Abstract: A buoyancy system is for a fish pen. The fish pen has an enclosure for keeping fish confined in the fish pen, the enclosure being secured to an inner flexible buoyancy body floating on a water surface. The buoyancy system has an outer buoyancy body on the outside of the inner buoyancy body. The inner buoyancy body is attached to the outer buoyancy body with a mooring so that the outer buoyancy body and the inner buoyancy body move independently of each other relative to waves.

Abstract: A nonlinear control design technique capitalizes on a wave energy converter comprising a shaped buoy having a variable geometry wave energy. For example, the shaped buoy can have an hourglass (HG) geometry having a variable cone or steepness angle. The HG buoy is assumed to operate in the heave motion of the wave. The unique interaction between the HG buoy and the wave creates a nonlinear cubic storage effect that produces actual energy storage or reactive power during operation. A multi-frequency Bretschneider spectrum wave excitation input was simulated for the HG design both with constant and varying steepness angle profiles which demonstrated further increased power generation with changing sea states for the variable design.

Abstract: An unmanned, autonomous, self-sustaining and self-repairable floating platform which is positioned at a fixed location within the sea, capable of constantly monitoring, without having to be removed, a specific maritime zone including a sea surface area and the aerial and underwater space pertaining to this sea surface area, the platform comprising telecommunication means adapted to exchange surveillance related information with a Command, Communication and Control center. The platform comprises a deck maintained well above sea surface through a connecting member with an underlying, fully or partially submerged, system of floaters and is equipped with a variety of sensors and surveillance systems such as radar, Li-dar, sonar, electromagnetic, unmanned vehicles (UAVs, UUVs and USVs), active and passive self-protection systems as well as research and rescue equipment.

Abstract: In various embodiments a variable buoyancy profiling float is disclosed. The variable buoyancy profiling float may comprise a spherical glass housing comprising a first hemisphere and a second hemisphere. The first and second hemispheres may be coupled by a partial vacuum within the spherical glass housing. A buoyancy system may be located at least partially within the spherical glass housing. The buoyancy system may be configured to provide variable buoyancy control to the variable buoyancy profiling float. A sensor bundle may be mounted to the spherical glass housing and may be configured to measure at least one environmental parameter.

Abstract: A seismic survey system for recording seismic data underwater. The system includes first plural buoys configured to descend to a first predetermined depth (H1) in water, at least one buoy having a seismic receiver for recording the seismic data; a first vessel configured to launch the first plural buoys; and a first acoustic system attached to the first vessel and configured to detect a position of the at least one buoy while underwater. The at least one buoy is instructed to maintain the first predetermined depth (H1) underwater while recording the seismic data.

Abstract: Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled or buoyancy-driven underwater vehicles are disclosed herein. An underwater vehicle configured in accordance with one embodiment of the disclosure, for example, can include a hull and a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed. The first liquid has a first compressibility and thermal expansion coefficient. The underwater vehicle can further include a compressibility and thermal expansion coefficient compensation system comprising a container filled or at least partially filled with a compressible liquid comprising silicone in the compartment. The compressible liquid has a second compressibility higher than the first compressibility and second thermal expansion coefficient higher than the first thermal expansion coefficient.

Abstract: A buoy for use in reducing the amplitude of waves in water and a system making use of plural buoys to create a floating breakwater. Each buoy is arranged to be constrained, e.g., connected to an anchor, and comprising a body e.g., a cylindrical member having at least one outwardly projecting fin, that is configured to be resonant and impedance matched. The buoy and anchoring approach allows for self-tuning to the changes in the wave spectrum due to the tidal or storm surge induced changes in the water depth. The body of the floating buoy is not limited to circular cylinder, and could be square, hexagonal, triangular, etc. but must have at least one exterior mounted fin.

Abstract: The present invention is an apparatus and method directed to a variable buoyancy gas-can buoyancy module or buoy having a flexible barrier between a variable volume gas chamber in the gas-can hull and water in the hull. More specifically, the present invention is directed to a variable buoyancy module for a Self Supporting Riser (SSR) wherein the tension in the SSR may be increased/decreased by increasing/decreasing the variable volume of a chamber formed by a flexible liner that provides a barrier between the variable volume gas chamber in the gas-can hull and water.

Abstract: A tube buoyancy can system for tensioning a top tension riser. In some embodiments, the system includes a tubular can coupled to the top tension riser and a pressurized gas system configured to selectably inject pressurized gas into the tubular can. The tubular can includes an enclosed upper end having at least one closeable opening therethough, an open lower end configured to allow seawater to flow freely into and out of the tubular can, and an inner surface extending therebetween. The inner surface is devoid of structural obstructions which substantially inhibit the free flow of seawater through the lower end. When the opening is open, the tubular can is ballasted by seawater. When the opening is closed and pressurized gas is injected into the tubular can, the tubular can is de-ballasted of seawater.

Abstract: Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled or buoyancy-driven underwater vehicles are disclosed herein. An underwater vehicle configured in accordance with one embodiment of the disclosure, for example, can include a hull and a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed. The first liquid has a first compressibility and thermal expansion coefficient. The underwater vehicle can further include a compressibility and thermal expansion coefficient compensation system comprising a container filled or at least partially filled with a compressible liquid comprising silicone in the compartment. The compressible liquid has a second compressibility higher than the first compressibility and second thermal expansion coefficient higher than the first thermal expansion coefficient.

Abstract: This invention relates to a GPS navigation system comprised of a submerged vessel having a navigation processor associated via buoyant cable with a buoy having a GPS device; wherein the cable contains: a data link between the vessel and the GPS device; and a location device for the determination of the location of the cable to the vessel; and wherein the processor computes a GPS position relative to the vessel. The invention also relates to a navigation process comprising the steps of: attaching a cable between a buoy and a submerged vessel; providing a GPS data relative to the buoy and cable location data over the cable to the submerged vessel; and using the GPS position of the buoy and location data to compute the GPS position of the submerged vessel.

Abstract: A system for and method of limiting and controlling the unintended subsurface release of an exploration or production riser system is provided including one or more means for anchoring the riser or casing stack at one or more pre-determined points upon the length of the riser, and/or on the housing of an associated buoyancy chamber or the like, and/or on a particular portion of the riser as dictated by the operational environment, and/or on an anchor portion secured in the sea floor; and a network of restraining members disposed on the anchoring means. A lower anchoring portion includes one or more anchors disposed in communication with a wellhead, or with the sea floor or below the sea floor mud line, or with a well casing portion. A network of restraining members forms an essentially continuous connection from the buoyancy member portion to said bottom anchor portion.

Abstract: Disclosed is a buoyancy device for tensioning an elongate vertical (or quasi vertical) subsea structure at a point below the sea surface, anchored at its bottom. The device comprises as its main buoyancy elements a plurality of hollow elongate objects, and further comprises at least one auxiliary buoyancy element comprising a solid buoyant material. Ideally, the solid buoyant material provides enough uplift to maintain the device afloat should the main buoyancy elements be flooded. A riser apparatus comprising such a buoyancy device is also described.

Abstract: A floatation device is disclosed that comprises a container 10 containing a liquefied gas, a gas chamber (60, FIG. 2) and a remotely operable device 29. The remotely operable device is switchable between a closed state in which fluid communication between the container and the gas chamber is prevented, and an open state in which fluid communication between the container and the gas chamber is enabled and vaporization of the liquefied gas charges the gas chamber with gas. The liquefied gas may be liquid nitrogen and the container may be heat insulated with an insulating vacuum cavity. A buoyancy unit (40, FIG. 2) which comprises a rigid enclosure (42, FIG. 2) defining an interior volume and a flexible diaphragm (55, FIG. 2) that partitions the interior volume into first and second chambers is also disclosed.

Abstract: An easily deployable data relay buoy, in some embodiments, has a diesel powered alternator and storage battery, providing long service life. The data relay buoy has mechanical characteristics that allow it to maintain antenna stability in the presence of seas states from at least zero through four and to survive in sea states up to sea state six.

Abstract: A buoyant actuator (10) for use in apparatus (11) for harnessing ocean wave energy and for converting the harnessed energy to high-pressure seawater. The buoyant actuator (10) comprises a body (21) defining a chamber (23) having a pliant outer skin (27). The chamber (23) is adapted to contain matter and a hydrodynamic property of the body (21) is selectively variable by varying the matter within the chamber (23). The variation to the hydrodynamic property may comprise a variation to the buoyancy (either positively or negatively) or a variation to the response area (such as the volume or shape) of the body (21), as well as a combination thereof. The variation to the matter may comprise addition of matter to, or extraction of matter from, the chamber (23). The matter may comprise a solid, liquid or gas, as well as any combination thereof. In the arrangement shown, the matter comprises foam spheres (53).

Abstract: Provided is a profiling float that can minutely and surely control effective buoyancy acting on the float in itself, and usage of the profiling float. The profiling float according to the present invention is equipped with a float chamber forming an airtight internal space, a fluid storage part provided in the float chamber and storing a fluid for control of buoyancy, a bladder provided at the exterior of the float chamber, in the interior of which the fluid for control of buoyancy is filled to change a volume thereof, thereby controlling buoyancy acting on the profiling float, a pump mechanism for transferring the fluid for control of buoyancy between the bladder and the fluid storage part, and a driving source for driving the pump mechanism, wherein the pump mechanism is composed of a gear pump.

Abstract: Described here are compositions, methods and apparatus for biological and physical geoengineering. Disclosed are inorganic particles, prill, pucks, or floats for dispersal on a body of water, the compositions having several properties: 1) positive buoyancy, 2) a sustained-release matrix for delivery of iron, calcium, magnesium, zinc, copper, molybdenum, manganese, cobalt, boron, selenium, vanadium, chromium, nickel, sulfur, nitrogen, phosphorus, silicon, preferably as a combination thereof, at biologically efficacious levels, and synergically, 3) a light-reflective surface for increasing planetary albedo when dispersed over large surfaces. These compositions are found to A) increase yields for pelagic aquaculture, B) increase carbon sequestration, and C) provide immediate relief from global warming by directly increasing surface albedo and indirectly by increasing cloud nucleation activity.

Abstract: A sinkable buoy system including a guide buoy, an inflatable air bladder, a weight component, an air supply line and an air supply, wherein the air bladder and the weight component are not housed within a common housing. A system for inflating and deflating an air bladder in order to float a buoy at the surface and sink a buoy below the surface as desired. A sinkable buoy system for use with a water sports course in order to float buoys of the course during course use and sink the buoys when the course is not in use.

Abstract: A partially flooding buoy includes a buoy body having a substantially cylindrical shape defining a cavity therein and a mooring mechanism attached to the buoy body to allow the buoy to be moored. The partially flooding buoy can be partially flooded with water after the buoy is deployed. The cavity is adapted to accommodate ballast therein. The buoy also includes at least one handle to allow more convenient handling of the buoy, wherein the handle is an opening formed within the buoy body.

Abstract: A lightweight constructed navigation buoy, and method for handling the same, is provided with waterborne stability comparable to the conventional and much heavier navigation buoys. The desired waterborne stability is achieved using a liquid-ballasting/-venting system in which a ballasting compartment and a connection cooperate to allow a liquid ballast to be added and/or removed from the ballasting compartment. The position-accuracy of said buoy can be improved by incorporating the liquid ballasted buoy with a high-strength, flexible, elastic tether providing a scope of between 1.5-to-1 and 1-to-1 at high water.

Abstract: A closed loop buoyancy system wherein a device housing the system is submerged in a liquid filled container, the device dives to the bottom of the container, remains for a regulated amount of time, and then floats back to the surface of the liquid.

Abstract: A buoy system includes a sea-bed pump station having separate reservoirs of lighter-than-water and heavier-than-water liquids. The reservoirs are in fluid communication with peristaltic pumps that are operated via a preprogrammed control within the station. A buoy has an upper chamber connected by umbilical to be in fluid communication with the lighter-than-water chamber of the pump station and also includes a lower chamber connected to be in fluid communication with the heavier-than-water chamber of the station. The sea-bed and buoy chambers for the heavier-than-water liquid are both gimbaled mounted to assist fluid transfer even when non-level. Selected venting at the sea-bed pump station and of the buoy permit sea flooding and pressure equalization.

Abstract: An automated system for periodically sampling water bodies, such as lakes, and delivering the test results to a remote computer using a communication system. In particular, the system has a variable buoyancy profiler with a dynamic buoyancy compensator responding approximately linear to a water pressure created by an external water body so as to actively or passively interact with an external force or pressure thereby moving the profiler to a target depth.

Abstract: A beverage accessory device having a housing with a cavity therein, a buoyant filler within the cavity, a buoyancy-reducing feature to incrementally decrease the buoyancy of the device, a straw receptacle attached to the housing, and a switchable light-source within the cavity.

Abstract: A floating target for naval gunfire. The target includes an inflatable buoyant superstructure with a drogue chute attached to the periphery of the bottom of the superstructure. The drogue chute, when in use is well underwater. The drogue chute is an open flexible structure with a bottom end weighted with ballast to deploy it, and with ports through its side to permit water to flow into and out of it. A line is attached to the bottom of the drogue chute to enable the target to be tipped and the drogue chute drained of water. A float can be attached to the free end of the line to facilitate recovery, or the line itself may be buoyant.

Abstract: An energy conserving moored buoyant ocean profiler wherein an instrument carrying vertically traversing buoyant member of low buoyancy is interconnected with a second buoyant member of high buoyancy to travel in the opposite direction at lesser distance, such that the potential energy of one buoyant member is increased as the potential energy of the other is decreased, thereby conserving energy as the instrument carrying buoyant member is raised and lowered.

Abstract: Flocculation apparatus and flotation apparatus useful in flocculation apparatus for floating paddles upwardly and allowing gravity to move paddles downwardly through a liquid to agglomerate particles suspended in the liquid.

Abstract: A depth control device (1) for a subsmersible body comprises a depth monitor (5) and depth controller (6). A variable volume buoyant body operates under the control of the depth controller and comprises three chambers, the first (10) containing air and the second and third chambers (7, 8) containing hydraulic fluid. The second and third chambers (7, 8) communicate reversibly with one another by means of a tube (13) and bypass valve (12) in a pump (3), so that a piston (9) at the entrance to the first chamber (10) is displaced in response to movement of fluid between the second and third chambers. Thus, the volume of the buoyant body is varied and hence the buoyancy of the subsmersible body which it controls. To keep the submersible body at a particular depth, a depth trigger value is set in the depth controller (6), so that a reversible change in the volume of the buoyant body is initiated in response to a change in depth sensed by the depth monitor (5) by pumping fluid between the two chambers (7, 8).

Abstract: A dock module comprises an air-tight flotation chamber with a buoyant foam material positioned within an upper end thereof. The flotation chamber includes aperture positioned on its bottom end to permit water to enter the chamber and serve as a ballast. To float the dock module, compressed air is injected into the flotation chamber to increase the module's buoyancy and adjust its freeboard so that the buoyant foam is lifted completely above the water contained within the flotation chamber. If the air-tight flotation chamber fails, the buoyant foam will prevent the dock module from becoming submerged. Each module comprises a plurality of longitudinally and laterally extending tubes that can be used to attach the module to a like module using tubular couplers and tensioned cabling. Multiple modules can thus be joined in any desired configuration to yield a floating dock system having virtually any desired geometry.

Abstract: A ballast system for toy submarines comprises a plumbing device, a flexible bag, a piece of wire and a rod. The ballast system draws water in and forces water out by decompressing and compressing the flexible bag.

Abstract: A portable, anchored sensor module for collecting fresh water environmental data over a range of depths, is supported relative to a buoy having a power supply and control circuitry. A depth control housing supports the underwater sensor module. The depth control housing can be controlled as to its buoyancy for supporting the sensor module at selected depths and collecting data at such depths. The control circuitry includes capabilities for transmitting data on suitable frequencies, such as those for a cellular phone, and has a computer with memory for storing the sensor signal for remote call up. Periodically the sensor information may be transmitted to a remote station used for control. The remote station also can control the depth from which the sensors are taking data.

Abstract: A variable buoyancy float/ballast assembly has control means allowing it to sink otherwise floating objects and bring sunken objects to the surface or control their placement in the water column. The assembly can be employed to tension mooring lines, reduce vertical uploads on anchors and dampen mooring line transients.

Abstract: Submarine (6) devices consisting of cavity to hold sand and an inflatable air bladder (10) are located beneath and connected to floating buoys (2). The weight of the sand when put inside the cavity is enough to sink buoy (2) until submarine (6) sits on the bottom of a lake or river. When bladders (10) are inflated by air supplied by an air compressor or a portable air tank, and distributed through a network of polyethylene tubing. They create enough buoyancy to offset the downward pull of the sand, thus allowing the buoys (2) to float back to the surface of the water.

Abstract: A floating device is arranged to provide for a stepped platform to permit accommodation of an animal trapped within a swimming pool environment, wherein the stepped platform includes a plurality of concentric rings, with an uppermost boss having a concave recess to accommodate an individual animal permitting the animal to escape the surrounding body of water. The invention is arranged to include a modified aspect to permit ballast structure to enhance stability within the water.

Abstract: There is disclosed a portable free drifting oceanographic instrument package for cyclically collecting oceanic and/or fresh water environmental data over a range of depths.

Abstract: A marker buoy for marking a particular spot on the bottom of the sea despite heavy seas. The buoy includes a hollow cylindrical chamber whose outer surface forms a spool. A length of line is attached to the chamber and wound around the spool with an anchor attached to the free end of the line. An elongated hollow tube is attached in axial alignment to one end of the cylindrical chamber. A cored foamed polystyrene ball whose diameter is slightly greater than the diameter of the cylindrical chamber is slidably mounted on the elongated tube. A cap affixed to the free end of the tube prevents the floatable ball from sliding off the tube. The buoy is placed on the surface of the water with the axes of the chamber and tube parallel to the water's surface. Small holes in the chamber gradually fill with water as the line runs out following the descending anchor.

Abstract: A rescue buoy package for use on a boat for marking the location of a person overboard and for remaining in that location until help can arrive includes an outer cylindrical tube that is mounted within arm's reach of the ship's helm and an inner cylindrical tube that fits into the outer tube and to which a heavily weighted cap is affixed. The cap extends downwardly over the open upper end of the outer tube keeping the contents dry and secure. The contents include an inflatable mast and a vest-type flotation device. The buoy can be packaged in a normal mode in which it must be deployed manually or in a second mode in which deployment is automatic. In the normal mode the buoy is deployed by pulling upwardly on a knob on the cap to remove the inner tube, the mast and the flotation device from the outer tube, and throwing the inner tube and its affixed cap into the water along with the mast and flotation device.

Abstract: A submersible cage system for cultivating aquatic animals comprises a rigid frame defining a geodesic enclosure, a net supported by the rigid frame to define a water permeable enclosure for the aquatic animals, the rigid frame being rotatable about a horizontal axis, flotation chambers disposed at opposite sides of the rigid frame, the flotation chambers being alternately fillable with a gas or a liquid to increase or decrease, respectively, the cage system's buoyancy, and a mooring for anchoring the frame in a fixed position in a marine environment.

Abstract: This subsea exploration apparatus comprises a ballast tank and a shuttle (7) with a watertight enclosure (10) which contains instrumentation for measurement, control and transmission of signals to a surface buoy. The enclosure is guided along a cable (1) fixed to the ballast tank and is provided with a chamber (26) whose lower opening is equipped with a hatch (29). When the shuttle is in high position, a load of ballast is transferred from the tank (5) into the chamber (26), causing the shuttle to descend. This load is jettisoned in a low position of the shuttle, by opening the hatch (29), in order to permit it to reascend.

Abstract: Apparatus is described for flaring large amounts of natural gas at a location spaced from an offshore production platform. The apparatus includes a spar buoy structure (32, FIG. 1) anchored at a location on the order of 0.1 kilometer from the platform (12) and coupled through an undersea conduit (44) to the platform. The structure is anchored by catenary chains (71-74), and has a ballasted lower portion and a buoyant upper portion to keep the structure upright so the flare (42) always remains high above sea level. The undersea conduit (44) which carries natural gas to the structure, connects to a buoy pipe (66) that extends along the structure, at a location (64) close to the center of gravity (80) of the structure, or at the bottom (keel) of the buoy, to minimize failure from constant structure pivoting. A wide lower part (34) of the structure includes several individually-sealed air-filled chambers (91-98, FIG. 2) spaced along its height. A mechanism (100, FIG.

Abstract: A mooring system and method of anchoring a buoyant module (16) in a submerged location in the sea for supporting an underwater structure such as a plurality of acoustical arrays (18) for receiving and transmitting acoustical signals is disclosed. The buoyant module (16) is held in a submerged position by at least one anchor leg or line (46) anchored to the sea floor and of a variable length to permit controlled movement of the module (16) to the sea surface (10) for servicing. The single anchor line (46) is a stretchable line and includes an upper segment (56) formed of a Kevlar material and a lower segment (58) formed of a nylon material. Line 46 may stretch easily for a length of 400 feet, a preferred submerged depth of the module (16). Module (16) includes a constant buoyant material (36) and a source of compressed gas (32) controlled by a remotely actuated valve (40) to provide a variable buoyancy.

Abstract: An inflatable float with timer and pressure controls to enable underwater gear to be automatically lifted off the sea bed at intervals and moved to a new location. The gas for inflating the float may be generated by chemical means or galvanic action.

Abstract: An improved ocean bottom seismometer is disclosed wherein a skirted spherical configuration provides bottom weight and provides a sealed area for seawater ballast which may be ejected to provide positive buoyancy for retrieval.

Abstract: A floating platform for supporting articles in a swimming pool or other body of water. The platform has a toroidal outer chamber filled with air, a toroidal middle chamber filled with water, and a toroidal inner chamber filled with air. An article supporting member that may take the form of one or more upstanding hollow columns projects upwardly from the inner chamber. The article supporting member in one embodiment is in fluid communication with the inner chamber but in a second embodiment it is not. In either embodiment, a decorative article such as an inflated flamingo, dolphin or other work of art may be in fluid communication with the support member or members. The weight of the water in the middle chamber provides a stable foundation to maintain the supported article in an upright disposition, and the pressure of the air in the inner and outer chambers maintains the water in the middle chamber in an evenly distributed disposition.

Abstract: A thermo-electric valve for scuttling floating devices comprising, a cyliical sleeve affixed to and passing through a bulkhead separating a pressurized medium on one side from a lower pressure space on the other side, a piston moveably mounted within the sleeve bore and exposed to the pressurized medium having a portion thereof blocking the sleeve bore, an O-ring sealing the gap between the piston head and the sleeve bore, a fully compressed spring pressing against the piston, a rigid dielectric washer and a low power resistor holding the piston against the spring. In operation a low current is passed through the resistor, disintegrating it which releases the spring's stored energy. This actuates the valve by expelling the piston which allows the pressurized fluid or gas to enter the lower pressure space.

Abstract: An improvement in buoyant marine devices, such as pyrotechnic markers, the displacement of which normally decreases during operation as a result of weight loss. The device is provided with a ballast means and means to enable the ballast compartment to fill progressively with water whereby, during operation, displacement of water by the marker is maintained to a degree which will ensure that the device remains in operative orientation. In this way, the problem of tilting by marine markers because of a gradual decrease in weight, to the point that the marker may be easily submerged by water and its operation thereby hampered, is significantly reduced.

Abstract: A marker bouy to positively mark positions on a water surface with respect to the bottom. The marker includes a generally hollow body with line wound around the approximate center thereof with a weight on the end of the line which will cause the marker to rotate when the marker is placed or thrown onto the water surface to cause the line to unwind from the marker. A line stop flange is provided on the marker to stop unwinding of the line when the weight strikes the bottom. This flange comes into effect when water partially fills the marker which will cause the marker to shift from a position of lying on the water surface to being erect within the water. When the marker is in the upright or erect position, the line is engaged by the line stop flange. When the marker is in this erect or upright position, one end will be above the surface of the water and therefore easily visible.

Abstract: A hydrocarbon sensor float for use in detecting the presence of hydrocarbons on the surface of a liquid provides an elongated floatation member having a top end and a bottom end and also having a cavity located centrally therealong and extending completely therethrough, a sensor assembly including a sensor and at least one electrical conductor coupled to the sensor, the sensor assembly being positioned in said floatation member for locating the sensor in the cavity for allowing access of the liquid thereto and for causing the electrical conductor to extend from the top end of the floatation member, and an attachment for a variable amount of weight at the bottom end of the floatation member for providing a variable floatation level for the member with respect to the liquid surface and likewise for the sensor for allowing adjustment of the detection depth for hydrocarbons at an installation site.

Abstract: A passive near neutral buoyancy platform includes a structure housing a series of gas-filled cells, restrained in their maximum volume regardless of the internal charge pressure, and collapsible in character when external pressure exceeds the charge pressure. With this structure, once a cell having a predetermined initial internal charge pressure reaches a depth where the external pressure exceeds this initial value, that cell contracts, resulting in a net buoyancy change for the structure. Where this series of cells is attached integrally to a single structure, the cells form a pre-loaded compressibility compensation device which is matched to the external environment.