IMPROVEMENTS IN APPARATUS FOR RAISING SUNKEN VESSELS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Ralph Hodgson at the Office of
the Commissioners of Patents on the 17th December 1881.
RALPH HODGSON, of 65 Grant Road, Clapham Junction London S.W.
"IMPROVEMENTS IN APPARATUS FOR RAISING SUNKEN VESSELS."
The first part of the Invention relates to the construction of the air chambers or
pontoons by which the raising of the sunken vessel is to be effected.
These air chambers or pontoons are constructed in the following manner.
Assuming the length of each to be 300 feet they are made of circular section at
both ends and about 50 feet in diameter. At the middle of the length they are
made about 70 feet deep but preserve the width of 50 feet throughout their length
so that they taper from an oval section in the middle of 70 feet by 50 feet to a
circular section of 50 feet diameter at both ends, the said ends being by preference
terminated by conical or pointed parts. These structures are composed of plate
iron work with angle iron ribs and are divided into any suitable number of
compartments by transverse partitions or bulkheads. A strong bar of iron runs
from end to end through the centre of the air chamber or pontoon and has a
strong ring fastened at each end to which may be fixed anchor, or towing chains or
ropes. This bar is secured to each of the transverse partitions by nuts, on each
side, or by other suitable means.
At certain distances apart are placed transversely round the chambers or
pontoons, a number of wrought iron or steel belts or straps, which are secured
below to beams or girders placed under the said chambers or pontoons, and above
they are secured to wrought iron or steel rims, which extend from end to end of
the chambers or pontoons. The aforesaid beams or girders extend under the
entire length of the chambers or pontoons, and are constructed of iron or steel in
any suitable way, being secured by the aforesaid belts and straps.
A steering rudder may be fixed at one end of the frame or girder and the
anchors may be carried at the other end whereby a balance of weight and equal
immersion are obtained. At the bottom of the chambers or pontoons are forined
holes through which the water is admitted or ejected to sink or float the same and
at the tops are formed openings fitted with valves to admit or release air as may

page_text: be required, the said air openings being placed in communication with air
compressing pumps by which air can be forced into the chambers or pontoons
when it is required to eject the water therefrom and to raise the same for the
purpose of lifting the sunken vessel. When raising a vessel two of the said
chambers or pontoons are employed one on each side, they are sunk by opening
the air valves which allow the air to escape from the upper part, and the water to
enter from the bottom. They are raised by pumping air into the upper part to a
pressure sufficient to eject the water through the bottom until floating power
enough is obtained to raise the chambers or pontoons with their load.
When the ship is brought to the surface by these means, but is not thereby
sufficiently out of water, beams or girders are placed across from one chamber or
pontoon to the other and the vessel is further raised by cables connected to the said
beams or girders and operated by any suitable motive power.
The second part of the Invention relates to means for removing the sand or other
ground in which the vessel to be raised may be embedded, or on which it may be
laying, for the purpose of passing lifting chains under the said vessel. For this
purpose a frame is employed, on which is a slide or slides which receive a number of
short semicircular tubes jointed together, so as to form a kind of sheath or sheathes,
sliding up or down in the aforesaid slides, and each long enough to extend from
the above mentioned frame to the ground under the vessel to be raised. In these
sheathes are arranged elevators or dredgers operated by suitable apparatus and
adapted to raise the sand or other ground from under the sunken vessel-at-such
points as it may be desired-to-pass-lifting-chains under it.
The semicircular sheathes are by preference made large enough for a diver to
pass down under the bottom of the vessel to guide a chain or cable into place
and they are placed on opposite sides of the vessel so as to meet in the centre
underneath the same.
When a small chain or cable has thus been passed under the vessel and
connected to another on the opposite side the aforesaid sheathes may be removed and
the larger lifting chain or cable drawn under the vessel by means of the smaller
one passed through the sheathes as above described.