Field of the Invention

The present invention generally relates to a buoyancy system for raising or lowering objects within a body of water.

In one application of the invention the buoyancy system is designed to raise malfunctioning or damaged objects, such as submarines and aircraft, from a depth, and/or to maintain them at the surface.

In another application of the invention the buoyancy system is designed to raise and/or lower objects from deep water enabling them to be raised and recovered at the surface of the water, or lowered into position. The object includes submerged ocean floor infrastructure such as sub-sea trees, manifojds and platform anchors.

Background Art

There are inherent difficulties associated with operations conducted in deep water. These problems are typically associated with the increasing pressure encountered at increased depths, as well as the weight of infrastructure, such as cables, which increase the deeper the operations are conducted.

At increased depths, the recovery of an object is increasingly difficult. This h'as been highlighted by several marine accidents in which rescue equipment was not available for situations in which a damaged submarine or aircraft was submerged in water beyond a certain depth. As a result, these accidents have resulted in fatalities.

Submarine escape and rescue/abandonment safety technology has evolved over the last few decades. The first generation consisted of a means of escape, which saw submarines being fitted with escape tower/hatches, and specially designed escape suits that would provide an escaping Submariner with both buoyancy and breathing air to reach the surface. This technique was, and indeed still is, limited by the depth at which the vessel lies. The second generation consisted of rescue using a submersible or rescue bell. This significantly increased the depth at which personnel can be extracted from a submarine and is also much safer than using escape suits.

However, both of these methods have significant limitations. If the submarine malfunctions or is damaged when operating in water deeper than its collapse/crush depth, then the current escape or rescue methods cannot be employed to save the occupants. Moreover, it takes many days to affect a rescue. During this time an increase in the internal pressure of the submarine, the consumption of vital survival stores (oxygen candles, carbon dioxide absorption devices, etc) and the deterioration and contamination of the atmosphere sustaining life (hydrogen sulphide, chlorine gas, etc) could be fatal.

Another industry in which operations are increasingly occurring at greater depths is the oil and gas industry. In this industry equipment is frequently employed on the ocean floor for a number of varied reasons and functions. The offshore oil and gas industry use equipment on the sea floor to extract fossil fuels and supply them to surface platforms and oil rigs. As the reservoirs of oil and natural gas at relatively shallow depths are consumed exploration for more reserves has inoved into deeper water.

Positioning and recovering heavy equipment from the ocean floor Is an expensive process that requires significant assets. Currently, equipment used on the ocean floor is positioned and later recovered using a high tensile wire and a winch located on a relatively large dynamically positioning vessel. However, this method is limited to certain depths depending on the recovery equipment's respective capability. As the depth of water increases, so too does the challenges and cost of positioning and later recovering such equipment.

The preceding discussion of the background to the invention _, is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application. SUMMARY OF INVENTION

It is an object of this invention to provide a buoyancy system which overcomes at least one of the problems of the prior art, or at least provides a useful alternative.

The present invention provides a buoyancy system for moving an object in a body of water, the system comprises:

at least one inflatable body which, when inflated, increases the buoyancy of the object;

an inflation apparatus to inflate the at least one inflatable body;

an activation system to activate the inflation apparatus;

where upon activation of the activation system the inflation apparatus causes a gas to flow to the at least one inflatable body, which once inflated to the required volume enables the object to be moved.

Preferably the buoyancy system is adapted to move the object in a substantially vertical orientation. The buoyancy system may be adapted to cause the object to ascend or descend. When the buoyancy system is used in operations where the object descends, the system provides a means to control the descent process.

The at least one inflatable body may be secured to the object. Preferably a shock absorbing device extends between the at least one inflatable body and the object. The shock absorbing device will ensure that the object ascent, particularly the Initial and end stages, Is relatively smooth.

Upon inflation each inflatable body preferably inflates external of the object.

The at least one inflatable body may have a release means so that the at least one inflatable body may be detached from the object. The release means may be operated if the buoyancy system is unintentionally activated. The ^' at least one inflatable body may comprise at least one upper pressure relief valve to release excess gas from the inflatable body. The requirement to release excess gas may be as a result of excess gas generated by the inflation apparatus, or may result from the expansion of the volume of gas In the inflatable body as the object ascends and the pressure exerted on the inflatable body from the body of water decreases.

Once the object has reached the required depth the pressure relief valve may lock closed to ensure the inflatable body remains inflated. This will retain the object at the desired level.

The at least one inflatable body may also comprise at least one lower pressure relief valve located at the bottom of the inflatable body. The at least one lower pressure relief valve may vent any increases in the pressure within the inflatable body once the at least one upper pressure relief valve is locked. This will prevent the at least one inflatable body over inflating and possibly rupturing.

The pressure relief valve may have a valve piston which is biased to a closed position. As the pressure against an external surface of the valve piston increases, the valve piston moves to allow the excess gas to vent from the inflatable body. Upon the initial movement of the valve piston, a locking means is released such that upon the valve piston returning to its closed position, the locking means locks the valve in said position.

The at least one inflatable body may also comprise a one way valve between the Inflation apparatus and an opening into the inflatable body. This will prevent the gas delivered into the inflatable body returning to the inflation apparatus.

In one aspect of the invention the at least one inflatable body is secured to a winch, whereby the winch feeds line out to the at least one inflatable body. This would allow the object to descend whilst the at least one inflatable body remains on the surface. When the object is required/able to ascend the winch is activated and the object moves upwardly. Similarly, the winch can be used to lower the object to a greater depth should the weather on the surface be poor, or to allow for controlled positioning of the object on the ocean floor.

Preferably the at least one Inflatable body is made from a material being heat resistant and having high tensile strength properties. An inner layer of the at least one inflatable body may be made from a material which is heat resistant and has high tensile strength properties Preferably the inflatable body is in the form of an inflatable bag.

Preferably the buoyancy system comprises a. plurality of inflatable bodies.

Preferably the plurality of inflatable bodies is positioned to ensure the object is raised or lowered in a desired orientation.

Preferably the buoyancy system also comprises control means to maintain the object at a certain level, such as at the surface of the water. Once inflated the inflatable body may remain inflated for a predetermined period of time.

Preferably the buoyancy system comprises an inflation apparatus for each inflatable body.

The inflation apparatus may comprise a regulatory apparatus to regulate the amount of gas passing in to the at least one inflatable body.

In one aspect of the invention the regulatory apparatus may be hydrostatically governed whereby the regulatory apparatus will provide the required volume of gas in order to account for the external pressure and allow the inflatable body to inflate to provide the desired amount of buoyancy. As the pressure exerted upon the object increases the deeper the object travels, the pressure required to inflate the inflatable body also increases,

The regulatory apparatus may comprise hydrostatic pressure sensors. The inflation apparatus may comprise a gas generation system, a gas storage system or It may be connected to an active gas generating system, or a combination of these systems.

The gas generation system may comprises a gas generating medium such as for example an explosive, propellant or other chemical compound contained within at least one vessel, whereby a charge activates the medium, creating a gas within the at least one vessel at pressure. The at least one vessel may have a series of passages and/or baffles located therein between the medium and a vessel outlet, whereby the gas generated by the medium passes through the passages before exiting the at least one vessel. This will ensure the vessel outlet is not exposed to the initial force of the medium as it generates gas.

The medium may be activated by an initiator or a detonator which is operabiy connected to the activation system. The gas generation system may comprise more than one initiator or detonator in the event that one or more of the initiators or detonators does not function correctly.

Preferably the molecular weight of the generated gas is closely matched to that of air.

Preferably the vessel outlet is connected to a gas delivery regulator so that the gas delivered to the inflatable body is delivered at the desired pressure.

Preferably the gas generated from the medium is cooled prior to being delivered to the at least one inflatable bag.

The inflation apparatus may also comprise a reservoir. When the object is descending, the reservoir may supply gas into the at least one inflatable body to ensure it retains the desired inflation, controlling the rate of descent and maintaining the weight, or negative buoyancy of the object. Preferably when the reservoir reaches a predetermined pressure the gas supply or gas generators are activated to supply further gas.

β In this application, the buoyancy system might be attached to a lowering or guiding wire, whereby the buoyancy system removes the vast majority of the weight or negative buoyancy to allow the object to be easily and accurately positioned on the ocean floor. Previously, the capacity of the cable would Jimit the allowable weight of the object being placed on the ocean floor at one time. In those applications in which the buoyancy system is used, the weight of the object may be significantly more as the buoyancy system would alleviate the weight burden which would otherwise be required to be restrained by the cable.

Once at the surface, the at least one Inflatable body may be flushed through with a supplied gas to dilute and/or remove the gas that was generated during the gas generation process. This function may be activated automatically and comprise of hydrostatic sensors or be activated manually or remotely. This will ensure any toxic gas has been discharged from the inflatable body prior to a recovery unit collecting the object.

The gas storage system may comprise a gas storage cylinder containing the gas. Preferably the gas storage cylinder is in fluid communication with the at least one inflatable body through an outlet passage. The outlet passage may have one or more pressure retaining disks to prevent the gas leaving the gas storage cylinder. Each pressure disk may be connected to a detonator. Each detonator may be operably connected to the activation system.

The active gas generating system may incorporate a gas supply external of the buoyancy system. Where the object is a submarine, this gas supply may be the compressed air produced for submarine operation. The activation system may comprise a cross valve which fluid Iy connects the buoyancy system with the gas supply.

The inflation apparatus may comprise at least one hydrostatic sensor or pressure relief valve ^' which is adapted to discontinue the delivery of gas to the at least one inflatable body once ascent has commenced. Once the ascent has commenced the inflatable body will continue to inflate even if there was no more gas being provided to the Inflatable body as the gas inside the inflatable body expands as the external pressure reduces.

The activation system may be activated in a variety of ways, largely dictated by the particular application. The buoyancy system may incorporate a plurality of activation systems. This is particularly important In applications relating to submarines and aircraft as it will ensure the buoyancy system can be activated regardless of the situation.

The activation system may be adapted to activate automatically when the object is at a predetermined depth. Such an application may occur when a submarine is damaged and is unable to return to the surface, or when an aircraft lands in water.

The activation system may be hydrostatically activated when the object reaches a predetermined depth. The automatic activation system may comprise one or more hydrostatically operated devices fitted external of the object. In the case of a submarine these devices may be located external to the pressure hull.

The hydrostatically operated device may comprise a substantially sealed unit having an exposed face with a series of perforations therein. The exposed face may be adjacent a first plate. The first plate may be biased into a normal condition whereby it is in spaced relation to a second plate. As the hydrostatic pressure increases, the pressure acting through the series of perforations causes the first plate to move towards the second plate. As the hydrostatic pressure increases further the first plate engages the second plate, completing a circuit to activate the activation system.

The activation system may comprise an override mechanism so that the automatic operation of the activation system can be disabled should it be required that the object descend below the predetermined depth.

The activation system may be acoustically operated. In those arrangements in which the buoyancy system is fitted to a submarine, the activation system may be incorporated into the submarine's emergency blow/surfaoe system.

The activation system may be manually operated.

Also in those instances where the object is a submarine or similar vessel in which an operator may be contained, the activation system may be internally activated from within the object.

The internal manual activation system may comprise a control panel within the submarine. The control panel may comprise a prime button to prime the activation system and an initiate button to activate the activation system. The control panel may also comprise a continuity button to check the integrity of the activation system and to commence the sequence of activating the activation system from the control panel. This is to ensure the buoyancy system is not accidentally activated.

The control panel may also comprise the release means to release the at least one inflatable body.

The manual activation system may also be externally activated by a remote operating vehicle (ROV). The external manual activation system may comprise a docking mount external of the object to which the ROV may dock. The ROV may be adapted to move the docking mount from a normal condition to an engaged condition wherein the activation system is activated. The external manual activation system may be adapted such that a unique key is required to access the system.

Preferably once the external manual activation system is activated the at least one inflatable body has a delayed inflation sequence to provide ample time for the ROV to disengage and move away from the object.

The buoyancy system may be powered from a generated power supply or from a battery pack. The object may have a plurality of buoyancy systems. The activation system of each of the plurality of buoyancy systems may be synchronised to activate simultaneously or within a prescribed time of each other.

Preferably the buoyancy system incorporates a locating beacon, such as an EPIRB, which is activated when the buoyancy system is activated. The locating beacon may be connected to the at least one inflatable body.

The buoyancy system may also comprise a propulsion means, whereby the propulsion means may be used to move, direct or guide the object in a variety of directions. Gas may be used to operate the propulsion means. The gas may be provided by the gas generation process.

In one application of the invention the object is a submarine. Preferably the buoyancy system does not substantially affect the acoustic characteristics or fluid dynamics of the submarine. The buoyancy system may be substantially contained within the submarine's casing until it is activated. The buoyancy system may be substantially contained between the submarines casing and pressure hull. The buoyancy system may be sealed in a recess extending from the casing to the pressure hull. The recess may have a cover thereacross. The cover may be released from the recess when the activation system is activated.

In another application of the invention the object is an aircraft, such as a helicopter or aeroplane. In these applications there may be a plurality of buoyancy systems. Each buoyancy system may be strategically placed to ensure the aircraft Is raised or remains in a desired position.

In another application of the invention the object is a diving suit or ROV. In the case of the ROV, the ROV may comprise means to disengage from its connection to a surface vessel.

In another application of the invention the object is a decompression chamber.

In a further application of the invention the object is production infrastructure or drilling equipment, including sub-sea trees, manifolds, and booster pumps. In such an application the buoyancy system may also comprise at least one guide wire extending from the water surface to the ocean floor. The guide wire provides a steadying line to control the object's ascent and predict its surfacing position.

The buoyancy system may also comprise at least one lifting strop secured to the object. This will allow the object to be recovered upon reaching the surface. The strop may be positively buoyant. This will ensure the strop remains in a vertical orientation for recovery.

When raising a sub-sea manifold from the ocean floor, other subsea infrastructure, pipes, cables etc are disconnected and the buoyancy system attached to the object's hard eye/lifting point prior to activating the buoyancy system.

This invention provides the next generation in deepwater heavy sub-sea recovery, salvage and installation. This new generation of deep water recovery consists of a concept of 'floating' the object to the surface regardless of the depth of water, to allow a surface vessel to recover the object inboard or tow it to a nearby port. It also allows for the controlled descent and installation of the object on the ocean floor.

The present invention further provides a buoyancy system for raising a submerged object towards the surface of a body of water, the system comprises:

at least one inflatable body which, when inflated, increases the buoyancy of the submerged object;

an inflation apparatus to inflate the at least one inflatable body;

an activation system to activate the inflation apparatus;

wherein upon activation of the activation system the inflation apparatus inflates the at least one inflatable body to inflate, which once inflated to the required volume enables the submerged object to move toward the surface of the body of water in which it is submerged. The present invention further provides a buoyancy system for raising a submarine to the surface of a body of water, the system comprises:

at least one inflatable body which, when inflated, increases the buoyancy of the submerged object;

an inflation apparatus to inflate the at least one inflatable body;

an activation system to activate the inflation apparatus;

wherein upon activation of the activation system the inflation apparatus causes the at least one inflatable body to inflate which once inflated to the required volume enables the submarine to move toward the surface of the body of water in which it is submerged.

Preferably the buoyancy system comprises means to maintain the submarine at the surface a sufficient time to allow the Submariners to escape.

The present invention provides a buoyancy system for raising production infrastructure or drilling equipment from the ocean floor for recovery, the buoyancy system being adapted to be connected to the equipment, the system comprises:

at least one inflatable body which, when inflated, increases the buoyancy of the equipment;

an inflation apparatus to inflate the at least one inflatable body;

an activation system to activate the inflation apparatus;

wherein upon activation of the activation system the inflation apparatus causes the at least one inflatable body to inflate which once inflated to the required volume enables the equipment to move toward the surface of the body of water in which it is submerged. The buoyancy system may be incorporated in a cradle which is adapted to be secured to the equipment. The cradle may be positively buoyant such that when it is attached to the equipment the buoyancy system remains in a desired orientation. The cradle may be connected to the equipment prior to the equipment being returned to the surface.

In such an operation a strop may be connected to the equipment to assist the recovery operation.

Also, the equipment may be connected to a guide wire extending between the ocean floor and surface, whereupon ascent the guide wire guides the ascent allowing the recovery location of the equipment to be predicted.

The equipment may remain below the surface until a vessel can attach a crane to the strop in order to lift the equipment from the ocean or to tow the object to a port with cranage facilities.

The present invention provides a buoyancy system for lowering production infrastructure or dπlling equipment to the ocean floor, the buoyancy system being adapted to be connected to the equipment, the system comprises:

at least one inflatable body which, when inflated, increases the buoyancy of the equipment;

an inflation apparatus to inflate the at least one inflatable body;

an activation system to activate the inflation apparatus;

wherein upon activation of the activation system the inflation apparatus causes the at least one inflatable body to inflate, partly offsetting the weight of the equipment and controlling the rate of descent towards the ocean floor.

Preferably the system comprises a reservoir which contains a gas, the reservoir supplying gas into the at least one inflatable body. When moving the equipment to the ocean floor the equipment is lifted into the water or towed floating on the surface to the deployment position whereby the at least one inflatable body is fully inflated and, if fitted, the reservoir pressurised. Upon descent the activation system will activate the inflation apparatus causing the at least one inflatable body to remain inflated whereupon the object is more easily and accurately moved toward the ocean floor.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which:

Figure 1 is a view of a submarine at the bottom of the ocean floor having a buoyancy system according to an embodiment of the invention installed thereon;

Figure 2 is a view similar to figure 1 but with the buoyancy system deployed;

Figure 3 is a schematic of the buoyancy system as installed on the submarine;

Figure 4 is a schematic of the buoyancy system according to a second embodiment;

Figure 5 a, b is a schematic of an activation system of the buoyancy system;

Figure 6 a, b is a plan and side cross sectional view of a hydrostatic sensor;

Figure 7 is a cross sectional schematic view of a gas generation system of a inflatable apparatus; Figure 8 is a cross sectional schematic view of a gas storage system of the inflatable apparatus;

Figure 9 a, b is a plan view and side view of an inflatable bag in an inflated condition;

Figure 10 is a cross sectional view of a pressure relief valve;

Figure 11 is a schematic view of an inflatable bag and associated vessels according to the second embodiment shown in figure 4;

Figure 12 is a schematic view of the buoyancy system according to a third embodiment of the invention;

Figure 13 is a schematic view of the buoyancy system according to a fourth embodiment of the invention;

Figure 14 is a schematic view of the buoyancy system according to a fifth embodiment of the invention as fitted to a helicopter;

Figure 15 is a schematic view of the buoyancy system according to a sixth embodiment of the invention as fitted to an aeroplane; and

Figure 16 is a schematic view of the buoyancy system according to a seventh embodiment of the invention as fitted to a chamber.

Figure 17 is a schematic view of a buoyancy system showing a layout of an upper level according to an eighth embodiment of the invention;

Figure 18 is a view similar to figure 18 but with the upper level removed;

Figure 19 is a side view of figure 17;

Figure 20 is a schematic view of the buoyancy system of figure 17 to 19 shown in two stages of recovery of equipment from the ocean floor; Best Mode(s) for Carrying out the Invention

The present invention has many applications across numerous industries. Certainly many more applications are also possible and these will come to light in the future, particularly owing to the human quest to explore the ocean depths.

Outlined below are several applications across several different industries. The majority of the below embodiments discuss applications in which a submerged object is raised towards the ocean's surface. However, the invention also has applications in controlled descent of objects to the- ocean floor, maintaining an object at a required depth and in propelling objects through the ocean.

The invention according to the various embodiments is in the form of a buoyancy system 11 for either raising an object 12 towards the surface 15 of a body of water, to lower the object 12 towards the ocean floor 14, or for maintaining it at the surface 15 or at a desired depth.

The buoyancy system 11 comprises a combination of one or more inflatable bodies 16, one or more inflation apparatuses 19 and one or more activation systems 21. In different applications and circumstances the buoyancy system 11 is configured to incorporate the required quantity and configuration of the aforementioned components.

Referring to figures 1 and 3, the invention according to a first embodiment is in the form of a buoyancy system 11 fitted to a submarine 13. Figure 1 shows the submarine 13 in a position on the ocean floor 14. This may occur when the submarine 13 malfunctions or has been damaged. The present invention would allow the submarine 13 shown in figure 1 to be readily returned to the surface 15 by activation of the buoyancy system 11.

Figure 2 shows the submarine 13 after the buoyancy system 11 has been activated and the plurality of inflatable bodies 16, in the form of inflatable bags 17, have been caused to deploy. As shown, the submarine 13 is raised to the surface 15 in an upright position, allowing personnel to escape the submarine 13. Submarines 13 are typically constructed to have a pressure hull 81 and an outer casing 83 towards the top of the vessel, wherein the two are spaced apart. This spacing provides an area in which the inflatable bags 17 may be stored in modules 18. It also permits the buoyancy system 11 to be fitted to a submarine without negatively affecting the fluid dynamics or acoustic characteristics of the submarine 13.

For submarines 13 without the outer casing 83, inflatable bags 17 may be stored in modules 18, engineered & incorporated into the pressure hull 81.

The components of the buoyancy system 11 according to this embodiment are best shown in figure 3.

The buoyancy system 11 comprises an inflatable apparatus 19, which in this embodiment, is provided by an active gas generating system 23 whereby the gas to inflate the inflatable bags 17 is provided by a gas supply 25 external of the buoyancy system 11. The external gas supply 25 is provided by the submarines internal air supply 27.

The inflatable apparatus 19 is activated by an activation system 21. The activation system 21 in this embodiment includes a manual external activation system 21a, a manual internal activation system 21b and an automatic activation system 21c. This provides multiple means to activate the buoyancy system 12, ensuring the submarine 13 may be raised to the surface regardless of the circumstances. Obviously other applications of the buoyancy system may only require one of these activation systems.

Figure 5 best illustrates the components of the activation system 21 utilised in this embodiment.

The manual external activation system 21a may be operated by a remote operating vehicle (ROV), not shown. The ROV is adapted to engage a docking mount 29 through which the activation system 21 can be activated. The manual internal activation system 21b may be operated from within the submarine 13 at one of three control panels 31.

The automatic activation system 21c comprises a hydrostatic operated device 33 fitted external the pressure hull 81. In this embodiment there are six hydrostatic operated devices 49 secured to the pressure hull 81.

Each hydrostatic operated device 49 comprises a substantially sealed unit having an exposed face 51 with a series of perforations 53 therein, as shown in figure 6a. The exposed face 51 is adjacent a first plate 55 as shown in figure 6b. The first plate 55 is biased away from a second plate 57 by a spring 59 such that in a normal condition the first plate 55 and second plate 57 are in spaced apart relation.

As the submarine 13 reaches a predetermined depth, the pressure acting through the perforations 53 causes the first plate 55 to move toward the second plate 57 until a contact brush 61a on the underside of the first plate 55 engages a contact brush 61b on the upper side of the second plate 57. This completes a circuit resulting in activation of the inflatable apparatus 19. which leads to deployment of the inflatable bags 17.

Considering the external manual activation system 21a as shown in figure 5, the external manual activation system 21a comprises the docking mount 29 having a nut 69 adapted to be rotated by an ROV. The nut 69 is threadingly received in a housing 71 of the docking mount 29. The nut 69 is uniquely configured such that only an ROV with a correctly configured arm is able to operate the nut 69. The nut 69 can be removed from the housing 71 to allow the ROV to access an activation screw 73, which is also threadingly received in the housing 71. Upon turning the activation screw 73 it engages an activation plate 75. Upon engagement therewith a circuit is completed and the activation system 21 activates the inflation apparatus 19. In order to allow the ROV to disengage and move away from the submarine 13, there will be a delay before the inflatable bags 17 inflate and the submarine 13 moves upwardly. Considering the internal manual activation system 21b as shown in figure 5, the control panel 31 comprises a prime button 77 to prime the activation system and an initiate button 79 to activate the activation system. The control panel 31 also comprises a continuity button 85 to check the integrity of the activation system 21 and to commence the sequence of activating the activation system 21b from the control panel 31.

The control panel 31 also comprises the release means 87 to release the inflatable bags 17 upon accidental activation of the buoyancy system 11.

The control panel 31 also comprises an override switch 89 which can be used to override the automatic activation system 21c as may be required should the submarine be required to go below the predetermined depth.

The inflatable bag 17 in an inflated state is best shown in figures 9 a, b. Each inflatable bag 17 comprises four upper pressure relief valves 91 designed to release excess gas from the inflatable bag 17, as well as the excess volume of gas generated as the submarine 13 ascends and the pressure exerted on the inflatable bag 17 from the body of water decreases. Once the submarine 13 has been raised to the required depth the pressure relief valve 91 locks, preventing any further gas from passing therethrough to ensure the inflatable bag 17 remains inflated.

The inflatable bag 17 also comprises two lower pressure relief valves 93 located in the lower region of the inflatable bag 17. The lower pressure relief valves 93 vent any increase in the pressure within the Inflatable body once the upper pressure relief valves 91 lock.

Referring to figure 10, each pressure relief valve 91 , has a valve piston 95 biased to a closed position. As the pressure against an external surface 97 of the valve piston 95 increases from the pressure within the inflatable bag 17 the valve piston 95 moves to allow the excess gas to vent from the inflatable bag 17 via the relief valve 91. Upon the initial movement of the valve piston 95, a locking means 99 is released whereby, upon the valve piston 95 returning to its closed position, the valve means 99 locks the valve piston 95 in said position.

Each inflatable bag 17 also comprises a one way valve 101 between the inflation apparatus 19 and an opening 103 of the inflatable bag 17. This will prevent the gas delivered into the inflatable bag 17 from returning to the inflation apparatus 19.

Each inflatable bag 17 also incorporates an EPIRB 105 which is activated when the bag 17 is inflated.

If the buoyancy system 11 is require to be operated, the activation system 21 will either be activated automatically, or manually from external or internal of the submarine 13. Upon activation the inflation apparatus 19 is activated to divert gas from the gas supply 25 external from the buoyancy system 11. The gas is used to inflate the bags 17 until sufficient lift is created to raise the submarine 13 to the surface 15.

A second embodiment of the invention is shown in figure 4. This embodiment Is very similar to that of the first embodiment and so like components will be similarly numbered. This embodiment builds on the first embodiment in that the inflation apparatus 19 of the buoyancy system 11 now also comprises a gas generating system 35 and a regulatory apparatus 43. In this embodiment the buoyancy system 11 does not rely solely on the supply of gas from the submarine 13.

In this embodiment the gas generating system 35 comprises a set of six vessels 37 for each inflatable bag 17, as shown in figure 11. Each vessel 37 is connected to a hydrostatic operated device 49 and is associated with the regulatory apparatus 43 to regulate the amount of gas passing in to the inflatable bags 17, taken into account the depth of the submarine 13.

Referring to figure 7 each vessel contains a gas generating medium 39, such as an explosive, propellant or other chemical compound which, upon detonation and/or activation, creates a gas. This gas is channelled through the outlet 41 of the vessel 37 to fill the inflatable bag 17. The gas may be cooled before entering the inflatable bag 17.

The regulatory apparatus 43 is located upstream from the outlet 41. In order to shield the regulatory apparatus 43 from the force of the rapid gas generation a series of passages/baffles 45 are located between the medium 39 and outlet 41. These passages 45 cause the force of the rapid gas generation to pass along a longer path, dampening the full effect of the explosion and rapid increase in pressure.

The medium 39 is ignited by an initiator or detonator 47 connected to the activation system 21. Figure 7 shows the medium 39 as having three detonators 47. This provides back up should one or two of the detonators 47 malfunction.

As shown in figure 11 each inflatable bag 17 is secured to the submarine 13 at a mounting point 63 which is secured to the pressure hull 81. The inflatable bag 17 and vessels 37 are located in the module 18. The module 18 has a cover 65 which is released upon removal of pins 67. These pins 67 are removed by detonation when the activation system 21 is activated.

The deployment of the inflatable bags 17 in this embodiment closely follow that as described for the first embodiment.

According to a third embodiment of the invention the inflation apparatus 19 comprises a gas storage system 107. This embodiment is very similar to that of the second embodiment and so like components will be similarly numbered. However, in this embodiment, rather than generate gas via medium 39, the gas is stored in a high pressure gas cylinder 109, as shown in figure 8.

In this embodiment the gas cylinder 109 of the gas storage system 107 has an outlet 111 which is In fluid communication with the inflatable bag 17. The gas is retained in the cylinder 109 by three retaining disks 113. Each disk 113 is connected to a detonator 115 which, when activated through the activation system 21 causes the disks 113 to rupture to allow the gas to pass to the bag 17. A further detonator 115a is positioned such that its charge is directed to the face of the disks 113. This will ensure the disks 113 are ruptured and the gas is able to pass through.

Figure 12 illustrates the configuration of the module 18 for storing the inflatable bags 17 according to this third embodiment.

A fourth embodiment of the invention is shown in figure 13. This embodiment has an inflatable apparatus 19 comprising a hybrid system incorporating the gas generation system 35 and gas storage system 107. Figure 13 represents how the inflatable apparatus 13 and inflatable bag 17 of this embodiment would be configured in a module 18.

In a fifth embodiment of the invention, as shown in figure 14, four individual buoyancy systems 211 are strategically placed on a helicopter 213. In this embodiment the inflatable apparatus 19 is in the form of a gas generation system 35, whilst the activation means is in the form of an automatic activation system 21c and a manual internal activation system 21b.

Figure 15 shows a sixth embodiment of the invention. This embodiment is similar to the fifth embodiment but instead of relating to a helicopter it is in relation to an aircraft 223.

In a seventh embodiment of the invention, as shown in figure 16, a buoyancy apparatus 311 is secured to a chamber, in this case a saturation diving bell 313. The buoyancy system 311 is similar to that described in the fifth and sixth embodiments but also incorporates a winch 315. This will allow the bell 313 to be lowered away from the surface 15 if required.

As identified in the above embodiments, this invention provides a third generation escape and rescue system. The third generation of escape and rescue/abandonment technology consists of a concept of 'self help ¹ that is capable of achieving a successful outcome regardless of the depth of water in which the asset (e.g. submarine, diving bell) is operating or located. In the event of a malfunction or the asset is damaged (loss of power, fire, flood, collision, mechanical failure or indeed any incident that could disable the asset), the ability to surface immediately negates the requirement to conduct risky buoyant ascent escapes from the ocean floor or wait for an operational rescue vehicle to be deployed. It could also prevent the asset from plunging to depths outside of its capability (crush depth), avoiding complete loss of asset and all personnel.

Referring to figures 17 to 20, the Invention according to an eighth embodiment is shown. As this embodiment has components similar to those mentioned in the previous embodiments, like components will be similarly numbered as those discussed above. In this embodiment the buoyancy system 11 is used to raise or lower equipment, such as subsea manifolds 401 from or to the ocean floor. Figure 20 shows the buoyancy system 11 raising a subsea manifold 401 from the ocean floor 14 (figure 20b) to the surface 15 of the ocean (figure 20a) for recovery by a ship.

As shown in figures 17, 18 and 19 the buoyancy system 11 in this embodiment is supported on a cradle 403. The buoyancy system 11 has an inflatable bag 17 located on an upper level of the cradle 403 and is stored in a collapsed condition as shown in figure 17. Underneath the inflatable bag 17 is located the gas generation system 35 comprising 14 vessels 37 which contain a medium 39, such as an explosive, propellant or medium for generating gas (not shown).

Each vessel 37 is coupled to a regulatory apparatus 43 and a hydrostatic sensor 407 for regulating the amount of gas which passes to the inflatable bag 17. Each vessel 37 is also coupled to a heat exchanger 405 to assist in cooling the generated gas prior to passing into the inflatable bag 17.

The activation system 21 is in the form of an acoustically operated activation system 21 d and a manually operated activation system 21a which may be activated by an ROV. The activation system 21 is connected to a power supply 409.

Referring to figure 20, two stages of the recovery process of the subsea manifold 401 is shown. The manifold 401 is secured to a guide wire 411 which extends from the ocean floor to the surface 15. This assists in guiding the manifold 401 back to the surface 15 and provides a recovery unit with an accurate location to recover the manifold 401 when it is raised.

In the first stage of the process, the cradle 403 of the buoyancy system 11 is secured to the manifold 401 and is positively buoyant so as to remain in an elevated position relative to the manifold 401. This may be done by an ROV. At the same time a strop 413 is also connected. This is also positively buoyant so that it remains above the manifold 401 , allowing a crane from the recovery unit to easily lift the manifold 401 from the ocean.

Once the buoyancy system 11 is secured to the manifold 401 and the manifold 401 has been disconnected from the surrounding infrastructure, the activation system 21 may be activated to cause gas to be generated and fed into the inflatable bag 17. Upon activation, preferably through manual time delay or acoustic means, a charge is sent from the power supply 409 to the hydrostatic sensors 407 that are responsible for activating the gas generation vessels 37. Water pressure, through hydrostatic sensors 407 determine the number of gas generation vessels 37 activated to provide sufficient gas to inflate the inflatable body 17. Gas produced by the gas generation vessels 37 pass through the heat exchanger 405 and regulator 43 providing gas to a pneumatic junction which then delivers the inflation gas to the inflatable body 17 via a pneumatic hose(s) 415.

Further inflation will result in the buoyancy system 11 moving the manifold 401 in an upward direction. The manifold 401 will then move to a recovery position whereby it sits below the surface 15 awaiting collection by the recovery unit.

As the manifold 401 rises, the pressure acting on the inflatable bag 17 reduces. In order to prevent the pressure of the gas inside the inflatable bag 17 from rupturing the inflatable bag 17, the excess gas is vented through the pressure relief valves 91 and/or 93 located at the top and bottom of the inflatable bag 17 respectively.

As the inflatable bag 17 is fully inflated, excess gas is vented out of the inflatable bag 17 through pressure relief valves 91 , 93. Upon reaching the surface, the gas pressure Inside the inflatable bag 17 reduces, the upper pressure relief valves re- seat and may lock in the closed position to ensure that gas does not escape from the inflatable bag 17, ensuring that the manifold 401 remains near the surface 15.

The required size and inflation of the inflatable body 17 depends on the weight of the submerged object. The number and size of gas generation vessels required to be activated depends on both the size of the inflatable body and the depth at which the submerged object is resting.

Where the buoyancy system is attached to the manifolds 401 hard eye/lifting point, a positively buoyant lifting strop 413 is also attached.. The positively, buoyant lifting strop 413 is to be long enough so its hard eye/lifting point is on the surface and accessible once the manifold 401 arrives at the surface. This allows a surface vessel to connect the positively buoyant lifting strop 413 to a suitable crane to lift the manifold 401 and the buoyancy system 11 out of the water and onto the deck of a ship, barge, etc.

Once recovered, the buoyancy system 11 can be detached from the manifold 401 , the inflatable body 17 deflated and repacked, activated/used gas generation vessels 37 replaced, upper relief valves 91 unlocked/reset and power supply 409 re-charged. The buoyancy system 11 then becomes ready for re-deployment.

A similar system as shown in figure 20 may also be used to lower the manifold 401 to the ocean floor 14 in a controlled descent. In such an application the buoyant force provided by the buoyancy system 11 would need to be slightly less than the force created by the weight of the manifold 401. However, as the manifold 401 descends further, it will be necessary to feed additional gas into the inflatable bag 17 to overcome the additional pressure acting on the inflatable bag 17 so as to maintain control of the descent. In this regard the buoyancy system 11 may further comprise a reservoir (not shown) for retaining a gas which may bleed into the inflatable bag 17 as required.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.