Improved Method of Raising Sunken Vessels and other Bodies, and Apparatus therefor.
Year: 1899

page_text: Date of Application, 20th Jan:, 1899-Accepted, 4th Mar., 1899
COMPLETE SPECIFICATION.
Improved Method of Raising Sunken Vessels and other Bodies,
and Apparatus therefor.
1, AUGUST EDVARD NILSSON, Mechanical Engineer, of Tjärhofsgatan 5, Stock-
holm, Sweden, 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:-
-
The method of raising sunken vessels and other bodies consists in using a
suction-pump, an air force-pump and pontoons simultaneously and combined in
the manner shown in the accompanying drawing.
Pontoons AA are connected with the vessel or body to be raised B by chains
or cables C. An air force-pump D and suction pump E, both mounted on a
lighter or the like communicate with the vessel by their respective hose-connec-
tions F and G, that leading from the suction-pump reaching down close to the
bottom of the vessel while the other one terminates just below the deck. The
raising of the vessel is effected after stopping the leaks hatchways etc. by exter-
nally-applied means by first forcing the pontoons down by means of jacks or by
filling them, and then emptying the pontoons so as to make them exercise a lift-
ing effort on the vessel equal to their total sustaining-power. Then the pumps
are set to work, air being forced into the ship by one of them while water is
drawn out by the other so as to lighten the ship and the pontoons a little, the
pumps subsequently being slowed down so as to draw no more water, than an
amount which corresponds to the leakage of the ship, the amount
of which can be readily judged from the depth to which the pontoons
are drawn down by the ship or vessel. When the vessel has been eased from the
bottom in this manner so as to remain suspended from the pontoons, the raising
operation is continued in the same manner, the pontoon chains being gradually
hauled in by means of the jacks until the vessel reaches the surface of the water.
The advantages of the method of raising described will be readily understood.
For the raising of the vessel there are used on the one hand the pontoons and on
the other hand the sustaining power of the vessel itself brought about by drawing
off water. By employing simultaneously suction- and air-forcing pumps the
pressure in the interior of the vessel can be controlled and by means of the pon-
toons, which act as floats, the movements of the vessel can be controlled. When
employing only the method of forcing in air, as usual heretofore, difficulty arose
in the first place in closing up all apertures so as to retain the air in the vessel,
and furthermore in freeing the vessel of water by forcing in air the total lifting
force was made to act on the upper deck which is rarely strong enough to resist
such a strain. Moreover, when in consequence of said water ejecting-operating
the vessel has acquired sufficient floating-power, it came suddenly to the surface
and in so doing it was liable to burst unless the air was quickly let out, while
on the way to the surface. The first mentioned difficulty, viz. the closing of
leaks, has been overcome according to the present method by using together with
the air-forcing pump a section-pump which creates a diminished pressure in the

page_text: vessel and admits of stopping the leaks externally by means of mats, boards,
oakum and sawdust in the usual manner, which materials are sucked fast against
the vessel and thus make the latter perfectly tight, so that the air is retained.
The danger of the bursting of the vessel is likewise removed, for, in place of an
internal excess of pressure being exerted on the walls of the vessel, as when air-
forcing alone is resorted to, which excess of pressure increases from the inner
water line up to the upper deck owing to the varying pressures on the outside, it
is here possible to so control this pressure by the aid of the pumps that, for
instance the difference of pressures at the upper deck will be equal to zero and
the strains due to the raising of the vessel consequently will act on the bottom
of the latter which has strength enough to resist them. The greatest danger of
bursting, with the air-forcing method, occurring when the vessel comes rapidly to
the surface, is entirely avoided according to the new method by the slow raising
of the vessel by means of the pontoons, thereby enabling the differences of pres-
sure between the inside and outside to be maintained unchanged. Pontoons
alone are well known to have been used in cases where it is possible to attach to
the vessel a sufficient number of them of sufficient sustaining-power, but in many
cases this is not possible.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is;-
:
1. A method for raising sunken vessels and other bodies, consisting in simul-
taneously drawing water from the vessel by means of a suction-pump, introducing
air by means of an air force-pump and raising, the vessel by means of pontoons,
while so limiting the internal raising-pressure in the vessel brought about by
drawing off the water or injecting air that a portion of the weight of the vessel
always rests on the pontoons, substantially as described.
2. Apparatus for raising vessels and other bodies in the manner described
characterised by the combination of a suction pump an air force-pump and pon-
toons the pumps communicating with the vessel by hose pipes and the pontoons
being connected to it in the usual manner by chains or cables substantially as
described.
Dated this 20th day of January 1899.