A NEW OR IMPROVED METHOD AND APPARATUS FOR REPAIRING THE AFTER PART OF SCREW STEAMERS AND OTHER SHIPS WITHOUT THE USE OF DRY DOCKS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Henry Hornby at the Office of the
Commissioners of Patents on the 2nd July 1880.
HENRY HORNBY, of Hamburg, in the German Empire, temporarily at 67, Strand,
in the City of Westminster. "A NEW OR IMPROVED METHOD AND APPARATUS
FOR REPAIRING THE AFTER PART OF SCREW STEAMERS AND OTHER SHIPS
WITHOUT THE USE OF DRY DOCKS."
My Invention has for its object to provide a means of repairing or exchanging
screw propellers, propeller-shafts, and bearings without placing the whole ship in a
dry-dock and without interfering with the loading or unloading of the ship. For
this purpose I construct a chamber, which may be called a partial floating dock,
open at one end and wide enough to let the largest screw propeller pass, for which
it is intended, while the length is sufficient to reach with the open end some
distance beyond the screw propeller, and leave some working space behind the ship.
The walls are preferably of sheet metal, and are made hollow to contain water,
which can be pumped out at will in order to reduce the weight of the structure and
thereby adjust its depth in the water, this being effected either by a pump
carried by the partial floating dock or in any other suitable manner. The
bottom of the partial floating dock is provided with an adjustable saddle or
bed for the keel of the ship, and the latter may be fixed in position by means of
press blocks and set screws, which press upon the keel from the side and may be
moved from the top of the partial floating dock. An important feature of my
Invention is the manner of closing the open end of the partial floating dock when
applied to the ship, so as to prevent the further influx of water. This I effect by
means of an elastic band or lining, preferably of india rubber, attached to the open
end of the partial floating dock and projecting over the same so that it can be put
in close contact with the sides and bottom of the ship. To prevent the said band
or packing to be pressed inside by the water in the direction of the keel, while
yielding to the lateral pressure of the water outside, the band is stiffened by a
number of short lugs (of wood or other stiff material) arranged around the open
end of the partial floating dock, and placed in such a manner that they can swing
on their inner ends against or from-the sides and bottom of the ship, but not move
to any considerable extent in the direction of the keel. When the after part of the
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page_text: vessel is introduced into the partial floating dock, and the latter placed at the
proper height, the elastic band is drawn by ropes or chains so as to close on the
sides and bottom of the ship, and the water inside the floating dock is then pumped
out. The outside water pressure upon the elastic band serves to produce a tight
fit between the latter and the ship, making the ropes subsequently unnecessary.
When the water has been pumped out of the partial floating dock and thereby the
after part of the ship laid dry, the repairs can begin. For obtaining access to the
ship the partial floating dock is provided with inside or outside staircases, and
suitable pipe connections, openings, valves, and cocks are applied for letting the
pump act at will on the inner space of the partial floating dock or on the hollow
space contained between the inside and outside walls.