A system for performing underwater earthworks, the system including a power pack situated outside the water, at least one submersible operating unit for performing underwater earthworks, wherein the operating unit is connected with the power pack through power supply means, and a control unit connected via data communication means with the power pack and the operating unit and with instrumentation indicating location and depth of the operating unit.

A device for the removal of a layer of sludge and/or sand from the bottom of a wetland includes: a diving bell with an open bottom and a lower free edge; a unit for driving the diving bell with its lower edge into the layer of sludge to be removed; a dredge pump installed in the space of the diving bell and provided with an inlet for pumping up the sludge and/or an outlet to which a pipe is connected for pumping the pumped up sludge and/or sand to a collector; and a compressor for pumping gas under pressure into the space of the diving bell during dredging. The diving bell is also provided with a gas outlet for the compressed gas, the gas outlet being adjustable in height in the diving bell because the outlet is attached to a float that can float on the sludge.

Systems and methods for recovering and concentrating rare earth elements from seabed sediment deposits using seabed excavators and shipboard processing systems.

Microdredging systems comprising a pumping platform and loading platform are described. In certain embodiments, system operates autonomously and is adapted to allow the loading platform undock from the pumping platform for disposal of the removed sediment.

A spud system for a dredging vessel with a longitudinal direction includes a spud carrier for mounting a spud therein in a generally vertical stance and a spud carrier cable driving device coupled with the dredging vessel and the spud carrier for driving the spud carrier with respect to the dredging vessel. The spud carrier is moveable with respect to a longitudinal direction of the dredging vessel for advancing the dredging vessel. The spud carrier cable driving device comprises at least an aft cable drive system which extends at an aft side of the spud carrier, and a fore cable drive system separate from the aft cable drive system. The fore cable drive system extends at a fore side of the spud carrier, and each of the aft cable drive system and the fore cable drive system is coupled with the dredging vessel and the spud carrier

A method and equipment for harvesting natural gas from seabed hydrates are disclosed. The preferred equipment includes a mobile riser, a water injection nozzle, a gas collector, a gas separator, a gas compressor, a water pump, and a water boiler. A fraction of produced gas is used to heat water which is in turn injected to seafloor for dissociating gas hydrates. The preferred method of the invention comprises producing natural gas from seabed hydrates using a production ship with a moving riser installed. This method eliminates the need of drilling wells and thus cuts cost of gas production tremendously.

Microdredging systems comprising a pumping platform and loading platform are described. In certain embodiments, system operates autonomously and is adapted to allow the loading platform undock from the pumping platform for disposal of the removed sediment.

A dredge head assembly is disclosed. The assembly includes: a shroud having a generally open bottom end and a top end; a screen structure covering the generally open bottom end of the shroud; a suction pipe with a first end connected to the top end of the shroud and a second end configured to be operatively connected with a pump which induces suction; a handle connected to and extending from the shroud and having at least one grasping portion; and one or more vacuum relief valve assemblies, each comprising a valve, at least one opening configured to be in communication with water, and an actuation mechanism positioned to be accessible to a diver. Dredging systems and methods of dredging are also disclosed.

The present application discloses a dredging system for a pre-paved gravel foundation bed surface in open sea deep water, including a dredging mechanism, which includes a dredging suction head, a power component and a dredging pipeline, wherein the dredging suction head is connected with the dredging pipeline; the dredging pipeline is communicated with the power component; the dredging suction head includes at least one ridge surface suction port and at least one furrow suction port; the openings of all the furrow suction ports are lower than those of all the ridge surface suction ports; a lifting mechanism, which is connected with the dredging suction head and is used for lifting the dredging suction head to the gravel foundation bed surface; a moving mechanism, which is connected with the lifting mechanism and is used for driving the dredging suction head to move within a dredging range of the gravel foundation bed surface. By the adoption of the dredging system for the pre-paved gravel foundation bed surface in the open sea deep water of the present application, the dredging suction head includes the ridge surface suction ports and the furrow suction ports, and may suck mud on the top surfaces of gravel ridges and the mud in furrows between two gravel ridges at the same time, thereby guaranteeing the dredging quality of the gravel foundation bed surface and improving the working efficiency. The dredging system is simple in structure, convenient to use and good in dredging effect.

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.