A plough for inserting a cable into a trench in the seabed is disclosed. The plough comprises a plough share for forming a trench in the seabed and a drawbar for enabling attachment of tensile members to the plough. The drawbar is moveable relative to the plough share between a first position, in which the plough is adapted to be towed by a towing cable to move the plough share relative to the seabed to form a trench, and a second position, in which the plough is adapted to be supported by the towing cable to enable the plough apparatus to be deployed to the seabed. A cable path receives the cable and an attachment part of the drawbar is moveable relative to the plough share between the second position and a third position, to enable the cable to be received in the cable path from above the plough.

An apparatus for forming a trench in a sea floor and/or displacing material on the sea floor is disclosed. The apparatus comprises a body and front skids mounted to the body for engaging the sea floor and supporting the body. The front skids are adjustable between a first mode, in which the front skids engage the sea floor, and a second mode, in which the front skids engage the sea floor adjacent the trench and at the trench walls.

A trenching assembly lays a continuous pipeline in a trench dug in a bed with uneven bathymetry, the trenching assembly including a trench digging device having a main body; at least four ground contact units, each unit having a height adjustment device, to position each ground contact unit with respect to the main body independently. A trench cutting tool digs in the bed includes a cutting depth adjustment device, for positioning the cutting tool with respect to the main body. A detection device detects bed bathymetry. A control device simultaneously allows cooperation between the detection device, the height adjustment device of each ground contact unit, and the cutting depth adjustment device. A command device cooperates with the control device to adjustment each ground contact unit and the cutting depth adjustment device, to obtain a trench having a height difference lower than a predefined tolerance and a predetermined burial depth.

A device for installing horizontal drains in a coal combustion residual or other sludge pond consists of a trenching device that extends downwardly to the depth of required installation of the drains and an attachment through which the drains are fed during installation. The trenching device and attachment are mounted onto a carrier for floatation of the required equipment on the surface of a water-filled sludge pond. The carrier can be winched, hauled or driven across the surface of the sludge. A hydraulic system may be used to raise and lower the trenching device and attachment. The trenching device may be equipped with a chain driven blade mechanism or dredging device for the purpose of cutting a trench into the pond sludge, and a vibratory trenching device may be used to effectively liquefy the material to make the trenching device easier to pull or tow through the sludge in the pond.

A wheel cutter tractor for inserting a cable into a trench is disclosed. The tractor comprises a wheel cutter for cutting a trench, and tracks for moving the tractor relative to the trench. A cable support tray supports the cable in a first position displaced from the wheel cutter in a direction transverse to a direction of travel of the tractor, and in a second position above the wheel cutter. A cable grab and lifting device transfers the cable into the cable support tray.

A subsea plough includes a plough share coupled to a chassis, boulder clearance and spoil clearance members, and front and rear support surfaces. In a first configuration, a maximum span of the boulder clearance member in an extended position is greater than a span of the spoil clearance member. The plough may be reconfigurable to include a backfill member. A method of use of the plough is provided in a boulder clearing only mode, and optional modes of simultaneous boulder clearing and trenching, second pass trenching, and backfilling a trench to bury a flexible elongate member in a seabed.

A seabed trenching plow has a chassis, a sled and a towing assembly. The towing assembly has a pair of wings extending laterally from each side of the chassis. The wings are aligned on an axis transverse to the chassis and adapted for connection to a towing line. The transverse axis is forward of the center of gravity of the plow and rearward of the sled, affording an over the stern releasable and retrievable trenching plow of sufficient weight and strength to excavate a three meter trench in a single pass. To assess the protective capabilities of the trench, a threshold signal indicative of a desired composition of seabed-trench soil is compared with a real-time data signal indicative of the actual to produce an alarm signal when the real-time data signal is not protective-capability compliant with the threshold signal.

A seabed plow capable of over-the-stern release and retrieval is usable in any of boulder clearing, trench cutting and backfill modes. In its boulder clearing mode, the plow uses its skid in torquing configuration followed by moldboards to push boulders out of the path to be trenched. In the trench cutting mode, the plow uses the skid in the same configuration with its share and moldboards for initial trench depth and the same share and moldboards with moldboard extensions for increasing trench depth in subsequent passes. In the backfill mode, the plow uses its skid in trench-straddling configuration following a blade with a passage designed to discharge fragmented spoil directly onto the pipe being covered. Thus, a single plow can be reconfigured for all modes for release and retrieval to and from a relatively small vessel without use of heavy lifting equipment.

A seabed trenching plow has a chassis, a sled and a towing assembly. The towing assembly has a pair of wings extending laterally from each side of the chassis. The wings are aligned on an axis transverse to the chassis and adapted for connection to a towing line. The transverse axis is forward of the center of gravity of the plow and rearward of the sled, affording an over the stern releasable and retrievable trenching plow of sufficient weight and strength to excavate a three meter trench in a single pass. To assess the protective capabilities of the trench, a threshold signal indicative of a desired composition of seabed-trench soil is compared with a real-time data signal indicative of the actual to produce an alarm signal when the real-time data signal is not protective-capability compliant with the threshold signal.

A plough for burying a cable has a base frame, an upper frame member and a ploughshare support; a topside of the ploughshare support features a cable trough; and a cable guiding path extends from a front end to a rear end of the plough. The cable guiding path is arranged between the base frame and the upper frame member and along the cable trough. The upper frame member is movably connected relative to the base frame, such that the upper frame member may move between a first position. The upper frame member is arranged above the cable guiding path, and a second position wherein the upper frame member is displaced away from the cable guiding path. The whole extent of the cable guiding path is accessible from above when the upper frame member is in the second position, such that a cable may be lowered onto the cable guiding path.