IMPROVEMENTS IN THE CONSTRUCTION OF SHIPS AND OTHER VESSELS PROPELLED BY SCREWS
Year: 1867

page_text: LETTERS PATENT to Thomas Edward Symonds, of Adam Street, Adelphi,
in the County of Middlesex, Captain in the Royal Navy, for the Inven-
tion of "IMPROVEMENTS IN THE CONSTRUCTION OF SHIPS AND OTHER VESSELS
PROPELLED BY SCREWS."
Sealed the 28th April 1868, and dated the 80th October 1867.
PROVISIONAL SPECIFICATION left by the said Thomas Edward Symonds
at the Office of the Commissioners of Patents, with his Petition, on the
80th October 1867.
I, THOMAS EDWARD SYMONDS, of Adam Street, Adelphi, in the County of
Middlesex, Captain in the Royal Navy, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF SHIPS AND OTHER
VESSELS PROPELLED BY SCREWS," to be as follows:-
In ships and vessels propelled by two screws at the stern, one on either
side of the stern, a system of propulsion now well known as the twin screw
system, the portions of the screw shafts which are exterior to the ship or
vessel are usually enclosed in trunks or tubes, the after extremities of which
have been hitherto supported and attached to the bottom and dead wood of
the ship or vessel by V or bracket frames carrying the bearings for the screw
shafts. To give additional support to these trunks or tubes and to the bearings
of the screws which they contain, so as to promote the rigidity of the structure
and lessen vibration in single-keeled ships, I fix a strong web or plate or
gusset piece to the trunk or tube from end to end, passing up until it meets

page_text: the bottom of the ship at an angle of about 45°, or somewhere thereabout,
with the vertical plane of the ship or vessel; or, in other words, I cause the
web plate or gusset piece to pass in the shortest manner possible to the
bottom. It is not essential that the web or plate or gusset piece should be
unperforated, it may be a lattice or other open frame. By this arrangement
the attachment of the tube or trunk is distributed over a larger surface of the
bottom of the ship or vessel, thereby imparting additional strength and
rigidity to that part of the body acted on more directly by the screws; there is
also less resisting surface opposed to the motion of the ship or vessel, less
liability to foul passing objects, and the flow of water to and delivery from the
screws less retarded and impeded than by any previous method. This arrange-
ment of web plate or gusset piece or frame is more efficient for checking
rolling, and will conduce to the general stiffness and steadiness of the ship or
vessel. It may be formed in continuation or connection with the bilge keels
usually fitted for the same purpose.
The second part of this Invention consists in capping the outer end of the
trunk with a metal cap, serving to retain the outer ends of the planking or
sheathing, and also having an overlapping flange to cover or close the space
or joint between the boss of the propellor and the bearing, so as to prevent
objects being drawn in to stop or interfere with the action of the propellor.
The fore side of the boss of the propellor should be so formed as to facilitate
the object of the Invention, and the overlapping flange may either be formed
with the cap or separately, and fixed to it by screws or otherwise.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Edward Symonds in the Great Seal Patent Office
on the 30th April 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
EDWARD SYMONDS, of Adam Street, Adelphi, in the County of Middlesex,
Captain in the Royal Navy, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
of our Lord
Patent, bearing date the Thirtieth day of October, in the year
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Edward Symonds, Her special licence that I, the said Thomas
Edward Symonds, my executors, administrators, and assigns, or such others 'as
I, the said Thomas Edward Symonds, my executors, administrators, and assigns

page_text: 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 "Iж-
PROVEMENTS IN THE CONSTRUCTION OF SHIPS AND OTHER VESSELS PROPELLED BY
SCREWS," upon the condition (amongst others) that I, the said Thomas Edward
Symonds, my executors or administrators, by an instrument in writing under
my, or their, or one of their 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 Thomas Edward Symonds, do hereby
declare the nature of the 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, that is to say :-
In ships and vessels propelled by two screws at the stern, one on either
side of the stern, a system of propulsion now well known as the twin screw
system, the portions of the screw shafts which are exterior to the ship or
vessel are usually enclosed in trunks or tubes, the after extremities of which
have been hitherto supported and attached to the bottom and dead wood of
the ship or vessel by V or bracket frames carrying the bearings for the screw
shafts. To give additional support to these trunks or tubes and to the
bearings of the screws which they contain, so as to promote the rigidity of the
structure and lessen vibration in single-keeled ships, I fix a strong web or
plate or gusset piece to the trunk or tube from end to end, passing up until it
meets the bottom of the ship at an angle of about 45°, or somewhere there-
about, with the vertical plane of the ship or vessel; or, in other words, I cause
the web plate or gusset piece to pass in the shortest manner possible to the
bottom. It is not essential that the web or plate or gusset piece should be
unperforated, it may be a lattice or other open frame. By this arrangement
the attachment of the tube or trunk is distributed over a larger surface of the
bottom of the ship or vessel, thereby imparting additional strength and
rigidity to that part of the body acted on more directly by the screws; there
is also less resisting surface opposed to the motion of the ship or vessel, less
liability to foul passing objects, and the flow of water to and delivery from
the screws less retarded and impeded than by any previous method. This
arrangement of frame web plate or gusset piece or frame is more efficient for
checking rolling, and will conduce to the general stiffness and steadiness of

page_text: the ship or vessel. It may be formed in continuation or connection with the
bilge keels usually fitted for the same purpose.
The second part of this Invention consists in capping the outer end of the
trunk with a metal cap, serving to retain the outer ends of the planking or
sheathing, and also having an overlapping flange to cover or close the space
or joint between the boss of the propellor and the bearing, so as to prevent
objects being drawn in to stop or interfere with the action of the propellor.
The fore side of the boss of the propellor should be so formed as to facilitate
the object of the Invention, and the overlapping flange may either be formed
with the cap or separately, and fixed to it by screws or otherwise.
Figures 1, 2, 8, and 4 of the Drawings hereunto annexed show my Inven-
tion applied to that class of vessel known as composite ships or vessels, the
nature of each view is marked upon the Drawing.
In each Figure a is the metal trunk or tube which encloses the portion of
the screw shaft which is exterior of the vessel; the construction of these
trunks is well understood, so that it is unnecessary to give here any description
of it; the trunk, as is usual, carries bearings in which the shaft turns; 6 is
the web or plate by which the trunk a is connected to the side of the vessel;
the web is for this purpose formed with flanges along its side edges, and the
flanges along one edge are attached to the wrought-iron tube, whilst the
flanges along the opposite edge are attached to the angle-iron ribs c of the
framing of the vessel; the flanges of the web are afterwards covered over by
the wooden planking of the sides of the vessel and by the planking with which
the trunk is surrounded, so that the points of connection between the web and
the wrought-iron ribs and trunk are protected from the action of the water.
The web or plate c it is preferred to make of a metal similar to that with
which the vessel is sheathed. For small vessels, such as gun boats and
launches, I prefer that the web plate or gusset piece b should be unperforated;
but for larger vessels a lattice or other open frame may be employed.
The manner in which I prefer to carry out the second part of my Invention
is also shown in Figures 2 and 4 of the Drawings. In these Figures the
metal cap which is applied to the end of the trunk is marked d; the inner
end of the cap häs secured to it the end of the wooden planking of the trunk,
and around the outer end of the cap is the overhanging flange d¹ which covers
over the space or joint between the boss of the propeller and the outer bearing
which is carried by the end of the trunk a.
At Figure 5 of the Drawings is shown the manner in which I prefer to
connect the web b to the trunk and to the sides of the vessel when the vessel
is entirely of iron. In this case in place of forming the web with flanges angle

page_text: pieces are rivetted to its ends, but other arrangements might be employed.
In the case of wooden vessels also the trunk may be similarly connected to
the sides of the vessel by a metal web 6 which passes directly or in the
shortest way from the trunk to the sides of the vessel, as herein-before
described.
In witness whereof, I, the said Thomas Edward Symonds, have here-
unto set my hand and seal, this Twenty-ninth day of April, in the year
of our Lord One thousand eight hundred and sixty-eight.
) Witness,
A. P. SYMONDS,
Lymington, Hants.
THOS. EDWP. SYMONDS. (L.S.)