Barrier arrangement and a method for producing the same

A barrier arrangement for blocking a water passage or channel against the admission of foreign or unfamiliar objects, such as underwater vessels, frogmen and the like, comprising a net (1) of extremely high tensile strength intended to be stretched across the passage or channel, and in which arrangement the net comprises lines (4) which incorporate electrical conductors (5) which are insulated from the surroundings and through which a close circuit current is intended to flow;

• in which the bottom edge of the net (1) is anchored to the sea-bed and the net arranged to be activated from a passive state, in which the net may rest against the sea-bed, to an active barrier state, to which end the net (1) is connected along its upper edge to an inflatable and deflatable lifting hose (3) which in its evacuated state is essentially flat and which when inflated is able to lift the upper edge of the net to the surface of the water, so as to stretch the net between the sea-bed and said surface, characterized in that the upper and lower edges of the net (1) are respectively braided to anchoring bodies (9) located on the sea-bed and to the lifting hose (3) with the aid of lines (12;
• 13) which incorporate electrical conductors which are insulated from the surroundings and through which a close circuit current is intended to flow;
• and in that the conductors are connected to an alarm device, to which the conductors (5) incorporated in the lines (4) forming said net are also connected;
• and in that the alarm unit is arranged to be activated on the occurrence of an earth fault or a short circuit in any of the connected conductors.