Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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_ The present invention relates to a device applicable to a semi-
submersibie craft having a deck structure of several decks which
on top of a number of legs, at least one leg in each corner, rests
on two longitudinally extended pontoons, the craft being partic-
5uiarly designed for diving or rescue operations and having a
work shaft, which is designed for raising and lowering, by means
of cranes, equipment to be used in diving operations and which
runs verticaliy from the main deck down through the decks below,
and two diving shafts, which are designed for iaunching and taking
~board diving beils through the lower deck, at least one of which,
the primary shaft, continues down below the surface of the water,
preferably in the main below the infiuence of waves, pressure
chambers being devised on the lower deck in connection with the
two diving shafts.
Apart from the type of craft described above, ordinary vesseis
are also used, generally with a diving shaft or diving shafts
devised midships. This is an advantageous placement with regard
to the vertical movement of the diving beli in a seawav. However,
2~t is not so advantageous as regards the movement of the diving
beii on the horizontal plane, since the diving vessel must be
positioned with its bow against wind and sea and a movement on
the horizontai plane will then mainly occur as a pendulum movement
with the bow as its center. Large horizontai swings of the
2~iving shaft wiii thus occur. Another disadvantage concerning
such vessels is that they, because of their relatively small size
and displacement, will have a relatively strong movement in a
seaway. On the open sea there will therefore be long periods
where diving cannot be undertaken because of a heavy sea.
Diving crafts of the type mentioned by way of introduction have
the advantage that they, in a semi-submersibie work position,
that is, with the pontoons submerged in the main below the
infiuence of waves, show reiatively smali fluctuations in the
3~erticai direction because of the heaving of the sea.
Previous diving crafts of this type have had their diving
,
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- shaft or diving shafts devised on one side of the craft. The
reason for this is that one thus can place the diving craft
ciose to a structure, for example a fixed structure or a float-
ing rig. ~uch of the diving work takes place relatively close
to such structures. The disadvantage of this placement, however,
is that the movement of the diving shafts on the horizontal
plane will be relatively large. The reason for this is that
such crafts are usually positioned dynamically, that is, they
are kept against the weather by means of the propellers. It
10 will be too expensive and too time-consuming to anchor up such
platforms. This will then greatly restrict the time during
which diving can take place, since there for long periods of
time will be too much wind, sea or current for positioning the
craft in such a way that there will not be too large horizontal
15 movements of the diving shafts.
The purpose of the present invention is to give directions for
a device, applicable to a semi-submersible craft, by which
diving can be undertaken close to existing structures at the
20 same time as the diving can be undertaken for longer periods
than before, since the craft is less dependent upon wind and
weather.
This is achieved according to the invention by a device of the
25 type mentioned by way of introduction, which is characterized
in that the primary shaft is installed in one leg of the craft,
that the second diving shaft is installed in such proximity to
the primary shaft that the diving bells for the two shafts can
be coupled to the same pressure chamber unit, and that the
30 work shaft is placed so close to one diving shaft that the div-
ing beil from this shaft can be coupled directly to a welding
chamber or the like, lowered through the work shaft, for dry
transfer of divers.
35 When the primary shaft is installed in one leg of the craft, one
will position the craft with this leg, that is, one corner of the
craft, against wind and sea, and a possible pendulum movement
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- will occur with this leg or this corner as its center. One
thus achieves minimal horizontal movement. By the very fact
that the second diving shaft is installed so close to the first
one that they can be served by the same pressure chamber unit,
the horizontal movement of this diving shaft will also be
relatively small. Apart from this advantage and the one
mentioned above, viz. that the two diving shafts can be served
by the same pressure chamber unit, one also obtains the further
advantage that, when the bells from both shafts are used, the
crew can cooperate on a common task without having to move
particularly far on the horizontal plane.
The characteristic that the work shaft is installed so close to
one diving shaft means, as previously stated, that one can make
15 a so-called dry transfer of a crew from a diving bell to, for
example, a welding chamber. This offers the same advantage as
the one mentioned above, viz. it saves the divers from covering
the distance between the diving bell and the welding chamber.
Any movment is very exhausting for a diver, especially at a great
20 depth, and will reduce a work capacity which is small enough
from before. In addition to the movement between the diving
bell and the work chamber, it also saves the divers the opening
of doors in and out of sluices.
25 Another characteristic of the invention consists in installing,
in connection with the work shaft, a gantry crane or a traveling
crane on the main deck. By means of such a crane the equipment,
for example a welding chamber, can be moved far more accurately
and carefully than by the jib cranes normally used, which are
30 installed on the main deck and mainly used for handling of goods
to and from the craft.'
In addition to the gantry crane or traveling crane, one or more
jib cranes may be installed.
A further object of the invention is to give directions for a
device relating to a craft of the type mentioned by way of
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_ introduction, by means of which one in addition to the above
advantages achieves great speed and mobility with the craft in
its transport position.
Crafts of this type will often have long periods without assign-
ments. A demand for the assistance of such a craft can suddenly
arise, if-an accident or a mishap has occurred. The craft which
then can move fastest wiil obviously have a great advantage as
far as assignments are concerned. Crafts of the above type
can usually only move at a very low speed, for example 3-4 knots.
Situations will thus easily arise where current and wind in
fact move at a greater speed, so that one in reality will have
a negative velocity for the craft. Such crafts are therefore as
a rule dependent upon the assistance of tugboats, which is very
costly. This disadvantage iseliminated by means of a device
relating to a craft of the type mentioned by way of introduction,
which is characterized by a combination of features, viz. that
the primary shaft is installed in one leg of the craft, that
the other diving shaft is installed in such proximity to the
20 primary shaft that the diving bells for the two shafts can be
coupled to the same pressure chamber unit, that the work shaft
is installed so close to one diving shaft that the diving bell
from this shaft can be coupled directly to a welding chamber
or the like, lowered through the work shaft, for dry transfer of
25 divers, that a cross section of the legs has an elongated shape,
oval, streamlined or the like, pointed in a forward direction,
and that all bracing of the legs is provided above the warerline.
By means of such an embodiment, the craft wiil be capable of
30 relatively high speed, for example 10-12 knots by its own
motors, and this relat~ively high speed combined with the possi-
bility of longer diving periods than normal, makes the craft
more competitive and thereby more profitable.
35 In what follows, the invention shall be described more fully
with reference to the drawings, which show an embodiment of
the invention.
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-- FIG. 1 shows a craft according to the invention seen from astern,
FIG. 2 shows the craft seen from the starboard side,
FIG. 3 shows the main deck seen directly from above, and
FIG. 4 shows the lower deck seen from above.
The semi-submersible craft according to the invention consists
10 of, in the main, a deck section 1 which on four legs 2, one in
each corner, rests on two longitudinal pontoons 3,4. During
transport the craft is lowered down to the waterline 5 and
during work to the waterline 6. Each pontoon is equipped with
several propellers 7,8, for example of the type Thruster. In the
15 shown embodiment there are three decks in the deck section, a
main deck 9, an intermediate deck 10 and a lower deck 11.
On the main deck 9 there is installed a work shaft 12 which
runs vertically down through all three decks. In connection
20 with the work shaft there is installed a gantry crane or a
traveling crane 13, which can run on tracks 14 and which has a
crab, not shown, for crosswise movements on the crane. In
addition to the gantry crane 13 there are installed two jib
cranes 15,16 which also can service the work shaft. These
25 cranes can, for example, transfer equipment of different kinds,
to be used in connection with the work shaft, from a delivery
boat to the craft and vice versa.
On the lower deck, FIG. 4, thereis installed a diving shaft 17,
30 which runs down through one leg 2 to an area in the main below
the influence of waves. Through this shaft a diving bell 18
can be lowered by conventional hoisting equipment, not shown.
Approximately diagonally beyond the diving shaft 17 there is
installed a second diving shaft 19 with a separate diving bell
35 20. This shaft runs only through the deck section, and the
diving bell is moved in the open down from the deck section to
the surface of the sea 6. In connection with the two diving
--- shafts there is devised a pressure chamber unit 21, which
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is divided into three chambers 22, 23 and 24 with different
pressures. The chamber 22 is connected to a lifeboat with a
pressure chamber. This means that a crew staying in the
pressure chamber unit 21 during an accident when the craft
must be abandoned, can go aboard the lifeboat and be saved,
since they will be maintained at the same pressure in the life-
boat as in the pressure chamber unit. The pressure chamber
unit is devised in such a way that both shafts 17 and 19
with diving bells 18 and 20 can be serviced. In connection
10 with the peessure chamber 22 there is devised a rescue pressure
chamber 26, alternatively a lifeboat with a pressure chamber.
At the same time as the two diving shafts 17 and 19 are in
such proximity to each other that they can be serviced by the
same pressure chamber, they are also so close to each other
that divers from the diving bells 1~ and 20, at a certain depth,
will be so close to each other that the divers from the two
bells at any moment can work together without having to cover
any significant horizontal distance. The work shaft is so
20 close to the diving shaft 19 that the diving bell 20 can be
coupled to, for example, a welding chamber (habitat) which is
lowered through the work shaft.
As one will see from FIG. 4, the main diving shaft is placed in
25 one corner of the deck. The craft is positioned with this
corner against wind and weather so that the pendulum movement or
swaying which takes place will occur with this corner as its
center. The horizontalmovementof the diving shaft 17 will
thus be quite minimal. ~wing to the fact that the craft is
30 submerged with the pontoons in the main below the influence of
waves, the vertical movement will also be minimal. It will
thus be possible to work from the main diving shaft even in
a heavy sea. Owing to the fact that the diving shaft 19 and
the work shaft 12 are placed at a relatively short distance
35 from the main shaft, all shafts being placed in the same
quadrant of the craft, the pendulum movement for shafts 12
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and i9 will also be relatively small. All shafts. particularly
shaft 17 can be brought very close to a structure if the diving
work shall take place at this structure.
As is apparent from FIGS. 1 and 2, there is no bracing of the
legs below or close to the waterline. In the shown embodiment
the bracing is placed in the deck structure.
