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: 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.