GB2181708A - Mooring system - Google Patents

Abstract

A mooring system has an auto-tensioning winch 20 and a pulley arrangement 22 mounted on a roll-on roll-off vessel 10, for example. The pulley arrangement 22 has a pulley 42 mounted on a vertical guideway 36 for movement relative to the vessel 10. A mooring rope 32 passes from the pulley 42 to a bollard 34 on a dolphin 16. The pulley 42 is moved on the guideway 36 in response to changes in the position of the vessel 10 relative to the dolphin 16 and in a sense to return the length of mooring rope extending from the pulley 42 to the bollard 34 to a substantially horizontal position. In modifications, the winch 20 or the pulley arrangement 22 or both can be mounted on the dolphin 16. <IMAGE>

Description

SPECIFICATION Mooring system The invention relates to mooring systems.

Mooring systems which incorporate autotensioning winches have been proposed to moor vessels relativelystationaryto a mooring despite adverse conditions, e.g. high winds, large high and low tide differences. However, when it is required to moor a roll-on roll-offvessel, for example, close to a mooring structure such as dolphins, the angles made by the mooring ropes extending between the winchesandthedolphinsasthetidechangesand/or the vessel is loaded or unloaded can preventthe winches exerting the required force to maintain the rope tension and the vessel can move away from the dolphins. The problem is aggravated when the tide changes are extreme.

It is an object of the present invention to provide a mooring system which reduces or obviates the aforementioned disadvantage.

According to the present invention, a mooring system for a vessel comprises an auto-tensioning winch and a pulley arrangement through which a mooring rope of the winch is reeved, the pulley arrangement comprising a pulley which is mounted for movement relative to the vessel, the mooring rope extending from the pulley and between a mooring structure and the vessel relative to the mooring structure to move the pulley relative to the vessel in a sense to return the length of mooring rope extending from the pulley and between the mooring structure and the vessel to a substantially horizontal position.

Preferably, said means comprises a lever pivoted adjacent the pulley and engageable at one end with said length of mooring rope and interactableatthe other end, in each of extreme positions, with are spective switch which actuates drive means for effecting said relative movement of the pulley and, in a position intermediate said two positions, with a switch which stops said drive means.

A mooring system will now be described to illustrate the invention by way of example only with refer ence to the accompanying drawings, in which Figure 1 is a schematic plan view of one end of a vessel moored between two dolphins byfourofthe mooring systems; Figure2 is a schematic part-section elevation on line A-A in Figure 1; Figures 3 and 4 are schematic side and end views, respectively, of the pulley of the arrangement; and Figure 5is a hydraulic circuit for operating the system.

Aroll-on roll-offvessel 10 has at one end four mooring systems 12 in accordance with the inven tion. The vessel 10 is shown (see Figures 1 and 2) moored in engagement with the buffers 14 of two dolphins 1 6whereby a bridge link (not shown) for rail or road vehicles can be registered with the deck 18 of the vessel 10. The other end of the vessel 10 is moo red by conventional techniques to anchor buoys, for example.

Each system 12 has a hydraulicauto-tensioning winch 20 and a pulley arrangement 22.

Each winch 20 has a divided barrel 24 driven by a hydraulic motor 26. One partofthe barrel 24carriesa mooring rope 28 which can be passed between guides 30 and used for conventionally mooring the vessel 10 when required. The other part of the barrel 24 carries a mooring rope 32 which is reeved through the pulley arrangement 22 and is secured to are spective bollard 34 on the respective dolphin 16.

Each pulley arrangement 22 has a vertical guideway 36 secured to thevessel 10; a first pulley38 mounted adjacenttheguideway36forreceivingthe rope 32 from the winch 20; a second pulley 40 mounted on the upper end of the guideway 36 to lead the rope 32 from the first pulley 38 over the upper end of the guideway36; and a third pulley 42 for receiving the rope 32from the second pulley40 andfrom which a length 44 of the rope 32 passes to a respective bollard 34,thethird pulley 42 being mounted on the guideway 36 for movement relative to the vessel 10 between upper and lower positions determined by the length ofthe guideway 36. The pulleys 38,40 and 42 together form a rope path for the rope 32.

The length of the guideway36 is determined by the maximum change in level relativetothedolphins 16 the vessel 10 is likely to experience. Typically, at Dover it is necessary to accommodate a low tide loaded vessel to a high tide unloaded vessel distance of some 8.7 metres.

The third pulley is mounted in a bracket 46 which carries two pairs of rollers 48 (one pair of rollers 48 is shown in Figure 3) which engage respective guide channels in the guideway 36. The opposite ends of a drive chain (not shown) are attached to the brackets 46, the endless loop formed thereby passing over upper and lower sprockets (not shown). The upper sprocket is driven by a hydraulic motor (indicated at 66 in Figure 5) mounted on the upper end of the guideway 36. The position of the lower sprocket on the guideway 36 is adjustable whereby the tension in the drive chain is adjustable.

A cranked lever 50 is pivoted on the bracket 46. One end of the lever 50 has two pins 51 locatable one on each side of the length 44 of the rope 32 wherebythe lever pivots on the bracket 46 in dependence upon the deviation of the length 44 of the rope 32 from the horizontal position (as shown in ghost outline in Figure 3) underthe influence of the changes in the tide and/or loading or unloading of the vessel 10. The other end of the lever 50 extends into a switch box 52 also mounted on the bracket 46. The switch box 52 contains three switches54, and 58, for example proximity switches. The switches 54, 56 and 58 control a solenoid valve 68 (see Figure 5) which regulates operation of the hydraulic motor 66 for the upper sprocket on the guideway 36.

The switches 54 and 58 are operated by the lever 50 in a respective one of its two extreme positions to actuate the motor66to move the pulley 42 down or up, respectively, to return the length 44 of the rope 32 to a substantially horizontal position. The corresponding movementofthe lever 50 results in operation of the central switch 56 to close the solenoid valve 68 and stop the motor 66.

The control circuit (not shown) for the valve 68 incorporates a delay timer so that actuation ofthe switch 54 or 58 by movement ofthe vessel 10 owing to the swell on thewaterdoes not occur.

Referring to Figure,5, an electric motor 60 drives a variable-displacement hydraulic pump 62 which drives the motor 26 the winch 20. Excess-pressure relief valves 64 are incorporated in the hydraulic circuit. The motor 66 for the upper sprocket on the guideway 36 is also connected to the pump 62 via the solenoid valve 68.

Modifications are possible within the scope ofthe invention. For example, the one or other or both of the motors 26 and 66 may be electrical motors; other mechanisms for effecting movement of the pulley 42 relative to the guideway 36 can be used. In one preferred modification, the pulley 42 is mounted for pivotal movement about a vertical axis to accommo- date some movement of the mooring rope in a horizontal plane. In other modifications, the winch 20 or the pu lley arrangement 22 or both can be mounted on the mooring structure, i.e. the dolphins 16.

Claims (10)

1. A mooring system for a vessel comprising an auto-tensioning winch and a pulley arrangement through which a mooring rope of the winch is reeved, the pulley arrangement comprising a pulley which is mounted for movement relative to the vessel, the mooring rope extending from the pulley and between a mooring structure and the vessel, and means responsiveto changes in the position ofthe vessel relative to the mooring structure to move the pulley relative to the vessel in a sense to return the length of mooring rope extending from the pulley and between the mooring structure and the vessel to a substantially horizontal position.

2. Asystemaccordingtoclaim 1, in which said means comprises a lever pivoted adjacentthe pulley and engageable at one end with said length of mooring rope and interactable at the other end, in each of two extreme positions, with a respective switch which actuates drive means for effecting said relative movementofthe pulley and, in a position intermediate said two positions, with a switch which stops said drive means.

3. Asystem according to claim 1 or claim 2, in which the pulley arrangement has a vertical guideway upon which the pulley is mounted for said movement,the arrangement further comprising pulleys positioned relative to the guidewayto form a rope path, which includes the movable pulley, forthe mooring rope,which rope path extends between the mooring structure and the vessel.

4. A system according to any one of the preceding claims, in which the movable pulley is mounted for pivotal movement about a vertical axis.

5. A system according to any one ofthe preceding claims, in which the pulley arrangement is mounted on the vessel.

6. A system according to any one of claims 1 to 4, in which the pulley arrangement is mounted on the mooring structure.

7. A system according to any one ofthe preceding claims, in which the winch is mounted on the vessel.

8. A system according to any one of claims 1 to 6, in which the winch is mounted on the mooring structure.

9. A system according to claim 1 substantially as hereinbefore described.

10. A system according to claim 1 substantially as hereinbefore described with reference to the accompanying drawings.