Abstract: A drag head of a trailing suction hopper dredger, comprises a visor which is dragged over the bottom in a dragging direction and herein loosens soil, and a suction conduit which connects to the visor and which discharges the loosened soil. The drag head is provided with cutting bodies for loosening the soil, with the proviso that the cutting bodies comprise conical bits. Harder soil can be dredged efficiently with a trailing suction hopper dredger equipped with the drag head.

Abstract: A cutter head for dredging ground under water is disclosed. The cutter head is suitable for attachment to the ladder of a cutter suction dredger and for being moved through the ground therewith in a lateral sweeping movement. The cutter head includes a rotation-symmetrical revolving body which is rotatable around its rotation axis by means of drive means and which is provided along its peripheral surface with a number of cutting tools for penetrating into the ground, wherein the rotation axis of the cutter head runs substantially perpendicularly of the longitudinal direction of the ladder and substantially tangentially to the direction of the sweeping movement. Likewise, a method for breaking ground underwater, making use of the cutter head is shown.

Abstract: The invention relates to a cutter head (10) for dredging ground under water, this cutter head being suitable for attachment rotatably around a central axis to the ladder (2) of a cutter suction dredger (1) and for being moved through the ground (9) therewith in a lateral sweeping movement, the cutter head comprising a base ring (13), a hub (14) situated at a distance in the direction of the central axis from the base ring, and a plurality of arms (15) extending from the base ring to the hub, wherein a passage opening (16) is located between arms and wherein the arms are provided with a first series of cutting tools on a leading part (15a) relative to the direction of rotation of the cutter head, and wherein at least one arm is provided with a second series of cutting tools on a part of the arm (15b) facing away from the central axis.

Abstract: A system for optimizing the dredging of an area by a vessel (25) equipped with a cutter head (4), including an apparatus to measure local seismic velocity in front of the vessel (25), said apparatus including a set of seismic receivers (11, 11?, 11?, 11??) supported by a frame (10) configured for attachment to and projection from the bow end of the vessel, which frame aligns the seismic receivers (11, 11?, 11?, 11??) above and in front of the cutter head (4). A method for optimizing dredging.

Abstract: A drag head of a trailing suction hopper dredger. The drag head comprises a rotatable visor connected to a suction pipe for discharging soil via the suction opening of the visor, wherein the visor is provided with a catching construction for undesirable objects. The catching construction closes the suction opening except for passage openings, wherein at least a number of passage openings have a variable passage area. A method for breaking up and/or dredging at least partially hard grounds under water using a trailing suction hopper dredger equipped with a drag head.

Abstract: The present invention relates to a method for optimizing the dredging of an area by a dredge equipped with a cutter suction head (4) comprising the steps of: obtaining conventional soil information of the area to be dredged; measuring local soil parameters in and around the position of the cutter head during dredging; calculating dredging parameters for a current and subsequent cutter head position based on the combination of conventional and local soil parameters to optimize yield and cutter wear; and adjusting the dredging parameters so giving optimum efficiency at a current and subsequent cutter head position. It also relates to a system that implements the method.

Abstract: The invention relates to a drag head of a trailing suction hopper dredger. The drag head comprises a visor which is dragged over the bottom and herein loosens soil, and a suction pipe which is connected to the visor and which discharges the loosened soil. The visor comprises at least two individually movable pressure elements transversely of the dragging direction which comprise a number of substantially disc-shaped penetrating bodies. The penetrating bodies transmit forces to the bottom via their peripheral edge under the influence of the weight of the pressure element in which they are received, whereby the bottom is broken. The drag head has an improved efficiency.

Abstract: In one embodiment of the present invention, an apparatus is disclosed for accommodating a substantially vertical spud of a dredging vessel with a longitudinal direction, including a spud carriage which is mounted for limited rotation around a horizontal transverse axis, wherein at least a first and a second spring device is arranged under bias between vessel and spud in the longitudinal direction for the purpose of absorbing a moment on the spud carriage, which first and second spring devices compensate each other in the non-loaded situation of the spud; and at least one spring device is provided with a spring force limiting device for limiting the tension in the spring element from a determined maximum moment on the spud carriage.

Abstract: The present invention relates to a draghead (1) for a trailing suction hopper, comprising a visor (2), revolvable around a first axis (6) for removing soil, and a suction line (31) connected to the visor (2) for the removal of the loosened soil, characterised in that the draghead (1) is provided with a pressure plate (21), which comprises a number of mainly disc-shaped penetrating bodies (22) on the soil-facing side of the pressure plate (21), in such a way that their circumferential edge (23) is capable of transferring forces to the soil.

Abstract: The present invention relates to a system for optimizing the dredging of an area by a vessel (25) equipped with a cutter head (4), comprising a means to measure local seismic velocity in front of the vessel (25), said means comprising a set of seismic receivers (11, 11?, 11?, 11??) supported by a frame (10) configured for attachment to and projection from the bow end of the vessel, which frame aligns the seismic receivers (11, 11?, 11?, 11??) above and in front of the cutter head (4). It also relates to a method for optimizing dredging.

Abstract: A device is disclosed for changing a suction mouth of a cutter suction dredge of a vessel with cutter ladder. In at least one embodiment, the device includes, comprising a work platform which, as seen in the transverse direction of the vessel, is provided substantially in the middle with an opening, wherein—a support structure is provided which can be fixedly connected to the work platform in a position substantially under the opening, which support structure is adapted to support a suction mouth;—and the work platform with support structure is tiltable around a first, substantially horizontal transverse axis between a substantially horizontal operating position and a high position in which the cutter ladder can be moved upward, which positions are such that the work platform with support structure is movable from its high position to its operating position when the cutter ladder is situated in a high raised position.

Abstract: Device for dislodging and recovering dredging material of varying nature, comprising a bearing housing (25), a drive shaft (11) mounted therein for rotatingly driving with a determined torque a cutter head (10, 10?) with a support ring (15, 15?), which cutter head is mountable on the drive shaft via a hub (9), and a suction pipe (13) which can be connected to a suction mouth (14, 14?) which is surrounded by a fixed cutter shield (21, 21?) which fills the space between the rotating support ring on the one side and the suction mouth and the bearing housing on the other, wherein a number of cutter heads with a different support ring diameter can be mounted on the drive shaft, wherein the support ring diameter is determined by the torque and the nature of the dredging material to be recovered.

Abstract: A cutter head for dredging soil, which is mountable to the ladder of a suction dredger for dredging soil, and connectable on a suction pipe for removing loosened soil, the cutter head comprising a cage-shaped support construction which is mountable to a drivable rotation shaft extending mainly in extension of the ladder and which has a circumferential surface provided with a number of cuffing tools for penetrating the soil, the cuffing tools comprising a number of disc-shaped penetration bodies of which the disc planes extend substantially perpendicular to the rotation shaft, so that they can transfer forces to the soil via their peripheral edges.

Abstract: An apparatus and method for dredging under water ground layers includes the steps of providing a dredging device composed of a mechanical dredging component having a part operative to contact the under water ground layers and exert a dredging action; and at least one water jet effective to inject water under pressure in an area where the mechanical dredging component is operative; mechanically impacting the underwater ground layers with the part to fracture the underwater ground layers and form fractured material; and injecting water under pressure from the at least one water jet simultaneously with the mechanical impacting to remove the fractured material so that an improved break-away pattern of material is obtained and reduced wearing of said part.

Abstract: A method for the displacement of mass A underneath the earth's surface and underneath a soil mass C to site B where the first step optionally treats mass A by known methods such that the composition of mass A is physically altered, mass A is then inserted underneath the earth's surface and soil mass C, displacing soil mass C vertically upwards, and optionally displacing a soil mass D, positioned under site B, vertically downwards.

Abstract: A dredge head for dredging sludge by a trailing and pushing motion thereby defining a trailing and pushing direction is configured to be fitted on a ladder of a stationary dredger. The ladder is movable in the trailing and pushing direction for moving the dredge head.

Abstract: There is described a device for underwater sealing ports or similar, whereby sliding panels are shifted along discharge openings, in which rubber sections are mounted about said discharge openings, in frames secured to a vessel side, and means are provided to exert a hydraulic pressure on said rubber sections.

Abstract: There is described a device for mounting and removing a cutter at the end of the cutter shaft from a hydraulic or suction dredge, whereby the cutter boss is provided with an inner screw-thread and the cutter shaft with an outer screw-thread. The device is comprised of two concentric rings those surfaces of which facing one another are provided with teeth fitting into one another, whereby the slanting of said teeth is opposite to the angle of said screw-threads, and means are provided to lock both rings during the screwing of the cutter on the shaft thereof, in such a position relative to one another where said rings have so rotated relative to one another that the joint thickness thereof is increased as compared with the joint thickness of the toothed rings when the teeth have completely rotated into one another.