Ammunition and explosives – Mines – Counter measure
Patent
1990-06-19
1991-11-12
Jordan, Charles T.
Ammunition and explosives
Mines
Counter measure
B63G 706
Patent
active
050638505
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for sweeping marine mines having a magnetic sensor, according to which spaced electrodes are towed by a vessel and said electrodes are supplied with electric current from the vessel to set up a magnetic field in the water, surrounding the electrodes with a magnetic field.
Sweeping for marine mines that are triggered by a magnetic sensor means requires that a magnetic field be set-up in the water which is strong enough to be sensed by the mine as a vessel target, causing the mine to be detonated. In order to protect the vessel carrying out the mine sweeping, it is desireable to limit the magnetic field to an area which is at a safe distance from the mine sweeping vessel. In practice, the mine sweeping arrangement is towed behind the mine sweeping vessel at a distance of approximately 200 to 600 meters.
A sweeping operation must fulfil two primary demands. The first demand is to make mines having a low sensitivity detonate even if they are displaced a large distance in the transverse direction of the track of the vessel. This is the so-called sweeping width preferably chosen to be of a size of the order of 100 to 500 m. The second demand is that mines having a high sensitivity shall not be initiated within a certain security zone surrounding the sweeping vessel. These demands are partially conflicting because a strong magnetic field required to satisfy said first demand makes difficult to satisfy said second demand.
The procedure of sweeping marine mines having a magnetic sensor by means of an electrode sweeping arrangement is as follows. Two or more electrodes are placed in the water and towed by one or more vessels. The electrodes are supplied with electric current through cables from the towing vessel, the current in the cables and through the water generating the desired magnetic field. In the so-called two electrode sweeping arrangement two rod-shaped electrodes made of some conducting material and associated feeding cables are utilized. This type of mine sweeping arrangement, the most simple one, has been improved in many ways according to prior art technique.
U.S. Pat. No. 2,937,611 discloses a system in sweeping marine mines by means of a plurality of vessels, each vessel towing two electrodes. The system provides a pulsating magnetic field between the several electrodes. U.S. Pat. No. 2,397,209 relates to a system in mine sweeping according to which a pulsating magnetic field is provided between two of the electrodes towed by the vessel. A more complicated system in mine sweeping is disclosed in U.S. Pat. No. 3,946,696. The system comprises two electrodes, a controlled current generator, and a magnetic field sensor. There is also included a control system controlling the current through the electrodes in dependence on the magnetic field in the vicinity of the mine sweeping vessel. By measuring the magnetic field adjacent to the mine sweeping vessel the desired safety of the mine sweeping vessel can be achieved.
Another simple contructive step to improve the protection of the mine sweeping vessel without imparing the desired mine sweeping properties is to extend the mine sweeping arrangement behind the vessel. However, practical problems in handling long cables limit the length of the mine sweeping arrangements.
A device in sweeping mines actuatued both acoustically and magnetically is described in EP A1 0 205 887.
An object of the present invention is to provide a method for sweeping marine mines initiated magnetically, which meets the demand of a safe detonation of mines, even if the mines are displaced a distance in the transverse direction of the track of the vessel, as well as the demand of a satisfactory safety of the mine sweeping vessel. This is accomplished by imparting to the generated magnetic field a desired propagation characteristic with a sufficiently weak magnetic field adjacent to the mine sweeping vessel.
The invention will be explained in more detail by means of embodiments, reference being made to the accompanying drawings, in which
FIG. 1
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patent: 3060883 (1962-10-01), Herbst et al.
patent: 3707913 (1973-01-01), Lee
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patent: 4627891 (1986-12-01), Gibbard
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Gustavsson Mats
hrwall Tomas
Olsson Thord
Jordan Charles T.
SA Marine AB
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