Abstract: The present invention relates to a system for subsea installation of elongate flexible element, comprising a container for allocating/storing/accommodating an elongate flexible element intended to be installed, said container being positioned on a trenching vehicle arranged to trench said elongate flexible element into the seabed, which container comprises a guide system arranged to control the release of the flexible element, and which trenching vehicle is further linked to a surface vessel via an umbilical cable whereby said vehicle is remotely operable subsea from said surface vessel wherein said guide system comprises a coiling arrangement for keeping the elongate flexible element in a defined coiled configuration inside said container.

Abstract: Retriever systems for marine geophysical survey sensor streamers. At least some of the illustrative embodiments are methods including attaching a retriever system to a sensor streamer by: wrapping a lifting bag assembly at least partially around the sensor streamer, the lifting bag assembly comprising a deflated lifting bag, a gas cylinder, and a depth trigger mechanism; and covering the lifting bag assembly with an outer cover.

Abstract: A method of joining two portions of an underwater pipeline laid on the bed of a body of water to conduct fluid and/or gas, the method including: joining a telescopic sleeve, having a first coupling head, to a first end of a first pipeline portion above the body of water; laying the first end, the telescopic sleeve, and the first coupling head on the bed of the body of water; joining a second coupling head to a second end of a second pipeline portion above the body of water; laying the second end and the second coupling head on the bed of the body of water, close to the first coupling head; roughly aligning the first and second coupling head in the body of water; and clamping the first and second coupling head to each other in the body of water.

Abstract: A method of joining two portions of an underwater pipeline for conducting fluid and/or gas on the bed of a body of water, the method including the steps of: joining a telescopic sleeve, having a first coupling head, to a first end of a first pipeline portion above the body of water; positioning the first end, the telescopic sleeve, and the first coupling head in a first given position on the bed of the body of water; joining a second coupling head to a second end of a second pipeline portion above the body of water; positioning the second end and the second coupling head in a second given position, close to the first coupling head, below the body of water; and connecting the first and second coupling head hermetically below the body of water.

Abstract: Disclosed are systems and methods for protecting subsea pipeline from damage caused by excessive stress or fatigue loading caused by geo-hazards, and environmental and operating loads. The systems and methods utilize lifting buoyancy modules capable of being attached to a section of subsea pipeline to lift the subsea pipeline off the seabed to a predetermined height over a predetermined length upon being activated by a planned or unplanned triggering event.

Abstract: An elongate sling section is disclosed. The elongate sling is cooperable with like sling sections to form a sling for use in abandonment or recovery of a pipeline. The sling section includes end-pieces at five opposite ends and complementary connector formations associated with each respective end-piece. Each connector formation is cooperable, in use when forming a sling, with a complementary connector formation of a neighbouring sling section in the sling. The sling section further includes a tensile load-bearing sling element extending between the end-pieces and a sleeve around the sling element.

Abstract: The present invention relates to an interconnection system and method for interconnecting hoses (40) for transmitting power, fluids, data, or any combination thereof in a marine environment by means of a leak-tight device (10) in the inlets (230) of which terminal covers (30) for the passage of umbilicals and blind covers (80) for sealing said inlets (230) can be interchanged, such that each of the hoses can be connected and disconnected independently. The inlets are arranged such that the umbilicals are laid according to one and the same direction and orientation.

Abstract: A method of abandoning or recovering an underwater pipeline from a laying vessel includes the steps of looping a first rope about a pulley connected to the free end of the pipeline; end-locking the first rope, on one side, to the laying vessel; and winding or unwinding the first rope, on the other side, by means of a first winch located on the laying vessel.

Abstract: A method and apparatus for deploying a plurality of seismic sensor units into a water column is provided. In one embodiment, a marine vessel is provided. The vessel includes a cable storage device disposed on the vessel, a workstation disposed on a deck of the vessel, a ramp at least partially disposed on the deck, and a node storage and handling system disposed on the vessel. The node storage and handling system comprises a cable handler disposed between the cable storage device and the ramp, the cable handler having a cable disposed thereon and the cable defining a cable path passing over the workstation during a node deployment or retrieval operation, a node storage rack positioned between a bow and a stern of the vessel, and at least one conveyor belt to transfer nodes between the workstation and the node storage rack.

Abstract: A method of abandoning a pipeline from an offshore vessel, wherein the method includes the steps of: providing a tubular member between a winch apparatus and the end of the pipeline being abandoned, the tubular member being received in a tensioning apparatus, and lowering the pipeline with the winch apparatus and the tensioning apparatus, the tensional load of the pipeline being held by the tensioning apparatus and the winch apparatus at the same time.

Abstract: A device for retrieving a subsea tubular comprises a housing. In addition, the device comprises a receiving body slidingly disposed within the housing. The body has a central axis, a lower end, and a receptacle extending from the lower end. Further, the device comprises an actuation member configured to move the housing axially relative to the body. Still further, the device comprises a plurality of cam members. Each cam member is rotatably coupled to the lower end of the body and has a cam head extending radially into the receptacle and a lever arm extending from the cam head. Each cam member is configured to rotate in a first direction to move the cam head radially inward and rotate in a second direction to move the cam head radially outward. Moreover, the device comprises a plurality of biasing members configured to bias the cam members in the first direction.

Abstract: A submarine pipeline towing equipment including: a floater of prismatic shape with a horizontal or vertical axis, with a variable or partially variable buoyancy, whose lower base is at least partially open by an opening or hole to operate as an air chamber. The floater includes: at least one inlet including a valve through which air is supplied; at least one outlet including a valve through which air is discharged; an actuator to control the valve to supply air; an actuator to control the valve to discharge air; a mechanism connecting the equipment to the pipeline; a mechanism transferring air to the floater; a mechanism actuating the actuator to control the valve to supply air in function of a predefined level in the floater; and a mechanism actuating the actuator to control the valve to discharge air in function of the distance of the floater itself from the seabed.

Abstract: A method of positioning on the sea floor, from a floating vessel, an unlaid end portion of a pipe that is being laid from its other end on the sea floor is disclosed. The method includes lowering the unlaid end portion of the pipe to a lowered position above the sea floor. Transfer of the load of the unlaid end portion of the pipe occurs from the lowering device to a line for suspending the unlaid end portion of the pipe. Lowering the line for suspending and the unlaid end portion of the pipe occurs. There is disclosed a corresponding method of recovery as well as associated apparatus. A method for effecting a subsea connection between one line and an object suspended below the surface of the sea by another line and associated apparatus are disclosed.

Abstract: A method of abandoning a pipeline being laid by a pipelaying vessel, wherein said pipeline is being held by a lay tower comprising a pipelaying and tensioning arrangement, comprising at least the steps of: (a) linking the end of the pipeline (103) to a flexible tubular handling conduit (102); (b) separately linking the pipeline to a lifting wire (104); and (c] lowering the pipeline towards the sea floor. In this way, the present invention, using the load capacity of both a flexible tubular handling conduit and a lifting wire for at least some of the pipeline lowering, is able to operate either more safely at existing depths, or at even greater depths to an ocean floor than before, or both.

Abstract: Systems for lifting drilling risers that serve as thrust collars to retain buoyancy modules on the risers and also enable the risers to be lifted using lifting lugs that are attached to the thrust collars. In one embodiment, a lifting device uses two annular ribs at the edges of a cylindrical collar, wherein the ribs have substantially constant height, but varying thickness. The thickness of each rib is greater at the position of the lifting lug, and may also be greater at its base than that its top or outermost edge. The collar may be segmented, where the segments are bolted together to assemble the device around the riser. The segments may be pre-stressed to reduce stresses during lifting. The device may include an elastomeric layer on its inner surface.

Abstract: Methods and systems are provided for replacing, repositioning and/or repairing a section of pipe within a pipeline located on a seabed. System components are delivered by a surface vessel to the vicinity of the damaged section of pipe. Piles are partially driven into the seabed adjacent the damaged section of pipe such that each of the piles has an exposed pile top above the seabed. Pile tops are employed to support load-bearing manipulator assemblies each having a hydraulically controlled manipulator arm having a a grapple capable of grasping and repositioning a section of pipe. The manipulator assemblies are operated to grasp, lift and manipulate pipe surrounding the damaged section. Other pile tops are employed to support spool supports capable of firmly holding a replacement spool piece of pipe during replacement operations. During replacement of a damaged section of pipe, the manipulator assemblies hold the pipe while cuts are made to free the damaged section.

Abstract: A method for repairing a damaged section of a subsea pipeline has the steps of cutting the damaged section at a first location on the subsea pipeline, cutting the damaged section of the second location on the subsea pipeline, removing the damaged section, affixing a first messenger line assembly to the subsea pipeline at the first location, affixing a second messenger line assembly to the subsea pipeline at a second location, and connecting a jumper line to the first messenger line assembly and to the second messenger line assembly so as to establish a continuous flowway between the first and second locations. Lift frame assemblies are positioned around the subsea pipeline at the first and second locations so as to elevate the subsea pipeline.

Abstract: The invention relates to a marine load raising and lowering system for use on a vessel, comprising: i. a first winch comprising first driving means for raising or lowering a first cable from the first winch; ii. a second winch comprising second driving means for raising or lowering a second cable from the second winch; iii. operating means connected to the first and second driving means of respectively the first and second winch for synchronising the driving means so as to perform synchronous raising or lowering of the first and second cable; iv.

Abstract: A method of abandoning or recovering an underwater pipeline from a laying vessel includes the steps of looping a first rope about a pulley connected to the free end of the pipeline; end-locking the first rope, on one side, to the laying vessel; and winding or unwinding the first rope, on the other side, by means of a first winch located on the laying vessel.

Abstract: A method for providing an umbilical connection for a well installation, the well installation being located at the bed or floor of a body of water, comprises the steps of providing an umbilical with first and second ends and prior to operative deployment of the umbilical, locating the umbilical such that at least a portion of the umbilical is substantially statically retained within the body of water. Additionally, an umbilical deployment system for a well installation located at the bed or floor of a body of water, comprises an umbilical, wherein, prior to operative deployment of the umbilical, at least a portion of the umbilical is substantially statically retained within the body of water.

Abstract: Method of positioning on the sea floor, from a floating vessel (100), an unlaid end portion (2) of a pipe that is being laid from its other end on the sea floor, comprising the steps of: (i) lowering the unlaid end portion of the pipe from a lowering device (20) on the vessel to a lowered position in the sea above the sea floor; (ii) transferring the load of the unlaid end portion of the pipe from the lowering device to means (30) for suspending the unlaid end portion of the pipe from the vessel at the lowered position in the sea; and (iii) lowering the means for suspending and the unlaid end portion of the pipe suspended thereby to the sea floor. There is also disclosed a corresponding method of recovery as well as associated apparatus. Further disclosed is a method for effecting a subsea connection between one line and an object suspended below the surface of the sea by another line, and associated apparatus.

Abstract: The present disclosure is directed to a method and system of laying pipe using a sacrificial pipe string to extend the length of an A&R winch wire. In one aspect, present disclosure is directed to a method of positioning a flowpipe on a sea floor from a vessel. The method includes lowering a first end of a flowpipe from the vessel. Additionally, the method includes connecting a pipeline end termination to a second end of the flowpipe. Also, the method includes connecting a first end of a sacrificial pipe to the pipeline end termination. In addition, the method includes connecting a winch wire to a second end of the sacrificial pipe. Furthermore, the method includes lowering the sacrificial pipe with the winch wire so that the pipeline end termination rests on the sea floor. Additionally, the method includes disconnecting the sacrificial pipe from the pipeline end termination.

Abstract: A marine pipeline installation system for laying an offshore pipeline and/or installing a subsea riser, the system at least allowing to carry out the reel lay method, wherein the system comprises: one or more storage reels for storage of pipeline, a pipeline launch tower adapted for launching the pipeline in the direction of the sea, a pipeline guide at an elevated position for guiding said pipeline to a pipeline launch trajectory along said tower, one or more tensioners, each tensioner comprising a tensioner frame and multiple tracks supported by said tensioner frame, said tracks being adapted for engaging the pipeline and supporting at least part of the weight of the launched pipeline, the tensioner frame being supported by said tower via an associated support assembly.

Abstract: A method and apparatus for storing, deploying and retrieving a plurality of seismic devices is described. The apparatus includes a ramp device coupled to a portion of a trailing end of a vessel, a cable handling device positioned between the ramp device and a leading end of the vessel to define a cable path across the ramp device, and at least one conveyor system having a first end located adjacent the ramp device and a second end extending toward the leading end of the vessel. A deployment method includes providing nodes from a storage area to a workstation where the nodes may be attached to a cable. A retrieval method includes routing a cable through a workstation to detach nodes from the cable section and transfer the detached nodes to the storage area.

Abstract: Apparatus and methods are described for subsea pipeline servicing, including line-pack testing, physical integrity testing, recovery of damaged sections of pipelines, and product removal from subsea structures. In one embodiment of the invention, a subsea pipeline service skid is provided including at least one sample collection bladder affixed to the skid and in fluid communication with a skid mounted pump dimensioned to pull a sample from the subsea pipeline. In another embodiment, a product removal bladder is provided for removal of the hydrocarbons from a subsea structure.

Abstract: A method for retrieval of self-contained, autonomous ocean bottom seismic data acquisition units secured to a non-rigid, non-conducing cable, wherein the cable is retrieved over the trailing edge of a working vessel on the surface of the water so as to permit the cable to billow out in the water column behind the vessel, thereby reducing stress on the cable and permitting greater control in cable handling.

Abstract: An articulating band saw apparatus provides a frame that includes a vertically extending section having upper and lower end portions. An elevator moves between the upper and lower end portions of the frame. A first hydraulic actuator is supported on the elevator for movement therewith. A first arm provides arm end portions, the first arm supported by the first hydraulic actuator. An end of the first arm supporting a second hydraulic actuator that is spaced away from the first hydraulic actuator. The second hydraulic actuator supports a second arm. An endless band type saw is mounted on the free end of the second arm generally opposite the second actuator. The band saw is movable by articulation of the first and second actuators and resulting movement of the first and second arms. In one embodiment, the band saw is a diamond wire saw.

Abstract: A method for installing a subsea flowline and riser assembly on a sea floor includes providing a flowline having an axis and an end connected to a hinge-over joint, and a riser having an axis and an end connected to the joint such that the axes of the riser and flowline extend substantially parallel. An end of the flowline opposite the joint is lowered to the sea floor. The end of the flowline connected to the joint is lowered to the sea floor. The joint is connected to a foundation that is installed in the sea floor. The riser is rotated about the hinge-over joint such that the riser axis is substantially perpendicular to the flowline axis. A subsea jumper is connected between an opening formed in the flowline and an opening formed in the riser so that the riser is in fluid communication with the flowline.

Abstract: A system for abandonment or recovery of a load, e.g., a pipeline or sub-sea structure, includes: at least two cables, each with a length adapted for a certain water depth and with a first end and a second end; a winch system for the at least two cables, the first ends of each cable being connected to the winch system; and a connection device for connecting the second ends of each cable to the load to be abandoned or recovered.

Abstract: A deepwater pipeline is towed to a predetermined position by a bottom towing method with a leading end of the pipeline attached to a towing vessel and the trailing end of the pipeline attached to a trailing vessel. The trailing end is supported near the seabed using the trailing vessel, while the pipeline is dragged along the seabed. A towing speed is established, and a hang off angle for the leading end is maintained by raising and lowering the trailing end to control the length of the pipeline dragged along the seabed, and thus the amount of drag applied by the seabed to the pipeline. In a method for bottom towing and submerged flying of a riser having a leading end and a trailing end, the riser is towed by the bottom towing method at a first speed until the trailing end of the riser lifts off the seabed, whereupon the towing speed is increased.

Abstract: Disclosed are a method and apparatus for laying down, abandoning and/or recovering a pipe on the sea floor. During lay-down and abandonment, the pipe is lowered by a high capacity winch to an intermediate depth, at which the loading exerted by the pipe has dropped to within the rated capacity of a low capacity winch, to which the loading is then transferred. The high capacity winch line is then recovered to the attendant vessel and the pipe lowered to the sea floor using the low capacity winch. Pipe recovery is essentially a reversal of the above procedure. In this way, the length of the line of the high capacity winch is considerably reduced, which reduces the winch size and hence cost.

Abstract: A marine seismic exploration method and system comprised of continuous recording, self-contained ocean bottom pods characterized by low profile casings. An external bumper is provided to promote ocean bottom coupling and prevent fishing net entrapment. Pods are tethered together with flexible, non-rigid, non-conducting cable used to control pod deployment. Pods are deployed and retrieved from a boat deck configured to have a storage system and a handling system to attach pods to cable on-the-fly. The storage system is a juke box configuration of slots wherein individual pods are randomly stored in the slots to permit data extraction, charging, testing and synchronizing without opening the pods. A pod may include an inertial navigation system to determine ocean floor location and a rubidium clock for timing. The system includes mathematical gimballing. The cable may include shear couplings designed to automatically shear apart if a certain level of cable tension is reached.

Abstract: An abandonment and recovery head apparatus comprises a head member. A lift member is moveably coupled to the head member. A retaining device is operable to hold the lift member in an accessible position.

Abstract: An apparatus for substantially horizontal connection of a conduit to a subsea structure: A frame connectable to and supportable by the subsea structure, the frame has a docking device operable to allow a horizontal connection device, including one of a remotely operated vehicle and a toolskid, to dock with the frame such that the frame is capable of bearing at least part of an operational load associated with the horizontal connection of the conduit to the subsea structure.

Abstract: A method for deploying and retrieving seafloor equipment modules is disclosed. A conveyor has a fixed end and a free end. The conveyor is deployed into a body of water until the free end reaches, or is proximate to, the seafloor. The conveyor is dragged through the water. The equipment modules are slidably attached to the conveyor. The equipment modules slide along the conveyor to the seafloor, where the equipment modules engage the seafloor and are secured at a fixed position.

Abstract: An apparatus for retrieving a cable or pipe buried under water in bed material comprises a shank (2) having a first surface and a fluke member (5) having a second surface. When the apparatus is towed in a towing direction, the fluke member (5) and shank (2) become buried in the bed material to a predetermined depth suitable for retrieving the cable or pipe. The first and second surfaces are arranged such that under normal working conditions the interaction between the material and at least the first and second surfaces generate opposing forces in these surfaces causing the apparatus to be maintained at substantially the predetermined depth. The apparatus may also be adapted for burial of a cable or pipe by ploughing a furrow in the bed material into which the cable or pipe is supplied using guiding means.

Abstract: Apparatus for connecting a conduit to a subsea structure includes a frame connectable to the subsea structure by a docking mechanism, a conduit handling mechanism on the frame to facilitate positioning of the conduit for attachment to the subsea structure and a second docking mechanism for attaching a mobile manipulating device to the frame. In use, the mobile manipulating device connects to the conduit by means of a pull-in rope on a winch, and travels under its own power to the subsea structure while paying out the pull-in rope. There, it docks with the frame and the pull-in rope is reeled in by the winch on the mobile manipulating device. The conduit is then connected to the subsea structure by the conduit handling mechanism on the frame. The invention also includes the method of attaching a conduit to a subsea structure using the described apparatus.

Abstract: To obviate the need for hydraulic lines, from the surface, external water pressure is used to compress a seal member and form a seal with a surrounding pip. Valve is opened at depth to allow water to act on a piston, moving it within a chamber so as to compress the seal member. A second valve may be opened so that water acts on the opposite end of the piston to release the seal member.

Abstract: A method of abandoning a pipeline (2) being laid by a vessel having an A/R system, wherein a sealine (2, 11, 13) is initially held by a pipe laying and tensioning arrangement. The method includes a step of reducing tension at sea level of the sealine (2, 11, 13), by connecting one or more buoyant members (13) to the end of the pipeline (2). The members (13) are then lowered into the sea, using a line (16). At least one member (13) is connected to the pipeline (2) through a connection (12) which allows pivoting of the member (13) so that the end of the member (13) at the end of the pipeline (2) projects upwardly from the seabed (3).

Abstract: To obviate the need for hydraulic lines, from the surface, external water pressure is used to compress a seal member and form a seal with a surrounding pip. Valve is opened at depth to allow water to act on a piston, moving it within a chamber so as to compress the seal member. A second valve may be opened so that water acts on the opposite end of the piston to release the seal member.

Abstract: A pipeline recovery tool is made from steel plates welded together instead of forging and machining. The rigged-up tool is lowered over the pipeline and engaged with the pipeline such that a fixed claw engages the collar on the pipeline. An ROV is used to cause a movable dog on the tool to engage the collar and then lock the fixed claw in position. Rigging on the fixed claw side of the tool is released. The pipeline is then lifted to the surface by a lift arm on the first end of the tool.

Abstract: A diverless process of tapping a pressurized subsea pipeline without removing the pipeline from service. The process includes the steps of lowering and landing a measurement tool onto the pipeline in order to check ovality and straightness of the pipeline. Pipe lift frames are lowered and landed onto the pipeline spaced from a chosen location. The pipeline is lifted by hydraulic actuators or mechanical screws on the lift frames. A hot tap machine and accompanying orientation frame are lowered from the surface and landed on the pipeline between the pipe lift frames. A fitting clamp is secured to the pipeline. A hot tap machine is lowered onto the hot tap fitting and orientation frame. The pipeline is then tapped with the hot tap machine.

Abstract: A diverless process of tapping a pressurized subsea pipeline without removing the pipeline from service. The process includes the steps of lowering and landing a measurement tool onto the pipeline in order to check ovality and straightness of the pipeline with the measurement tool. Pipe lift frames are lowered and landed onto the pipeline spaced from a chosen location. The pipeline is lifted by hydraulic actuators or mechanical screws on the lift frames. A hot tap fitting and accompanying orientation frame are lowered and landed on the pipeline between the pipe lift frames. The pipe lift frames are incrementally raised until the pipeline is fully seated in the hot tap fitting and orientation frame. A fitting clamp is secured to the pipeline. A hot tap machine is lowered onto the hot tap fitting and orientation frame. The pipeline is then tapped with the hot tap machine. The pipeline is thereafter lowered by deflating the lift frame bags.

Abstract: A pipeline recovery apparatus which automatically locks onto the exterior surface of a remote and/or subsea pipeline by allowing contact of interlocking pivoted bowl half sections in a downwardly depending position to rotate the bowl sections to an engaging position between the pivot points and then locking the bowl sections into that locked position.

Abstract: A pipeline recovery system (10) is disclosed having a recovery vessel (11) with an upper deck (12) and a pivotal pipeline ramp (13) mounted to the bow of the vessel. The system also includes a pipeline support bed (22) having a middle portion (23), two grated portions (24) straddling the middle portion, and a liquid collection trough (25) coupled to a seawater contaminate separator (26). A pipeline positioning winch (30) is mounted to a rearward end of the pipeline support bed. A length of a pipeline (P) is lifted from the seabed and onto the support bed where it is secured by a pair of clamping arms (40) and a vertical clamp (41), and cut with a pipe shear (42).

Abstract: A modular seismic cable handling system contained in a knockdown intermodal freight container, the freight container configured for secure containment and shipment of the system, as well as being configured to open to a platform designed to engage the main deck of a marine vessel, providing, with cable handling equipment contained therein, a relatively portable, self contained seismic cable handling system, on a vessel which may not specifically be designed for such an activity. The present invention may include a large wheel mounted in the front of the vessel for retrieving seismic cable from the water, a horizontally mounted cable handler comprising an eight wheel cable puller for pulling the cable from the wheel, urging same to the main deck level of the vessel, the cable puller comprising four pairs of tires configured for frictional, rotational contact another along their outer surface, to frictionally grab and pull a seismic cable along a linear path.

Abstract: The present invention relates to a method and means for transferring a construction--consisting of an elongated article (2,21) provided with at least one termination (3,20,40)--between a vertical position and a horizontal position and vice versa. Handling means (10,22,31,44) are attached to the termination housing (3,20,40) so as to balance and handle the termination substantially at a combined center of gravity (14,26,34,45) and thereby prevent undue bending of the elongated article (2,21) during the transfer.

Abstract: A marine seismic cable deployment and retrieval system for utilization in conjunction with a marine vessel. The present, searched for invention teaches a large wheel mounted in the front of the vessel for retrieving seismic cable from the water, and a horizontally mounted cable handler comprising an eight wheel cable puller for pulling the cable, the cable puller comprising four pairs of tires in frictional, rotational contact with one another along their outer surfaces configured to frictionally grab and pull a seismic cable along a linear path. A smaller rear cable puller further urges the cable to the rear of the vessel, and down into the main deck via a chute arrangement.

Abstract: A marine seismic cable deployment and retrieval system for utilization in conjunction with a marine vessel. The present, searched for invention teaches a large wheel mounted in the front of the vessel for retrieving seismic cable from the water, and a horizontally mounted cable handler comprising an eight wheel cable puller for pulling the cable, the cable puller comprising four pairs of tires in frictional, rotational contact with one another along their outer surfaces, configured to frictionally grab and pull a seismic cable along a linear path. A smaller rear cable puller further urges the cable to the rear of the vessel, and down into the main deck via a chute arrangement.

Abstract: A method consisting in forming a preliminary excavation along the pipe and in then digging, starting from the bottom of the preliminary excavation, two lateral trenches that are adjacent to the sides of the pipe, converge downwardly, and go deeper than the level set for the final excavation bed that lies below the pipe, so as to form respective lateral collection channels; and in removing, by cutting, the wall that separates the trenches in the region below the pipe, dumping the corresponding residual material into the lateral collection channels. The invention also relates to an apparatus, of the integral type or composed of dedicated units, for digging the lateral trenches and/or for cutting away the wall that lies below the pipe.