Abstract: A control method includes: (a) setting a first operation mode using a first deviation threshold as a threshold to detect a deviation error in an amount of control and a second operation mode using a second deviation threshold that is higher than the first deviation threshold; and (b) selecting one of the first operation mode and the second operation mode and executing an operation of a robot.

Abstract: A field configurable autonomous vehicle includes modular elements and attachable components. The vehicle can be assembled from these modular elements and components to meet desired mission and performance characteristics without the need to purchase specially designed vehicles for each mission. The main body of the vehicle is a spherical body.

Abstract: A system for deploying and recovering an autonomous underwater device (AUD) using a surface carrier ship, includes, in addition to the carrier ship, a subaquatic vehicle (SV) guided by a connection wire connected to the carrier ship, the SV able to be positioned in a storage configuration wherein the SV is fixedly but removably joined to the carrier ship in a storage zone, or in a configuration for use, in which the SV, separated from the carrier ship, is in the water and at a distance from the carrier ship while remaining connected by the connection wire, the SV including propulsion, guiding and stabilizing systems and a station for receiving the AUD allowing it to be removably attached to the SV, the receiving station and the AUD including a complementary automated docking unit allowing the AUD to automatically dock with the receiving station during recovery and attach itself thereto.

Abstract: A submersible habitat 100 for the repair of subsea cable 11, the habitat comprising a cable maintenance environment 108 being suitable for receiving a portion of the subsea cable under repair 115 while the subsea cable 11 is submerged. The submersible habitat further comprising raising and/or lowering component 25 configured for raising and/or lowering the submersible habitat 100 relative to the subsea cable 11. The entire repair is carried out within the submersible habitat 100 without the requirement to transport any portion of the subsea cable 11 to the surface.

Abstract: A subsea manipulator for a remotely operated underwater vehicle (ROV) that includes at least one linear, oil-filled electric actuator to control a motion of the manipulator in a subsea environment is disclosed. The remotely operated underwater manipulator includes an electric actuator for each axis of motion of the manipulator, and an end effector that includes a rotational joint and a tool motor for controlling a tool affixed to the end effector. A method for changing the tool of the manipulator in a subsea environment is disclosed.

Abstract: A remote-controlled, semi-autonomous or autonomous recovery apparatus includes a drive as well as a unit for launch and recovery of an autonomous underwater vehicle. The drive is dimensioned such that a large range, such as more than 5 nautical miles, is obtained.

Abstract: A marine installation system for installing an item on a riser includes a cable extending between two supporting points, the cable being inclined relative to the horizontal; a first ROV arranged to mount the item on the cable at a first position; and a second ROV arranged to remove the item from the cable at a second position, and to install the item on the riser.

Abstract: A drilling system configured to install a tap assembly into a ship skin is disclosed. The drilling system comprises a remotely-operated underwater vehicle and a drilling assembly configured to be operated by the remotely-operated underwater vehicle. The drilling assembly comprises a frame comprising an attachment element configured to hold the drilling assembly to a surface of the ship skin. The drilling assembly further comprises a drill actuation system comprising a linear actuator attached to the frame and a rotary actuator, wherein an actuation of the linear actuator is configured to move the rotary actuator relative to the frame to install the tap assembly into the ship skin by driving the tap assembly with the rotary actuator and the linear actuator.

Abstract: Device for offshore work by machining tools, such as cutters, saws, drills and the like, with a geared motor comprising a drive, a drive coupled to the transmission and at least one multi-part housing for receiving the drive and transmission, wherein the transmission at least one through the Housing leading to the outside shaft, in particular output shaft (18), to which the machining tool outside the housing can be connected, characterized in that the geared motor is equipped by a waterproof designed housing enclosure for underwater operation, wherein the housing parts along their joining surfaces by sealing means, in particular sealing rings, and the housing on the drive side and driven side rotating surfaces, in particular shafts relative to the housing (4) are sealed by pressurizable ring seals.

Abstract: A method for performing operations using a water environment robotic system on a target section of pipeline located in an underwater environment is provided. The method includes the steps of deploying the underwater robotic vehicle into the water and visually inspecting the underwater environment to locate the pipeline and its plurality of weld joints. A cleaning operation is performed at one of the plurality of weld joints using the underwater robotic vehicle. The robotic vehicle can land on the sea floor and deploy a robotic arm to inspect the cleaned weld joint. The underwater can then swim to a next weld joint and land and perform cleaning and inspection operations, which can be repeated until all inspection sites are inspected.

Abstract: The present invention relates to a method for lowering a subsea structure to be installed on the seabed into the water through the splash zone, said subsea structure comprising subsea equipment arranged on a substantially flat support base for preventing the subsea equipment to sink into the seabed. The method according to the invention comprises: lifting the subsea structure into the air in a horizontal position in which the flat support base extends substantially parallel to the horizontal plane; tilting the subsea structure while suspended in the air from the horizontal position into a tilted position in which the flat support base is angled with respect to the horizontal plane; lowering the subsea structure into the water through the splash zone in the tilted position; and tilting the subsea structure while suspended in the water below the splash zone back into the horizontal position.

Abstract: A system and method for the installation and removal of monitoring equipment is disclosed. In some embodiments, the monitoring equipment may be installed or removed using a remotely operated vehicle. In certain implementations, the monitoring system includes a sensor assembly connectable to a tubular member, an alignment tool for installing or removing the sensor assembly to and from the tubular member, and an alignment cage for facilitating access of the alignment tool to the sensor assembly. In some embodiments, the alignment tool may be aligned with the sensor assembly for installation or removal as a result of the alignment tool being inserted through the alignment cage.

Abstract: A coupling head 8, coupled to an autonomous underwater vehicle 4 via a rendezvous head 18 that is connectable to or part of the underwater vehicle 4. The coupling head 8 has an alignment stabilizing arrangement 12 for stabilizing its alignment and position in the water below the water surface. The invention further relates to a coupling device 2 having the coupling head 8 and having a cable 10 which is detachably connectable, mechanically, electrically and in a signal-connecting manner, to the coupling head 8, and to a rendezvous device 16 having the rendezvous head 18. The underwater vehicle 4 has the rendezvous head 18 and/or the rendezvous device 16, and a coupling system 1, which comprises at least the coupling and rendezvous heads. The invention further relates to a coupling method 58 and a deployment method 56 of an autonomous underwater vehicle 4 which includes the coupling method 58.

Abstract: In various embodiments, an apparatus for use in the recovery of unmanned underwater vehicles includes a recovery vehicle configured to be coupled to a winch via a tether. The recovery vehicle includes one or more sensors for locating the unmanned underwater vehicle, a first mechanical linking device for coupling the recovery vehicle to the unmanned underwater vehicle, and a plurality of steering mechanisms for actively guiding the unmanned underwater vehicle in such a way as to allow the first mechanical linking device to capture the unmanned underwater vehicle by locking onto a second mechanical linking device of the unmanned underwater vehicle.

Abstract: A subsea docking unit 2 including an electronic module for being removably connected to a subsea docking station 1 comprises a canister B containing electronics to be connected to the docking station, and a selectively, engageable locking device for locking the docking unit to the docking station. The locking device comprises one or more arm structures adapted for being pivotally mounted into a corresponding arm holding detail on said docking unit, and an actuator means for moving said arm structure in relation to one or more corresponding arm receiving and retaining details on said docking station, whereby a releasable locking engagement and disengagement of the docking unit and docking station is obtained. The docking station correspondingly comprises arm receiving and retaining detail adapted for receiving and retaining a docking unit. The docking unit and docking station are parts of a multiphase flow meter.

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: 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: Subsea connection apparatus comprising: a frame (5) connectable to a subsea structure (1); docking means for connecting the frame to the subsea structure; conduit handling means (10) positioned on the frame to facilitate the positioning of a conduit for attachment to a subsea structure; and means for docking a subsea tool and/or vehicle (20) onto the frame.

Abstract: To install a modular seabed processing system (1) on a seabed, a monopile foundation (3) is first lowered down and driven into the seabed. A docking unit (4) is lowered towards the installed foundation (3) so that a mating clamp system (6) mounted on the docking unit is aligned with a spigot (5) on the foundation. The clamp system then clamps the spigot to fix the docking unit onto the foundation. Flowlines (2) and an electrical power connector plug (18) are connected to the docking unit. A first retrievable substantially autonomous module (8) is lowered and connected to the docking unit (4) by a multi-bored connector (10, 11) and the plug (18) on the docking unit is engaged by a corresponding socket (17) on the module. Isolation valves (14, 16) in the docking unit and module are opened so that the module (8) is able to act on fluid received from the flowlines (2) via the multi-bored connector (10, 11).

Abstract: A system that is usable with subsea wells that extend beneath a sea floor includes a station that is located on the sea floor and an underwater vehicle. The underwater vehicle is housed in the station and is adapted to service at least one of the subsea wells.

Abstract: An apparatus for preventing or minimizing decompression illness in a scuba diver, consisting of a first safety bar, at least one first cable attached to the first safety bar, and an oxygen delivery system. The first cable supports the first safety bar at a predetermined depth. The oxygen delivery system consists of an oxygen tank, an oxygen delivery line, a manifold attached to the oxygen delivery line, and a plurality of regulators attached to the manifold. When the oxygen delivery system will be used by only one scuba diver, the oxygen delivery line can be connected directly to a single regulator without the manifold. The first cable and oxygen tank are attached to a float, which is either secured to a boat or platform via a tether line or anchored to the sea floor. In an alternative embodiment, the first cable is attached directly to a boat or platform, and an oxygen supply is provided on the boat or platform.

Abstract: To install a modular seabed processing system (1) on a seabed, a monopile foundation (3) is first lowered down and driven in to the seabed. A docking unit (4) is lowered towards the installed foundation (3) so that a mating clamp system (6) mounted on the docking unit is aligned with a spigot (5) on the foundation. The clamp system then clamps the spigot to fix the docking unit onto the foundation. Flowlines (2) and an electrical power connector plug (18) are connected to the docking unit. A first retrievable substantially autonomous module (8) is lowered and connected to the docking unit (4) by a multi-bored connector (10, 11) and the plug (18) on the docking unit is engaged by a corresponding socket (17) on the module. Isolation valves (14, 16) in the docking unit and module are opened so that the module (8) is able to act on fluid received from the flowlines (2) via the multi-bored connector (10, 11).

Abstract: A method for carrying out work on an object which is present under water, in particular, a shipwreck, wherein persons make their way to the object under water and carry out the work in artificial light. A cover is provided over the object, which cover in the main abuts the bottom on which or in which the object is present in surrounding relationship with respect to the object. The cover encloses a space in which persons can work and it comprises an entrance for admitting persons to the space.

Abstract: A method for attaching subsea manifolds to subsea pipelines which includes attaching a tee member into the pipeline on a vessel, running the portion of the pipeline through support structures which would not pass the manifold, and to an underwater location between the vessel and the ocean floor, then attaching the manifold to the tee section, and then lowering the tee and manifold to the ocean floor.

Abstract: A novel automatically submersible and refloatable underwater tubular pipe platform geometric structure adapted for deployment in underwater target monitoring systems and the like, wherein the floating upon the surface of the water enables flooding of the pipe structure and its submergence, and the introduction of compressed air drives the water out of the pipe platform structure to enable its automatic re-floating.

Abstract: A dive rescue search device has a stanchion with a locating mechanism for the device mounted thereon and a search area determining device based on a reel of rope cooperating therewith to properly direct the search.

Abstract: A system and methods for diverless replacement of a functional component installed on a service unit on a sea bottom-based installation is provided. The component is fitted releasably into the service unit as an insert with an externally extending maneuverable part. The replacement is carried out by a tool mounted on a remotely operated vehicle (ROV). The invention utilizes ROV supported weight compensation means for compensating the weight of the component in order to maintain the ROV in a substantially neutral buoyancy state during operations. The weight compensating means comprises a separate adapter element having the same weight as the component to be replaced. The adapter element or adapter are equipped to be releasably supported by the ROV tool. The adapter has an upper end and a lower end and a central axis extending therethrough, and a centrally extending throughgoing opening having transverse dimensions larger than the largest transverse dimension of the component.

Abstract: A dive rescue search device has a stanchion with a locating mechanism for the device, a marking device to assist the diver and a search area marker to properly direct the search.

Abstract: The instant invention is an improved multi-purpose dive reel which automates underwater line-handling. The improved multi-purpose dive reel includes an anti-fouling line control system that includes a flexible line wiper and line exit guide. The reel is manufactured using a high impact reinforced polymer construction which is lightweight, inexpensive and not effected by the often corrosive marine environment. The improved dive reel has an on/off spool lock switch and contoured smooth surface including a comfort grip containing a lanyard attachment loop. Optionally, the reel may further include a ratcheting spool lock switch, a luminous polymer pigment and a wave-washer spool tension control.

Abstract: A water profiling apparatus having a streamlined body with a traction drive capable of repeatedly profiling along a moored or suspended cable or wire, for transporting sensing and sampling equipment through a body of water, such as an ocean, lake or river. The water profiling apparatus is able to operate unattended on a pre-programmed schedule over long periods of time, profiling to full ocean depth, with the option of changing its schedule depending on the observations it makes or operating situations encountered.

Abstract: There is disclosed a means and a method for inspecting and repairing a propeller on a propeller shaft on a ship. The ship is in the water. A truss is positioned on the propeller shaft. A habitat bag is positioned over the upper part of the propeller and is attached to the truss. Then, the truss is inflated with air. An inspector and/or a repair person can enter into the habitat and work in a dry environment while the ship is in the water. There is no need, in many instances, to place the ship in a dry dock.

Abstract: A CO.sub.2 deep sea throw-away system includes a floating offshore base (2), receiving liquefied CO.sub.2 carried by a liquefied CO.sub.2 carrier (1). The base has a throwing pipe (3) and a throwing pipe outlet (4) to deliver the liquified CO.sub.2 in an enclosing bag (11) in the sea at a depth where a liquid phase state of the liquified CO is maintained. An unmanned submersible working boat (10) is provided and has a plurality of capsules (26) mounted thereon. Each capsule contains an enclosing bag (11) to enclose the liquified CO.sub.2. The boat transports the capsules into the sea at a depth where a liquid phase state of the liquified CO.sub.2 is maintained and operates to enclose the liquified CO.sub.2 in the enclosing bags (11). The liquified CO.sub.2 in the enclosing bag (11) and the capsule (26) are then released so as to fall onto the sea bottom. Also, a control base (9) is provided on the offshore sea to control the unmanned submersible working boat (10).

Abstract: A system for recovering petroleum products such as oil from a sunken oil transportation vessel. The system includes first and second flexible conduits communicating with the oil-containing compartments. The conduits are released upon the vessel becoming submerged. The free ends of the conduits are connected respectively to a pump for pumping sea water into the compartment to displace the oil. The second conduit is connected to a recovery container on the surface. The displaced oil is forced through the second conduit to the recovery container. The recovery container is, in the preferred embodiment, provided on a fleet or network of recovery vessels which then transport the recovered oil to port for off-loading. In the preferred embodiment, the flexible conduits are associated with a float which releases or carries the conduits to the surface so that underwater recovery operations are minimized.

Abstract: Embodiments of a pipeline repair habitat are disclosed which may be used to facilitate the repair of vertical underwater pipelines or risers. Two hollow, half-cylindrical shells are provided which form a stable, rigid shell around the section of pipe to be repaired. Structure is provided for introducing an atmosphere into the habitat which is breathable while most repairs are accomplished. Under certain conditions a non explosive atmosphere which is not breathable is introduced into the habitat so that welding may be safely performed. Various useful accessories are provided including an elevator by which a person accomplishing repairs may move up and down within the pipeline repair habitat.

Abstract: A method and apparatus for connecting vessels which have equal or different internal pressures, or which are surrounded by equal or different pressures to permit transport between the connected vessels. An articulating apparatus for connecting vessels which comprises: (a) a first vessel having on one side thereof an orifice; (b) a first rotary bearing and seal associated with the circumference of the orifice; (c) a first hollow wedge shaped segment having first and second sides with a first side thereof rotationally associated with the first rotary bearing and seal; (d) a second rotary bearing and seal associated with the second side of the first hollow wedge-shaped segment; and (e) a second hollow wedge-shaped segment having first and second sides with a first side associated with the second rotary bearing and seal, the second hollow wedge-shaped segment being capable of rotation relative to the first hollow wedge-shaped segment.

Abstract: A carriage movable in waste including: a body having a float at its upper portion and a weight at its lower portion to suspend in the water, the body having an opening in its abdomen; a thrust fan provided on a back of the body, the fan being rotatable in a normal or reverse direction thereby enabling the body to translate in the water and to suctionally attach itself onto a wall or leave the wall; a skirt provided around the opening formed in the abdomen of the body to contact the wall thereby maintaining the bodies interior to a negative pressure as the body suctionally attaches itself onto the wall; and a drive wheel provided on the abdomen of the body to contact the wall upon suctional attachment on the wall. This underwater carriage can move on a vertical wall, have small dimensions and be lightweight.

Abstract: A method for the reparation of a submerged pipeline for faults includes installing a habitat system proximate the reparation zone, clearing the pipeline in the fault zone, aligning a plurality of sets of half pipes with the reparation zone for installation surrounding the reparation zone, welding the two longitudinal ends of the first half pipe of each of the plurality of sets of half pipes to the two longitudinal ends of the second half pipe of each of the plurality of sets of half pipes to form a plurality of sleeves, welding the two reparation sleeve ends to the pipeline to join the reparation sleeve to the pipeline to form an annular space between the pipeline and the reparation sleeve, and injecting resin into the annular space.

Abstract: All points at which torque is usually applied to subsea equipment, particularly in the search for and production of oil, are centralized at a single panel upon which standard kinds of connecting terminals fitted with sockets are clearly marked and corresponding to torque working points, in order to make access easier by remote operated vehicles.Individual connection between applying points and the sockets on the panel is achieved by means of flexible devices.

Abstract: A robot comprised of a platform, tendons and a control system. The platform contains proximal reels for the storage, retraction and extension of the tendons, with each tendon having a reel. The distal ends of the tendons are anchored at separate locations. The work space of the robot is primarily determined by the location of the tendon anchors, although it can be expanded by having pairs of tendons cross each other in between the platform and their distal anchor points. The platform is translated and rotated in the work space by controlling the lengths of the tendons extending from their respective reels. A master computer located on the platform controls each reel and coordinates their actuation. When used with at least six tendons and reels, the platform has six degrees of freedom: translation in three axes and rotation about each of the foregoing three axes. Numerous types of end effectors can be mounted on the platform, thus enabling the robot to perform a wide variety of tasks.

Abstract: A method of positioning a pipeline across a water-course. A first coffer dam is formed to isolate a first area of the water-course and a first part of the pipeline is then positioned in the first area. A chamber is put at the distal end of the first part of the pipeline. The chamber has an upper portion with an open top and a lower portion as opposed ports to receive the pipeline. The first coffer dam is then dismantled. A second coffer dam is formed to isolate a second area of the water-course. The second area includes the chamber. The first and second areas of the water-course are positioned to include the path of the pipeline across the water-course. A second part of the pipeline is located in the chamber and a aligned with the first part of the pipeline. The ports are sealed around the pipeline. Water is removed from the chamber to allow make-up of the pipeline by joining of the first and second parts within the chamber. The upper portion of the chamber is removed and the second coffer dam is dismantled.

Abstract: A flexible envelope, of fabric, plastic sheet or similar material, is made buoyant by being filled with water of lower salinity than the surrounding medium, and used to lift loads underwater. The lift can be generated in situ by pumping water into the envelope after it has been attached to the load through a hose form the surface, and reduced by either releasing the water from within the envelope or pumping it back to the surface again. By combining these two operations, the lift can be exactly controlled. Several envelopes can be used to lift a single load, and the load itself can be made up of small objects placed in a suitable container by other means. The envelopes may be towed into position, or may be provided with their own means of propulsion.

Abstract: A support system for supporting an underwater work platform includes a work platform submerged in a body of water and a support structure supported by the body of water above the work platform. The work platform is supported by a plurality of cables connected between the support structure and the work platform. Motions of the support structure in the body of water are sensed, and the length of the cables is adjusted in response to the sensed motions of the support structure so that the work platform can be maintained stationary even when the support structure is subjected to wave forces and currents.

Abstract: A pipe attachment and receiving apparatus for severing and handling a subsea pipe. The apparatus including a chassis adapted to mount onto a subsea pipe and clamps for clamping the chassis to the subsea pipe. An interface assembly is connected to the chassis. The interface assembly is adapted to extend and retract relative to the chassis. The interface assembly is adapted to receive modules. The modules are adapted to be releasably mounted to the interface assembly. A cutting module is mounted to the interface assembly to cut the pipeline and a docking module is mounted to the interface assembly to repair the pipeline with a replacement spool.

Abstract: A pipeline connector apparatus comprising piston actuated means for gripping and sealing a pipe comprising a cylinder having an inner surface, the cylinder having a first groove for receiving a spring biased ring, a piston movable in the cylinder and actuating one of the gripping and sealing means, the piston having a second groove holding a spring biased ring. A plurality of compressible and relaxable spring biased rings are provided, each having an outer surface and a radius such that each will compress within the second groove and will expand within the first groove. The outer surfaces of the different rings have shoulders of different widths which allows the operator to control the piston stroke in the cylinder. The apparatus further comprises a means for predetermining and/or monitoring the displacement of the pistons.

Abstract: A modular caisson for use in performing underwater tasks in a dry environment includes a plurality of interconnected modules. The end of at least one of the modules is equipped with an end cover through which piping or other equipment can be passed into the caisson without leakage of water into the caisson. In a preferred embodiment, the end cover includes flexible doors. The caisson can be supported by a transport vehicle, or it can be anchored to piles by means of guides formed on the outside of the modules. As a result, the caisson can be prevented from exerting undesirable loads on the piping or other structure being worked upon inside the caisson.

Abstract: A flexible, submersible compartment for underwater work in dry conditions which is particularly suited for work on petroleum drilling structures. The flexible, submersible compartment includes a flexible bell of reinforced elastomeric material having an opening surrounded by a collar at its top portion. A rigid platform-brace having a contractible outer ring is located beneath and attached to the flexible bell. The platform-brace also includes an inner ring which can be secured to a submerged portion of the petroleum drilling structure. In the event of contact with a rigid obstacle, the flexible bell adapts to the shape of the obstacle while the platform-brace contracts.

Abstract: A device for depositing and recovering a heavy load on the ocean floor including a first part which can be attached mechanically to a handling and recovery cable and a second part which can be attached mechanically to the load to be deposited. The second part is buoyant and includes means for attaching it flexibly to the load. Each of the two parts include a cylindrical joining element, one of which fits inside the other. The device also includes means for locking and unlocking the cylindrical joining elements.

Abstract: Mechanically cooperating assemblies on an undersea vehicle and an instrumation target assure the making of a rigid coupling for passing electrical, optical or fluid information between the vehicle and the instrumentation and reduce the complexity of such a coupling from a three-dimensional to a two-dimensional maneuver by the vehicle. An undersea vehicle locates a pair of spaced-apart vertical cables which are attached to an instrumentation target assembly and engages them anywhere along their length with a converging grabber assembly mounted on the forward moving underwater vehicle. After engaging the cables, the grabber assembly merely slides along the cables toward the instrumentation target assembly.

Abstract: A recovery system for a submerged instrument that includes a buoyant member and an electrically promoted magnetic flux diversion device comprising a pair of pole pieces, a permanent magnet disposed substantially centrally between said pole pieces, and a release plate comprising ferromagnetic material bridging one end of said pole pieces, the pole pieces and permanent magnet forming tow flux paths with the metal release plate forming a portion of one of said flux paths. A control winding associated with the pole pieces are disposed for producing a momentary magnetic field opposite to that of the permanent magnet to divert the flux path from the path that includes the release plate to the other flux path. A remotely activated electrical pulse to the control winding diverts the flux path and releases the release plate form the pole pieces allowing the marker buoy to rise to the surface for recovery of instrument or device to which the buoy is attached.

Abstract: The immersion and positioning of a sink element on the sea bottom is controlled by providing a weight system suspended from the sink element. An auxiliary surface vessel has a control cable directly connecting the vessel with the weights system suspended from the sink element. The sink element is immersed with the weight system suspended therefrom and therebelow until the weight system contacts the sea bottom and the sink element reaches a preselected stabilized equilibrium elevational position above the sea bottom. Then the sink element can be laterally displaced while substantially maintaining the height of the sink element above the sea bottom by having the auxiliary surface vessel pull on the control cable connected to the weight system in a direction of movement towards the final location site. The weight system contacts the sea bottom during this movement to help control the movement of the sink element and minimize the influence of outside forces.