IMPROVE- MENTS IN MEANS OR APPARATUS FOR PROTECTING SCREW PROPELLERS FROM ENTANGLEMENT, OR BEING FOULED BY ROPES OR OTHER BODIES, ALSO IMPROVE- WONDON MANO OR ADDADANO DOD CLASTED UP THE SCREW APERTURE
Year: 1862

page_text: LETTERS PATENT to Henry Duncan Preston Cunningham, of Bury, near
Gosport, in the County of Hants, Esquire, for the Invention of "IMPROVE-
MENTS IN MEANS OR APPARATUS FOR PROTECTING SCREW PROPELLERS FROM
ENTANGLEMENT, OR BEING FOULED BY ROPES OR OTHER BODIES, ALSO IMPROVE-
WONDON MANO OR ADDADANO DOD CLASTED UP THE SCREW APERTURE."
Sealed the 11th July 1862, and dated the 15th January 1862.
PROVISIONAL SPECIFICATION left by the said Henry Duncan Preston
Cunningham at the Office of the Commissioners of Patents, with his
Petition, on the 15th January 1862.
I, HENRY DUNCAN PRESTON CUNNINGHAM, of Bury, near Gosport, in the
County of Hants, Esquire, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN MEANS OR APPARATUS FOR PROTECTING SCREW PRO-
PELLERS FROM ENTANGLEMENT, OR BEING FOULED BY ROPES OR OTHER BODIES, ALSO
IMPROVEMENTS IN MEANS OR APPARATUS FOR CLOSING UP THE SCREW APERTURE," to
be as follows:-
My improvements consist in protecting screw propellers from being fouled
or entangled by means of chains and bars, as hereafter described, which are
capable being removed or raised up out of the water when the protection is
not required, in order that they may not then offer any impediment to the
progress of the ship. I connect to the second or after stern post, and at each

page_text: side by a hinge joint, a bar or frame, the outer end of which is free to move
upwards and downwards, the movement being effected by a chain carried up
inboard, then to the outer end of these bars or frames I connect chains or
bars, which are carried along to certain points on the ship's side or counter.
When for protecting the screw the outer ends of the stern post bars are
lowered carrying with them the protecting chains or bars, which extend over
and to some distance below the upper part of the blade of the screw when
vertical. By hauling up the outer ends of the stern post bars the protecting
gear is raised out of the water.
My improvements in closing up the screw aperture consist in the employ-
ment of a shutter hung on the after stern post or other convenient part
to close the aperture in the dead wood when the screw is raised out of the
water.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Duncan Preston Cunningham in the Great Seal
Patent Office on the 15th July 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
DUNCAN PRESTON CUNNINGHAM, of Bury, near Gosport, in the County of Hants,
Esquire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of January in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Henry Duncan Preston Cunningham, Her special licence that I, the said
Henry Duncan Preston Cunningham, my executors, administrators, and
assigns, or such others as I, the said Henry Duncan Preston Cunningham,
my executors, administrators, and assigns, should at any time agree with, and
no others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MEANS OR
APPARATUS FOR PROTECTING SCREW PROPELLERS FROM ENTANGLEMENT OR BEING
FOULED BY ROPES, OR OTHER BODIES, ALSO IMPROVEMENTS IN MEANS OR APPARATUS
FOR CLOSING UP THE SCREW APERTURE," upon the condition (amongst others)
that I, the said Henry Duncan Preston Cunningham, my executors or admi-
nistrators, by an instrument in writing under my, or their, or one of their

page_text: hands and seals, should particularly describe and ascertain the nature of the
'said Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Duncan Preston Cunningham,
'do hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, reference being had to the Drawings
hereunto 'annexed, that is to say:-
My improvements consist in affording protection to screw propellers from
being fouled or entangled by hawsers, ropes, wreckage, and other bodies by
means of chains and bars, as hereafter described, which are capable of being
removed or
raised up
out of the water when the protection is not required,
in order that they may not then offer impediment to the progress of the ship.
The manner in which I carry my Invention into effect is shewn in the
Faccompanying Drawings.
Figure 1 is à view of the stern of a ship, and Figure 2 is a side view. Upon
the after stern post I attach bars or rods A, A, A, A, working upon axes or
joints fixed to the stern post at B, B; or to the dead wood. The outer ends of
these bars are bent downward into a form to correspond, as nearly as may be,
with that of the counter or tuck of the vessel. The bars are capable of being
raised or lowered by chains or ropes leading into or on board the ship. On the
right or starboard side of the ship, shewn at Figure 1, the bar is represented
lowered; and the apparatus in position for protecting the screw; on the left or
port side the bar and apparatus are represented raised. It will be seen that
when in position for protecting the screw the outer end of the bar is immersed
'to some distance below the axis of the screw. From the end and other parts
of the bar, chains, ropes, or bars are carried to fixtures on the vessel. The
chain a is-led forward to about where the ship's side or bottom commences to
fall or curve into the run; the chain 6 extends from the bend of the bar to
'about the same point; the chain a, which also serves as a suspensory support,
stretches up to the counter; the chain P serves not only as a protecting chain
in an aft direction, but also as a support or guy to the bar, while the chain C,
which is capable of being slacked when the bar is raised, forms the guard to
the lower part of the screw. Now, it will be seen that in the event of the
ship running over a hawser or rope, or of a hawser, rope, or other such like
body getting round the stern or otherwise, the chains will interpose and
prevent the hawser, rope, or other body from coming in contact with the screw.
By extending smaller chains, ropes, netting, canvas, or other textile or metal

page_text: fabric from the chains and a to the counters, or as high as may be desired,
a further protection is afforded against entanglement from floating bodies. On
the left or port side of the stern of the ship, Figure 1, the bar is represented
as raised and "laying" up and down the stern post, into which position it is
raised; when this apparatus is not required for protecting the screw, such as
when the ship is pursuing her course in clear water, when there may not be
danger of encountering anything likely to foul the screw, the bar and pro-
tecting apparatus are raised by pulling on the chain P, Figure 2, or rope,
Figure 1, or they may be otherwise raised, and thus impediment to the pro-
gress of the ship through the water from the apparatus is removed. Jointed
or flexible bars or ropes may be substituted for the chains, herein-before
described, as forming the protecting apparatus. The bars may be placed
inside cavities or open spaces in the stern post or dead wood, or they may
be arranged to work inside the screw aperture, or on the aft side of the stern
post, so as to be more flush, or on a level with the stern or dead wood when
hauled up instead of, as herein-before described, at the outer sides of the stern
post or dead wood. Although I have described bars on the after stern post
only, yet bars may be fitted in front of the screw aperture as well as abaft
it; in order to form a framework for enclosing or protecting the screw the
bars before and abaft the screw aperture would be connected.
I have herein-before confined myself to describing an open-like enclosure
for protecting the screw, but by increasing the number of the bars on the
principle of a carriage hood or fan, and by applying circular shutter like
plates or bars to the outer surface I obtain a more complete enclosure of the
screw.
8
My improvements in closing up the screw aperture consist in the employ-
ment of a shutter hung on the after stern post or other convenient part to
close the aperture in the dead wood when the screw is raised out of the water.
Figure 3 represents a side view of the stern and dead wood of a screw steam
ship. A is the screw aperture; B is a shutter, hung on hinges on the fore
part of the stern post, capable of being turned round and enclosed over the
aperture A by means of the chain C worked inboard. The after stern post
must be the same width or wider than the screw aperture to carry a shutter
wide enough. There is a shutter on each side.. Figure 4 represents the
shutter closed over the screw aperture when the screw is hauled up and the
ship under canvas.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I am aware that fixed
guards to protect screw propellers have been heretofore proposed, and that

page_text: therefore I lay no claim to any fixed protections to or for screw propellers ;
but I claim,-.
First, the apparatus, herein-before described, for affording protection to
screw propellers from becoming fouled or entangled by ropes and other bodies,
which apparatus is capable of being raised when not required for purposes of
protection, in order not to impede the progress of the ship, or to offer as little
impediment as may be thereto.
And, second, the employment of a shutter for closing the screw aperture in
screw propelled ships, as herein-before described.
In witness whereof, I, the said Henry Duncan Preston Cunningham,
have hereunto set my hand and seal, this Fifteenth day of July
One thousand eight hundred and sixty-two.
H. D. P. CUNNINGHAM. (L.s.)