Abstract: When sucking ground material through a lying, elongated suction slot moved ver the ground, the water stream for suctioning this ground material is adjusted in dependence upon the types of ground material to be fluidized.

Abstract: Method and device for safeguarding hydraulic transport of a suspension of edging spoil and water by supplementing a dosed water amount onto the suction side of the pump, whereas as much and as long as possible suction power is maintained in the suction duct for feeding much material to be transported and little water into the suction duct.

Abstract: An artificial island is constructed by depositing material such as sand, y or the like on the building site on the bottom and by providing inhibiting means formed by branched, relatively spaced elements positioned on the building site, to reduce the rate of effluence of the material such as sand, clay or the like along the sea bottom.

Abstract: In a method of loading a suction dredger in which a suspension of sand and ater is pumped into the hold an effluent device is intermittently passed to lower and lower levels in dependence upon the weight of the load in the hold to an extent such that the suction dredger remains loaded substantially up to its maximum permissible carrying capacity.

Abstract: When loading a loading space 2 of a dredging vessel 1 with sand the head er 5 is removed from the loading space 2 by means of more than one siphon 12 and is conducted away into the water stream 26 moving around the vessel 1. This head water can be polluted with much sludge or another pollutant.In order to reduce pollution of the environment with the aid of effluent means which are not very expensive and which can be easily adjusted, said effluent means comprises in accordance with the invention a tubular sheath 24, inside which is telescopically arranged a level-adjustable common outlet conduit 21 which can be withdrawn into said tubular sheath and be brought out thereof to a considerable distance below the vessel 1 respectively, and which is connected with coupled conduits 16, 19, 18 of more than one siphon 12.

Abstract: Hard ground beneath a water surface is controllably cut away by a device ch includes a buoyant body having a work support depending therefrom and forced against the hard ground so as partially to support the weight of the body. A cutter assembly is releasably clamped to the work support and the clamp has arms connecting it to a short, rigid carrier which mounts a rotatable cutter head at one end. The arms allow the carrier to swing about a horizontal axis and a vertical axis and hydraulic motors are provided to sweep the carrier about such axes in controlled fashion. A winch on the body allows the carrier to be clamped at desired vertical positions on the work support.

Abstract: In order to accurately control the cutter head of a cutter head suction dredger anchored by means of ropes, the tension in at least one of the two longitudinal ropes is measured and the winch of at least one of the two longitudinal ropes is actuated in dependence upon the tension measured in the one longitudinal rope.

Abstract: In a method of loading the hold of a suction dredger vessel, in which a sension of sand and water is pumped into the hold during loading which is carried out in a first stage and a subsequent second stage for avoiding that a siphon effect is not possible and that the last quantity of water cannot be replaced by a sand-water mixture, the effluent means are kept, after the suspension level in the hold has reached the external water level, under the action of a suction pump for lowering the suspension level to below the external water level.

Abstract: When breaking up lumps of stone from a subaqueous stony ground, the lumps are loosened by means of at least one chisel inserted into the ground and being moved along the ground surface. In order to break up lumps of stone by low power and to main a predetermined size of the loosened lumps of stone suitable for being lifted by a suction dredger system, the structure of the top layer of the stony ground is disturbed by inserting displacers from above into the ground at places distributed over the ground surface.

Abstract: A trailing dredger comprises a vessel, a pump, a suction pipe connected with said pump and a suction head connected with said suction pipe and having a suction chamber having at least one suction opening and communicating with the suction pipe, said suction head being adapted to roll along a soil beneath the water by means of a hollow roller being freely rotatable about an axis transverse of the direction of movement of the dredger and being journalled on the suction head, said roller being provided with a contact surface. The surface of the roller is provided with openings which concentrate the suction force and present an ever-changing contact pattern with the soil which correspondingly provides an ever-changing flow pattern to erode and pick up the soil.