Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to an apparatus for launching
a rescue vessel from a ship or an offshore platform, wherein
the rescue vessel is suspended under a boom with one or more
hoist carrier wires.
For such an apparatus to function properly, it has
to fulfill various requirements. It should be possible to
launch the rescue vessel from a ship or platform in distress,
in which the power supply may be failing. It thus has to
function without external supply of power, i.e. by means of
the energy available in the apparatus itself.
Further it should be possible to launch the rescue
vessel from a heeling ship or platform. It should move the
rescue vessel as far away from the side of the ship or plat-
form as possible and preferably turn the rescue vessel with
the bow away from the ship or platform. The release should be
simple to enable the rescue vessel to be launched without
assistance from anyone other than the operator responsible for
the launching. The apparatus should not occupy unnecessary
valuable space, and should preferably be a unit which can be
mounted on existing platforms and ships.
According to the present invention there is provided
an apparatus for launching a rescue vessel from an offshore
platform or a supporting vessel, wherein the rescue vessel is
carried from a boom by one or more winch-born wires, said boom
being pivotable to move the rescue vessel from a storage posi
tion into a launch position, and said boom comprising an inner
boom pivotally mounted about a substantially horizontal or
horizontally adjustable axis, and an outer boom for carrying
the rescue vessel pivotally attached with its inner end to the
inner boom about an axis~which is generally perpendicular to
the inner boom and its axis of support to enable a substan-
tially vertical positioning of the pivoting axis between the
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inner boom and the outer boom independently of the heeling of
the platform or the supporting vessel.
With this apparatus, the rescue vessel will not only
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be launched to a relatively large distance from the platform
or ship, but will also have -the bow turned away from the hull.
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By adjustment of the -firE~ boom, the launching may be adapted
to various degrees of heeling, to have the rescue vessel always
launched from a horizontal boom.
The invention will now be described in more detail,
by way of example only, with reference to the accompanying
drawings, in which:-
Figs. 1 and 2 show a front view and end view respec-
tively of an apparatus for carrying a life-boat;
Figs. 3 and 4 show an upper plan view and an end view
respectively of the apparatus with the inner boom lowered;
Figs. 5 and 6 show an upper plan view and an end view
of the apparatus of Fig. 1, with both booms lowered respectively
turned in operative position for launching; and
Fig. 7 shows a hydraulic circuit suitable for con-
trolling and operating the apparatus.
The rescue apparatus comprises an inner boom 11 and
an outer boom 12. The booms 11 and 12 are pivotable and joined
as described further below.
The inner boom 11 is carried by a support structure
13, pivotable around a horizontal axis 14 or an axis which can
be placed in a horizontal position and which extends along the
hull of the carrying ship. The support structure 13 may be a
part of the ship or of an offshore platform.
The inner boom 11 is preferably bifurcated or provid-
ed with two legs 15, each pivotably linked to a lug 16 with a
bolt 17. The lugs 16 are a part of the support structure 13.
The inner boom 11 is further connected to the support
structure 13 by a hydraulic cylinder 18, linked to an attachment
19 at the free end of the inner boom 11 and an attachment 20 at
the mounting structure 13. The control of the cylinder 18 wlth
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its piston is described further below. On extension of the
cylinder, the inner boom 11 is pivoted from an upper position
close to the mounting structure to a lower, protruding position
as shown in Fig. 4.
The second boom 12 is linked to the inner boom 11 to
be pivotable around an axis 21 at the free end of the inner boom,
generally perpendicularly to the length axis of both booms 11
and 12, and the axis 21 is also situated in a plane perpendicu-
larly to the axis 14.
The outer boom 12 is pivotable between an inner posi-
tion (Figs. 1 and 3), wherein it has its length axis generally
perpendicularly to the inner boom 11, and an outer position
(Figs. 5 and 6) wherein the axis of the booms 11 and 12 extends
in the same direction. This pivoting movement is effected by
means of a power cylinder 22 which is linked between the booms
11 and 12 outside the pivoting axis 21. The control of the
power cylinder 22 will be further described below.
The inner boom 11 may suitably be constructed as a
box-beam to have space available for the control gear described
below, while the outer boom suitably is a truss beam or another
suitable kind of beam.
The outer boom 12 carries a rescue vessel 23 by means
of two wires 24 and 25. The wires 24 and 25 are attached to
the vessel. The wires run from the vessel over an inner lead
sheave 26 and an outer lead sheave 27 respectively, and from
these pass onto a double winch drum 28 arranged on the inner
boom 11, between the legs 15. The sheaves 26 and 27 are attach-
ed to the outer boom 12 to allow pivoting of the rescue vessel
23 from the position shown in Fig. 1, wherein the wires 24 and
25 are extending substantially parallel to the inner boom 11,
to another end position as shown in Fig. 6, situated substan-
tially 90 to the first. The importance of this will appear
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from the description below.
The wires 24 and 25 are carried by a double sheave 29
arranged adjacent to the axis 21 linking the booms 11 and 12.
In its inner position, the rescue vessel 24 has its
axis generally parallel to the side of the support structure 13
or part thereof to which the lugs 16 are attached.
The launching of the rescue vessel 23 is effected in
three phases. From the start position shown in Figs. 1 and 2,
the inner boom 11 is turned away from the support structure 13
and moves into the lower position shown in Figs. 3 and 4. In
this position, the inner boom 11 is generally horizontal, even
if the carrying vessel or platform is heeling. The attainment
of this end position is effected by means of the control gear
described below.
Subsequent to the pivoting down of the inner boom 11,
the pivoting of the outer boom 12 starts, the axis 21 being sub-
stantially vertical or inclined outwardly in the upper part.
At the end of the pivoting movement, the booms 11 and 12 extend
in the same direction. This is shown in Figs. 5 and 6.
As the third and final phase of the lowering, the
rescue vessel 23 is lowered by releasing the wires 24 and 25.
It is convenient to design the attachment for the wires 24 and
25 so that they are automatically released as the rescue vessel
hits the sea.
As will appear from the description of the control
system below, the lowering can be effected without external
power supply, and a high degree of self control is provided.
This means that lowering in an emergency can be effected quickly
and safely, without risk of failure due to human errors or in-
sufficiency, e.y. due to xeduced consciousness, lack of train-
ing etc.
In Fig. 7 an example of a control system for the
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launch apparatus above is shown. The main parts of this system,
in addition to a winch motor 30 connected to the drum 28, are
the cylinders 18 and 22.
The cylinder 18 through a release valve 31 is connect-
ed to a pressure accumulator 32 and an oil reservoir 33. The
connection between the release vaLve 31 and the accumulator 32
and the reservoir 33, is controlled by a three-way valve 34
actuated by a pendulum. The valve member 35 of the valve 34 is
biased toward an end position connecting the cylinder 18 to the
accumulator 32 and the oil reservoir 33. The connection to the
reservoir 33 is however controlled by a safety valve 36 opening
when the pressure of the accumulator 32 exceeds a predetermined
level.
The accumulator 32 is connected by the valve 34 oper-
ated by the pendulum to the cylinder 22 to effect outward move-
ment of the piston rod 37.
To brake the movement of the rod 38 of the cylinder
18, a choke valve 39 is arranged in the outlet to give a prede-
termined maximum lowering speed of the inner boom 11 for an ex-
pected weight of the rescue vessel 23.
A choke valve 41 is arranged in the outlet pipe 40 ofthe cylinder 22 to limit the speed of pivoting of the outer
boom 12.
To avoid return movement of the outer boom 12 when
the lowering has started, a one-way valve 43 is arranged in the
supply pipe 42 to the cylinder.
The valve 34 connects the accumulator 32 to the cylin-
der 22 when the valve member 35 is moved from the shown neutral
position into the second end position by a pendulum 44. The
pendulum 44 is journalled to effect switching of the valve 34,
i.e. closing of the connection between the cylinder 18 and the
accumulator 32 and opening of the connection between the accumu-
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lator 32 and the cylinder 22 when the inner boom has reached a
horizontal position, independent of a heeling of the carrying
structure 13.
The pressure side of the winch motor 33 on release of
the wires 24 and 25 is connected to the oil reservoir 33 through
valve 45 which is opened when the outer b~om 12 has reached its
outer position. This may be effected by an activator or a
release member 46, which in the embodiment shown is attached to
the piston rod 37 of the cylinder 22. To control the lowering
of the rescue vessel 23 a choke valve 48 is inserted in the
outlet pipe 47 o~ the winch motor 30. During lowering the winch
motor 30 acts as a pump, powered by the force acting on the
wires 24 and 25.
The lowering of the rescue vessel 23 is thus started
by opening the valve 31 by an operating handle 49. Then the
pivoting down of the inner boom 11, the pivoting out of the outer
boom 12 and the lowering of the rescue vessel 23 is effected as
described above.
Apart from the cylinders 18 and 22, the remaining
parts of the control system of Fig. 7 are arranged in the inner
boom 11, which is of the box-type. The operating handle 49 is
conveniently arranged to be operated from the rescue vessel 23
in its start position as shown in Figs. 1 and 2.
The main advantage of the launching arrangement is
firstly that it carries the rescue vessel 23 relatively far
away from the carrying structure 13, and secondly that it turns
the rescue vessel 23 so that it has its bow facing away from
the carrying structure 13, ready to move or be towed away from
the platform or the vessel. This is a particular advantage in
bad weather and unfavourable wind, when the rescue vessel is
liable to be thrown against the supporting structure or adjoin-
ing parts.
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The arrangement described above may be modified in
various ways. The most important relates to the design of the
inner boom. This may be shortened to reduce its contribution
to the outward movement of the rescue vessel 23. The basic
principle is that it can move the linkage of the outer boom 12
so that it has its pivotal axis 21 moved from a position in
which the outer boom 12 is locked up into a position close to
vertical. It is particularly advantageous to move the inner
boom 11 so that is has the axis 21 pointing outwardly in the
upper end, from the platform or vessel. Thus the outer boom
will be self pivoting toward the outer position. The accumula-
tor 32 and the cylinder 22 may then be delected when this is
allowed.
The winch arrangement may alternatively be positioned
on the outer boom 12. On launching a rescue raft the winch may
be of a modest size and only one wire may be sufficient.
The described launching apparatus assures a 90 turn-
ing of the rescue vessel, to make this ready for movement away
from the platform or support vessel. This turning also makes
the rescue vessel less inclined to be thrown against the sup-
port structure.
The apparatus also allows launching in a heelin~ situ-
ation and when the support structure is out of trim. To cope
with the last possibility the inner boom 11 may be linked so
that it is slightly pivotable around a central position and has
its axis 14 horizontal, when the carrying vessel or the plat-
form is out of trim in either direction.
The launching apparatus has a substantially larger
lateral extension than the prior art. This increases the safe-
ty of launching, particularly in bad weather and heeling condi-
tions. The safety is also increased due to the fact that
launching can take place without the need for an external ~ower supply.
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