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 dredging head assembly for deploying on the bed of a body of water, is provided, the assembly comprising a cutter housing having a cutting opening for extending over a section of the bed from which material is to be removed; a cutting assembly disposed within the cutter housing, the cutting assembly operable through the cutting opening in the cutter housing to loosen material from the bed; and an outlet opening in the cutter housing for removing water and entrained material from within the cutter housing under suction; wherein the cutter housing comprises a plurality of holes therein, in use water being drawn into the cutter housing through the holes under the action of reduced fluid pressure within the cutter housing. A dredging assembly comprising the dredging head assembly and a method of dredging are also provided.

A hydraulic excavation apparatus may be used for providing access to a pipeline buried under shallow water or in wetland locations, for example, in order to install an electro-mechanical clamp on the pipeline. This clamp can then be used for connecting externals anodes to the pipeline, for monitoring the level of corrosion protection of the pipeline, or for any other purpose.

De-trenching apparatus (100) for extracting a buried line, such as a cable or pipeline, is disclosed. The de-trenching apparatus comprises a channel (112) configured to receive a buried line to be extracted, the channel comprising a first flared opening (114) at a front end of the de-trenching apparatus and a second flared opening (115) at the rear end of the de-trenching apparatus, the first and second flared openings each having a curved surface (111) configured to support the line during extraction, and material removal means for removing material from around the buried line ahead of the de-trenching apparatus.

An excavator bucket has several embodiments adapted for use underwater. A first embodiment includes a front lip and a heel section, with suction ports through the heel section. Another embodiment includes a grated or skeleton bucket with apertures communicating with a suction hopper having suction ports. Yet another embodiment includes a drum grate rotating inside a fitted shroud offset from and conforming to a swept volume of the rotating grate, with the shroud having suction ports, and another embodiment includes a first hopper with rotating arbors forming a crushing screen, communicating with a second suction hopper having one or more suction ports.

Embodiments of the invention provide apparatus and method for seabed resources collection. The apparatus comprises a main module and a plurality of seabed resources collecting devices releasably attached to the main module, wherein the main module and the plurality of collecting devices are configured to be launched from a surface vessel towards a seabed; the main module includes a control module which is configured to determine a mining path for each of the collecting devices based on characteristics of the seabed, control each of the collecting devices to collect seabed resources along the determined mining path and control transfer of the seabed resources collected by the collecting devices, wherein each collecting device is configured to be released from the main module after the apparatus is launched, and to collect seabed resources along the mining path determined by the main module after being released.

A submarine shallow hydrate exploitation device, including an exploitation unit and a collection unit. The exploitation unit includes: a submarine ship working on a seabed; a drain chamber arranged on the submarine ship, wherein a pressure valve is arranged at a top of the drain chamber, one-way drain holes are formed in a bottom of the drain chamber, and water from massive hydrates is controlled to be discharged out of the drain chamber; a high-speed spiral bit configured to mine and convey sediments; a rotary ring arranged at an inlet end of the drain chamber and configured to connect the drain chamber with the high-speed spiral bit to provide rotation power for the high-speed spiral bit; a steering arm arranged on the submarine ship and configured to realize a rotation of the high-speed spiral bit; a crusher arranged on the submarine ship and configured to crush dried massive hydrates.

A dragging apparatus has a carriage body. The carriage body has at least one attachment portion. The attachment portion is configured to connect the carriage body to a drag barge. At least one ripper shank is disposed on the carriage body. The ripper shank extends downwardly from the carriage body. A method for operating a dragging apparatus includes providing a barge and a dragging apparatus, and then lowering the dragging apparatus to a floor or bottom of a body of water to agitate the floor or bottom.

A submarine shallow hydrate exploitation device, including an exploitation unit and a collection unit. The exploitation unit includes: a submarine ship working on a seabed; a drain chamber arranged on the submarine ship, wherein a pressure valve is arranged at a top of the drain chamber, one-way drain holes are formed in a bottom of the drain chamber, and water from massive hydrates is controlled to be discharged out of the drain chamber; a high-speed spiral bit configured to mine and convey sediments; a rotary ring arranged at an inlet end of the drain chamber and configured to connect the drain chamber with the high-speed spiral bit to provide rotation power for the high-speed spiral bit; a steering arm arranged on the submarine ship and configured to realize a rotation of the high-speed spiral bit; a crusher arranged on the submarine ship and configured to crush dried massive hydrates.

The invention relates to a manoeuvrable trailing dredging vessel comprising; a vessel propulsion member coupled with a propulsion shaft provided with a single gear for driving the propulsion member, a drive system having a central drive shaft coupled with the vessel propulsion member for providing power to the vessel propulsion member, a transmission device having at least a trailing transmission shaft provided with a trailing pinion and a sailing transmission shaft provided with a sailing pinion, wherein the central drive shaft is coupled with the single gear of the propulsion shaft through one of the trailing transmission shaft and the sailing transmission shaft.