A Moveable Stern-dock for Screw Steamers.
Year: 1887

page_text: Date of Application, 1st June, 1887
Complete Left, 1st Mar., 1888
Complete Accepted, 6th Apr., 1888
A Moveable Stern-dock for Screw Steamers.
I, ALEXANDER CUNNINGHAM BOOTHBY of No. 2 Storey's Gate Westminster in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this invention
to be as follows:-
It is often necessary to get access to the propellers of screw steamers for repairs
and other purposes, but owing to their being submerged such access can only be got
by divers or by docking the whole vessel. My invention relates to the construction
and arrangement of a moveable dock of moderate size which can be applied to the stern
part of a steamer so as to give access to the propeller while the rest of the vessel
remains immersed as usual in the water.
I make this dock with a hollow watertight bottom and walls which in plan may be
three sides of a rectangle or may have the form of a horse shoe so as to leave the
front quite open. I divide the structure into compartments which can be more or
less charged with water so as to sink the dock more or less. At the front ends I
provide vertical hinges like those of dock gates each of these hinges carrying a gate
which is not in one piece, but consists of a number of horizontal bars or girders,
fitted to slide along each other and having at their ends packing material which is
preferably a bag or tube that can be inflated or distended by internal pressure. While
the dock is afloat with only its bottom submerged I slide the bars of the gates into
such relative positions that they present between their inner ends an opening having
a contour approximately that of the vertical section of the vessel at the part where
they are intended close upon it.
I then open the gates widely and by means of
water ballast sink the dock to such depth that its bottom can pass under the keel of
the vessel. I float it to the desired position at the stern of the vessel and then close
in the gates so that the bars of which it consists bear obliquely against the sides of
IDQ11

page_text: the vessel, in which position I make the dock fast to the vessel by suitable cables.
I then inflate or distend the packing bags or tubes by forcing air or water into them
and thus cause them to press against the vessel's sides making a joint watertight or
nearly so. The water can then be pumped from the interior of the dock so as to give
access to the stern part of the vessel enclosed by it. Although the chief purpose of
such a dock as I have described is to give access to the propeller at the stern of a
vessel, obviously it might be used to enclose part of the vessel at the bow should it
be necessary to get access thereto.
1002

page_text: A Moveable Stern-dock for Screw Steamers.
1, ALEXANDER CUNNINGHAM BOOTHBY of No. 2 Storey's Gate Westminster in the
County of Middlesex Civil Engineer do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :—
It is often necessary to get access to the propellers of screw steamers for repairs
and other purposes, but owing to their being submerged, such access can only be got
by divers or by docking the whole vessel. My invention relates to the construction
and arrangement of a moveable dock of moderate size which can be applied to the
stern part of a steamer so as to give access to the propeller, while the rest of the vessel
remains immersed as usual in the water I make this dock as shewn in the accompanying
drawings, Fig. 1 being a transverse section, Fig. 2 a plan and Fig. 3 a perspective
view. Its bottom B and walls A are hollow and watertight. It may be as shewn in
such form as to occupy three sides of a rectangle or it might have the form of a
horse shoe so as to leave the front quite open. I divide the structure into
compartments which can be more or less charged with water so to sink the dock
more or less. At the front ends I provide vertical hinges C like those of dock gates
each of these hinges carrying a gate which is not in one piece but consists of a
number of horizontal bars or girders D fitted with tongues and grooves to slide along
each other, as indicated in Fig. 3 which is a transverse section of one of them, and
having at their ends packing material E which is preferably a flexible tube that can
be inflated or distended by internal pressure.
While the dock is afloat, with only its bottom submerged, I slide the bars D of the
gates into such relative positions that they present between their inner ends an opening
having a contour approximately that of the vertical section of the vessel at the part where
they are intended to close upon it. In order to suit various forms of vessels I prefer
to make each of the sliding bars D with an exchangeable end piece D¹ fitted on to it,
as shewn in the side elevation and plan Figs. 4 and 6. Having fitted the sliding
bars D D and their packing E nearly to the contour of the vessel, I open the gates
widely and by means of water ballast I sink the dock to such depth that its bottom
can pass under the keel of the vessel. I float it to the desired position at the stern
of the vessel and then close in the gates so that the bars D bear obliquely against the
sides of the vessel, in which position I make the dock fast to the vessel by suitable
cables. I then push the bars D D¹ close up to the vessel and inflate or distend the
packings E by forcing air or water into them and thus I cause, them to press against
the vessels sides, making a joint watertight or nearly so.
The water can then be
pumped from the interior of the dock so as to give access to the stern part of the
vessel enclosed by it. Although the chief purpose of such a dock as I have described
is to give access to the propeller at the stern of a vessel, obviously it might be used
to enclose part of the vessel at the bow should it be necessary to get access thereto.
Also by making the dock with gates such as I have described at each end, it may be
used to enclose any part of the hull between the stem and stern.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what
I claim is
The construction and use of a floating dock for enclosing the stern or other part
of a vessel, the gates of the said dock consisting of horizontally sliding bars that are
shaped and advanced approximately to fit the section of the vossel and are faced with
packing, substantially as herein described and illustrated by the drawings.
Dated this 1st day of March 1888.
ABEL & IMRAY,
Agents for the Applicant.