Abstract:
Thermal warming suits for a human occupant of a wet submersible vehicle are described. The thermal warming suits provide a dedicated envelope configured to encase at least a portion of the human occupant in a deformable suit that can be assembled around or donned, as well as be removed, by the occupant or others before or after entry and seating in or on the wet submersible vehicle, while underwater or surfaced. The suits provide a deformable, weight and space (i.e. volume) conscious, collapsible loose fitting perimeter around the occupant. The suits can be used to create a pneumatic barrier around at least a portion of the occupant by using a gas such as air provided from a gas reservoir to force water from the interior of the suit.

Description:
FIELD 
       [0001]    This disclosure relates to wet manned submersible vehicles and to systems for providing thermal control and water management about a human occupant or rider of wet manned submersible vehicles as well as providing thermal control and water management about a human in other underwater applications. 
       BACKGROUND 
       [0002]    When riding a wet manned submersible vehicle, a human occupant may be exposed to long duration submersions in water that is at temperatures that may be below normal human comfort, and perhaps even survival, levels potentially leading to hypothermia. This can create significant energy drain and fatigue on the human occupant caused by core thermal cooling processes that result from the human body&#39;s response to maintain thermal equilibrium while exposed to such temperatures and rapid exothermic heat loss due to water thermal film coefficients. The result after such exposure can be a drastic reduction in human physical and intellectual performance. In the case of military personnel, at the end of a transit excursion on a wet submersible, this reduction in physical and intellectual performance may occur at the exact time when maximum exertion and optimal decision-making is required. 
         [0003]    Currently, underwater thermal protection is provided by wet suits, dry suits, circulatory hot water hydronic heating, and electric heating. The most energy efficient solution is a dry suit that can be worn by the human occupant of the wet submersible vehicle. However a dry suit does not provide the volume or space for an individual of average dexterity to withdraw their hands and arms from the sleeve and glove area of the suit into a main core zone of the dry suit in such a way as to provide tactile access of the wearer to certain dry zones (for example, head, neck, shoulders, torso) with his/her own hands. Further, a dry suit requires open circuit buoyancy, i.e. inflation/pressurization, control by the individual wearing the dry suit. However, variations in the dry suit buoyancy affect the individual&#39;s buoyancy and therefore affect the overall buoyancy of the wet submersible vehicle. In addition, air is expelled from the dry suit&#39;s dump valve as the buoyancy is adjusted during venting procedures such as during an ascent of the wet submersible vehicle. As expelled air ascends to the water surface it expands due to the decreasing pressure differential, creating a tell-tale eruption of bubbles at the water surface which, in the case of military operations, can undesirably signal the presence of military personnel below. 
       SUMMARY 
       [0004]    Thermal warming suits for a human user operating submerged in water are described. The thermal warming suits described herein provide a dedicated envelope configured to encase at least a portion of the user in a deformable, flexible suit that can be assembled around or donned, as well as be removed, by the user while the user is submerged underwater or at the surface. The suits described herein provide a deformable, weight and space (i.e. volume) conscious, collapsible loose fitting perimeter around the user. The suits can be used to create a pneumatic barrier around at least a portion of the user by using a gas such as air provided from a gas reservoir to force water from the interior of the suit. 
         [0005]    The barrier can be achieved with very low stored power or manual power, and can utilize a re-useable gas, such as air, from a reservoir. Because the gas is re-useable, the gas does not require regeneration. In addition, the suit provides silent or near-silent operation, there is no expelled gas that is prone to observation resulting from a tell-tale eruption of bubbles at the water surface. The space created by the suit further facilitates nutrient intake and excrement by the occupant utilizing conventional means, without special additional apparatus. 
         [0006]    The suits described herein can be worn by a human user that is submerged underwater in any application. In one specific, non-limiting application, the suit can be worn by an occupant or rider of a wet submersible vehicle. In such an application, the user can don the suit before or after entry and seating in or on the wet submersible vehicle. However, other applications of the suit are possible 
         [0007]    The suits described herein eliminate high heat loss from the user by enveloping defined areas or body parts of the user in air or other gas to isolate those areas from surrounding water by a pneumatic barrier or envelope. The gas in the interior of the suit is heated by the user&#39;s body heat and/or the gas can be heated by a suitable electro-mechanical heating device during or prior to the gas being introduced into the suit. In one embodiment, the suits are configured so that at least the occupant&#39;s head and neck are enveloped in a single common or contiguous pneumatic barrier. In another embodiment, the user&#39;s chest, lower abdomen, waist, upper thighs, shoulders, arms and hands can also be enveloped. In still another embodiment, the entirety of the occupant&#39;s thighs and the occupant&#39;s knees can also be enveloped. In still another embodiment, the occupant&#39;s lower legs and feet can also be enveloped. The suits described herein can be configured so that any desired portions of the human body can be enveloped by the pneumatic barrier. 
         [0008]    In one embodiment, the pneumatic barrier formed by the suit will be large enough to permit the user to use their hands to reach into the interior space of the suit to access their own body. For example, the suit can be configured to permit the user to retract their arms, hands, legs, feet and/or head into the interior space of the suit to permit the user to access areas of his body using the user&#39;s hands that can maneuver within the suit. The suit can also include arm, hand and head protuberances to allow the user to access and control equipment and perform activities external to the suit. 
         [0009]    In one embodiment, when the suit is used by an occupant or rider of a wet submersible vehicle, the suit can comprise an individual flexible waterproof hermetic envelope that may be stowed on the vehicle near the location of the occupant or rider prior to use, and that can be unfolded and pulled over the top of, or fastened about the occupant and, in some embodiments also fastened to the vehicle if the suit is not already fastened to the vehicle, while the vehicle is at the water surface or submerged underwater. Once donned by the occupant, the upper end of the suit is completely sealed, and the lower extremity of the suit is open to the surrounding water environment to allow water to be displaced from the interior of the suit out the lower end of the suit by a gas as the gas is pumped into the suit. A reservoir of gas including, but not limited to, air, nitrogen, or argon, is accommodated within the vehicle and is fluidly connected to the suit. The gas reservoir is also open to the surrounding water environment via one or more openings located below the lowermost anticipated gas/water interface in the reservoir so that the gas reservoir is water-floodable and the gas cannot escape from the reservoir through the opening(s). A motorized or manual pump can be provided for pumping gas between the reservoir and the suit. As the gas is introduced from the gas reservoir into the suit, water is displaced out of the suit, and at the same time a corresponding amount of water enters into the gas reservoir. Likewise, as the gas is transferred from the suit into the gas reservoir, the gas forces water from the gas reservoir and a corresponding amount of water enters into the interior of the suit. Therefore, for a given depth, the total volume of gas in the gas reservoir and the interior of the suit remains the same so that the total buoyancy acting on the wet submersible vehicle does not change. 
         [0010]    In one embodiment, a system described herein includes a wet submersible vehicle and a suit that is configured to be worn by a human occupant of the wet submersible vehicle. The wet submersible vehicle can accommodate one or more human occupants thereon, includes its own propulsion mechanism, or is designed to be towed by a towing means, for propelling the wet submersible vehicle through water, and includes a water-floodable gas reservoir that contains a gas and that is open to water ingress/egress. The suit is deformable and includes a main portion that defines a single common interior space that when donned by the human occupant envelops at least the head and neck of the user, and optionally envelopes the chest, lower abdomen, waist, upper thighs, shoulders, arms and hands of the human occupant. The single common interior space is open to water ingress/egress which permits water to be forced out of the interior space by gas introduced into the interior space, as well as allow entry of water into the suit when gas is transferred out of the interior space. A valved fluid line extends between the suit and the water-floodable gas reservoir that can be controllably opened and closed providing fluid communication between the suit and the water-floodable gas reservoir to exchange gas therebetween. 
     
    
     
       DRAWINGS 
         [0011]      FIG. 1A  illustrates an example of a wet manned submersible vehicle on which the suits described herein can be utilized. 
           [0012]      FIG. 1B  illustrates another example of a wet manned submersible vehicle on which the suits described herein can be utilized. 
           [0013]      FIG. 2  illustrates a human occupant of the wet submersible vehicle in a seated position on a seat and wearing a suit described herein where the seat acts as a gas reservoir. 
           [0014]      FIG. 2A  illustrates details of one embodiment of a gas transfer mechanism described herein. 
           [0015]      FIGS. 3A-C  illustrate the suit, the occupant, and the seat, respectively, shown in  FIG. 2 . 
           [0016]      FIG. 4  is a view similar to  FIG. 2  but with the suit extending down to cover the knees of the occupant. 
           [0017]      FIG. 5  is a view similar to  FIG. 2  but with the suit extending down to cover the feet and the lower legs of the occupant which are in the same space. 
           [0018]      FIG. 6  is a view similar to  FIG. 2  but with the suit extending down to cover the feet and the lower legs of the occupant which are in separate leg sleeves. 
           [0019]      FIG. 7  is a side view of the suit showing example locations of an internal dry storage pouch formed inside the suit. 
           [0020]      FIG. 8  is a perspective view of the suit showing example locations of a suit closure mechanism. 
           [0021]      FIG. 9  is a view similar to  FIG. 2  with a gas reservoir separate from the seat. 
           [0022]      FIG. 10  illustrates example steps in one embodiment of a method of using the suit. 
           [0023]      FIG. 11  is a view similar to  FIG. 2  but with the suit extending down to cover the head and neck of the occupant. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    A wet manned submersible vehicle or the like as used herein is intended to encompass any manned vehicle that can have its own on-board propulsion mechanism or that is intended to be towed by another vehicle, that is intended to operate underneath the water surface with one or more human operators or occupants riding on or in the vehicle. During normal operation, the occupants are exposed directly or indirectly to the combined ambient pressure and water environment while riding on or in the vehicle. This is in contrast to a dry manned submersible vehicle such as a submarine where the water is intended to be kept out of most portions of the vehicle and the human operators are not intended to be exposed directly or indirectly to the combined ambient pressure and water during typical operation. Examples of wet manned submersible vehicles include, but are not limited to, the SEAL Delivery Vehicle, British Mk 1 “chariot”, the Pegasus swimmer propulsion device, and other diver assist vehicles such as those similar to the various underwater scooters once produced by Farallon USA. 
         [0025]    The term gas as used herein is intended to refer to a material in a gaseous state. Examples of gases that can be used include, but are not limited to, air or inert gases such as nitrogen or argon, and are not necessary for inhalation or life support. 
         [0026]    A water-floodable reservoir or water-floodable suit as used herein is intended to refer to a reservoir or suit that contains gas at the top and water beneath the gas separated by a free surface water/gas interface, and where additional water can automatically flood into the reservoir or suit in an amount that is proportional to the amount of gas that is transferred out of the reservoir or suit, and where water can be forced out of the reservoir or suit in an amount that is proportional to the amount of gas that is introduced into the reservoir or suit. 
         [0027]      FIG. 1A  illustrates one example of a wet manned submersible vehicle  10  with which the concepts described herein can be utilized. In the illustrated example, the vehicle  10  is configured to be ridden by two human occupants  12   a ,  12   b  in a front and rear arrangement. When riding on the vehicle  10 , the two occupants  12   a ,  12   b  are exposed to and in direct contact with the surrounding water  14  in which the vehicle  10  is submerged. Although two occupants  12   a ,  12   b  are illustrated, in other embodiments the vehicle  10  can include a single occupant or more than two occupants. In addition, in other embodiments, the occupant(s) can be positioned in a side-by-side arrangement as discussed below with respect to  FIG. 1B  or an over-under arrangement. The occupants  12   a ,  12   b  are illustrated in a seated position while riding on what is essentially the outside of the vehicle  10 . However, in other embodiments, the occupant(s) could be partially or completely disposed within a flooded interior space of the vehicle while still being considered as exposed to the surrounding water as discussed below with respect to  FIG. 1B . 
         [0028]      FIG. 1B  illustrates another embodiment of the vehicle  10  which is known as a SEAL Delivery Vehicle. In the vehicle  10 , the occupants  12   a ,  12   b ,  12   c ,  12   d  are seated in a front and rear arrangement, with the front occupants  12   a ,  12   b  seated generally side-by-side and the rear occupants  12   c ,  12   d  seated generally side-by-side. The occupants  12   a - d  are seated so they are completely disposed within the vehicle  10 , yet the vehicle  10  is open to the surrounding water so that the interior of the vehicle  10  where the occupants sit is flooded with water. In other embodiments of vehicles, the occupant(s) could ride in a generally prone position or a generally supine position in or on the vehicle. The embodiments illustrated in  FIGS. 1A and 1B  are examples only. Many other examples and variations of wet manned submersible vehicles are known and can be utilized. 
         [0029]    In some embodiments, a vehicle may not even be used. Instead, a person that is submerged in water but not riding in or on a vehicle can also use one of the suits described below. So even though the following description describes use of the suits by occupants of a wet manned submersible vehicle, and the drawings illustrate wet manned submersible vehicles, the concepts described herein, including the suits described below, are not limited to use with wet manned submersible vehicles. 
         [0030]    Referring to  FIG. 1A  (along with  FIG. 1B ), the vehicle  10  includes a vehicle body  16  with a front end  18  and a rear end  20 . The vehicle body  16  is generally hydrodynamically shaped to facilitate efficient travel through the water  14 . A propulsion mechanism  22  is provided, for example at the rear end  20 , for propelling the vehicle  10 , along with the occupants  12   a ,  12   b , . . . n through the water  14 . A suitable steering mechanism  24 , such as one or more steerable fins, may also be provided for controllable maneuvering of the vehicle  10  through the water  14 . In the illustrated example of  FIG. 1A , the vehicle body  16  defines two occupant stations  26   a ,  26   b  at which the occupants  12   a ,  12   b  are positioned while riding the vehicle  10 . In the illustrated example of  FIG. 1B , the vehicle body  16  defines four or more occupant stations at which the occupants  12   a ,  12   b ,  12   c ,  12   d  are positioned while riding the vehicle  10 . 
         [0031]    With reference to  FIG. 2 , one of the human occupants  12   a  of the wet submersible vehicle  10  of  FIG. 1A  or  FIG. 1B  is illustrated in a seated position on a seat  30  that can be part of the wet submersible vehicle  10 . The occupant  12   a  is wearing a flexible, deformable suit  32  described herein. In this embodiment, the seat  30  is configured to act as a gas reservoir that exchanges gas with an interior of the suit  32 . 
         [0032]    With reference to  FIGS. 2 and 3C , in the illustrated embodiment, the seat  30  includes a back portion  34 , a sitting portion  36 , and a base portion  38 . The back portion  34 , the sitting portion  36 , and the base portion  38  can be an integrally formed, one-piece construction constructed from a suitable material such as sealed wood, metal, a coated fabric, elastomer, or plastic. The seat  30  is partially or completely hollow so that the back portion  34 , the sitting portion  36 , and the base portion  38  define a water-floodable, hermetic gas reservoir  40  in the interior thereof. The size of the gas reservoir  40  formed in the seat  30  is sufficient to contain enough gas therein so that enough gas can be transferred into the suit  32  as discussed further below to force water from the interior of the suit  32  to form the pneumatic barrier around the occupant  12   a . The seat  30  is also open to the surrounding water environment so that as gas is transferred from the gas reservoir  40  into the suit  32 , a corresponding amount of water enters into the reservoir  40 , and when gas is transferred from the suit  32  back into the reservoir  40 , water is forced out of the reservoir  40  back into the surrounding water environment. Any means for allowing water ingress and egress into and from the reservoir  40  can be utilized. In the illustrated example, a bottom edge  42  of the base portion  38  is open to allow ingress and egress of water into and from the reservoir  40  as indicated by the arrows in  FIG. 3C . Ingress and egress of water into and from the reservoir  40  can be achieved in any suitable manner including, but not limited to, using vents, drain tubes, scuppers, or the like. 
         [0033]      FIG. 3C  illustrates an example of a first condition of the seat  30  prior to transferring gas into the suit  32 , where a first water/gas interface  44  is located in the base portion  38  so that the reservoir  40  contains a maximum amount of gas located above the interface  44  and a minimum amount of water below the interface  44 . When gas is transferred from the reservoir  40  into the suit  32 , the volume of gas is reduced and replaced with water which enters into the reservoir  40  through the ingress means, such as through the bottom edge  42 , opening(s), vent(s), pipe(s), scupper(s), etc. An example of a second condition after the gas is transferred into the suit  32  is illustrated by a second water/gas interface  46  which in this example is shown as being located in the upper back portion  34  so that the reservoir  40  contains a minimal amount of gas located above the interface  46  and a maximum amount of water is present in the reservoir  40  below the interface  46 . The first water/gas interface  44  can be located at a level that is just above the location(s) of the water ingress/egress means formed in the reservoir  40  through which water can enter and exit the reservoir  40 . 
         [0034]    Returning to  FIGS. 2, 2A and 3C , a gas transfer mechanism  50  is provided at an elevation above the top of reservoir  40  and the suit  32  for transferring gas between the reservoir  40  and the suit  32 . The gas transfer mechanism  50  includes a fluid line  52  that has a first end  54  that is in fluid communication with the reservoir  40 , and a second end  56  that is connectable to the suit  32 . The connections between the fluid line  52  and the reservoir  40  and the suit  32  can be, for example, at or near the upper-most regions of both. The gas transfer mechanism  50  further includes a pump  58  ( FIG. 2A ), for example a reversible pump, for pumping the gas in one or both directions through the fluid line  52  into and/or from the suit  32 , and a valve  60  ( FIG. 2A ) that controls the gas flow through the fluid line  52 . If either the reservoir  40  of the suit  32  are located at different elevations relative to one another, then a single direction pump  58  can be used to convey gas from the upper volume (i.e. whichever one of the reservoir  40  or the suit  32  is higher in elevation) to the lower volume (i.e. whichever one of the reservoir  40  or the suit  32  is lower in elevation). Both the pump  58  and the valve  60  can be controllable, for example via a control mechanism  62 , and power can be provided by one or more batteries on the vehicle  10 . Control commands to control the transfer of gas between the reservoir  40  and the suit  32  can be initiated by the occupant  12   a  using, for example, suitable controls on the vehicle  10 . In some embodiments, the valve  60  can be manually opened and closed by the occupant  12 , and the pump  58  can be manually driven by the occupant  12   a , for example by rotating a handle or using the occupant&#39;s foot to actuate a bellows, diaphragm or the like. In some embodiments, the gas in the fluid line  52  can flow through and be heated by a powered heater  64  that mechanically/electrically/chemically warms the gas prior to delivery into the interior space of the suit  32 . 
         [0035]    With reference now to  FIGS. 2, 3A, and 3B , the suit  32  is configured to be worn by the occupant  12   a . The suit  32  is deformable and the material forming the suit  32  is designed to be both gas and water impermeable so that gas in the interior of the suit cannot escape through the material of the suit, and water in the surrounding water environment cannot permeate through the material of the suit into the interior. The suit  32  can be formed of any materials providing these properties. Examples of materials that can be used include, but are not limited to, materials used to form dry suits such as elastomeric coated fabrics or rigid geometric shapes interconnected with sealed hinge joints. The suit  32  is illustrated in  FIGS. 2 and 3A  in an “inflated” condition where gas has been introduced into the interior of the suit  32  from the reservoir  40 . When the gas is transferred from the suit  32  back into the reservoir  40 , the suit  32  would assume a collapsed or non-inflated configuration about the occupant  12   a . The suit  32  is illustrated in the figures as being transparent to help in understanding the construction and operation of the suit. In actual practice, the suit  32  may be transparent, translucent or opaque. 
         [0036]    In the example illustrated in  FIGS. 2, 3A, and 3B , the suit  32  includes a main portion  70  that defines a single common interior space that when donned by the human occupant  12   a  envelops the head  72 , neck  74 , chest  76 , lower abdomen  78 , waist  80 , upper thighs  82 , shoulders  84 , arms  86  and hands  88  of the human occupant  12   a  as shown in  FIG. 2 . In another embodiment, the suit  32  can be extended downward so that the single common interior space also envelopes the knees  90  of the occupant  12   a  as shown in  FIG. 4 . In still another embodiment, the suit  32  can be extended downward so that the single common interior space also envelopes the lower legs  92  and the feet  94  of the occupant  12   a , with the lower legs  92  and feet  94  being side-by-side in a common space  95  as shown in  FIG. 5 . In still another embodiment, the suit  32  can be extended downward so that the single common interior space also envelopes the lower legs  92  and the feet  94  of the occupant  12   a , with the lower legs  92  and feet  94  being disposed in separate left and right leg sleeves  96   a ,  96   b , respectively, as shown in  FIG. 6 . The leg sleeves  96   a ,  96   b  are both in communication with and form part of the single common interior space. In still another embodiment illustrated in  FIG. 11 , the suit  32  extends downward so that the single common interior space envelopes the head  72 , neck  74  and tops of the shoulders  84  of the human occupant  12   a . Many other configurations of the suit  32  covering different portions of the occupant&#39;s  12   a  body are possible. 
         [0037]    Returning to  FIG. 3A , the main portion  70  of the suit  32  includes a head protuberance  98  in which the head  72  of the occupant  12   a  is disposed during use. The main portion  70  also includes a pair of arm and hand protuberances  100   a ,  100   b  into which the occupant&#39;s arms  86  and hands  88  can extend to permit the occupant  12   a  to access and control equipment and conduct activities external to the suit  32 . In one embodiment, main portion  70  of the suit  32 , and the interior space thereof, can be sized to permit the occupant to withdraw their arms  86  and hands  88  into the interior space so that the occupant can maneuver their arms and hands inside the interior space, for example to access other parts of their body using their hands  88 . In the case of the embodiments illustrated in  FIGS. 4-6 , the occupant  12   a  may also be able to withdraw their legs (thighs, knees, lower legs) and feet into the interior space for access by the occupant&#39;s hands. In one non-limiting example, when “inflated”, the interior space of the main portion  70  of the suit  32  illustrated in  FIG. 3A  can have an interior volume of about 8400 in 3 . 
         [0038]    The suit  32  further includes a fluid port  102  thereon that is connectable to the second end  56  of the fluid line  52 , and through which gas is introduced into the interior space of the suit  32 . In the example illustrated in  FIG. 3A , the fluid port  102  is formed in the head protuberance  98  at the top of the suit  32 . However, the fluid port  102  can be provided at any location on the suit  32  that can result in water being forced from the interior of the suit  32  when gas is introduced into the suit  32  through the fluid port  102  and where water will completely displace the gas from the interior volume of the suit  32  when gas is withdrawn from interior of the suit  32  via the fluid port  102 . The head protuberance  98  further includes a transparent viewing panel  104  on a front side thereof that is positioned to permit the occupant  12   a  to see through the suit  32 . The viewing panel  104  can be formed of a rigid plastic material such as polycarbonate, vinyl, or the like. 
         [0039]    In one embodiment, a breathing portal  106  is formed in head protuberance  98  through which the occupant  12   a  breaths. In one non-limiting example, the breathing portal can be formed in the viewing panel  104 , although other locations of the breathing portal  106  are possible. As shown in  FIG. 2 , the breathing portal  106  can be connected to an external air regulating apparatus  108  such as one or more SCUBA devices that provide a sanitary breathing gas mix (such as air) for the occupant  12   a . In another embodiment where adequate recirculation of the gas in the interior space of the suit  32 , including gas re-conditioning and removal of harmful constituents from the gas, can be provided, the occupant  12   a  may be able to breath the gas that is in the interior space of the suit  32 , avoiding the need for the breathing portal  106  and the external air regulating apparatus  108 . 
         [0040]    Like the reservoir  40 , the suit  32  is also water-floodable to allow ingress and egress of water into and from the interior space of the suit  32 . Any means for allowing water entry and egress into and from the suit  32  can be utilized including, but not limited to, a scupper(s), standpipe(s) or tube(s), vent(s), louver(s), and the like. In the illustrated example of  FIG. 3A , the main portion  70  of the suit  32  includes a skirt  110  that is open and through which water can enter and exit the interior space of the suit  32 . 
         [0041]      FIG. 3A  illustrates an example of a first condition of the suit  32  prior to gas being introduced into the suit  32  (the suit  32  is shown inflated for sake of convenience even though gas may not have been introduced into the suit  32  to inflate the suit  32 ) as well as a second condition of the suit  32  after gas being introduced. In the first condition, the interior of the suit  32  may be entirely filled with water particularly if the suit  32  is donned by the occupant  12   a  while under water. In the first condition, the reservoir  40  contains a maximum amount of gas and a minimum amount of, or no, water as indicated by the gas/water interface  44  shown in  FIG. 3C . When gas is transferred from the reservoir  40  into the suit  32 , the gas forces water from the interior of the suit  32  out of the skirt  110 . The occupant  12   a  can control how much gas is introduced into the suit  32  to determine the level of a resulting gas/water interface  112  in the suit as shown in  FIG. 3A . The level of the gas/water interface  112  can be located at a level that is just above the water ingress/egress means of the suit  32 . 
         [0042]    To prevent the suit  32  from floating free when the interior space is filled with gas, the suit  32  can be fastened to the vehicle  10 . For example, with reference to  FIG. 2 , the suit  32  can be fastened to the seat  30 . In one embodiment, the skirt  110  of the suit  32  can be fastened to the sitting portion  36  and/or to the back portion  34  using buttons, snaps, hoop and loop fasteners, or other fastening means. In one embodiment, the suit  32  is detachably fastened to the vehicle  10 , such as to the seat  30 , to allow detachment of the suit  32  from the vehicle. In one embodiment, the fastening that is used is not continuous around the skirt  110 ; instead gaps or spaces can be provided between the fasteners to permit the ingress and egress of water through the skirt  110  between the spaced fasteners. In another embodiment, the suit  32  is fastened to the occupant  12   a , for example to the occupant&#39;s thighs, instead of being fastened to the vehicle  10 . 
         [0043]    In some embodiments, when not in use the suit  32  may be stowed in a folded and compressed state in an accessible storage location, for example in a compartment  124  on or near the seat  30  (see  FIG. 2  showing the compartment  124  underneath the seat  30 ). When the suit  32  is to be used, the suit  32  is removed from its storage location, unfolded and donned by the occupant  12   a  and fastened to the seat  30 . The suit  32  can be accessed and donned by the occupant  12   a  at any time while occupant  12   a  is on the vehicle  10 , for example while the vehicle  10  is at the surface of the water or submerged under the water. In another embodiment, the suit  32  can be donned by the occupant prior to the occupant occupying the vehicle  10 , with the occupant then attaching the suit  32  to the fluid line  52  and fastening the suit to the vehicle  10  after occupying the vehicle. 
         [0044]      FIG. 7  illustrates a variation of the suit  32  where the interior of the suit  32  is formed with one or more internal dry storage pouches  120 , for example on an interior front surface  122   a , on an interior side surface  122   b , and/or on an interior rear surface  122   c  of the suit  32 . The pouch  120  can be opened and closed, for example by a flap or a waterproof zipper, and forms a storage area allowing storage of items that the occupant  12   a  may want to access while within the suit  32 . Because the pouch  120  can be closed in a water tight manner, the storage area and the contents contained therein can be kept dry even while the suit is flooded and folded prior to or after use. Once the occupant  12   a  introduces the gas into the interior of the suit  32  to force out the water to the desired level, typically below the level of the pouch  120 , the occupant  12   a  can then withdraw one or both arms into the interior of the suit to open the pouch  120  and access contents within the pouch  120 . 
         [0045]    In some embodiments, the suit  32  may be simply pulled over the occupant  12   a  by the occupant  12   a  entering the suit  32  through the skirt  110 . In other embodiments, the suit  32  can be opened and closed by one or more waterproof closure mechanisms that permit the main portion  70  of the suit  32  to be opened and closed to facilitate donning and removal of the suit  32  by the occupant  12   a . For example, with reference to  FIG. 8 , the suit  32  can include a waterproof zipper  126  on a side of the main portion  70  and/or on the front of the main portion  70 . The waterproof zipper  126  extends from the skirt  110  up toward the head protuberance  98  and can be designed to close in the upward or downward directions relative to the skirt  110 . In other embodiments, the waterproof zipper  126  can extend circumferentially around the suit  32  instead of extending vertically on the suit. Waterproof closure mechanisms other than the waterproof zipper  126  can be used. 
         [0046]    The embodiments described above describe the gas reservoir  40  as being formed by the seat  30 . However, other gas reservoirs on the vehicle  10  in place of or in addition to the gas reservoir  40  in the seat  30  can be used. For example,  FIG. 9  illustrates a water-floodable gas reservoir  150  that communicates with the fluid line  52  for exchanging gas with the interior of the suit  32 . The reservoir  150  can be positioned at any location on the vehicle  10  where the reservoir  150  is exposed to or communicates with the surrounding water environment, and the reservoir includes drains, scuppers or other openings to permit ingress and egress of water from the reservoir  150  as indicated by the arrows in  FIG. 9 . The reservoir  150  functions similarly to the reservoir  40  and can also include a gas transfer mechanism similar in construction and function to the gas transfer mechanism  50  described above. 
         [0047]      FIG. 10  illustrates an example method  160  of using the suit  32 . In a first step  162 , the occupant dons the suit  32 . As explained above, the suit can be donned by the occupant prior to or after occupying the vehicle  10 , as well as while the vehicle is at the water surface or submerged underwater. In some embodiments, the suit  32  can be pre-connected to the fluid line  52  prior to the occupant donning the suit  32  and/or the suit can be pre-attached to the vehicle  10 . In other embodiments, after the occupant dons the suit  32 , the occupant or another person connects the fluid port  102  of the suit  32  to the fluid line  52 , and fastens the suit  32  to the vehicle  10 , for example fastening the skirt  110  to the seat  30 . 
         [0048]    Once the suit  32  is donned, the gas connection is established, and the suit  32  fastened to the vehicle  10 , the occupant introduces gas from the gas reservoir into the interior of the suit  32  in step  164 . The introduction of the gas can be initiated and controlled by the occupant in any manner, for example using an automated control located on the vehicle  10  or manually by the occupant. When gas introduction is initiated, the valve  60  is opened, automatically or manually, and the pump  58  pumps the gas, automatically and/or manually, from the reservoir into the interior of the suit  32  at an elevated pressure. Depending upon the relative elevations of the suit  32  and the reservoir, the gas in the reservoir may already be at a high enough pressure to flow into the suit  32  without use of the pump  58 . 
         [0049]    As gas is introduced into the suit  32 , water is forced from the interior of the suit  32  out through the skirt  110 . At the same time, the water level in the reservoir rises to replace the gas that has been transferred into the suit  32 . In step  166 , the occupant controls the amount of gas introduced into the suit which controls the level of the water/gas interface  112  in the suit  32  allowing the occupant to control how much water is forced from the interior of the suit  32 . 
         [0050]    The gas in the interior of the suit creates a pneumatic barrier around the occupant. The gas is heated by the occupant&#39;s body heat, and if additional heating is desired, the gas can also be heated by the heater  64 . High heat loss from the occupant is reduced by enveloping at least the occupant&#39;s core in the gas barrier to isolate the occupant&#39;s core from the surrounding water while being transported on the vehicle  10 . 
         [0051]    Once the vehicle reaches a desired destination, the occupant can then pump the gas from the interior of the suit back into the reservoir, forcing the water from the interior of the reservoir and allowing water to flood into the suit. Because the total volume of gas in the reservoir and the interior of the suit, for any given depth, remains constant, the overall buoyancy acting on the wet submersible vehicle does not change for any given depth. In addition, because the gas is re-useable, the gas does not require regeneration. In addition, there is no expelled gas that is prone to observation resulting from a tell-tale eruption of bubbles at the water surface. 
         [0052]    The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.