WO1990010574A1

WO1990010574A1 - Improvements relating to the handling of a submersible from a mother ship

Info

Publication number: WO1990010574A1
Application number: PCT/GB1990/000387
Authority: WO
Inventors: Robert Mccallum
Original assignee: Anderson Group Plc
Priority date: 1989-03-16
Filing date: 1990-03-15
Publication date: 1990-09-20
Also published as: AU5270290A; GB8906076D0

Abstract

In order to facilitate the handling of a submersible from a mother ship and avoid manual operations in the water there is provided a lift hook assembly for a submersible, the assembly comprising a hook (1), a latch (2) for the hook (1), the latch (2) being in the form of a bell-crank pivotally mounted at (3) on the hook (1) for movement between a first position where one arm (4) of the bell-crank forms a cradle alongside the opening of the hook (1) and the other arm (7) blocks the hook (1), and a second position where the one arm (4) closes the hook (1), and the other arm (7) unblocks the hook (1). Means for actuating the latch (2) are provided in the form of an air cylinder (8), and a throat (10) is provided for guiding a soft eye of a lift line onto the cradle. An opening (13) through the one arm (4) is provided for the passage therethrough of a haul-down line (14), and a pulley (15) is provided for guiding the haul-down line (14) so that the soft eye can be pulled by the haul-down line (14) through the throat (10) and onto the cradle.

Description

Improvements relating to the handling

of a submersible from a mother ship.

DESCRIPTION

This invention relates to improvements relating to the handling of a submersible from a mother ship.

It is known to handle a submersible from a mother ship provided with a stern-mounted 'A' frame pivotally moveable between a first position where its transom lies inboard of the ship and a a second position where the transom lies outboard beyond the stern. In the launch mode it is the practice for a swimmer from an inflatable, to detach the lift line manually from the floating submersible in order that it may commence its mission. In the recovery mode it is again the practice for a swimmer manually to attach the lowered lift line to the submersible and to remain on the submersible while tension is taken-up on the lift line in order to prevent possible snagging.

The procedure is hazardous for the swimmer and particularly so in the recovery mode of the submersible.

An object of the invention is to obviate or mitigate the hazards.

According to one aspect of the invention there is provided a lift hook assembly for a submersible, the assembly comprising a hook, a latch for the hook, the latch being in the form of a bell-crank pivotally mounted on the hook for movement between a first position where one arm of the bell-crank forms a .cradle alongside the opening of the hook and the other arm blocks the hook, and a second position where the one arm closes the hook, and the other arm unblocks the. hook, means for actuating the latch, a throat for guiding a soft eye of a lift line onto the cradle, an opening through the one arm for the passage therethrough of a haul-down line, and a pulley for guiding the haul-down line so that the soft eye can be pulled by the haul-down line through the throat and onto the cradle.

According to another aspect of the invention there is provided a method of handling a submersible from a mother ship, the submersible being equipped with the above-mentioned lift hook assembly, wherein, after the submersible has been lowered from the mother ship into the water with the soft eye of a lift line engaged in the hook and the latch being in the second position, the actuating means are operated from within the submersible so as to move the latch into the first position and thereby cause the other arm of the bell-crank to eject the soft eye from the hook so that the soft eye can be raised out of the throat and clear of the submersible, and wherein, after the submersible has completed its mission, a tow line is shot from the surfaced submersible towards the mother ship, the tow line

removably carrying the two ends of a haul-down line which is threaded through the opening through the one arm of the bell-crank, the tow line is recovered by the mother ship and attached to a towing winch thereon which is then operated to tow the submersible to a lifting position relative to the mother ship, the end of the haul-down line extending from the opening through the one arm and out through the throat is attached to the soft eye of the lift line and the other end is attached to a tag winch alongside the lift line, the lift line is lowered as the tag winch is operated so as to pull the soft eye through the throat and onto the cradle formed by the one arm of the bell-crank in the first position, the actuating means are operated from within the submersible so as to move the latch into the second position and thereby move the soft eye into the hook and close the latter so that the submersible can be lifted.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Fig.1 is a side elevation of a lift hook assembly;

Fig.2 is a front elevation of part of the assembly in Fig.1;

Fig.3 illustrates a first phase in the recovery of a submersible by a mother ship;

Fig.4 illustrates a second phase in the recovery;

Fig.5 illustrates a third phase in the recovery; and

Fig.6 illustrates a fourth phase in the recovery.

In Figs. 1 and 2 a lift hook assembly comprises a hook 1 and a latch 2 for the hook. The latch is in the form of a bell-crank pivotally mounted at 3 on the hook 1 for movement between a first position shown in Fig.1 in full lines and a second position shown in Fig.1 in broken lines. The latch 2 has one arm 4 comprising a block 5 and parts of two spaced-apart crescentlike side plates 6. The other arm 7 simply comprises the remainder of the two side plates 6. In the first position the arm 4 forms a cradle alongside the opening of the hook 1 and the arm 7 blocks the hook. In the second position the arm 4 closes the hook 1 and the arm 7 unblocks the hook.

The latch 2 is moved by actuating means in the form of an air cylinder 8. The assembly also comprises two domed cowls 9 between which is formed a throat 10 for guiding a soft eye 11 of a lift line 12 onto the said cradle. An opening 13 is provided through the block 5 for the passage therethrough of a haul-down line 14. A pulley 15 is also provided for guiding the haul-down line 14 so that the soft eye 11 can be pulled by the haul-down line 14 through the throat 10 and onto the cradle.

In launching a submersible 16 from a mother ship 17, which submersible is equipped with the assembly shown in Figs.1 and 2, reference may be had to Figs. 3 to 6 although these figures show succeeding phases in the recovery of the submersible as will be later described. An A-frame 18 mounted at the stern of the ship 17 is in its inboard position (Figs. 3 and 4) and a suspended hydraulically-operated telescopic leg 19 is in its raised position. The submersible 16 is moved on a carriage from its hangar on the ship 17 to a- position where the hook assembly is under the leg 19. The lift line 12 is lowered and the soft eye 11 is attached to the hook 1 with the aid of an operative on the ship. A light auto-tension is applied and the lift winch 20 is operated to take up slack on the lift line. The leg 19 is lowered and latched to the submersible. A tow line is attached to the forward end of the submersible and a light auto-tension is applied at the towing winch 21. The submersible 16 is lifted from its carriage using the leg 19 and thereafter the lift winch is set to neutral with brakes on and full tension is engaged.

In this condition, the A-frame 18 is moved to its outbound position (Figs. 5 and 6). Then the leg 19 and the lift line 12 are lowered together to the full extent of the leg 19. Thereafter the lift winch 20 is operated to take the weight of the submersible. The leg 19 is unlatched from the submersible which is then lowered into the water by the lift line 12. Whereupon, the towing winch 21 is put into full tension and the lift winch is put into light auto-tension.

Thereafter, the lift winch 20 pays out so as to give a little slack to the lift line 12. The air cylinder 8 is operated from within the submersible to move the latch 2 into its first position so that the arm 7 ejects the soft eye 11 from the hook 1 ready to be raised through the throat 10 clear of the submersible 16. Finally, after paying out the tow line from the tow winch 21 so as to position the submersible well astern of the ship, the tow line is released from within the submersible.

In recovering the submersible 16 after surfacing again, a float 22 is shot from the submersible, towards the ship 17 and a light tow pilot line 23 extends therefrom to a tow line on the submersible (Fig. 3). The float 22 is recovered by the ship and the pilot line 23 is attached to the towing winch 21. The tow line 24 is then pulled by the winch 21 from the supply on the submersible 16 and then the submersible is towed to a position closely astern of the ship ready for lifting (Fig. 4). The two ends of the haul down line 14 are removably attached to the tow line 24. The haul down line is threaded through the opening 13 and under the pulley 15 and on the ship the end of the haul-down line 14 which extends from the opening 13 and out through the throat 10 is attached to the soft eye 11 of the lift line 12 while the other end is attached to a tag winch 25 alongside the leg 19.

The A-frame 18 is then moved to its outboard position (Fig. 5) and the lift line 12 is put in light tension mode while the tag winch 25 is operated to pull the haul down line 14 and then the soft eye through the throat 10 and onto the cradle formed by the arm 4 with the latch 2 in the first position. From within the submersible 16 the air cylinder 8 is operated to move the latch 2 into its second position so as to engage the soft eye with the hook 1 and close the hook 1.

The submersible 16 is then hoisted by the lift line 12 to the leg 19 and latched thereto (Fig. 6), whereupon the A-frame 18 is moved back to its inboard position carrying with it the submersible.

It will be noted that any manual operations are all carried on board the ship and not in the water.

Claims

1. A lift hook assembly for a submersible, the assembly comprising a hook, a latch for the hook, the latch being in the form of a bell-crank pivotally

mounted on the hook of movement between a first position where one arm of the bell-crank forms a cradle alongside the opening for the hook and the other arm blocks the hook, and a second position where the one arm closes the hook, and the other arm unblocks the hook, means for actuating the latch, a throat for guiding a soft eye of a lift line onto the cradle, an opening through the one arm for the passage therethrough of a haul-down line, and a pulley for guiding the haul-down line so that the soft eye can be pulled by the haul-down line through the throat and onto the cradle.

2. A lift hook assembly according to claim 1, wherein the one arm of the latch comprises a block and parts of two spaced-apart crescent-like side plates and the other arm comprises the remainder of the two side plates.

3. A lift hook assembly according to claim 1 or 2, wherein the actuating means is in the form of an air cylinder.

4. A lift hook assembly according to claim 1, 2 or 3, wherein the throat is formed between two domed cowls.

5. A method of handling a submersible from a mother ship, the submersible being equipped with a lift hook assembly according to any preceding claim, wherein, after the submersible has been lowered from the mother ship into the water with the soft eye of a lift line engaged in the hook and the latch being in the second position, the actuating means are operated from within the submersible so as to move the latch into the first position and thereby cause the other arm of the bell- crank to eject the soft eye from the hook so that the soft eye can be raised out of the throat and clear of the submersible, and wherein, after the submersible has completed its mission, a tow line is shot from the surfaced submersible towards the mother ship, the tow line removably carrying the two ends of a haul-down line which is threaded through the opening through the one arm of the bell-crank, the tow line is recovered by the mother ship and attached to a towing winch thereon which is then operated to tow the submersible to a lifting position relative to the mother ship, the end of the haul-down line extending from the opening through the one arm and out through the throat is attached to the soft eye of the lift line and the other end is attached to a tag winch alongside the lift line, the lift line is lowered as the tag winch is operated so as to pull the soft eye through the throat and onto the cradle formed by the one arm of the bell-crank in the first position, the actuating means are operated from within the

submersible so as to move the latch into the second position and thereby move the soft eye into the hook and close the latter so that the submersible can be lifted.