Abstract:
A vessel transfer system utilizes a larger, surface effect vessel with a hull and a cargo deck, having a pressurized volume of air under its hull. The larger vessel cargo deck is lowered relative to a water surface in order to receive a smaller vessel. Lowering is achieved by depressurizing the volume of pressurized air under the hull. Movable propulsors on an air cushion vehicle permit efficient operation under way in an outer position, while minimizing the envelope dimensions for stowage in a well deck, providing clearance from bridges, docks, etc. in an inner position. In the outer position, the propellers operate in more uniform inflow conditions, resulting in improved performance and lower noise levels. In addition, the craft can be arranged to use a full width stern ramp resulting in time saved during cargo loading/unloading. The propellers will be less likely to ingest green water in high sea states.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Priority of U.S. Provisional Patent Application Ser. No. 60/748,449, filed 7 Dec. 2005, incorporated herein by reference, is hereby claimed. 
   Priority of U.S. Provisional Patent Application Ser. No. 60/756,951, filed 5 Jan. 2006, incorporated herein by reference, is hereby claimed. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the deep water transfer of a first, smaller marine or amphibious vessel to a second, larger vessel that is a surface effect or air cushion vessel that travels upon a pressurized volume of air, wherein transfer includes depressurizing of the air cushion under the second vessel so that its cargo deck is lowered to an elevation that is at or near the water surface. Such transfer can optionally include a combination of ballasting and a lowering of pressure (or depressurization) of the volume of air under the second vessel. 
   The present invention also relates to an improved air cushion vehicle having a multiple lane loading ramp and deck arrangement with air propulsors that move between inner and outer positions for enabling transfer to a larger vessel (inboard propulsion position) and increased propulsion efficiency (outboard propulsion position). 
   2. General Background of the Invention 
   In the prior art, transfer of a smaller vessel to and from a larger vessel (or a first vessel to a second vessel) has typically been achieved by ballasting with water. Usually, a larger marine vessel is ballasted until a cargo deck of the larger marine vessel is at an elevation sufficiently low in the water to enable the smaller marine vessel to float on the water surface while traveling to the cargo deck of the larger vessel. 
   In general, air cushion vehicles or “ACV&#39;s” (also known as surface effect ships or hovercraft) are known. Examples of such ACV&#39;s are disclosed in the US Patents listed in the following table. The following table also lists some patents that involve transfer of item(s) to or from a surface effect vessel. 
   
     
       
             
             
             
           
         
             
               TABLE 1 
             
             
                 
             
             
               U.S. Document 
                 
               Date 
             
             
               No. 
               Title 
               (MM/DD/YYYY) 
             
             
                 
             
           
           
             
               1,976,046 
               Waterfoil 
               10/09/1934 
             
             
               2,405,115 
               Floating Structure 
               08/06/1946 
             
             
               3,065,723 
               Supercavitating Hydrofoils 
               11/27/1962 
             
             
               3,077,173 
               Base Ventilated Hydrofoil 
               02/12/1963 
             
             
               3,141,436 
               Hydrofoil Assisted Air 
               07/21/1964 
             
             
                 
               Cushion Boat 
             
             
               3,458,007 
               Captured Air Bubble (CAB) 
               07/29/1969 
             
             
                 
               Ground Effect Machine 
             
             
               3,589,058 
               Toy Ground Effect Vehicle 
               06/29/1971 
             
             
                 
               With Adjustable Stabilizing 
             
             
                 
               Weight 
             
             
               3,621,932 
               Gas-Cushion Vehicles 
               11/23/1971 
             
             
               3,817,479 
               Helicopter Powered Air 
               06/18/1974 
             
             
                 
               Cushioned Platform 
             
             
               3,893,538 
               Ground Effects Vehicle and 
               07/08/1975 
             
             
                 
               An Air Terminal 
             
             
               3,917,022 
               Twin Cushion Surface Effect 
               11/04/1975 
             
             
                 
               Vehicle 
             
             
               3,987,865 
               Gas-Cushion Vehicle Skirt 
               10/26/1976 
             
             
               4,469,334 
               Sealing System For The Air 
               09/04/1984 
             
             
                 
               Cushion Of An Air-Cushion 
             
             
                 
               Vessel 
             
             
               4,489,667 
               Surface Effect Ship Seals 
               12/25/1984 
             
             
               4,506,618 
               Propeller And Keel 
               03/26/1985 
             
             
                 
               Arrangement For Surface 
             
             
                 
               Effect Ships 
             
             
               4,535,712 
               Variable Air Cushion Mode 
               08/20/1985 
             
             
                 
               Vehicle 
             
             
               4,543,901 
               Surface Effect Ship Air 
               10/01/1985 
             
             
                 
               Cushion Seal System 
             
             
               4,646,866 
               Surface Effect Type, Side 
               03/03/1987 
             
             
                 
               Keel Vessel Fitted With An 
             
             
                 
               Improved Forward Buoyancy 
             
             
                 
               Cushion Seal Apparatus 
             
             
               4,660,492 
               Catamaran Air Cushion Water 
               04/28/1987 
             
             
                 
               Vehicle 
             
             
               4,708,077 
               Hull Shapes For Surface 
               11/24/1987 
             
             
                 
               Effect Ship With Side Walls 
             
             
                 
               And Two Modes Of 
             
             
                 
               Operation 
             
             
               4,714,041 
               Structure of surface effect 
               12/22/1987 
             
             
                 
               ship with side walls 
             
             
               4,739,719 
               Movable bow seal air ride 
               04/26/1988 
             
             
                 
               boat hull 
             
             
               4,767,367 
               Integrated Combination 
               08/30/1988 
             
             
                 
               Propeller Drive Shaft 
             
             
                 
               Fairing and Water Intake 
             
             
                 
               Sea Chest Arrangement, For 
             
             
                 
               High Speed Operating Marine 
             
             
                 
               Craft 
             
             
               4,984,754 
               Heli-Hover Amphibious 
               01/15/1991 
             
             
                 
               Surface Effect Vehicle 
             
             
               5,651,327 
               Displacement, Submerged 
               07/29/1997 
             
             
                 
               Displacement, Air Cushion 
             
             
                 
               Hydrofoil Ferry Boat 
             
             
               5,711,494 
               Aero-Hydroglider 
               01/27/1998 
             
             
               5,860,383 
               Displacement, Submerged 
               01/19/1999 
             
             
                 
               Displacement, Air Cushion 
             
             
                 
               Hydrofoil Ferry Boat 
             
             
               5,934,215 
               Stabilized Air Cushioned 
               08/10/1999 
             
             
                 
               Marine Vehicle 
             
             
               6,293,216 
               Surface Effect Ship (SES) 
               09/25/2001 
             
             
                 
               Hull Configuration Having 
             
             
                 
               Improved High Speed 
             
             
                 
               Performance and Handling 
             
             
                 
               Characteristics 
             
             
               6,439,148 
               Low-Drag, High-Speed Ship 
               08/27/2002 
             
             
               2002/0164231 
               Craft for Embarking/Landing 
               11/07/2002 
             
             
                 
               On Unequipped Shorelines 
             
             
               6,487,981 
               Air Assisted Landing Craft 
               12/03/2002 
             
             
               2003/0000440 
               Air Assisted Landing Craft 
               01/02/2003 
             
             
               6,526,903 
               High speed M-shaped boat hull 
               03/04/2003 
             
             
               6,609,472 
               Stable efficient air 
               08/26/2003 
             
             
                 
               lubricated ship 
             
             
               2005/0211150 
               Variable Hybrid Catamaran 
               09/29/2005 
             
             
                 
               Air Cushion Ship 
             
             
               2005/0236200 
               Wrapped-cone fingers for 
               10/27/2005 
             
             
                 
               skirt systems 
             
             
               7,013,826 
               Hybrid Catamaran Air Cushion 
               03/21/2006 
             
             
                 
               Ship 
             
             
                 
             
           
        
       
     
   
   Incorporated herein by reference are the foregoing and U.S. Pat. Nos. 4,767,367; 4,984,754; 6,293,216; and 6,439,148. These incorporated by reference patents relate generally to air cushion vehicles, surface effect ships or hovercraft. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention includes a vessel transfer system which utilizes a larger vessel, that is a surface effect vessel with a hull and a cargo deck, having a pressurized volume of air under its hull. The larger vessel cargo deck is lowered relative to a water surface in order to receive a smaller vessel. Lowering is achieved by depressurizing or lowering the pressure of the volume of pressurized air under the hull. The present invention further relates to the use of movable propulsors on an air cushion vehicle or ACV to permit efficient operation under way in an outer position, while minimizing the envelope dimensions for stowage in a well deck, providing clearance from bridges, docks etc. in an inner position. In the outer position, the propellers operate in more uniform inflow conditions, resulting in improved performance and lower noise levels. In addition, the craft can be arranged to use a full width stem ramp resulting in time saved during cargo loading and unloading, and the propellers will be less likely to ingest green water in high sea states. 
   The present invention relates to the use of an air cushion to vary the cargo deck height of a large ship for the purpose of loading and unloading a smaller craft or crafts from the sea, cargo from another ship or cargo from a dock. In all cases, the pressure in the cushion is varied to adjust the elevation of the cargo deck to facilitate cargo transfer. Cushion pressure may be used either alone, or in combination with ballast to achieve the desired cargo deck elevation. Relative to ballast however, pressure variation is much faster, and could be used dynamically to compensate for wave induced motions in addition to the adjustment of steady state deck height. 
   The present invention provides a method of transferring a first, smaller marine or amphibious vessel to and from a second, larger vessel in a deep water marine environment. The terminology “deep water” as used herein means that neither vessel is supported upon land or a sea bottom during the transfer. The subject first smaller and second larger vessels and their component parts can be constructed from any high strength, light weight material, including but not limited to, high strength steel, aluminum, titanium, composites, or the like. 
   The invention can be scaled to a wide range of sizes. The range of pressures most likely to be used are 50-250 lb./sq.ft. (24.41 to 122.06 gf/cm 2 ), or ⅓psi (23.41 gf/cm 2 ) to 2 psi (140.61 gf/cm 2 ) and typically less than 5.0 psi (351.53 gf/cm 2 ). 
   Overall length of the larger vessel could range, for example, from around 500 to 1000 feet (152.40 to 304.80 meters), and overall length of the smaller air cushion vehicle would probably be, for example, about 50 to 150 feet (15.24 to 45.72 meters). 
   The present invention provides a method of transporting a first marine vessel upon a second marine vessel in a deep water environment, wherein neither vessel is supported by land or a seabed. 
   The method of the present invention includes providing a first marine vessel and a second vessel that is a surface effect vessel. The second vessel (surface effect vessel) provides a hull with a bow and a stem. The hull has a cargo deck and an under deck volume that can be pressurized with air so that the hull is primarily supported with a pressurized volume of air when it is propelled along the water surface. The first and second vessels are transported to a selected locale in the deep water marine environment. 
   After reaching the selected locale, the pressure of the volume of air under the hull of the second marine vessel is lowered, so that the hull and cargo deck of the second marine vessel are lowered in elevation relative to the surrounding water surface. Thereafter, the first vessel is transferred to the surrounding water surface of the deep water marine environment from the lowered cargo deck of the second marine vessel. 
   For recovery, the second marine vessel assumes a lowered position with its under hull volume of air depressurized. The first vessel then travels on the water surface from the surrounding water surface to the cargo deck of the second vessel. At this time of transfer, the lowered cargo deck of the second vessel can be partially submerged. The lowered cargo deck can be at least in part at the level of the water surface. The second vessel can then transfer the first vessel (now on board) to a selected destination once the volume of air under the hull of the second vessel is pressurized. This procedure can be reversed to off load the first, smaller vessel. 
   The present invention also provides an air cushion vehicle (e.g. the first, smaller vessel) having a hull with a hull periphery, bow, stem, port side, starboard side and deck. 
   An air based propulsion system is provided for propelling the hull by thrusting into the surrounding air mass. 
   The air propulsion system includes one or more air propellers that move in reference to the hull between first and second positions, one position placing the air propeller at least in part outboard of the hull periphery. 
   Hydraulic rams or linear motors are possible mechanisms for pivoting the air propellers between first and second positions. 
   The air propellers engage the air during use. 
   One of the air propeller positions places the air propeller within the periphery of the hull. 
   There are preferably two air propellers, one placed on the port side of the hull, the other placed on the starboard side of the hull. 
   The port side air propeller preferably moves between an outer position wherein it is at least partially outboard of the hull periphery on the port side of the hull to an inner position within the hull periphery next to the port side of the hull. Similarly, the starboard side air propeller moves between an outer position wherein it is at least partially outboard of the hull periphery on the starboard side of the hull to a position within the hull periphery and next to the starboard side of the hull. 
   Each air propeller thus moves to a position outside the hull periphery for maximum thrust to a position inside the hull periphery for use in loading onto the deck of another vessel or other use wherein a narrowed width is of value. The air propellers are preferably positioned at the stern of the vessel. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the attached drawings which are identified as follows: 
       FIG. 1  is a perspective view illustrating the method of the present invention; 
       FIG. 2  is an additional perspective view illustrating the method of the present invention; 
       FIG. 3  is a partial perspective view of the preferred embodiment of the apparatus of the present invention showing the position of the first and second vessels during a launch or recovery of the first vessel; 
       FIG. 4  is a side, elevation view illustrating the method of the present invention and showing a smaller vessel that has been transferred from a surrounding water surface to a larger vessel and wherein the larger vessel is in a lower transfer position that is a displacement mode; 
       FIG. 5  is a side, elevation view illustrating the method of the present invention and showing a smaller vessel that has been transferred from a surrounding water surface to a larger vessel and wherein the larger vessel is in a higher position, pressurized, travel mode; 
       FIG. 6  is a perspective view of the preferred embodiment of the apparatus of the present invention showing the smaller, first marine vessel; 
       FIG. 7  is a perspective view of the preferred embodiment of the apparatus of the present invention showing in more detail, the deck loaded with multiple vehicles occupying multiple (three) lanes; 
       FIG. 8  is a front, elevation view of the preferred embodiment of the apparatus of the present invention showing the main propulsors pivoted outward for increased thrust, efficiency and full width stem ramp capability; 
       FIG. 9  is a front, elevation view of the preferred embodiment of the apparatus of the present invention showing the main propulsors pivoted inward for well-deck compatibility; 
       FIG. 10  is a fragmentary elevation view of the preferred embodiment of the apparatus of the present invention and showing the propulsor fan in an outboard operating position; 
       FIG. 11  is a fragmentary elevation view of the preferred embodiment of the apparatus of the present invention and showing the propulsor fan in an inboard loading position; 
       FIG. 12  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating a mechanism for moving the propulsor fan in between inboard and outboard positions; 
       FIG. 13  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating a mechanism for moving the propulsor fan in between inboard and outboard positions; and 
       FIG. 14  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating a mechanism for moving the propulsor fan in between inboard and outboard positions. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-5  show generally the preferred method of the present invention and the transfer system of the present invention which is designated generally by the numeral  10 . 
   The method of the present invention involves the use of a first, typically smaller marine vessel  11  that is to be transferred to or from the cargo deck  18  of a second, typically larger marine vessel  12 . The second vessel  12  will receive the first marine vessel  11  and transport it to a selected locale. The first, smaller vessel  11  can then be off loaded. Such a transfer enables the two vessels  11 ,  12  to travel with the first vessel  11  resting upon a cargo deck  18  of the second vessel  12 . 
   The first vessel  11  can be any vessel that floats and can include for example a hovercraft, an amphibious vessel or any floating vessel that is able to travel upon a surrounding water surface  30  of a surrounding deep water marine environment  29 . As part of the method of the present invention, the first, smaller vessel  11  travels from water surface  30  to the upper surface  19  of cargo deck  18  of second marine vessel  12 . 
   In  FIGS. 1 and 2 , the first marine vessel  11  is a smaller marine vessel that provides a continuous inflatable wall that surrounds a pressurized volume of air under the hull of the vehicle. Vessel  11  can also be of the type that has a continuous inflatable skirt or wall  57  that extends around the periphery of the vessel  11 . Such a vessel with continuous inflatable skirt can be seen in U.S. Pat. No. 4,984,754, which is hereby incorporated herein by reference. 
   The second marine vessel  12  is preferably an air cushion vehicle, hovercraft or surface effect vessel. Vessel  12  can be the type that has two spaced apart rigid hulls (e.g. catamaran) and that provides sealing members or skirts forward and aft. The second marine vessel  12  provides a hull  13  that can be a single hull or a pair of spaced apart hull members providing a catamaran type hull. Hull  13  has a bow  14  and a stem  15 , a port side  16  and a starboard side  17 . 
   In such a catamaran rigid hulled vessel  12 , a pressurized volume of air  28  (see  FIG. 5 ) is trapped under the hull  13 . The pressurized volume of air  28  is trapped in between the two rigid hulls and in between front and rear seals or skirts  21 . Such rigid hull catamaran surface effect vessels can be seen in U.S. Pat. Nos. 3,987,865 and 4,714,041, each hereby incorporated herein by reference. In  FIGS. 3 and 4 , the vessel  12  that is shown is a larger vessel that has spaced apart rigid hulls including a port side hull  22  and a starboard side hull  23 . Flexible seals  21  can be provided fore and aft. A pressurized volume of air  28  (see  FIG. 5 ) can be trapped under hull  13  in between the spaced apart rigid hulls  22 ,  23 , under the cargo deck  18 , in between fore and aft flexible seals  21 , and above the water surface  30 . 
   Hull  13  provides a cargo deck  18  having an upper surface  19  that is receptive of first, smaller vessel  11  according to the method of the present invention. The cargo deck  18  can provide an inclined section  20  that is next to or that communicates with the water surface  30 . Inclined section  20  or surface  19  can be positioned near or below water surface  30  when a transfer (see  FIGS. 2 and 4 ) of vessel  11  to cargo deck  18  is to take place. 
   In  FIG. 4 , cargo deck  18  can provide an inclined section  20  that is near that part of vessel  12  that will receive vessel  11 . In  FIGS. 3 and 4 , vessel  11  transfers from surrounding deep water marine environment  29  to cargo deck  18  at a position next to stem  15  of hull  13 . However, it should be understood that such a transfer could take place at the bow of vessel  12 , or at another location if desired. 
   Hull  13  can provide a superstructure  24 . Hull  13  can be propelled using propellers  25  or jets as examples. In the embodiment shown in  FIGS. 1-4 , a propeller  25  can be provided to each of the hulls  22 ,  23 . Steering is provided with a rudder  26  that is preferably positioned behind each propeller  25 , a rudder  26  is thus mounted on each of the port and starboard hulls  22 ,  23 . 
   Gate  31  is an optional feature that is shown in  FIGS. 1-4 . Gate  31  can be a part of cargo deck  18  that pivots to an open position which is shown in  FIGS. 1 ,  2  and  4 . Gate  31  can pivot to a closed position as indicated schematically by arrow  33  in  FIG. 3 . It should be understood however that gate  31  is an optional feature that can help dampen waves during transfer. 
   In  FIGS. 1 and 2 , arrow  32  schematically illustrates the forward movement of first vessel  11  toward cargo deck  18  of second vessel  12 . In  FIGS. 1 ,  2  and  4 , second vessel  12  is in its lowered or displacement mode, as indicated by the reference line  36  designating the water line relative to the vessel hull  13 . In  FIG. 5 , arrows  34  illustrate schematically the elevation of the hull  12  relative to the water surface  30 . Reference line  27  in  FIG. 5  shows the water line in reference to hull  13  when the hull  13  is on its air cushion  28  for traveling. Arrows  34  show that the upper deck  19  of cargo deck  18  has been elevated a distance indicated by arrows  77  in  FIG. 5 , i.e. the distance between reference lines  27  and  36 . 
   In order to transfer the vessel  11  to the cargo deck  18  of the vessel  12 , the vessel  12  simply lowers the pressure of the pressurized volume of air that is contained under its hull  13 . For a hovercraft or surface effect ship such as the vessel  12 , this is accomplished by deactivating the powered fans that create the pressurized cushion of air upon which the vessel  12  travels. When a pressure lowering occurs, the vessel  12  is lowered in the water from a higher position shown in  FIG. 5  (reference line  36 ) to the lower position shown in  FIG. 4  (reference line  27 ). 
   In  FIG. 5 , reference line  27  indicates the position of the water line when the vessel  12  is supported by the air cushion. In  FIG. 5 , a pressurized cushion or pressurized volume of air elevates the vessel  12  to the position shown. In  FIGS. 1 ,  2  and  4 , the pressure of the pressurized volume of air has been reduced so that the vessel  12  lowers in the water. This lowering of vessel  12  places cargo deck  18  upper surface  19  at, near or next to the water surface  30 . 
     FIGS. 6-14  show a more detailed view of a suitable first, smaller marine vessel  11 . First vessel  11  provides a hull  41  having bow  42  and stern  43  portions. The hull  41  provides a port side  44  and a starboard side  45 . A hull periphery  46  is shown for purposes of reference when discussing the movement of the air propulsors or propellers  48  between the inner or inboard position of  FIG. 9  and the outer or outboard position of  FIG. 8 . 
   A stem ramp  47  is positioned at stern  43 , in between propulsors  48 . Ramp  47  is preferably of a width that enables full width loading of three lanes of vehicles  50  when the propulsors  48  are in the outboard position of  FIGS. 7 and 8 . 
   The hull  41  provides a deck area  49  for containing vehicles  50 . As shown in  FIG. 7 , multiple lanes of vehicles  50  are provided so that three vehicles  50  at a time can be loaded to deck area  49  using the three lane stern ramp  47 . A bow ramp  55  is likewise provided for unloading vehicles  50 , three lanes at a time. 
   In  FIGS. 8-14 , the movement of air propulsors or propellers  48  is shown between the inner or inboard position  51  ( FIGS. 9 and 11 ) and the outer or outboard position  52  ( FIGS. 8 and 10 ). Each of the propellers  48  is a variable geometry main propulsor  48  that moves to the position of  FIGS. 8 and 10  for enabling more efficiency and the position of  FIGS. 9 and 11  which allows the first vessel  11  to be loaded onto second larger vessel  12  without damage to the propulsors  48 . 
   In  FIGS. 8 and 9 , reference numbers  53  and  54  are provided on the port and starboard sides of hull  41 . Vertical reference line  53  extends upwardly from the periphery  46  of hull  41 . Vertical reference line  54  extends upwardly from the inside edge of propulsor  48 . In the position of  FIG. 8 , it can be seen that at least a part of each of propulsors  48  is outboard of hull periphery  46  and thus outboard of reference lines  53  and  54 . When the propulsors  48  are in the position of  FIG. 8 , the distance between them as indicated by arrow  56  is equal to or wider than the width of the multiple (e.g. three) lane stem ramp  47 . In the position of  FIG. 9 , it can be seen that at least a part of each of propulsors  48  is inboard of hull periphery  46  and thus inboard of reference lines  53  and  54 . 
   As can be seen in  FIGS. 8-11 , the air propulsion system includes a pair of air propellers  48  that each move generally laterally in reference to the hull between first and second positions (see  FIG. 9 ), one position  52  placing each air propeller at least in part outboard of the hull periphery  46  (see  FIG. 8 ), and a second position  51  (see  FIG. 9 ) placing a majority of each propeller inboard of the hull periphery  46 . 
   The propulsors  48  in the position of  FIG. 8  do not in any way interfere with the loading of vehicles  50  to deck area  49 , including when loading multiple lanes at a time using the full width of multiple lane stem ramp  47 .  FIGS. 10-14  show in more detail the movable connection between the propeller  48  and hull  41 . In  FIGS. 10 and 11 , a pivotal connection  59  can be used to join propeller  48  to support structure  62  which is connected (for example, bolted or welded) to the vessel hull  41 . A motor such as hydraulic cylinder  60  can be used to rotate propeller  48  relative to ships hull  41  as indicated schematically by the arrow  58  in  FIGS. 9 and 11 . Hydraulic cylinder  60  can thus be connected to support structure  62  with pinned connection  61 . A pinned connection  74  can be used to attach hydraulic cylinder  60  to propeller  48 . 
   In  FIGS. 12-14 , alternate methods for driving the propeller blades  66  are illustrated. In  FIG. 12 , motor drive  63  interfaces with propeller shaft  65  using a transmission  64 . Arrow  67  illustrates that transmission  64  rotates with motor drive  63  and with shaft  65  and fan  48 , as the fan  48  moves in an arcuate path as shown by arrow  67 . Similarly, the motor drive  63  in  FIG. 13  interfaces with drive shaft  69  using a transmission  68 . A right angle drive  70  connects shaft  69  to propeller shaft  72  using a gear box  71 . 
   In  FIG. 14 , a power generator  73  produces electricity that travels via transmission lines  75  to electric motor  76  which rotates propeller shaft  72  to which blades  66  are attached. 
   The following is a list of suitable parts and materials for the various elements of the preferred embodiment of the present invention. 
   
     
       
             
           
             
             
           
         
             
                 
             
             
               PARTS LIST 
             
           
        
         
             
               Part Number 
               Description 
             
             
                 
             
             
               10 
               vessel transfer system 
             
             
               11 
               first marine vessel 
             
             
               12 
               second marine vessel 
             
             
               13 
               hull 
             
             
               14 
               bow 
             
             
               15 
               stern 
             
             
               16 
               port side 
             
             
               17 
               starboard side 
             
             
               18 
               cargo deck 
             
             
               19 
               deck upper surface 
             
             
               20 
               inclined section of cargo deck 
             
             
               21 
               flexible seal or skirt 
             
             
               22 
               port hull 
             
             
               23 
               starboard hull 
             
             
               24 
               superstructure 
             
             
               25 
               propeller 
             
             
               26 
               rudder 
             
             
               27 
               reference line 
             
             
               28 
               pressurized air volume 
             
             
               29 
               deep water environment 
             
             
               30 
               water surface 
             
             
               31 
               gate section of cargo deck 
             
             
               32 
               arrow (vessel 1 launch/recovery) 
             
             
               33 
               arrow (gate movement) 
             
             
               34 
               arrow vessel 2 (on/off cushion) 
             
             
               35 
               arrows 
             
             
               36 
               reference line 
             
             
               41 
               hull 
             
             
               42 
               bow 
             
             
               43 
               stern 
             
             
               44 
               port side 
             
             
               45 
               starboard side 
             
             
               46 
               hull periphery 
             
             
               47 
               stern ramp 
             
             
               48 
               propulsors 
             
             
               49 
               deck area 
             
             
               50 
               vehicle 
             
             
               51 
               inner position 
             
             
               52 
               outer position 
             
             
               53 
               reference line 
             
             
               54 
               reference line 
             
             
               55 
               bow ramp 
             
             
               56 
               arrow, ramp width 
             
             
               57 
               inflatable skirt 
             
             
               58 
               arrow 
             
             
               59 
               pivot 
             
             
               60 
               hydraulic cylinder 
             
             
               61 
               pinned connection 
             
             
               62 
               support structure 
             
             
               63 
               motor drive 
             
             
               64 
               transmission 
             
             
               65 
               propeller shaft 
             
             
               66 
               propeller blade 
             
             
               67 
               arrow 
             
             
               68 
               transmission 
             
             
               69 
               drive shaft 
             
             
               70 
               right angle drive 
             
             
               71 
               gear box 
             
             
               72 
               propeller shaft 
             
             
               73 
               power generator 
             
             
               74 
               pinned connection 
             
             
               75 
               transmission 
             
             
               76 
               electric motor 
             
             
                 
             
           
        
       
     
   
   All measurements disclosed herein are at standard temperature and pressure, at sea level on earth, unless indicated otherwise. 
   The forgoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.