WO1990005107A1

WO1990005107A1 - Holding and storage device for rope

Info

Publication number: WO1990005107A1
Application number: PCT/NO1989/000117
Authority: WO
Inventors: Ivar Krogstad; Jon HØVIK
Original assignee: Pusnes A/S
Priority date: 1988-11-09
Filing date: 1989-11-09
Publication date: 1990-05-17
Also published as: NO165336B; JPH03505324A; ATE111053T1; NO165336C; NO884981D0; DE68918110D1; EP0442929B1; JPH0798636B2; NO884981L; EP0442929A1

Abstract

Holding and storage device for mooring rope (1) in which the rope end termination (2, 3, 4, 5) can align itself in the pulling direction radial from the drum barrel surface (9) when the rope (1) is used for mooring, and pivot within allowed angles in height and side direction without bending the rope. When the rope (1) shall be stored, the drum (9) is put in rotation and the end termination (2, 3, 4, 5) is first pivoting approximately 90 degrees against a recess (8) in the drum (9), and further spooling of rope (1) is done in the usual way. A strong bracket (6) which rotates around the drum axis and holds the end termination (2, 3, 4, 5), is a natural part of the holding device. The bracket (6) with bearing brackets (7, 7') and end termination (2, 3, 4, 5) has to be dimensioned according to the breaking load of the rope (1), while the rest of the drum (9) can be dimensioned for spooling of slack rope.

Description

Holding- and storage device for rope.

This invention is comprising a device fitted on a fixed or a floating structure for the purpose of mooring a second floating structure to the first structure by means of one rope, and the procedure for this operation.

Storing of a mooring line on a drum or on a conveyor belt when the line is not in use, is known technology. A mooring drum is normally functioning as a holding device, when the line is in operation, and the drum is then locked by a brake or similar.

The substantial part of the rope tension is transmitted to the drum by friction during several rope turns, and the possible remaining tension is normally held by a rope lashing or a clamping device. The largest drawback with a usual mooring drum is that the rope normally must be bent over a fairlead outside the drum, and it can then occur rope wear in the contact surface, especially for fibre rope.^*

When using conveyor belts for storage of the mooring rope, it is usual that the bight of the rope is pulled in on the conveyor belt in such a way that the line is stored in a long 0. The inner end of the mooring line can then be contineously connected to it's holding device. Holding devices for termination of large mooring ropes offshore are often brackets with links or hinges, permitting rope deflection in both directions, perpendicular to the normal hawser pulling direction. Fixed brackets or chain stoppers are also frequently used as holding devices on ships, but the rope has then been attached to a chain which is led further through a fairlead to the holding device.

10

Termination for mooring ropes are normally eye splices fitted on a thimble, grooved sheave or bolt, but designs similar to sleeves also exist. Steel wire rope is often cast in to a conical sleeve.

15

The purpose of this invention is to provide a device which can hold the inner end of a mooring line, and which can allow the mooring line to change lead to the relevant mooring directions

2.0 without line contact with guide plates or rollers, and which can allow the complete mooring line with thimbles and auxiliary lines to be spooled on a drum for storage between the mooring operations with a minimum of handling.

25

This problem is solved by hinging the rope termination to a strengthened part of a drum, and the strengthening must be further transferred into the bearings of the drum. When the device is in

30 operation, the rope tension is acting radial to the drum surface, while the rope tension on a conventional mooring drum is acting tangential to the drum surface. When the rope is stored, the function is similar to a conventional mooring drum.

35 But first the drum must be put in rotation, and the rope termination will swing about 90 degrees in it's hinged connection to the drum. Thereafter the rope will be spooled onto the drum as usual.

Hinging of the rope termination must be possible in both directions, perpendicular to the pulling direction when the rope is in operation. The drum axis can function as one of these degrees of freedom, but the other degree of freedom will then be in the longitudinal direction of the drum. The rope termination can then not be swung to tangential direction when the rope shall be spooled, and the rope must be bent further from the longitudinal to the tangential direction. This will be a cumbersome operation. The most suitable execution therefore is to arrange a first hinge axis parallel with the drum axis, and near the drum barrel surface. If the axis is positioned slightly more than a half rope diameter inside the drum barrel surface, the hinging arrangement and the rope termination can be recessed into the drum barrel surface when the rope is stored in such a way that further spooling is easier to arrange.

Hinging in the second direction must be as close to the first hinge as possible, in order to avoid large size of the hinging mechanism including the rope termination, which is first spooled onto the drum when the rope shall be stored. A cardan joint or a gyro suspension can give a very compact hinging arrangement, and a ball joint can solve the same problem.

In a rope termination consisting of an eye splice around a thimble or a sheave which can turn on a bolt, this turning can be the one degree of freedom. If the bolt is turning with the thimble. it can always be oriented in the tension direction, and thereby be used as a loadcell for tension measurement. A preferred solution with such eyesplice and thimble is shown on the figures. Figure 1 and 2 show the device seen from the side and from above when the rope is under tension. Figure 3 and 4 show the device from the same angles when rope is being spooled on. Figure 5 and 6 show the device added with a torsinal spring mechanisme, and seen from the same two angles.

The figures show the device fitted on a ship 13, or on a quay.

Figure 1 and 2 show a situation when for instance a shuttle tanker (not shown) is moored to the stern of a storage tanker 13 with a hawser 1. The eye splice of the hawser is put around the thimble 2 which is fixed to the bolt 3, and which can turn in the bracket 4 to orient itself in the hawser pulling direction. Thereby the bolt 3 also can be used as a loadcell for measurement of the hawser tension. The bracket 4 is hinged in two bearing brackets 5, 5', 20 which are fixed to the bracket 6, which is hinged in two bearing brackets 7, 7' , which are supported on the deck 14. These details 2 - 7 are all dimensioned according to the breaking load of the hawser 1, acting within defined angles which for instance can be +/- 15 degrees vertically, and +/- 60 degrees to the side relative to the shown horizontal direction of the rope 1.

The large bracket 6 can rotate freely in it's bearing brackets 7, 7', while the small bracket 4 can turn the angle A which is slightly above 90 degrees until it stops in the recess 8 in the drum 9. The small bracket 4 can also turn to orient itself in the hawser pulling direction, but the substantial part of this orientation will be by turning of the large bracket 6.

The drum 9 is a light weight design which is dimensioned for pulling in and storing slack hawser.

The drum 9 is fixed on a bracket 6, and turns consequently on the same axis. A gear box 10 has a pinion 11 which can be coupled for engagement with a gear wheel 12 on the drum 9, and turn this when the rope 1 shall be spooled on. If it is arranged a cut out for the drum 9 in the deck, the bearing brackets 7, 7' can be much lower, and it will then be more simple to transfer the large hawser forces into the deck 14.

Figure 1 shows a section through the device slightly outside the bearing bracket 5, and is seen towards the hawser 1. The cylindric drum barrel is also sectioned, but because of the thin dimension, the drum barrel is shown with a single line.

Figure 2 is a horizontal section slightly above the large bracket 6, and seen downwards.

Figure 3 is a vertical section through the thimble 2 when rope etc. is being spooled on the drum 9. The small bracket 4 is turned against the recess 8, and is thereby below the cylindrical barrel of the drum 9. The part of the hawser adjacent to the thimble 2 is led further from the recess 8 in a groove 15 to the cylindrical drum barrel surface. The complete hawser 1 is spooled on together with the thimble 24, and the chain 16 which has been held in a chain stopper acting as a holding device onboard the shuttle tanker. The chain has also been led through a fairlead onboard the shuttle tanker. because the hawser would have been subject to chafing demage during the passage of a fairlead. Figure 3 and 4 show the situation when starting spooling on a rope 17 which serves as a messenger line when the chain 16 shall be transferred to the shuttle tanker.

On figure 4 it is seen that the pinion 11 is engaged and is driving the drum 9 through the gear wheel 12.

Figure 5 shows the bracket 6 connected to a torsional bar 18. The shaft 19 in the bracket 6 is hollow. The section is arranged similar to figure 1 , and shows the same details. The bracket 6 can turn the angle B from "No torsion" to "Max torsion" where it is horizontal. The bracket 6 is engaged to the torsion bar 18 when this is exposed to "No torsion", and can turn until it approaches the angle B. The force K multiplied with the arm C gives the torsional angle D. When the torsional angle D approaches B, the arm C is approaching 0, and thereby the torsional angle D always will be less than B.

The purpose of this spring action is to increase the hawser elasticity.

Figure 6 shows the respective members of the torsional spring mechanism, but in order to illustrate the members better, the mechanism is not engaged. Apart from the shaft which is sectioned in center, the remaining part of this figure is sectioned similar to figure 2.

The shaft 19 for the bracket 6 can rotate freely in the bearing of the bearing brackets 7 and 7' . Outside the bearing bracket 7' , the shaft 19 has fitted coupling dogs 20. A dog clutch 21 which is sliding on a key 22 on the torsion bar 18, is shown disengaged, but it is in mesh with the coupling dogs 20 when engaged. In the opposite end the

torsion bar 18 is rigidly connected to the bearing bracket 7 through a tube 23.

The procedure for use of the system will be as follows :

Connection to the floating structure which shall be moored, for instance a shuttle tanker, is established in advance by means of a line which is substantially thinner than the messenger line 17. The end of the messenger line 17 is attached to the connecting line, and the messenger line is pulled over to the shuttle tanker while the drum 9 is rotated to render line.

When the messenger line has passed over the bow of the shuttle tanker, it is connected to a winch which starts pulling in the messenger line. The drum 9 is switched from feeding out to braking off rendered line. Braking can be executed through the gear box 10, or through a drum brake which is not shown. Special attention is made to hold sufficient tension in the messenger line 17 when the chain 16 and the thimble 24 shall be pulled off the drum 9, in such a way that the chain is not falling off the drum because of it's own weight. This is the position shown in fig. 3 and 4. If the chain is secured to the drum, the drum is stopped and the lashing removed.

The messenger line is pulling the chain 16 and the thimble 24 off the drum 9 and further over board, while the drum 9 continues to render hawser 1 under brake action. When the hawser 1 is pulled off the drum 9, the drum will stop by itself when the direction of the large bracket 6 is in line with the direction of the hawser. The brake is disengaged and the mooring operation is completed in this end of the hawser.

If the torsion spring mechanism 18 is desired used, the drum is rotated backwards the angle B as shown on fig. 5. The dog clutch 21 is engaged with the claws 20 as shown on fig. 6, and the bracket 6 will then turn within the angle B and give spring action in the hawser.

On board the shuttle tanker the chain 16 is pulled in to the chain stopper and locked, and thereby the shuttle tanker is moored.

When the mooring periode is completed, the procedure is reversed. The shuttle tanker releases the chain 16 and is rendering the messenger line 17. The pinion 11 is coupled for engagement with the gear wheel 12, and the gear box 10 is putting the drum 9 into rotation for pulling in hawser 1. During the first 90 degrees rotation of the drum 9 until the large bracket 6 is pointing vertically upwards, the small bracket 4 with thimble 2 will automatically turn against the recess 8 in the drum 9. Further spooling of the hawser 1 can then be on the approximately cylindric drum barrel surface. The hawser 1 is preferably spooled side by side to the one drum flange and back. Approximately the whole hawser 1 will then be spooled on one side of the drum, and the space demanding thimble 24 can be positioned on the drum surface followed by the chain 16 in the space to the other flange. The end of the chain 16 adjacent to the messenger line 17 can either be secured to the drum barrel surface before further spooling, or the messenger line 17 can be kept relatively tight during spooling of the first wraps in order to prevent that the chain is falling off the drum 9 caused by it's own weight. The remaining part of the messenger line 19 and possible smaller forerunning lines are spooled on top of the hawser and the chain 16. The complete spooling operation can be simplified by assistance of a spooling device which is activated when necessary.

The distinctive characteristic of this invention is that the rope (1 ) is entering the cylindric drum surface (9) in such a way that it is running radially from the drum surface when it is loaded.

Claims

1. A holding and storage device for mooring or towing rope comprising a storage drum for the rope

5 when it is not in use, and a holding device for the rope end attached to the drum, c h a r a c t e r i z e d i n t h a t the holding device (2,3,4,5) is pivoted fixed to the drum in such a way that the rope (1 ) can 10 be pulled radial relative to the drum barrel surface when it is loaded.

2. Device according to claim 1 , c h a r a c t e r i z e d i n t h a t

15 the holding device (2,

3,4,5) is fixed to a bracket (6) or similar which can turn on an axis, and that this bracket is a part of a drum (9), which can turn on the same axis.

-20 3. Device according to claim 2, c h a r a c t e r i z e d i n t h a t the bracket (6) is dimensioned according to the maximum load of the rope, while the remaining part of the drum (9) is dimensioned for handling of 25 slack rope.

4. Device according to one of the previous claims c h a r a c t e r i z e d i n t h a t the holding device is comprising a second bracket 30 (4) with rotating axis parallel with and fixed to the first bracket (6).

5. Device according to one of the previous claims c h a r a c t e r i z e d i n t h a t

35 the termination (2) for the rope (1) can turn in the second bracket (4) on an axis which is perpendicular to a plane through the rotating axis of the second bracket (4).

6. Device according to claim 5, c h a r a c t e r i z e d i n t h a t the holding device for the rope (1) consist of an eye splice positioned around the periphery of a sheave (2) with groove for the rope, as the sheave (2) is journalled in the second bracket (4).

7. Device according to claim 6, c h a r a c t e r i z e d i n t h a t it is used a thimble instead of the sheave (2).

8. Device according to one of the previous claims c h a r a c t e r i z e d i n t h a t it is arranged a recess (8) adapted for the holding device (2,3,4,5) in the cylindrical drum barrel surface (9), in such a way that the holding device (2,3,4,5) primarily will be positioned below the drum barrel surface when the rope is spooled on the drum.

Device according to one of the previous claims, c h a r a c t e r i c e d i n t h a t it comprises means (10,11,12) for driving the drum

(9).

10. Device according to one of the previous claims c h a r a c t e r i c e d i n t h a t i comprises a spring mechanism (18-23) which can be coupled between the first bracket (6) and it's bearing bracket (7), and which preferably allows 80-135 degrees rotation of the first bracket(1 6) between unloaded and horizontal position.