GB2092103A

GB2092103A - Launching life-boats

Info

Publication number: GB2092103A
Application number: GB8202897A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-02-02
Filing date: 1982-02-02
Publication date: 1982-08-11
Also published as: GB2092103B

Abstract

A structure 1 such as an oil rig, has an extensible support arm 2 for a life-boat 3 or like equipment for providing safety and accommodation, the arm 2 being swung away from a stored position on the structure with a downward component of movement to carry the life-boat 3 clear of the structure. The arm 2 extends under gravity and a coupling 4 is released to drop the life-boat which may contain a seat which may swivel to protect an occupant of the seat from impact forces or be inflatable. The invention is not restricted to marine use. As shown the arm 2 is telescopic and may include inertia brake means employing one or more cables within the arm 2, which cable may be connected to the life-boat 3 by the coupling 4 and able to extend beyond the end of the arm 2 to reduce the drop into the sea or eliminate it completely. <IMAGE>

Description

SPECIFICATION Improvements in or relating to life-boats and like safety equipment This invention refers to life-boats and the like, that is to say, to life-boats and like safety equipment intended to provide shelter and accommodation in an emergency; for example, inflatable life-rafts.

As used herein, the term "life-boat" is intended to include such like equipment, and is not intended to be restricted to equipment for marine use.

A problem exists in the launching of life-boats from high structures such as off-shore oil rigs and the decks of super-tankers, particularly if the structure has tilted over. Whilst the problem is less acute on the side of the structure nearest to the horizontal, it is far more serious on the opposite side thereof.

According to the invention, a structure is provided with at least one life-boat support arm, of extensible form, one end of the arm adapted for connection to a life-boat and the other end thereof being mounted on the structure, so that the arm can be swung away from the structure with a downward component of movement, such that, in operation, a life-boat connected to said one end is caused to clear the structure and to fall away therefrom as the arm extends under the effect of gravitational forces. The arm is preferably of telescopic form.

Means may be provided whereby falling movement of the life-boat may be retarded. For example, inertia brake means.

The life-boat may be provided with means to reduce the effect of impact forces as it comes to rest after falling.

The life-boat is preferably provided with at least one seat operable so as to automatically assume a position intended to protect its occupant against impact forces.

The invention also comprises the combination of the life-boat support arm and a life-boat connected thereto.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, wherein:- Figure 1 is a plan view of part of an off-shore oil rig provided with a life-boat and a life-boat support arm, with the arm in a non-operative position, Figure 2 is a side view of the life-boat and the life-boat support arm, with the arm in an operative position, Figure 3 is a side view of a seat with which the life-boat may be provided, Figure 4 is a side view of a further life-boat and life-boat support arm, with the arm in an operative position, and Figure 5 shows an arrangement with stackable life-boats.

With reference to Figures 1 and 2, a structure comprising an off-shore oil rig 1 is provided with a life-boat support arm 2 of extensible form. One end (2a) of the arm provides support for a selfrighting life-boat 3 releasably connected thereto by a coupling 4. The other end (2b) of the arm 2 is pivotably mounted on the structure by a support 5, so that the arm can be swung away from the oil rig 1 through substantially 900 (to assume the position shown in chain-dotted lines in Figure 1), with a simultaneous downward component of movement (dropping substantially 600). The coupling 4 may be releasable by a manually operable pull-cord or may automatically release in response to a predetermined extension of the arm.

Support 5 comprises an angled base plate and a tube with a spiral (helical) slot in its wall. The slot locates and guides a pin connected to the arm 2. When a locking pin is removed, gravitation moves the arm downwards and outwards from the horizontal parked or stowed position and a downwardly and outwardly inclined operative position.

In operation, the life-boat3 may be caused to clear the oil rig 1 (see the chain-dotted lines in Figure 1), and to fall away therefrom as the arm 2 (see Figure 2), extends under the effect of gravitational forces.

The coupling 4 is then operated (perhaps automatically), so as to allow the life-boat 3 to fall into the water 6. The coupling 4 is formed so that it can be connected to the life-boat3 in a pivotable manner (see Figure 2), so that the lifeboat is horizontal when parked on the rig.

The arm 2 is of telescopic form, comprising interfitting tubular elements. More than one arm 2 may be provided if deemed desirable. For example, they may operate together, each being connected to the same life-boat 3 by a coupling 4.

Alternatively, each may operate in an independent manner.

Means are preferably provided whereby falling movement of the life-boat 3 may be retarded as the arm extends. For example, by inertia brake means employing one or more cables disposed within the tubular elements forming the arm 2.

Undesirable "G" forces may alternatively or additionally be reduced by the provision of springs in the tubular elements.

The life-boat3 may be of standard manufacture but preferably is constructed whereby the effect of impact forces applied to the life-boat as it comes to rest after falling into the sea 6 may be reduced.

With reference to Figure 3, the life-boat 3 is preferably provided with one or more seats 10.

Seat 10 is pivotably mounted by a swivel support 11 so that it automatically assumes a position intended to protect its occupant against impact forces. Accordingly, as the life-boat 3 falls towards the sea 6, the seat occupant's back will be turned to face the direction in which the life-boat is moving.

With reference to Figure 2, distances "X" and "Y" are variabie in accordance with requirements.

The life-boat .3 is preferably provided with an auxiliary motor propulsion unit and/or a saiiing mast, which may be telescopic. The mast may penetrate the canopy of the life-boat 3 in such a manner that it (the mast) is supported by the canopy.

With further reference to Figure 2, it will be noted that, before falling into the sea 6, the lifeboat 3 assumes an angle whereby resistance to entry of the boat into the water is reduced because the life-boat 3 is at an angle to the horizontal.

The seat 10 (Figure 3), is preferably provided with body restraint means such as a seat belt.

Figure 4 shows a preferred arrangement in which dimension C may be 30.5 m, dimension A may be 13.5 m, angle 0 may be 450, angle 0 may be 250, and dimension B is the North Sea 100 year maximum wave height of 16.5 m.

In this arrangement the inner end 2a of the arm 2 is connected to a pillar 20. Connection between arm 2 and pillar 20 is the same as that between arm 2 and support 5. Movement of the arm 2 sideways may be by suitable power means such as an electric motor. An inertia or gravity brake is incorporated in the telescopic arm 2 and includes cable 21 connected to the life-boat3 by releasable coupling 4. In this case the cable 21 can extend beyond the end 2b of arm 2, for example, by 60 to 90 metres, to reduce the height from which the boat 3 is dropped.Alternatively, the cable 21 could be long enough to drop the lifeboat 3 completely into the sea 22 before disconnection of coupling 4 which is at the top of the boat 3 and can be released or disconnected either from on-board the boat 3,so that an occupant can release the coupling 4 when the boat is at a desired or selected height above the sea, or automatically or manually after the boat has hit the water and the weight has been taken off the coupling or fitting 4.

In any of the above arrangements, the arm 2 instead of being packed or stowed horizontally on top of the rig 1, could be stowed in the inoperative positive vertically at the side of the rig 1, and the arm 2 would stow vertically on top of the pillar 20 which is at the side of the rig.

The seat 10 could be inflatable and nonrotatable and have one or more lap and seat belts which should reduce the chance of injuries experienced by an occupant of the seat during the drop of the boat 3, the inflatable seat acting as a cushion. The seat is inflated by gases stored in bottles under pressure and releasable either manually or automatically, for example on release of coupling 4. The seat could approximate to a tube.

The life-boat 3 could be fully inflatable, or inflatable with a rigid bottom (a rigid hull inflatable life-raft), or a totally enclosed glass reinforced plastics boat. Figure 5 shows a stacking arrangement for life-boats with a rigid bottom 23 and inflatable cover 24. The top boat in the stack is already inflated; in the lower ones, which are not yet inflated, the cover 24 is located in the respective bottom 23.

The arm 2 can be recovered or retracted for example, by electric or hydraulic means, and in one arrangement may comprise a hydraulic accumulator in which pressure is built up in response to extension of the arm 2, which pressure is used to assist retraction of the arm. For example, as the cable 21 extends, it rotates a drum which drives a compressor to supply the accumulator which can be used to drive a motor to retract the arm. Alternatively, a hydraulic or electrical windlass could be used.

Claims

1. A structure provided with a life-boat support arm of extensible form, one end of the arm being adapted for connection to a life-boat and the other end thereof being mounted on the structure so that the arm can be swung away from the structure with a downward component of movement, such that, in operation, a life-boat connected to said one end is caused to clear the structure and fall away therefrom as the arm extends under the effect of gravitational forces.

2. A structure as claimed in Claim 1, in which the arm is of telescopic form.

3. A structure as claimed in Claim 1 or Claim 2, in which means are provided for retarding falling movement of the life-boat.

4. A structure as claimed in Claim 3, in which the retarding means comprise inertia brake means.

5. A structure as claimed in Claim 4, in which the inertia brake means are in the arm.

6. A structure as claimed in any preceding claim, including a cable arranged for connection to the life-boat.

7. A structure as claimed in any preceding claim, including means for retracting the arm after use.

8. A structure as claimed in Claim 7, in which the retraction means comprise a hydraulic accumulator arranged to be pressurised in response to extension of the arm.

9. A structure as claimed in Claim 1 and substantially as hereinbefore described with reference to and as shown in Figures 1 and 2, or Figure 4, of the accompanying drawings.

10. In combination, a structure as claimed in any preceding claim and a life-boat connected to said one end of said arm.

1 A combination as claimed in Claim 10, in which said connection comprises a releasable coupling.

12. A combination as claimed in Claim 11, in which the connection comprises a cable which remains connected to the life-boat on release of said releasable coupling.

13. A combination as claimed in any of Claims 10 to 12, in which the life-boat is provided with means to reduce the effect of impact forces as the boat comes to rest after falling.

14. A combination as claimed in Claim 13, in which the life-boat is provided with a seat operable to assume a position for protecting an occupant of the seat against impact forces.

1 5. A combination as claimed in Claim 13, in which the life-boat is provided with an inflatable seat for acting as a cushion against impact forces.

1 6. A life-boat as hereinbefore defined including a seat mounted such as to provide protection to an occupant of the seat when the life-boat is dropped.

1 7. A life-boat as claimed in Claim 16, in which the seat is pivotably mounted so that the back of the occupant is turned to face a direction in which the life-boat is moving.