Abstract: A clamp assembly comprising a pair of clamps may couple to an assembly body. The clamps may pivot to receive material beneath the assembly body. The clamps may include opposing surfaces that define a scoop space beneath the assembly body. Each of the clamps may include a cutting plate. The cutting plate may include a perforating edge configured to extend into the scoop space relative to a corresponding one of the opposing surfaces. The clamp may further include a retention plate. The retention plate may include an inner surface that faces the cutting plate. The cutting plate and the retention plate further define the scoop space between the clamps. The clamp assembly may couple to a lift assembly. The lift assembly may include a hydraulic actuator configured to raise and lower the clamp assembly.

Abstract: A piece of submarine mining equipment comprises an equipment body, a plurality of adaptive submarine mining collectors and respective mineral delivery pipes. The equipment body and the adaptive submarine mining collectors are connected through the mineral delivery pipes. The lengths, stretching out of the equipment body, of the mineral delivery pipes can be adjusted under control. The adaptive submarine mining collectors are provided with tracked traveling mechanisms and can autonomously travel under control. An underwater detector is used for detecting the submarine topography and mineral distribution in the vicinity of an operation area, and the traveling path of the submarine mining collectors and a mineral storage vehicle is reasonably planned according to detected information. The multiple adaptive submarine mining collectors simultaneously and independently work and are made light and small, thus reducing damage of mining operations to the submarine ecological environment.

Abstract: A wide format dredge apparatus provides a floating vessel or hull with one or more anchor lines, anchors or spuds that enable an operator to hold the hull in a selected locale. Port and starboard booms extend in generally opposite directions from the hull. An elongated ladder is pivotally attached to the hull. The ladder is configured to swing between port and starboard positions. Port and starboard swing devices are rigged to the booms. When the ladder swings to the port position, the starboard swing device is lengthened and the port swing device is shortened. When the ladder swings to the starboard position, the port swing device is lengthened and the starboard swing device is shortened. Each swing cable spans from a boom at a position spaced away from the hull to the outer end portion of the ladder. A lifting device is provided for raising and lowering the ladder. A float or tank travels along the ladder. The float or tank at least partially supports the ladder.

Abstract: A moveable platform apparatus comprising a platform adapted to receive and support a moveable drilling rig or drilling equipment. The platform comprises a first set of legs connected to the platform, wherein the first set of legs support the platform in a first vertical position above ground, wherein each leg of the first set of legs is extendable with respect to the platform to vertically move the platform. The platform further comprises a second set of legs connected to the platform, wherein the second set of legs support the platform in a second vertical position above ground, wherein each leg of the second set of legs is extendable with respect to the platform to vertically move the platform. A method for a moving a platform apparatus along the ground.

Abstract: A jetting system for an undersea trencher has jetting conduits extending aftward of its trench-cutting jetting swords. Jetting conduit nozzles direct liquid radially from their jetting conduits into the trench after the trench is excavated by the jetting sword cutting nozzles. The jetting conduits direct sufficient liquid into the trench to maintain the mix of trenched soil and water in the trench along the length of the conduits at not more than a super-critical density.

Abstract: A mobile digging and backfill system for removing and collecting material above a buried utility. The system comprises a mobile chassis, a collection tank mounted to the chassis, a water pump mounted to the chassis for delivering a pressurized liquid flow against the material for loosening the material at a location, a vacuum pump connected to the collection tank so that an air stream created by the vacuum pump draws the material and the fluid from the location into the collection tank, and at least one backfill reservoir mounted to the chassis for carrying backfill for placement at the location.

Abstract: A spiral cam has a tubular shaped portion defined by an interior cavity and an exterior surface that includes a cam contour. A linear slide assembly having a length defined along a rotational axis is defined to slide lengthwise into the interior cavity of the spiral cam. The linear slide assembly allows for movement of the spiral cam along the rotational axis and prevents rotation of the spiral cam relative to the linear slide assembly. A cam roller is fixed at a position proximate to the exterior surface of the spiral cam. The cam roller is disposed separate from the linear slide assembly and within the cam contour of the spiral cam. The cam roller engages the cam contour to move of the spiral cam along the rotational axis when the linear slide assembly and spiral cam are rotated in unison about the rotational axis relative to the cam roller.

Abstract: Novel subsea excavation apparatus and methods that exert force between a subsea anchor point and an excavator using a subsea actuator. In some examples the subsea actuator is attached to an anchor point on the seabed and the excavator directly. In other examples, a guide frame is anchored to the seabed to provide anchor points fixed relative to the seabed and the subsea actuators are attached to the guide frame and the excavator. In further examples, the subsea actuators can be attached to the excavator through a carrier frame or other excavator guides rather than directly to the excavator.

Abstract: A method of dredging a pond uses a submersible assembly, having a dredging cutter and submersible pump, which is submersed in the pond. The submersible assembly is moved along a bottom of the pond by winches. A controller receives signals from a global positioning system as to the position of the submersible assembly in the pond and moves the submersible assembly in a continuous dredging pattern through the coordinated operation of the winches.

Abstract: A foldable floating vessel providing a large surface area and heavy payload capability when deployed into a liquid, such as a manure lagoon. The vessel may be folded for transport using linear actuators to fold two hulls of the vessel from a first position substantially horizontal to a second position substantially vertical. Driving and steering assemblies are provided on a center frame to which the foldable hulls are pivotably connected.

Abstract: An underwater trenching apparatus comprises at least one trenching tool; a lifting attachment point configured for attachment of a lifting means for lowering the trenching apparatus to, or raising the trenching apparatus from, its location of operation; at least two steerable endless track units for transmitting tractive effort to move the underwater trenching apparatus in use; and for each steerable endless track unit, a first mounting arrangement permitting rotation of the track unit about a vertical axis, and a first actuator configured to move the track unit about the vertical axis, and control means configured to control the action of the actuator. In alternative forms, in addition to, or alternative to the steerable endless track units, the apparatus includes height adjustment means for adjusting the vertical spacing between the main body portion and the respective endless tracks; and control means configured to control the action of the height adjustment means.

Abstract: An underwater trenching apparatus comprising a soil cutting arrangement having a forwardly disposed cutting portion and a rearwardly disposed non-cutting portion, a soil removal device configured to remove soil from a location forward of the soil cutting arrangement and barrier device located and configured substantially to prevent passage of soil to the non-cutting portion of the soil cutting arrangement. The soil cutting arrangement is typically a rockwheel or chain cutter. The soil removal device is typically a dredge pump or eductor.

Abstract: An excavation system employing a high-pressure pulsed air jet in combination with a low-pressure high velocity blower for excavating improvised explosive devices or other buried objects. The excavation system may also be employed to operate a pneumatic tool such as a cut-off tool or a chisel. The high velocity blower may incorporate a bifurcated fan duct having two air outlets. The system may include a pressure control module for regulating the from a high-pressure air source to an evacuation valve. The evacuation valve employs first and second valves where the second valve controls the operation of the first valve.

Abstract: A system and method for stockpiling material on the seafloor, the system and method using seafloor collection machines, such auxiliary or bulk cutters or collection machines, to capture seafloor material to be stockpiled. The captured seafloor material is carried in slurry form over a flexible transfer pipe to an outlet at a desired seafloor site. In a preferred form the outlet is mounted in a seafloor stockpiling hood that sits on the seafloor at the desired seafloor site and captures and contains slurry from the outlet while allowing egress of water. The captured seafloor material can then be extracted to a surface vessel.

Abstract: A fluid jet apparatus includes a body having a fluid flow path defined between a fluid inlet and a fluid outlet. A thrust device is mounted within the fluid flow path to direct in use a flow of fluid along the fluid flow path. At least a portion of the fluid flow path includes a duct. The thrust device includes a propeller mounted within the duct. The apparatus further includes a plate spaced from the fluid inlet defining a space therebetween. A plurality of elongate pivotable vanes is positioned in a generally circular orientation in the space and about the axis of the flow path and with their pivoting axes aligned with the axis of the flow path. The thrust device is adapted to rotate in a direction opposite the direction of flow of fluid through the vanes into the space.

Abstract: In one embodiment, a gas hydrate conversion system is provided comprising a floating factory, an appendage for harvesting a gas hydrate from an oceanic hydrate deposit, and one or more storage tanks. The floating factory comprises one or more heat exchange assemblies, one or more heat pump assemblies and an engine. In another embodiment, a method for harvesting hydrocarbon hydrate deposits is provided, the method comprising providing a gas hydrate conversion system; inducing release of methane from an oceanic hydrate deposit; capturing the methane from a primary methane capture zone and/or a secondary methane capture zone; and converting the methane to hydrogen and carbon.

Abstract: A system for seafloor mining. A seafloor auxiliary mining tool works a seafloor site to prepare a bench, and deposits cut ore in a gathering area. A seafloor bulk mining tool undertakes production cutting of a bench and deposits cut ore in a gathering area. A seafloor gathering machine gathers cut ore deposited in the gathering area and pumps gathered ore as a slurry to a riser base. A riser and lifting system receives slurry from the gathering machine and lifts the slurry to the surface. A surface vessel receives slurry from the riser and lifting system.

Abstract: Novel subsea excavation apparatus and methods that exert force between a subsea anchor point and an excavator using a subsea actuator. In some examples the subsea actuator is attached to an anchor point on the seabed and the excavator directly. In other examples, a guide frame is anchored to the seabed to provide anchor points fixed relative to the seabed and the subsea actuators are attached to the guide frame and the excavator. In further examples, the subsea actuators can be attached to the excavator through a carrier frame or other excavator guides rather than directly to the excavator.

Abstract: An apparatus, system and method for remediation of contamination in aquatic environments. The apparatus comprises: a vessel including an opening, and an uptake line or pump coupled to the vessel and configured to transport the contained and suspended materials from an interior of the vessel to an exterior of the vessel. The opening is facing a bottom of a body of water, and the vessel is in direct physical contact with the bottom of the body of water. The vessel has been configured to contain and suspend materials inside the vessel. The uptake line or pump housing includes an attachment selected from the group consisting of an impeller, e.g. an air and/or water cannon, a pump, and a sliding collar.

Abstract: Disclosed herein is a velocity and concentration adjustable coupling pipe apparatus equipped between a lifting pipe and a collector. The apparatus includes a coupling pipe having a lower inlet and an upper outlet which are different in diameter from each other. A seawater inlet pipe passes through a side surface of the coupling pipe to permit inflow of seawater. A slurry flow control valve is provided in the coupling pipe to control the inflow of slurry. A seawater flow control valve is provided in the seawater inlet pipe to control the inflow of the seawater. A first sensor measures concentration of slurry discharged through the upper outlet. A second sensor measures velocity of the discharged slurry. A third sensor measures velocity of slurry introduced into the lower inlet. A control panel controls the opening ratio of each of the slurry and seawater flow control valves.

Abstract: An apparatus to gather and relocate benthic life and life supporting material for use in combination with a seabed or aquatic bed dredger, plough, mole or other seabed disturbing apparatus comprising a means of gathering the benthic life and life supporting material in, on or above the seabed in front of and in the path of the draghead or said seabed disturbing apparatus, thereby preventing entrainment or damage to the benthic life, and a means of releasing the benthic organisms and life supporting material via a directional exit duct, away from the work area.

Abstract: Provided is an apparatus for collecting marine deposits.

Abstract: There is disclosed an underwater excavation apparatus (5) comprising: means (10) for disturbing or excavating an underwater location, comprising mass flow excavation means (20); and means (15) for extracting or sucking excavated material from the location to another location comprising further mass flow means (25). Means (30) to restrict spoil and/or direct spoil to the suction means (25) are provided and comprises a baffle (35) provided within a cavity (45) of a housing (40) having an open base (60). An outlet (105) of the mass flow means (20) and an inlet (110) of the suction means (25) are located within the housing (40), while an inlet (100) of the mass flow means (20) and an outlet (115) of the suction means (25) are located external of the housing (40).

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: 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: An apparatus to gather and relocate benthic life and life supporting material for use in combination with a seabed or aquatic bed dredger, plough, mole or other seabed disturbing apparatus comprising a means of gathering the benthic life and life supporting material in, on or above the seabed in front of and in the path of the draghead or said seabed disturbing apparatus, thereby preventing entrainment or damage to the benthic life, and a means of releasing the benthic organisms and life supporting material via a directional exit duct, away from the work area.

Abstract: A cutoff device with a liquid bag includes a framed housing that supports a cover having a cutoff wall. The cutoff wall is opened at a lower end thereof with a liquid bag attached along the opened lower end of the cutoff wall. The housing includes telescopic columns, upper support frames coupled to the upper ends of the telescopic columns, and a lower support frame coupled to the lower ends of the telescopic columns. The upper end of the liquid bag may be fastened to the opened lower end of the cutoff wall using a zipper. The liquid bag contains liquid, such as water, therein, with a heavy substance, such as sand, soil and powdered or granulated metal, added to the liquid.

Abstract: An apparatus, system and method for removing and treating contaminated materials on a bottom of a body of water and introducing growth packets to revitalize the treated bottom of the body of water. The structure may comprise a vessel with an open face. The vessel may be lowered down to the bottom of the body of water with the face facing down. As a result, the vessel and the bottom form an isolated space. The structure may comprise at least one agitating device(s) for stirring up the materials inside the vessel so as to form a mixture containing the sediment materials which in turn contain the contaminants. Multiple at least one pipe(s) may be coupled to the vessel for transporting the mixture out of the vessel for processing (filtering, treating with chemicals, etc.) so as to neutralize or eliminate the contaminants in the mixture. Then, the treated mixture can be returned to the inside of the vessel via the at least one pipe(s).

Abstract: A method for constructing or rehabilitating a marsh or wetland comprises the step of inserting propagatable material into liquid or slurry emerging from a high-pressure spray nozzle to form a mixture. The liquid/ or slurry/propagatable material mixture is then sprayed over a marsh or wetland area desired to be constructed or rehabilitated.

Abstract: An apparatus for dewatering dredge spoils includes a floating barge having a planar upper surface or deck. One end of the barge, such as the stern, is partially flooded or otherwise ballasted so that the deck slopes downwardly from the bow toward the stem. Dredge spoils removed from a waterway are deposited onto the bow where they flow down toward the stem. A plurality of concrete blocks on the deck form an attenuator that, in turn, defines one or more settling ponds on the surface of the barge. A weir across the stem of the barge forms an additional settling pond at the rear of the barge. Solids suspended in the water removed from the waterway settle out onto the deck when the dredge spoils are deposited onto the bow. Remaining solids suspended in the water deposit onto the deck as the water flows through the settling ponds. The relatively clear water that remains then flows back into the waterway off the stem of the sloped barge after passing through the settling ponds.

Abstract: An article of manufacture produced by a process comprising the steps of: erecting a sediment-containment structure comprising a plurality of floating boom segments; and introducing sediment into the shape formed by the sediment-containment structure. A system for building up sediment in a water-covered area comprises: a plurality of floating boom segments connected in an essentially closed shape; a sediment source depositing sediment inside the area substantially enclosed by the essentially closed shape formed by the boom segments; and a wasteweir segment disposed so as to close the essentially closed shape formed by the floating boom segments. The wasteweir segment has two posts and a removable barrier element. A method for building up land in a water-covered or water-surrounded area comprises the steps of: erecting a sediment-containment structure comprising a plurality of floating boom; and introducing sediment into the shape formed by the sediment-containment structure.

Abstract: A system for treating sediments contaminated with organic contaminants, such as polychlorinated biphenyls (PCBs) and other contaminants polyaromatic hydrocarbons (PAHs) and dichlorodiphenyltrichloroethane (DDT) includes treating the sediments with ozone to react the contaminants. The system is particularly effective for remediation of PCBs. In an in-situ system for remediating sediments in underwater sediment beds that are contaminated with (PCBs) and other contaminants, the contaminated sediments are treated with ozone with an ozonator conveyed over the sediment bed to mix the sediment with the ozone. The ozone reacts with the PCBs to form more reactive and biodegradable products. The treated sediment is then redeposited upon the sediment bed.

Abstract: An amphibious dredging vehicle includes a base including a pair of floatable pontoons linked together in essentially parallel relation; a cutterhead dredge system that is mounted on the base and that includes a cutterhead mounted on the front end portion of the base, a first directable discharge mounted to the rear end portion of the base, and a dredge pump in operative connection with the cutterhead and the directable discharge so as to develop suction at the cutterhead and to propel material from the cutterhead to the directable discharge. The directable discharge is configured so that the operator can aim the directable discharge in order to use the dredge pump to propel the amphibious dredging vehicle through water. The amphibious dredging vehicle may be used as part of a system and may be used with a method for building up land in a water-covered or water-surrounded area.

Abstract: A method of forming a trench in the bed of a body of water, the bed having an initial undisturbed upper surface, comprises suspending a pressure line from a vessel floating on the body of water, the pressure line terminating downwardly in a downwardly directed nozzle. The nozzle is positioned a small distance above the bed, and water is pumped under pressure on board the vessel and is discharged via the pressure line and nozzle downwardly against the bed surface with the water pumped at an overpressure between 0.01 bar and 20 bar and at a flow rate of 0.25 to 20.0 cm per second. The distance of the nozzle above the surface of the bed is not more than ten times the diameter of the water jet defined by the nozzle, preferably about six times the diameter of that water jet.

Abstract: A method and system for laying and burying pipe a seabed using a pipe trenching plow that is advanced along the seabed to form a continuous trench. The pipe trenching plow cuts a pilot hole in the seabed using a cutting apparatus and widens and forms a trench from the pilot hole using expandable spreading side sections. A pipe guiding sled also is used to support and guide the pipe into the trench and a trench box section retains the trench geometry as the pipe trenching plow is continuously advanced in a forward direction. The pipe trenching plow cutting the trench and burying the pipe with minimal turbidity and seabed disturbance.

Abstract: An amphibious vehicle with submersible capacity includes a first portion and a second portion, coupled by an extension, and a valve assembly. The first portion is capable of floating on water while the second portion is contemporaneously submerged beneath the surface and performing a variety of operations on the water's bottom. The valve assembly allows the vehicle to move between an amphibious mode and a submerged mode.

Abstract: A method and apparatus for collecting and processing granular material admixes granular material with a fluid to produce a slurry and then removes and processes the slurry. The apparatus enables fluid flowing into the apparatus to be directed substantially simultaneously between a first conduit for admixing granular material with the fluid to produce a slurry and a second conduit for producing suction to remove the slurry.

Abstract: A chain with opposite plane links is disclosed and may be utilized in connection with an excavator or other heavy-duty operation. Each opposite plane link includes two discrete loop portions orthogonally-oriented with respect to each other. The excavator may be, for example, a dragline excavating operation that includes a drag rope and a dragline bucket. The opposite plane link chain forms a portion of the drag system positioned adjacent to the dragline bucket and secured to the dragline bucket. In operation, the opposite plane link chain drags against the ground and experiences wear. By rotating the opposite plane link chain and reversing the ends of the opposite plane link chain, four discrete wear surfaces are sequentially positioned to engage the ground.

Abstract: A dragline excavating machine includes a gearless direct drive AC drive motor for driving each of the hoist and the drag drums in the system. The gearless AC motor is driven using a digital system which receives AC power from the utility system rectifies the power using active front end circuits, and converts the resultant DC to a frequency controlled AC using an inverter circuit. The resultant AC signal is employed to drive the gearless AC motor, resulting in reduced harmonic distortion, unity or leading power factor, and increased efficiency, reduced operating costs, and reduced mean time between failure.

Abstract: An apparatus for forming a trench in a seabed for burying a line generally consisting of a main frame, at least one buoyancy tank mounted on the main frame, a pair of endless track assemblies, each engageable in gripping relation with a side of the line for propelling the frame along the line, a pair of jet legs mounted on the main frame and communicable with a source of fluid under pressure, for ejecting high velocity streams of fluid to dislodge portions of the seabed when the track assemblies grip the line and propel the main frame along the line to form a trench and allow the line to fall therein.

Abstract: A method for automatically operating a dredge having a swingable and elevatable ladder with a cutting head having a speed comprising the steps of: providing an automatic swing sequence; providing a cutter head rate control; and providing an automatic ladder raise control sequences. A dredge in which this method is used is also disclosed.

Abstract: An apparatus for recovering oil has a bucket for skimming and collecting water and oil floating on the surface of the water. The bucket has a base plate having apertures for draining water collected by the bucket. The apertures have a preselected diameter and length to allow separation of the oil and water utilizing differences in specific gravities and viscosities of the oil and water so that the oil can be discharged from the bucket into an oil recovery tank after the water drains out of the bucket through the apertures but before the oil begins to drain out of the apertures.

Abstract: A sediment removal system includes a vessel adapted to float on the surface of a body of water, and a crawler adapted to be submerged in the body of water, wherein the crawler includes a drive system for moving the crawler across a bottom of the body of water, and wherein the crawler includes a suctioning device that supplies a suctioning force that is utilized to remove sediments resting on the bottom of the body of water. The sediment removal system also includes a sediment removal line in communication with the suctioning device and adapted to carry the sediment from the suctioning device away from the crawler.

Abstract: A method is described for containing dispersed particulate or soluble matter during contaminated sediment remediation operations in the marine environment. The preferred method comprises the use of a specially designed marine vessel that establishes a negative differential pressure gradient between a defined remediation control zone and the external ambient water environment, thereby preventing the release of contaminants dispersed during the remediation process. The preferred method also includes the use of marine vessels to remove contaminants contained within said control zone and to provide for the management of solids collected in the process.

Abstract: A dredger for removing sand, silt and like material from a river or seabed has application to clearing wrecks and providing trenches in which, for example, pipeline may be laid. The dredger includes a body having first thrusters to direct, in use, a wash of water downwards an area of seabed. The dredger also includes an additional thruster to maintain the body of the apparatus above the seabed and to propel the body through the water.

Abstract: The depth of sediment material under a body of water having a minimum desirable consistency or strength for a dredging operation is determined by an arm assembly having one end portion pivotally connected to a substantially horizontal platform, and a plate member associated with the opposite end having a predetermined cross-sectional area for encountering a resistance force from the sediment material and causing the arm assembly to pivotally rotate relative to the horizontal member. A mechanism exerts a biasing force on the arm assembly which acts against the resistance force of the sediment material. The arm assembly achieves an equilibrium position determining the depth of the sediment material having a minimum desirable consistency or strength for a particular dredging operation.

Abstract: The present invention is useful for dredging underneath a floating vessel, where a conventional dredge cannot reach the location of the material to be dredged. A neutral buoyancy pipe is attached to the end of the suction pipe and acts as an extension of the suction pipe. The vertical position of the neutral buoyancy pipe is controlled by adjusting the buoyancy of the neutral buoyancy pipe. The horizontal position of the neutral buoyancy pipe is controlled both by the anchoring system which sweeps the dredge back and forth and by a position adjusting system at the forward end of the neutral buoyancy pipe.

Abstract: A material delivery system conveys material from a supply location at or above an area surface to a working location below the area surface. The delivery system includes a supply hopper located at the supply location and having an inlet for receiving material to be conveyed and an outlet for discharging material. An injection hopper is adapted for mounting on a movable working arm of a self-propelled vehicle, and has an inlet for receiving material and an outlet for discharging material. The arm of the vehicle carries the injection hopper below the area surface to the working location. A supply line is connected to the outlet of the supply hopper and to the inlet of the injection hopper for conveying material from the supply location to the working location.

Abstract: A dredging apparatus comprising a body mounting thruster to direct, in use, a wash of water downwards towards an area of sea bed or the like, connection device to connect the dredging apparatus to a support vessel above the sea bed, said connection device including attitude adjusted to selectively adjust the attitude of the dredging apparatus in a side to side (roll) orientation.

Abstract: A bidirectional dredge provides active dredging on both forward and reverse passes across an area being dredged. The dredge includes a pivot turning mechanism that allows a turnaround of the dredge, allowing each pass to start at the terminating point of the previous pass. The dredge is driven by a winch attached to an overhead cable strung between the perimeter of the dredging area. The winch is mounted on a pivot mechanism which is operative to rotate the dredge at each end of a dredging pass. The pivot mechanism includes a pair of plates which rotate, a lower plate being attached to the dredge, and an upper plate attached to the winch. At the end of each pass, the pivot unit is activated and the dredge rotated. Following rotation, the dredge is now facing forward toward the distal end of the dredging area, and ready to effect an active dredging pass in the opposite direction, thereby utilizing every pass over the area for active dredging.