I can use
propellors either of the wheel class with the axis lying transversely to the vessel,
or propellors of the screw or inclined blade class, which have the axis longitudinally
of the vessel, but usually I prefer the former.
I form two separate chambers in the bottom of the vessel, and large enough to
contain either wheel or screw propellor. The chamber is open at the bottom and
I keep it charged with compressed air by air compression pumps, so that I can
maintain the water level within it to what I require for the proper working of the
propellor. If I use wheels I so place them that the outer edges of the iron floats
descend to the full draft of water.
I use the wheels or screws as propellors either in line across the ship or place
one forward of the other, so that the openings in the bottom may not affect the
strength of the ship, one propellor being on the port and the other on the star-
board side of the bottom of the ship. The propellors are to be driven by separate
engines. The water is allowed to rise in the chambers to the height which best
suits the propellor, say, so that its wheel floats are just immersed.
Sometimes I employ in these air supplied chambers inclined blade propellors
on longitudinal axis, or there may be screws immersed only for a small portion of
their outside diameter, so that the boss and axis remain well out of the water at
all times. In the present ships the boss is a great obstruction. Any repairs that
may be required to the propellor can be done on the voyage without placing the
ship in dock. All and every part employed in this new mode of propulsion can
be come at without docking.
In order that my said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.

page_text: a, a, are the chambers formed in the ship to receive the propellors, which in the
arrangement represented by the Drawings are paddle wheels; b, b, are the paddle
wheels, and c, c, are the engines by which they are driven.
The propellor shafts pass through stuffing boxes in the sides or walls of the
chambers a.
There are air pumps worked by the main or preferably by auxillary engines,
which force air into the chambers a to maintain the water level about in the
position in which it is indicated. An automatic regulator keeps the pressure in
these chambers at any point to which the regulator may be set. Gauges are
provided; so that the position of the water line in the chambers may be always
under the observation of the engineer. Double doors are also provided to the
chambers, so that they may be entered when the propellors are not in movement
to effect repairs or for any other purpose. It is obvious that in place of paddle
wheels other descriptions of propellors may be employed, as already stated, within
this compressed air casing.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I claim,-
My improvements in the propulsion and construction of ships and vessels con-
sisting in providing chambers a, which may be charged with compressed air to
control the position of the water line therein, and in mounting the propellors to
work within the said chambers, substantially as described.
In witness whereof, I, the said William Coppin, junior, have hereunto set my
hand and seal, this Thirty first day of December, in the year of our Lord
One thousand eight hundred and eighty-one.
WILLIAM COPPIN, J. (L.S.)