Note: Descriptions are shown in the official language in which they were submitted.
DESCRIPTION
Title of the invention: Towed underwater device and
system for handling the underwater device
[0001]The present invention relates to an underwater device intended to be
towed by
a surface ship and a handling system intended to be installed on the surface
ship and
used for storing and deploying the underwater device. The invention is of
particular
utility in the field of underwater devices of the active sonar type comprising
a cable
towing a towed body incorporating a transmission antenna known as a
transmission
array. The towed body is sometimes referred to as a "tow fish" on account of
its
shape. A linear reception antenna known as a reception array, forming a
flexible
elongate body, is towed behind the tow fish. The linear reception array is
sometimes
referred to as a "streamer", likewise on account of its shape. The towed body
may be
a body of volume suspended from the tow cable or else may be of elongate shape
along a longitudinal axis and incorporate a linear transmission array
comprising
transducers distributed along the longitudinal axis.
[0002]The handling of such underwater devices is tricky. More specifically,
outside of
periods of use, the underwater device is stored on a deck of the surface ship,
generally a stern deck. The launch and recovery of the underwater device
requires
operators to be present on the stern deck of the surface ship. The operators
have to
handle heavy loads, and this may be dangerous, particularly in a developed
sea.
[0003]The tow cable generally comprises a core formed of electrical and/or
optical
conductors for transmitting power and information between sonar equipment
situated
onboard the ship and the antennas of the array. The core of the cable (or
"core
cable") is generally covered with a strand of metal wires that give the cable
its
mechanical strength. The towed body is generally massive. It may be fitted
with
rudders to provide its hydrodynamic stability. The linear reception array may
extend
over a length of the order of around hundred meters in order to detect
soundwaves
travelling through the water at low frequency. These may be echoes of
soundwaves
emitted by the transmission array when the sonar is operating in active mode.
The
sonar may also operate in passive mode without the transmission of soundwaves.
[0004] In patent application WO 2018/065385 Al filed in the name of the
Applicant
Company, a single winch is used for handling the tow cable and the reception
array.
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The tow cable and the reception array are secured to one another. Upon launch,
the
towed body is attached and connected at the junction between the tow cable and
the
reception array. Such an arrangement of the tow cable and of the reception
array on
one and the same winch does present certain problems. In particular, the winch
needs to be suited to the greatest radius of curvature permitted by the tow
cable and
by the reception array. That may lead to the drum of the winch being
significantly
oversized. In addition, it may be beneficial to handle the tow cable and the
reception
array separately, something that a single winch is unable to permit.
[0005]The invention anticipates the use of two distinct winches, one for the
tow cable
and the other for the reception array. The objective of the invention is to
facilitate the
maneuvers of launching and recovering the various elements of the towed
underwater device.
[0006]To that end, the invention proposes an underwater device intended to be
towed by a surface ship and handling system intended to be installed on the
surface
ship and used for storing and deploying the underwater device, the underwater
device comprising a tow cable, a towed body and a flexible elongate body, the
towed
body being situated between the flexible elongate body and the tow cable
during use
of the underwater device, the handling system comprising two distinct winches,
the
first winch being used for storing and deploying the tow cable and the towed
body,
the second winch being used for storing and deploying the flexible elongate
body.
According to the invention, the underwater device comprises an attachment
mechanism for attaching the flexible elongate body to the second winch and an
arm
articulated at a first of its ends to the towed body and at a second of its
ends,
removably, to the flexible elongate body, in a deployed first position, the
arm being
aligned with the flexible elongate body allowing the first winch to tow the
entire
underwater device, in a second position, the arm being unaligned with respect
to the
flexible elongate body allowing the flexible elongate body to be aligned with
the
second winch.
[0007]Advantageously, the articulation of the arm to the flexible elongate
body is
disconnectable.
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[0008]The underwater device may comprise an electrical and/or optical
connection
between the towed body and the flexible elongate body. The electrical and/or
optical
connection is advantageously disconnectable.
[0009]Advantageously, the arm comprises, at its second end, a fairlead for
guiding
the flexible elongate body. The flexible elongate body then comprises a
stopper
configured to come into abutment against the fairlead, the stopper being
positioned
at one end of the flexible elongate body, the end articulated to the arm.
[0010]The handling system may comprise an actuator configured to cause the arm
to
switch between its two positions: the position aligned with the flexible
elongate body
and the position unaligned with respect to the flexible elongate body.
[0011]The actuator may be the second winch or distinct from the second winch.
[0012]The handling system may comprise two gates that can be maneuvered
separately from one another, a first of the two gates being positioned between
the
first winch and the sea, a second of the two gates being positioned between
the
second winch and the sea. When the arm is in the second position, the handling
system is configured so that the first of the two gates can remain closed.
[0013]Another subject of the invention is a method for implementing the
underwater
device and the handling system allowing the launching of the device; in order
to
launch the underwater device, the method consists in performing the following
sequence of operations:
a. paying out from the second winch in order to launch the flexible elongate
body,
b. connecting the flexible elongate body to the second end of the arm in the
unaligned position,
c. bringing the arm into the aligned position,
d. paying out from the first winch.
[0014] In a first variant, the method consists, between operations c and d,
in:
e. detaching the flexible elongate body from the second winch by maneuvering
the
attachment mechanism.
[0015] In a second variant, the method consists, between operations band c,
in:
f. operating the actuator to take up the load of the flexible elongate body on
the arm,
g. detaching the flexible elongate body from the second winch by maneuvering
the
attachment mechanism,
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operation c being performed by maneuvering the actuator.
[0016]The invention will be better understood and further advantages will
become
apparent from reading the detailed description of an embodiment given by way
of
example, the description being illustrated by the attached drawing in which:
[0017]figure 1 schematically depicts a ship towing an active sonar;
[0018]figure 2 depicts the ship of figure 1 the sonar of which is in the
process of
being launched or brought back up;
[0019]figures 3, 4, 5, 6, 7 and 8 illustrate the launching and the bringing
back up of a
reception array of the sonar depicted in figures 1 and 2;
[0020]figures 9, 10 and 11 illustrate a first variant of a system for handing
the sonar
depicted in figures 1 and 2;
[0021]figures 12, 13, 14, 15, 16 and 17 illustrate a second variant of a
system for
handling the sonar depicted in figures 1 and 2.
[0022] For the sake of clarity, throughout the various figures, the same
elements will
bear the same references.
[0023]The invention is described in connection with the towing of an active
sonar by
a surface ship. Of course the invention may be implemented for any type of
towed
underwater device.
[0024] Figure 1 depicts a ship 10 towing an active sonar 12 comprising a towed
body
14 incorporating an acoustic transmission array and a flexible elongate body
16
forming an acoustic reception array. Hereinafter, the towed body will be
referred to as
a tow fish 14 and the flexible elongate body will be referred to as a streamer
16. The
sonar 12 also comprises a cable 18 for towing the tow fish 14 and the streamer
16.
The cable 18 also carries signals and power between the ship 10, the tow fish
14 and
the streamer 16.
[0025]The tow fish 14 and the streamer 16 are mechanically anchored and
electrically and/or optically connected to the cable 18 in an appropriate way.
Conventionally, the streamer 16 is formed of a linear array of tubular shape
identical
to those found in passive sonars, hence its name streamer, while the
transmission
array is incorporated into a structure of volume forming the towed body 14 and
having a shape like that of a fish. The streamer 16 is anchored to the tow
fish 14
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which is itself anchored to the end of the cable 18. During an underwater
acoustic
mission in active mode, the array of the tow fish 14 transmits soundwaves into
the
water and the reception array of the streamer 16 picks up any echoes bouncing
off
targets on which the soundwaves originating from the transmission array are
reflected.
[0026]A handling device 20 is placed on a stern deck 22 of the ship 10. The
handling
device 20 comprises two winches 24 and 26. The winch 24 is used for storing
and
paying out the tow cable 18 and the tow fish 14. The winch 26 is used for
storing and
paying out the streamer 16. When the active sonar 12 is in the deployed
position as
depicted in figure 1, only the winch 24 is in operation. The winch 24 tows the
entire
sonar 12. More specifically, the cable 18 tows the tow fish 14 and the
streamer 16 is
attached behind the tow fish 14.
[0027] In figure 1, the winch 24 is situated on the portside of the ship 10
and the
winch 26 on the starboard side. Other configurations are also possible, with
the
winch 24 on the starboard side and the winch 26 on the portside, winch 24
above or
below the winch 26. More generally, the two winches 24 and 26 are offset
relative to
one other.
[0028]The sonar 12 comprises an arm 30 articulated at one of its ends 32 to
the tow
fish 14 and at its second end 34 to the streamer 16. In figure 1, when the
active
sonar 12 is in the deployed position, the arm 30 is aligned with the streamer
16. More
specifically, the arm 30 and the streamer 16 both extend substantially along
the
same axis 36. When the ship 10 is sailing in a straight line, the axis 36 is
substantially parallel to the line of travel of the ship. In practice, the
forces of drag
experienced by the streamer 16 orient the arm 30 and the streamer 16 naturally
in
the water along the axis 36 which may fluctuate notably according to
variations in the
heading followed by the ship 10 and according to the weather conditions.
[0029] Figure 2 depicts the ship of figure 1 the sonar 12 of which is in the
process of
being launched or brought back up. More specifically, the tow fish 14 is
placed on the
deck 22, possibly in a cradle designed to hold it. The winch 24 is stationary.
The
cable 18 is almost completely wound on the winch 24. The arm 30 is unaligned
with
respect to the streamer 16 allowing the streamer 16 to be aligned with the
winch 26.
This unaligned position of the arm 30 is dependent on various dimensional
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parameters of the handling device 20, notably the length of the arm 30, the
relative
position of the tow fish 14 and of the winch 24, the distance separating the
two
winches 24 and 26 and the relative position thereof.
[0030]To ensure good alignment between the arm 30 and the streamer 16, at the
end 32, the articulation between the tow fish 14 and the arm 30 is
advantageously of
the pinned ball joint, or ball joint type, which is to say having at least two
degrees of
freedom in rotation about axes perpendicular to the axis 36. Likewise, at the
end 34,
the articulation between the arm 30 and the streamer 16 advantageously has at
least
one degree of freedom to rotate about an axis that allows the streamer 16 to
be
aligned with the winch 26. The streamer 16 advantageously maintains a degree
of
freedom to rotate about the axis 36. This degree of freedom may be provided
either
at the end 32 by means of a ball joint connection or at the end 34 by means of
a
pinned ball joint connection. It is also possible for this degree of freedom
to be
situated both at the end 32 and at the end 34, thereby making it easier to
align the
streamer 16 with the winch 26.
[0031] In the absence of an arm 30, the operator tasked with handling the
sonar 12 in
order to launch it and bring it back onboard the ship 10 has to operate behind
the tow
fish 14 to attach the streamer 16 when launching and to detach it when
bringing the
sonar 12 back up. This maneuver on the part of the operator is performed in a
position that is uncomfortable because the operator is impeded by the shape of
the
tow fish 14. In addition, this maneuver is performed very close to the water
and may
be dangerous, particularly in a developed sea. The presence of the arm 30
allows the
operator tasked with coupling the streamer 16 to the tow fish 14 not to have
to take
up a position behind the tow fish 14 in order to perform the coupling.
[0032] It is possible to improve operator safety still further by means of a
system of
gates isolating the deck 22 from the sea.
[0033] Figure 3 depicts the stern of the ship 10 during the launching of the
streamer
16. The handling system may comprise two gates 38 and 40 isolating the winches
24
and 26 and the tow fish 14 from the sea when the gates are closed. More
specifically,
the gate 38 is positioned between the winch 26 and the sea. The gate 40 is
positioned between the winch 24 and the sea. The two gates 38 and 40 can be
maneuvered independently of one another. In the variant depicted, the gate 40
has a
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larger surface area than the gate 38. Specifically, when the gate 40 is open
it needs
to allow the tow fish 14 through whereas the gate 38 has to allow the streamer
16
through, which has a cross section far smaller than that of the tow fish 14,
the cross
sections being defined perpendicular to the axis 36. Alternatively, the two
gates 38
and 40 may have equal surface areas. The gate 40 could even have a smaller
surface area than the gate 38.
[0034] In figure 3, the gate 40 is closed. The tow fish 14 is positioned on
the deck 22.
The tow fish 14 is protected from the sea. The gate 38 is open and the
streamer 16 is
partially in the water. The streamer 16 is partially wound onto the winch 26
and
partially in the water astern of the ship 10. The gates 38 and 40 may be
pivoting
gates as depicted in figure 3. So long as the arm 30 is in the unaligned
position, the
gate 40 may remain closed. Any type of gate opening may be implemented in the
context of the invention: the gates may for example be sliding gates, folding
gates or
rollup gates. It is advantageous to provide two distinct gates 38 and 40
allowing
either the one or the other to be opened. More specifically, in the
configuration of
figure 3, only the gate 38 is open. In the configuration of figure 1 in which
the arm 30
and the streamer 16 are aligned, the gate 40 needs to remain open and it is
possible
to reclose the gate 38. Alternatively, to simplify the handling system, it is
possible to
provide just one gate, for example a sliding gate, that is opened partially in
the
configuration of figure 3 and that is opened fully in the configuration of
figure 1.
[0035]The handling system may comprise a tongue 42 on which the streamer 16
rests when the gate 38 is open. More specifically, the tongue 42 is capable of
translational movement with respect to the deck 22 along an axis of an
orientation
similar to the direction adopted by the streamer 16 as it exits the ship 10
before
trailing in the water. The tongue 42 is able to support the streamer 16 before
it
reaches the water so that it does not enter the water at too steep an angle
when
carried along by its self-weight alone. Once the streamer 16 has reached the
water, a
drag force applied to the streamer 16 has a tendency to limit its inclination.
In the
retracted position, the tongue 42 may be hidden by the gate 38. In the
deployed
position, the tongue 42 may extend beyond the volume occupied by the gate 38
when the gate is closed. The tongue 42 is therefore deployed only when the
gate 38
is open.
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[0036]The handling system may comprise, at the end 34 of the arm 30, a
fairlead 44.
The fairlead 44 guides the streamer 16 when the winch 26 is maneuvering the
streamer 16 either in order to launch it or in order to bring it back up. The
fairlead 44
guides the streamer 16 along the axis 36. The dimensions of the cross section
of the
streamer 16 perpendicular to the axis 36 are smaller than the dimensions of
the
internal cross section of the fairlead 44. The fairlead 44 leaves the streamer
free to
rotate about the axis 36. A pivot connection is therefore sufficient to
connect the
fairlead 44 to the arm 30 at the end 34 thereof.
[0037] In the variant depicted, the fairlead 44 has a cross section that is
closed
around the streamer 16. Alternatively, the cross section of the fairlead 44
may be
open, so that the streamer 16 can be positioned in the fairlead 44 after the
streamer
16 has started to be launched. The fairlead 44 may have a mobile gate able to
close
its open section.
[0038]The mechanical connection of the streamer 16 to the arm 30 may be
performed by means of a stopper 46 secured to the streamer 16. The stopper 46
is
positioned at that end of the streamer 16 that is intended to be articulated
to the arm
30. During the launching of the sonar 12, the streamer 16 runs through the
fairlead
44. When almost all of the streamer 16 has passed through the fairlead 44, the
stopper 46 comes into abutment against the fairlead 44. Dimensions of the
cross
section of the stopper 46 perpendicular to the axis 36 are greater than
dimensions of
the internal cross section of the fairlead 44 so as to allow the stopper 46 to
come into
abutment against the fairlead 44. In figure 3, the streamer 16 is slipping
through the
fairlead 44. Figure 4 depicts the stopper 46 before it comes up against the
fairlead
44, and figure 5 depicts the stopper 46 in abutment against the fairlead 44.
Other
mutually complementing shapes of the stopper 46 and of the fairlead 44 able to
halt
the translational movement of the stopper 46 with respect to the fairlead 44
along the
axis 36 in the configuration of figure 1 are possible. For example, provision
may be
made for the stopper 46 to fit conically into the fairlead 44.
[0039]As an alternative to the fairlead 44, the articulation between the arm
30 and
the streamer 16 may simply be removable. The articulation formed here by a
connection having at least one degree of freedom to rotate, such as, for
example, a
pivot connection allowing the arm 30 to rotate with respect to the streamer 16
may be
disconnectable so as to allow the end of the streamer 16 to be freed from the
arm 30
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so that the streamer 16 can be wound onto the winch 26. In other words, when
the
end of the streamer 16 is articulated to the arm 30 at the end 34 thereof, the
articulation has one or more degrees of freedom to rotate so as to allow the
arm 30
to switch between its two positions: the so-called deployed first position in
which the
arm 30 is aligned with the streamer 16 and the second position in which the
arm 30 is
unaligned with respect to the streamer 16, the second position allowing the
streamer
16 to be aligned with the second winch 26. In order to allow the streamer 16
to be
wound onto the winch 26, this rotational connection is removable. The fairlead
44
makes it possible to maintain guidance of the streamer 16 with respect to the
end 34
of the arm 30. It is also possible to completely release the streamer 16 from
the end
34 of the arm 30.
[0040]The winch 26 is able to wind in and pay out the streamer 16. An
attachment
cable 52 is temporarily fixed between the winch 26 and the streamer 16. The
attachment cable 52 allows the streamer 16 to be paid out completely in order
to
bring one of its ends to the arm 30 to which it can be mechanically connected.
When
the sonar 12 is being brought back up, once the streamer 16 is aligned with
the
winch 26, the winding onto the winch 26 begins with the winding of the
attachment
cable 52 and then the winding of the streamer 16 onto the winch 26. The
stopper 46
forms an interface between the streamer 16 and the attachment cable 52. The
stopper 46 is also wound onto the winch 26.
[0041]As an alternative, it is possible to attach the streamer 16 directly to
the winch
26, for example using a shackle secured to the winch 26. In general, any
mechanism
can be used for attaching the streamer 16 to the winch 26. The attachment
mechanism can be maneuvered by the operator who can attach the streamer 16 to
the winch 26 when bringing the streamer back onboard the ship and who can
detach
the streamer 16 from the winch 26 during launch.
[0042] In service, when the sonar 12 is being towed, the streamer 16 is
subjected to
drag caused by the speed of the ship 10. The drag has a tendency to keep the
stopper 46 in abutment against the fairlead 44. Certain maneuvers of the ship
101
notably when it stops moving ahead or starts to move astern, may cancel the
drag
applied to the streamer 16. The sea state may also at least temporarily cancel
out the
drag applied to the streamer 16. In order to prevent the stopper 46 from
separating
from the fairlead 44, it is possible to provide two-way means of immobilizing
the
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streamer 16 with respect to the fairlead 44. These means may be achieved by
adherence, for example by means of a tight fit of part of the stopper 46
entering the
fairlead 44. Alternatively or to complement this, the two-way immobilization
means
may be achieved using an obstacle, for example by means of a latch 48 as
depicted
in figure 6. The latch 48 is articulated with respect to the fairlead 44 and
in the
locked position catches on a protruding part 50 of the stopper 46. In the
unlocked
position, the latch 48 releases the protruding part 50 thus allowing the
stopper 46 to
be removed from the fairlead 44.
[0043]To complement the mechanical connection between the streamer 16 and the
arm 30 at the end 34 thereof, the sonar 12 may have an electrical and/or
optical
connection between the tow fish 14 and the streamer 16. This connection is
then
disconnectable. More specifically, the streamer 16 may have a fixed connector
54,
for example secured to the stopper 46. A cable 56, electrically and/or
optically
connected to the tow fish 14, may pass inside the arm 30. One end of the cable
56 is
equipped with a plug 58 that an operator 60 couples to the fixed connector 54
when
the stopper 46 is in abutment against the fairlead 44 or, more generally, when
the
streamer 16 is mechanically connected to the arm 30. The electrical connection
between the streamer 16 and the arm 30 is visible in figures 7 and 8. More
generally,
any type of connection between the streamer 16 and the tow fish 14 may be
employed. The connection may be made without physical contact, for example
using
a radio frequency connection developed between two terminations situated close
to
one another, one being positioned in the arm 30 and the other positioned in
the
fairlead 44 or even in the stopper 46.
[0044] In a variant alternative to connection with physical contact, it is
possible to
avoid the manual operation of connecting the plug 58 to the fixed connector
54. To
do that, the connection points of the plug 58 are incorporated into the
fairlead 44. The
connection points of the fixed connector 54 remain incorporated into the
stopper 46.
Connection between the tow fish 14 and the streamer 16 is achieved by
inserting the
stopper 46 into the fairlead 44.
[0045] Figures 9, 10 and 11 illustrate a first variant of the handling system
20. In this
variant, the arm 30 switches from its position unaligned with respect to the
streamer
16, allowing the streamer 16 to be aligned with the winch 26, to its position
aligned
with the streamer 16, by means of the winch 26. During the switch between the
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unaligned position to the aligned position, the stopper 46 remains in abutment
against the fairlead 44. More generally, the streamer 16 is connected to the
arm 30.
Figures 10 and 11 depict the arm 30 in the position aligned with the streamer
16 and
figure 9 depicts an intermediate position of the arm 30 somewhere between its
unaligned position and its position aligned with the streamer 16. During the
switch
between its two positions, the arm 30 pivots about the articulation of its
first end 32
with respect to the tow fish 14. The streamer 16 is already in the water and
pulls on
the end 34 of the arm 30. The attachment cable 52 also applies load to the arm
30 at
its end 34. The attachment cable 52 holds the arm 30 in position by balancing
the
force exerted on the arm 30 by the streamer 16. The switching of the arm 30
between its two positions is accomplished by maneuvering the winch 26: by
paying
out the attachment cable 52 in order to reach the aligned position and by
winding in
the attachment cable 52 in order to reach the unaligned position of the arm
30.
[0046] During the launching of the sonar 12, in the first variant of the
handling system
20, it is necessary to release the arm 30 from the attachment cable 52. The
operator
60 performs this release as illustrated in figures 10 and 11. The attachment
cable 52
may be fixed removably to the stopper 46. The operator 60 then has to
intervene on
the end 34 of the arm 30, and this may present a danger. Alternatively, the
attachment cable 52 may be produced in two parts 52a and 52b, as can be seen
in
figures 10 and 11. The part 52a is secured to the arm 30 and is fixed to the
end 34
thereof. The part 52b is secured to the winch 26. The two parts 52a and 52b
are fixed
to one another removably, for example by means of a shackle. The attachment
cable
52 is released by detaching the parts 52a and 52b. The part 52a can then be
stored
along the arm 30. Thus, the operator 60 is no longer working at the end of the
arm 30
but only at the position of the removable fixing-together of the two parts 52a
and 52b.
As a further alternative, it is possible to provide an automatic device for
connecting
and disconnecting the attachment cable 52. Such a device may for example
comprise a shackle secured to the stopper 46 and which opens when the tension
in
the attachment cable 52 drops below a predefined threshold.
[0047] During launching of the sonar 12, after having detached the attachment
cable
52 from the arm 30, the winch 24 is maneuvered in order to launch the tow fish
and
pay out the tow cable 18 to the desired length.
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[0048]The sonar 12 is brought back up by reversing the order of the operations
described above, namely by: winding in the tow cable 18 by means of the winch
24 to
bring the tow fish 14 back up onto the deck 22, attaching the attachment cable
52 to
the stopper 46 or attaching the two parts 52a and 52b to one another,
operating the
winch 26 to bring the arm 30 from its position aligned with the streamer 16 to
its
unaligned position and to wind in the attachment cable 52 and the streamer 16.
[0049] Figures 12 to 17 illustrate a second variant of the handling system 20.
In this
variant, the arm 30 switches from its position unaligned with respect to the
streamer
16, allowing the streamer 16 to be aligned with the winch 26, to its position
aligned
with the streamer 16, by means of an actuator distinct from the winch 26. This
variant
allows the operator 60 to move even further back from the edge of the deck 22
than
this operator could in the first variant. In this second variant, there is
again the winch
26 and its attachment cable 52 able to restrain the streamer 16 during the
launching
of the sonar 12 prior to the operation of mechanically connecting the streamer
16 to
the arm 30 and more specifically before the stopper 46 comes into abutment
against
the fairlead 44. During the launching of the streamer 16 and the mechanical
connecting to the arm 30, only the gate 38 is open. The electrical connection
can
also be performed at the time of the mechanical connection. With the
connection or
connections made, it is then possible to open the gate 40. Figure 12 is a
perspective
depiction of the sonar 12 of which the streamer 16 has been launched. The tow
fish
14 is still on the deck 22. The two gates 38 and 40 are open. The handling
device 20
in this second variant comprises an actuator 62, in the inactive position in
figure 12.
The actuator 62 is for example formed of a cylinder actuator of which the rod
64 is
motorized in translational movement and in rotational movement with respect to
the
deck 22. In figure 13, the rod 64 is depicted in the active position, which is
to say
applying a force to the arm 30 in order to keep it in the unaligned position,
the
streamer 16 still being held by the winch 26 by means of the attachment cable
52.
With the rod 64 in this position, the winch 26 is maneuvered to release the
force
applied by the attachment cable 52. Once the attachment cable 52 is no longer
applying any force to the streamer 16, all of the force applied to the
streamer 16 is
taken up by the rod 64 via the arm 30 and the operator 60 can detach the
attachment
cable 52 from the stopper 46, as depicted in figure 14. In order to continue
with the
launching of the sonar 12, the rod 64 pivots to bring the arm 30 progressively
into its
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position of alignment with the streamer 16. Figure 15 depicts the arm 30 in an
intermediate position, and figure 16 depicts the arm 30 aligned with the
streamer 16,
the rod 64 having completely released its force on the arm 30 and no longer
being in
contact therewith. In figure 17, the actuator 62 has regained its inactive
position and
the winch 24 is ready to pay out the tow cable 18 in order to launch the tow
fish 14.
[0050]The sonar 12 is brought back up by reversing the order of the operations
described above, namely by: winding in the tow cable 18 by means of the winch
24 to
bring the tow fish 14 back up onto the deck 22, operating the actuator 62 to
bring the
arm 30 from its position aligned with the streamer 16 to its unaligned
position,
attaching the attachment cable 52 to the stopper 46, unlocking the stopper 46
from
the fairlead 44, operating the winch 26 to wind in the attachment cable 52 and
the
streamer 16. During the winding in of the attachment cable 52, it is possible
to stow
the actuator 62.
CA 03154206 2022-4-8
