IMPROVEMENTS IN FLOATING DOCks
Year: 1874

page_text: LETTERS PATENT to Druitt Halpin, Engineer, Manager Victoria
Graving Dock, London, for the Invention of "IMPROVEMENTS IN
FLOATING DOCks."
Sealed the 8th June 1875, and dated the 12th December 1874.
PROVISIONAL SPECIFICATION left by the said Druitt Halpin at the
Office of the Commissioners of Patents, with his Petition, on the
12th December 1874.
I, DRUITT HALPIN, Engineer, Manager, Victoria Graving Dock,
London, do hereby declare the nature of the said Invention for "Iм-
PROVEMENTS IN FLOATING DOCKS," to be as follows:-
In order to carry out my Invention I provide a dock made watertight
and consisting of one or more parts or compartments. This dock is first
submerged so that a vessel may be floated over it and then raised partly
by displacing water in its compartments by air, and partly by hydraulic
rams or other means, by which also the manner of its lifting may be
assisted and controlled.

page_text: pursuance of the cottons of the Letters ratent,
filed by the said Druitt Halpin in the Great Seal Patent Office on
the 11th June 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DRUIT
HALPIN, Engineer, Manager, Victoria Graving Dock, London, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of December, in the
year of our Lord One thousand eight hundred and seventy-four, in the
thirty-eight year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Druit Halpin, Her special
licence, that I, the said Druitt Halpin, my executors, administrators,
and assigns, or such others as I, the said Druit Halpin, 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
FLOATING DOCKS," upon the condition (amongst others) that I, the said
Druit Halpin, 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 Druit Halpin, 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, reference being had to the Drawings
annexed, and to the letters and figures marked thereon, that is to
say:―
This Invention relates to various improvements in the construction
and use of floating docks or pontoons that have hitherto been raised by
hydraulic or other nowor

page_text: The ordinary system may be described as consisting of a number of
hydraulic rams, marked A, A, &c., in the Figures, and connected by
cross heads & slings with cross girders B, B, &c. Upon these girders
a pontoon C is submerged by being filled with water, which enters
through valves opened in the bottom when necessary.
The submerged pontoon is shewn in Figures 1 and 4, Sheet I. The
hydraulic girders being used to control the descent of the pontoon. A
ship S is floated over the pontoon, and pumps are employed to force
water into the hydraulic presses under the rams, and so raise the cross-
girders B, B, &c., the pontoon C, and the ship S clear of the water level.
Valves are then shut in the pontoon bottom, the rams with their girders
are lowered, and the pontoon with the vessel upon it is floated away.
This arrangement is known as Clark's Patent, and is fully described in
his Specification, No. 157, and dated 19th January 1857.
The first to be described of my improvements in pontoons or floating
docks consists of the following addition to these arrangements.
Figure I., Sheet I., is the side elevation of pontoon lowered, with a.
vessel properly blocked upon it, ready to be raised; and Figure 2 is a
plan omitting the vessel; Figure 3 represents the vessel floating upon
the pontoon with the hydraulic girders B, B, lowered; and Figure 4
gives a cross section of a pontoon resting upon girders B, B, and ready
for being raised up.
My improvements in the construction of this class of pontoon is
shewn in Figure 4, and it consists in the addition of air chambers D, D,
of sufficient capacity to float the pontoon alone, when the other com-
partments are full of water, or at least materially to reduce its weight
when sunk. These air chambers may be conveniently made to form
part of the pontoon itself or they may be separato constructions.
When the pontoon is constructed that the air chambers shall be of
sufficient capacity to float it, the girders B, B, may be attached thereto
in order to sink it, and this relieves the hydraulic rams of so much load
as is due to the buoyancy of the air chambers in excess of that necessary
to keep the pontoon itself afloat.
A further improvement in the use of these pontoons consists in the
application of centrifugal or other pumps to pump the water out when
the edge of the pontoon is raised just above the level of the water,

page_text: instead of as heretofore raising the ship and pontoon clear of the water.
Of course with the adoption of this plan the outlet valve at the bottom
of the pontoon must be closed before pumping begins.
Another of my improvements is shewn by Figures 5, 6, 7, 8, and 9,
Sheet II. Here the hydraulic rams A, A, and lifting girders B, B, are
similar to the usual construction, or made as most convenient. This
improved pontoon is really a species of floating dock provided with gates
at the ends, or a gate at one end only, and the sides form strong longi-
tudinal girders which may or may not be used for purposes of floatation.
In the latter case suitable air chambers may be added elsewhere, and it
is preferred to make this pontoon so as to float itself nearly or
altogether, or else to have sufficient buoyancy as to require the attach-
ment of hydraulic lifting girders B, B, &c., to sink it, or it may be sunk
by admitting water into its body or closed compartments.
When the floating dock is sunk in position a ship may be floated over
and blocked in the ordinary manner, and then the rams are set to work
to raise both dock and ship. When the upper edge of the dock has
arrived above the water level, and its gate been closed, further lifting
may be accomplished by pumping some or all of the water contained in
it overboard, and this lifting may be assisted and controlled by the
hydraulic rams when desired.
It is not necessary that the number of hydraulic rams B, B, should be
sufficient to reach the ends of the floating dock, as they may be usefully
applied, if so desired, at those portions only where the heaviest parts of
ships are generally situated. Figures 5 and 6 are side elevation and
plan of these arrangements; Figure 7 shews the dock sunk with a ship
in outline; Figure 8 is the dock raised; and Figure 9 shews the dock
with centrifugal pumps complete for pumping out water from the main
compartment of the dock or from the air chambers.
A modification of this arrangement is shewn in Figures 10, 11, 12,
and 13, Sheet III. This also represents a dock with sides and ends, one
end being preferred permanently closed, while the the other end can be
closed by a gate. Here floatation is obtained partly by hollow longi.
tudinal boxed girders and partly by camels underneath. These camels
in the Drawing are shewn placed between each pair of hydraulic lifting a
girders, and at the ends of dock, where same is clear of lifting girders;
but though this plan possesses advantages, it is not an essential feature

page_text: of my Invention. This dock, like the one last described, may be pro-
vided with sufficient permanent buoyancy to float by itself and require
the attachment of hydraulic girders to sink it, or it may be sunk by
admitting water into the girders or camels; but the plan I prefer to
adopt is to give it an excess of buoyancy from the longitudinal girders,
and to sink it by attaching the hydraulic girders, then to float a ship
over, close the gate, and raise by hydraulic rams, as above described, or
by supplementary pumping from camels. At this period furthur lifting
may be accomplished by pumping out all or part of the water from the
body of the dock or some of its compartments. When a suitable
elevation is obtained any water remaining in the body of the dock may
be allowed to run into the empty camels underneath or pumped over-
board.
Where it is desired only to relieve the rams of superfluous weight the
hydraulic girders may be constructed to some extent hollow, and thus
possess any desired amount of buoyancy or floatation, or camels may be
permanently attached to them.
In witness whereof, I, the said Druit Halpin, have hereunto set
my hand and seal, this Tenth day of June, in the year of our
Lord One thousand eight hundred and seventy-five.
DRUITT HALPIN
(T.α)