Minehunting and disposal system

Abstract

 The present invention relates to minehunting and disposal systems. Known methods of minehunting and disposal comprise the deployment of several relatively large ships each having a crew of the order of thirty personnel. The known ships are expensive since they have to be specially fabricated so as to present a low magnetic signature and low noise generation.
This invention provides a system comprising a parent ship providing support facilities for a plurality of operational craft (10, 12, 14, 16), the operational craft (10, 12, 14, 16) being relatively small and being provided with known mine detection and destruction equipment (34). The parent ship is preferably designed and equipped so as to be capable of carrying the operational craft (10, 12, 14, 16) on board, such that the operational craft may be transported to the area of deployment. The operational craft (10, 12, 14, 16) preferably have hulls (16) providing a substantial portion of its buoyancy submerged together with a relatively small water plane area, for example a Small Water Plane Area Twin Hull type craft.
This system reduces the number of personnel exposed to a single risk and the operational craft present a low magnetic signature and low noise generation due to their size and these endowments are particularly enhanced if the preferred form of hull (16) is utilised.

Description

[0001] The present invention relates to a minehunting and disposal system.

[0002] The conventional system of hunting for and disposing of marine mines consists of sending a relatively large ship normally 35 to 47 metres in length into the water area which is suspected of having been mined. The conventional minehunting ship has a crew of the order of 30 members. Such ships are provided with sonar detection equipment which is used to locate mines together with mine destruction equipment which is used in order to dispose of the mines once they have been located. Several disadvantages exist in the known system. There are a relatively large number of personnel at risk, and the system is costly because the ships involved have to have a low magnetic signature together with a low 'noise' generation.

[0003] With a view to mitigating at least one of the above mentioned disadvantages the present invention provides a minehunting and disposal system characterised by a parent ship and a plurality of operational craft, the parent ship providing support facilities for the operational craft, and the operational craft being relatively small and being provided with mine detection and destruction equipment.

[0004] Preferably, the minehunting and disposal system is further characterised in that the parent ship has sufficient space and stability and is provided with apparatus for loading and unloading the operational craft such that the operational craft may be stored on the parent ship.

[0005] This enables the operational craft to be transported to the area of deployment by the parent ship.

[0006] The operational craft preferably have a hull form which has a substantial portion of its buoyancy.'below the waves' together with a relatively small water plane area. Such semi-submerged hulls are known per se, examples being the 'semi-submersible' oil-rig and the semi-submerged or SWATH (Small Waterplane Area Twin Hull) ship.

[0007] Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

Figures 1 and 2 show, in diagrammatic form, side and end elevations respectively of an operational craft employing the 'semi-submersible' type of hull.

[0008] The exemplary minehunting and disposal consists of a parent ship and a number of smaller operational craft. The parent ship is intended to be anchored in a safe area and to act as a general back up and refuelling ship for the operational craft. The operational craft are deployed for short periods in the area known to be or suspected of being mined and return to the parent ship for refuelling or crew changes.

[0009] This system has many advantages over the conventional system which comprises one or several independent ships of relatively large size. The operational craft need only carry basic facilities required for a single day's operations. Only a small crew is required to operate the mine detection and disposal equipment. Large supplies of fuel and munitions need not be carried and only basic amenities need be provided since the craft need only be deployed for short periods. Consequently the craft may be small and relatively inexpensive. The number of crew at risk is drastically reduced typically from the thirty or forty crew members of a conventional minehunting ship to the five or six crew members required to control one of the operational craft.

[0010] The parent ship can be a stern trawler or an offshore supply vessel which has been specially converted. The parent ship is less expensive than a conventional minehunting ship. The parent ship is provided with a crane structure together with sufficient space and stability to store the operational craft onboard. This enables the operational craft to be transported to the vicinity of the minehunting area by the parent ship.

[0011] The operational craft are small enough (length in the order of 15m, breadth in the order of 6m) and light enough (in the order of 30 tonnes) to be taken onboard the parent ship. They are capable of providing a steady platform for sonar transducer equipment, used for mine detection, in rough seas. A typical maximum sea state in which the operational craft would function would be one with a significant wave height of 2.5 metres. The crew of an operational craft would typically consist of six members consisting of 4 sonar operators, 2 on duty and 2 off duty at any one time, one helmsman and one officer. Each operational craft is equipped with a known minehunting sonar and a known remotely controlled mine disposal vehicle.

[0012] In order to provide an operational craft of the required weight, size and stability the hull is of the semi-submerged type. The hull has most of its buoyancy 'below the waves' and at the same time has a small waterplane area. Due to the utilization of such a hull the operational craft has a wave response which is reduced by an order of magnitude in comparison with an ordinary boat hull.

[0013] One example of an operational craft is illustrated in Figures 1 and 2. This embodiment utilizes the 'semi-submersible' or SWATH type of hull. The operational craft comprises a platform 10 having a front cabin area 12 and a rear open deck area 14. The 'semi-submersible' hull 16 comprises one or more streamlined legs on both side of the platform 10. On each side of the platform 10 the legs 18 are joined at their lower ends by a hull body 20 which houses a propulsion unit having a propeller 22 at its rear end. A structural strengthening and hydrodynamic cross member 26 interconnects the two hull bodies 20. The buoyancy of the hull 16 is such that the base of the platform 10 is held approximately one and half metres above the still water level 24. The hull bodies 20, which constitute the main buoyant volumes of the hull, float at slightly less than 3 metres below the still water level 24. Suspended from the platform 10 beneath the cabin area 12 and centrally with respect to the breadth of the platform 10 is a farther leg 28. At the lower end of the leg 28 is positioned the sonar transducer 30, signals to and from which are transferred to and from the cabin 12. Alternatively the sonar transducer may be mounted within one hull. The leg 28 is strengthened by member 32 which interconnect the leg 28 with the hull bodies 20. A mine disposal vehicle 34 is held by a suitable supporting means 36 at the rear of the platform.

[0014] The relatively small size of the operational craft together with the fact that most of the necessary electrical equipment is positioned on the craft's platform, which is held out of the water, present several advantages for their use in a minehunting system. The operational craft have an extremely low magnetic signature and also produce very little underwater noise since the main 'noise' producing machinery is also situated out of the water. The amount of power being transferred to the propellers is small due to the size of the craft. Low 'noise' and low magnetic signature are desirable features of a minehunting system since mines are known which may be triggered by the detection of such features exceeding a pre-set threshold. Although the top speed of the operational craft is (approximately) only 10 knots, this is adequate for minehunting purposes. 6 The operational craft have a high shock resistance due to their size and the fact that most of the equipment is situated high above the water.

Claims

1. A minehunting and disposal system characterised by a parent ship.and a plurality of operational craft (10,12,14,16), the parent ship providing support facilities for the operational craft (10,12,14,16) and the operational craft (10,12,14,16) being relatively small and being provided with mine detection and destruction equipment (34).

2. A minehunting and disposal system as claimed in claim 1, characterised in that the parent ship has sufficient space and stability a.nd is provided with apparatus for loading and uloading the operational craft (10,12,14,16) such that the operational craft (10,12,14,16) may be stored on the parent ship.

3. A minehunting and disposal system as claimed in claim 1 or 2, characterised in that each operational craft (10,12,14,16) has a hull (16) which, when floating, has a substantial portion of its buoyancy submerged and presents a relatively small waterplane area.

4. A minehunting and disposal system as claimed in claim 3, characterised in that the hull (16) of each operational craft (10,12,14,16) is of the Small Waterplane Area Twin Hull type.

5. An operational craft for a minehunting and disposal system as claimed in claim 3 or 4.

Drawing