CA1223485A - Arrangement for launching a rescue vessel - Google Patents

Arrangement for launching a rescue vessel

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Publication number
CA1223485A
CA1223485A CA000422587A CA422587A CA1223485A CA 1223485 A CA1223485 A CA 1223485A CA 000422587 A CA000422587 A CA 000422587A CA 422587 A CA422587 A CA 422587A CA 1223485 A CA1223485 A CA 1223485A
Authority
CA
Canada
Prior art keywords
boom
axis
vessel
inner boom
rescue vessel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000422587A
Other languages
French (fr)
Inventor
Ola K. Dalsbo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CA000422587A priority Critical patent/CA1223485A/en
Application granted granted Critical
Publication of CA1223485A publication Critical patent/CA1223485A/en
Expired legal-status Critical Current

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  • Emergency Lowering Means (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE
In an apparatus for launching a rescue vessel from an offshore platform or a vessel, it is desirable to launch the rescue vessel as far away as possible from the support structure and with the bow facing outwards. The apparatus has a first, inner boom pivotally mounted about an axis positioned substan-tially horizontally and perpendicularly to the length axis of the inner boom, and an outer boom pivotally carried by the inner boom, with a pivotal axis substantially perpendicular to the length axis of both booms. The carrying wires are suspended from the outer boom.

Description

~Z23~85 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 '. ',d ~1223485i 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 - la -~223~85 be launched to a relatively large distance from the platform or ship, but will also have -the bow turned away from the hull.
,~6l~
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 3~8~

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 3L2;~3~1S
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 ~2Z:~485 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-~3~85i 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.

~Z23~85 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.

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for launching a rescue vessel from an offshore platform or a vessel, comprising an inner boom pivo-table around a substantially horizontal axis of a support, and an outer boom linked to an outer end of the inner boom, the outer boom carrying the vessel by one or more winchborne wires, the outer boom being linked with its inner end to the inner boom, about an axis which is generally perpendicular to the inner boom and to its axis of support.
2. An apparatus according to claim 1, provided with a hydraulic cylinder, with a choking valve in its outlet, to lower the inner boom around its axis.
3. An apparatus according to claim 2, in which the hydraulic cylinder is connected to a pressure accumulator to store a part of the energy released on the lowering of the inner boom to provide energy to pivot the outer boom from an inturned to an outturned position.
4. An apparatus according to claim 3, in which the transfers of pressure fluid from the accumulator to the cylinder is governed by a pendulum operated valve opening for the opera-tion of the cylinder extending its piston rod only when the axis of linkage is in substantially upright position.
5. An apparatus according to claim 1, 2 or 3, provi-ded with means allowing pump operation of a winch motor when the outer boom is in its outer extended position.
6. An apparatus according to claim 1, 2 or 3, in which the inner boom is adapted to provide space for operating gear.
CA000422587A 1983-03-01 1983-03-01 Arrangement for launching a rescue vessel Expired CA1223485A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA000422587A CA1223485A (en) 1983-03-01 1983-03-01 Arrangement for launching a rescue vessel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA000422587A CA1223485A (en) 1983-03-01 1983-03-01 Arrangement for launching a rescue vessel

Publications (1)

Publication Number Publication Date
CA1223485A true CA1223485A (en) 1987-06-30

Family

ID=4124673

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000422587A Expired CA1223485A (en) 1983-03-01 1983-03-01 Arrangement for launching a rescue vessel

Country Status (1)

Country Link
CA (1) CA1223485A (en)

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