Abstract:
Autonomous, unmanned submersible can turn upside down in order to use instrumentation placed on one side only. Batteries ( 106 ) and instrumentation housing ( 104 ) are installed on frame rails ( 112,14,108,110 ) and can change their relative positions, thus inverting the relative positions between center of buoyancy and center of gravity and subsequently inverting the submersible.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 61/652,933, filed on May 30, 2012, which is incorporated by reference herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    This invention was made with Government support under N00174-07-D-0008 awarded by NAVSEA Indian Head. The Government has certain rights in this invention. 
     
    
     BACKGROUND 
       [0003]    Various unmanned submersible crafts are in use today by the military, scientific, and recreational communities. The submersible crafts may be used for a variety of tasks, and may be outfitted with a variety of equipment for performing those tasks. 
         [0004]    One such task may include inspection of underwater structures or of the seafloor via sonar devices. However, due to size constrains, weight constraints, and cost, it may not be practical to outfit a submersible craft with a sonar system capable of directing sonar to both sides of the craft simultaneously. For example, the sonar might be limited to being directed out of the port side of the craft only. Thus, a need exists for a submersible craft that is capable of being inverted so as to direct the sonar out of the opposite side of the craft, and a system and method for achieving such an inversion. 
       SUMMARY 
       [0005]    In one embodiment, a submersible craft is provided, the submersible craft comprising: an apparatus for selectively positioning a battery and a main electronics housing (“MEH”) within the submersible craft, the apparatus comprising: a battery; a battery rail apparatus comprising a first battery frame rail substantially vertically oriented within the submersible craft and a second battery frame rail substantially vertically oriented within the submersible craft, wherein the first battery frame rail is positioned on a first side of the submersible craft and the second battery frame rail is positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, wherein a first end of the battery is slidably connected to the first battery frame rail and a second end of the battery is slidably connected to the second battery frame rail; an MEH; an MEH rail apparatus comprising a first MEH frame rail substantially vertically oriented within the submersible craft and a second MEH frame rail substantially vertically oriented within the submersible craft, wherein the first MEH frame rail is positioned on a first side of the submersible craft and the second MEH frame rail is positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, wherein a first end of the MEH is slidably connected to the first MEH frame rail and a second end of the MEH is slidably connected to the second MEH frame rail; and wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy. 
         [0006]    In another embodiment, a submersible craft is provided, the submersible craft comprising: an apparatus for selectively positioning a battery and an MEH within the submersible craft, the apparatus comprising: a battery rail apparatus comprising a first battery frame rail substantially vertically oriented within the submersible craft and a second battery frame rail substantially vertically oriented within the submersible craft, wherein the first battery frame rail is positioned on a first side of the submersible craft and the second battery frame rail is positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, and wherein the first battery frame rail and the second battery frame rail are configured to be slidably connected to first and second ends of a battery, respectively; an MEH rail apparatus comprising a first MEH frame rail substantially vertically oriented within the submersible craft and a second MEH frame rail substantially vertically oriented within the submersible craft, wherein the first MEH frame rail is positioned on a first side of the submersible craft and the second MEH frame rail is positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, and wherein the first MEH frame rail and the second MEH frame rail are configured to be slidably connected to first and second ends of an MEH. 
         [0007]    In one embodiment, a system for selectively positioning a battery and an MEH within a submersible craft is provided, the system comprising: a battery; a battery rail apparatus comprising a first battery frame rail configured to be substantially vertically oriented within the submersible craft and a second battery frame rail configured to be substantially vertically oriented within the submersible craft, wherein the first battery frame rail is configured to be positioned on a first side of the submersible craft and the second battery frame rail is configured to be positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, wherein a first end of the battery is slidably connected to the first battery frame rail and a second end of the battery is slidably connected to the second battery frame rail; an MEH; an MEH rail apparatus comprising a first MEH frame rail configured to be substantially vertically oriented within the submersible craft and a second MEH frame rail configured to be substantially vertically oriented within the submersible craft, wherein the first MEH frame rail is configured to be positioned on a first side of the submersible craft and the second MEH frame rail is configured to be positioned on a second side of the submersible craft substantially opposite the first side of the submersible craft, wherein a first end of the MEH is slidably connected to the first MEH frame rail and a second end of the MEH is slidably connected to the second MEH frame rail; and wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy. 
         [0008]    In another embodiment, an apparatus for selectively positioning a battery and an MEH within a submersible craft is provided, the apparatus comprising: a battery; a battery rail apparatus substantially vertically oriented within the submersible craft, wherein the battery rail apparatus includes a first battery rail and a second battery rail, and wherein the first battery rail and the second battery rail are slidably connected to the submersible craft; an MEH; an MEH rail apparatus substantially vertically oriented within the submersible craft, wherein the MEH rail apparatus includes a first MEH rail and a second MEH rail, and wherein the first MEH rail and the second MEH rail are slidably connected to the submersible craft; wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy. 
         [0009]    In another embodiment, a method for selectively inverting a submersible craft is provided, the method comprising: providing a battery contained on a battery rail apparatus, wherein the battery rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the battery in one of a battery lower position and a battery upper position; providing an MEH contained on an MEH rail apparatus, wherein the MEH rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the MEH in one of an MEH upper position and an MEH lower position; providing an external shell upon the submersible craft; removing the external shell; moving the battery from the battery lower position to the battery upper position; moving the MEH from the MEH upper position to the MEH lower position, wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy; and replacing the external shell. 
         [0010]    In another embodiment, a method for selectively inverting a submersible craft is provided, the method comprising: providing a battery contained on a battery rail apparatus, wherein the battery rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the battery in one of a battery lower position and a battery upper position; providing an MEH contained on an MEH rail apparatus, wherein the MEH rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the MEH in one of an MEH upper position and an MEH lower position; moving the battery from the battery lower position to the battery upper position; and moving the MEH from the MEH upper position to the MEH lower position, wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy. 
         [0011]    In another embodiment, a method for selectively inverting a submersible craft is provided, the method comprising: moving a battery contained within the submersible craft from a battery lower position to a battery upper position; and moving an MEH within the submersible craft from an MEH upper position to an MEH lower position, wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying figures, which are incorporated in and constitute a part of the specification, illustrate various example apparatuses, systems, and methods, and are used merely to illustrate various example embodiments. 
           [0013]      FIG. 1  illustrates an example arrangement of a submersible craft configured to selectively invert. 
           [0014]      FIG. 2  illustrates an example arrangement of a submersible craft configured to selectively invert. 
           [0015]      FIG. 3  illustrates an example arrangement of a submersible craft configured to selectively invert. 
           [0016]      FIG. 4  illustrates an example arrangement of a battery in a submersible craft configured to selectively invert. 
           [0017]      FIG. 5  is a flowchart illustrating an example method for inverting a submersible craft. 
           [0018]      FIG. 6  is a flowchart illustrating an example method for inverting a submersible craft. 
           [0019]      FIG. 7  is a flowchart illustrating an example method for inverting a submersible craft. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  illustrates a perspective view of an example arrangement of a submersible craft  100  configured to selectively invert. Submersible craft  100  may be configured to operate in a liquid medium, such as water. Submersible craft  100  includes a frame  102 , an MEH  104 , and a battery  106 . MEH  104  includes an MEH rail apparatus including a first MEH rail  108  and a second MEH rail  110 . Battery  106  includes a battery rail apparatus including a first battery rail  112  and a second battery rail  114 . In one embodiment, frame  102  further includes a first MEH frame rail  116 , a second MEH frame rail  118 , a first battery frame rail  120 , and a second battery frame rail  122 . 
         [0021]    Submersible craft  100  may include any unmanned submersible craft. Submersible craft  100  may be fitted with various propulsion systems, including for example thrusters and propellers. Submersible craft  100  may be fitted with various steering components, including for example rudders and hydroplanes. In one embodiment, submersible craft  100  includes an exterior shell or fairing (not shown) which may be configured to provide protection to interior components and/or improve hydrodynamic characteristics of submersible craft  100 . The exterior shell or fairing may comprise at least one of a metal, polymer, and composite material. Submersible craft  100  may include various optical devices, including for example cameras. Submersible craft  100  may include a ballast device to affect its buoyancy. 
         [0022]    Submersible craft  100  may additionally include a sonar device. In one embodiment, submersible craft  100  includes a sonar device configured to direct sonar out of only one side of the craft, including, for example, the port or starboard side of the craft. In one embodiment, submersible craft  100  is configured to invert by rotating 180 degrees about the x-axis and/or z-axis. As a result, the sonar device will selectively direct sonar out of either side of the craft. 
         [0023]    Frame  102  may comprise the structural components of submersible craft  100 . In one embodiment, frame  102  includes a rigid tubing material. In another embodiment, frame  102  includes panels. In another embodiment, frame  102  includes a combination of rigid tubing material and panels. Frame  102  may comprise at least one of a metal, polymer, and composite material. In one embodiment, frame  102  comprises a tubing material oriented about the exterior of submersible craft  100  to provide both rigid structure to submersible craft  100  and protection of the various components of submersible craft  100 . In this embodiment, panels may be oriented on at least the port and starboard sides of submersible craft  100  and configured to support the various components of submersible craft  100 . 
         [0024]    MEH  104  may include at least one of the electronic controls, signaling components, and processing components. In one embodiment, MEH  104  is the central computer of submersible craft  100  and is responsible for all electronic function of submersible craft  100 . In one embodiment, MEH  104  includes the electrical circuitry responsible for controls and signaling in submersible craft  100 . MEH  104  may be sealed so as to be at least substantially impervious to a liquid (e.g., water). In one embodiment, MEH  104  includes a series of wires and cables extending therefrom and connected to the various electrical components of submersible craft  100 . In another embodiment, MEH  104  is connected to a host vessel, which is one or more of physically, electrically, or optically connected to submersible craft  100 . In another embodiment, MEH  104  is connected to a host vessel, which is a ship on the surface of the water from which submersible craft  100  operates. In one embodiment, MEH  104  has a substantially positive buoyancy, wherein the weight of liquid that MEH  104  displaces is greater than the weight of MEH  104 . Stated alternatively, the buoyant force acting on MEH  104  is greater than the gravitational force acting on MEH  104 . In this embodiment, MEH  104  may have a tendency to float toward the surface of the liquid medium. In another embodiment, MEH  104  has a substantially negative buoyancy. 
         [0025]    MEH  104  includes an MEH rail apparatus, including in one embodiment a first MEH rail  108 , a second MEH rail  110 , a first MEH frame rail  116 , and a second MEH frame rail  118 . In another embodiment, the MEH rail apparatus includes a first MEH rail  108  and a second MEH rail  110 . In another embodiment, MEH rail apparatus includes a first MEH frame rail  116  and a second MEH frame rail  118 . In one embodiment, the MEH rail apparatus is substantially vertically positioned within submersible craft  100  so as to be substantially parallel to the y-axis. First MEH rail  108  is positioned on a first side of submersible craft  100 , and second MEH rail  110  is positioned on a second side of submersible craft  100 . In one embodiment, first MEH rail  108  is positioned substantially opposite second MEH rail  110 . First MEH rail  108  and second MEH rail  110  may be removably connected to a first and second end of MEH  104 , respectively, for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In another embodiment, first MEH rail  108  and second MEH rail  110  are integrally connected to a first and second end of MEH  104 , respectively. First MEH rail  108  and second MEH rail  110  may comprise at least one of a metal, a polymer, and a composite material. 
         [0026]    First MEH frame rail  116  and second MEH frame rail  118  may be removably connected to submersible craft  100  and/or frame  102 , for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In another embodiment, first MEH frame rail  116  and second MEH frame rail  118  are integrally connected to frame  102 . First MEH frame rail  116  and second MEH frame rail  118  may comprise at least one of a metal, a polymer, and a composite material. In one embodiment, first MEH frame rail  116  and second MEH frame rail  118  are substantially vertically positioned within submersible craft  100  so as to be substantially aligned with the y-axis. 
         [0027]    In one embodiment, first MEH rail  108  and second MEH rail  110  are slidably connected to first MEH frame rail  116  and second MEH frame rail  118 , respectively. In one embodiment, first MEH rail  108  and second MEH rail  110  include at least one of a groove, a ridge, and a channel configured to mate in slidable connection with a corresponding groove, ridge, or channel on first MEH frame rail  116  and second MEH frame rail  118 . In another embodiment, first MEH rail  108  and second MEH rail  110  include a ring or rod configured to mate in slidable connection with a corresponding ring or rod on first MEH frame rail  116  and second MEH frame rail  118 , such that the ring portion fits around the periphery of the rod portion and is able to selectively slide along the rod. In one embodiment, first MEH rail  108  slidably connects to first MEH frame rail  116 , and second MEH rail  110  slidably connects to second MEH frame rail  118 . In one embodiment, a first end of MEH  104  is slidably connected to first MEH frame rail  116  and a second end of MEH  104  is slidably connected to second MEH frame rail  118 . 
         [0028]    In one embodiment, one or more of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118  may include devices to assist in the slidable connection, including for example bearing surfaces or roller bearings. 
         [0029]    In one embodiment, first MEH rail  108  and second MEH rail  110  are selectively slidably connected to first MEH frame rail  116  and second MEH frame rail  118 , respectively, and at least one of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118  include at least one stop configured to act as the bound of slidable movement of MEH  104 . In one embodiment, the at least one stop is removably connected to at least one of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118 , for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In another embodiment, the at least one stop is integrally connected to at least one of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118 . In one embodiment, each set of corresponding rails (i.e., first MEH rail  108  and first MEH frame rail  116 , and second MEH rail  110  and second MEH frame rail  118 ) includes an upper stop and lower stop (as defined by the y-axis), such that the slidable movement of MEH  104  is constrained between the upper stop and the lower stop. 
         [0030]    In one embodiment, MEH  104  is selectively slidably positioned in relation to submersible craft  100 . MEH  104  may be selectively locked in an MEH upper position and MEH lower position. In one embodiment, MEH  104  is selectively locked into position by one or more of a captive screw, a bolt, a pin, a clip, and a strap. In one embodiment, MEH  104  is selectively locked into position using a captive screw configured to engage at least one of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118  and prevent movement between first MEH rail  108  and first MEH frame rail  116 , and between second MEH rail  110  and second MEH frame rail  118 . In another embodiment, MEH  104  is selectively locked into position using a captive screw configured to engage MEH  104  with frame  102 . In another embodiment, MEH  104  is selectively locked into position using a captive screw configured to engage at least one of first MEH rail  108 , second MEH rail  110 , first MEH frame rail  116 , and second MEH frame rail  118  with frame  102 . 
         [0031]    Battery  106  may include any known battery device capable of storing electrical energy. In one embodiment, battery  106  is configured to electrically connect to MEH  104  thereby providing electrical energy to MEH  104 . In another embodiment, battery  106  is electrically connected to the various electrical components within submersible craft  100  thereby providing electrical energy to the various electrical components within submersible craft  100 . In one embodiment, battery  106  sealed so as to be at least substantially impervious to a liquid (e.g., water). In one embodiment, battery  106  has a substantially negative buoyancy, wherein the weight of liquid that battery  106  displaces is less than the weight of battery  106 . Stated alternatively, the buoyant force acting on battery  106  is less than the gravitational force acting on battery  106 . In this embodiment, battery  106  may have a tendency to sink toward the floor of the liquid medium. In another embodiment, battery  106  has a substantially positive buoyancy. In one embodiment, battery  106  may include a mass that is greater than the mass of MEH  104 . In another embodiment, battery  106  may include a mass that is less than the mass of MEH  104 . 
         [0032]    Battery  106  includes a battery rail apparatus, including first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122 . In another embodiment, battery rail apparatus includes a first battery rail  112  and a second battery rail  114 . In another embodiment, the battery rail apparatus includes a first battery frame rail  120  and a second battery frame rail  122 . In one embodiment, the battery rail apparatus is substantially vertically positioned within submersible craft  100  so as to be substantially aligned with the y-axis. First battery rail  112  is positioned on a first side of submersible craft  100 , and second battery rail  114  is positioned on a second side of submersible craft  100 . In one embodiment, first battery rail  112  is positioned opposite second battery rail  114 . First battery rail  112  and second battery rail  114  may be removably connected to a first and second end of battery  106 , respectively, for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In another embodiment, first battery rail  112  and second battery rail  114  are integrally connected to a first and second end of battery  106 , respectively. First battery rail  112  and second battery rail  114  may comprise at least one of a metal, a polymer, and a composite material. 
         [0033]    First battery frame rail  120  and second battery frame rail  122  may be removably connected to frame  102 , for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In one embodiment, first battery frame rail  120  and second battery frame rail  122  are integrally connected to frame  102 . First battery frame rail  120  and second battery frame rail  122  may comprise at least one of a metal, a polymer, and a composite material. In one embodiment, first battery frame rail  120  and second battery frame rail  122  are substantially vertically positioned within submersible craft  100  so as to be substantially aligned with the y-axis. 
         [0034]    In one embodiment, first battery rail  112  and second battery rail  114  are slidably connected to first battery frame rail  120  and second battery frame rail  122 , respectively. In one embodiment, first battery rail  112  and second battery rail  114  include at least one of a groove, a ridge, and a channel configured to mate in slidable connection with a corresponding groove, ridge, or channel on first battery frame rail  120  and second battery frame rail  122 . In another embodiment, first battery rail  112  and second battery rail  114  include a ring or rod configured to mate in slidable connection with a corresponding ring or rod on first battery frame rail  120  and second battery frame rail  122 , such that the ring portion fits around the periphery of the rod portion and is able to selectively slide along the rod. In one embodiment, first battery rail  112  slidably connects to first battery frame rail  120 , and second battery rail  114  slidably connects to second battery frame rail  122 . In one embodiment, a first end of battery  106  is slidably connected to first battery frame rail  120  and a second end of battery  106  is slidably connected to second battery frame rail  122 . 
         [0035]    In one embodiment, one or more of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122  may include devices to assist in the slidable connection, including for example bearing surfaces or roller bearings. 
         [0036]    In one embodiment, first battery rail  112  and second battery rail  114  are selectively slidably connected to first battery frame rail  120  and second battery frame rail  122 , respectively, and at least one of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122  include at least one stop configured to act as the bound of slidable movement of battery  106 . In one embodiment, the at least one stop is removably connected to at least one of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122 , for example, through the use of bolts, screws, rivets, pins, straps, cam locks, and keyhole slots. In another embodiment, the at least one stop is integrally connected to at least one of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122 . In one embodiment, each set of corresponding rails (i.e., first battery rail  112  and first battery frame rail  120 , and second battery rail  114  and second battery frame rail  122 ) includes an upper stop and lower stop (as defined by the y-axis), such that the slidable movement of battery  106  is constrained between the upper stop and the lower stop. 
         [0037]    In one embodiment, battery  106  is selectively slidably positioned in relation to submersible craft  100 . Battery  106  may be selectively locked in a battery upper position and a battery lower position. In one embodiment, battery  106  is selectively locked into position by one or more of a captive screw, a bolt, a pin, a clip, and a strap. In one embodiment, battery  106  is selectively locked into position using a captive screw configured to engage at least one of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122 , and prevent movement between first battery rail  112  and first battery frame rail  120 , and between second battery rail  114  and second battery frame rail  122 . In another embodiment, battery  106  is selectively locked into position using a captive screw configured to engage battery  106  with frame  102 . In another embodiment, battery  106  is selectively locked into position using a captive screw configured to engage at least one of first battery rail  112 , second battery rail  114 , first battery frame rail  120 , and second battery frame rail  122  with frame  102 . 
         [0038]    In one embodiment, submersible craft  100  includes: an apparatus for selectively positioning battery  106  and MEH  104  within the submersible craft  100 , the apparatus comprising: battery  106 ; a battery rail apparatus comprising first battery frame rail  120  substantially vertically oriented within submersible craft  100  and second battery frame rail  122  substantially vertically oriented within submersible craft  100 , wherein first battery frame rail  120  is positioned on a first side of submersible craft  100  and second battery frame rail  122  is positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . The apparatus additionally comprises a first end of battery  106  slidably connected to first battery frame rail  120  and a second end of battery  106  slidably connected to second battery frame rail  122 . The apparatus further includes MEH  104 ; an MEH rail apparatus comprising first MEH frame rail  116  substantially vertically oriented within submersible craft  100  and second MEH frame rail  118  substantially vertically oriented within submersible craft  100 , wherein first MEH frame rail  116  is positioned on a first side of submersible craft  100  and second MEH frame rail  118  is positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . A first end of MEH  104  is slidably connected to first MEH frame rail  116  and a second end of MEH  104  is slidably connected to second MEH frame rail  118 . In one embodiment, battery  106  comprises a substantially negative buoyancy and MEH  104  comprises a substantially positive buoyancy. 
         [0039]    In another embodiment, a submersible craft  100  comprises: an apparatus for selectively positioning battery  106  and MEH  104  within submersible craft  100 , the apparatus comprising: a battery rail apparatus comprising first battery frame rail  120  substantially vertically oriented within submersible craft  100  and second battery frame rail  122  substantially vertically oriented within submersible craft  100 , wherein first battery frame rail  120  is positioned on a first side of submersible craft  100  and second battery frame rail  122  is positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . First battery frame rail  120  and second battery frame rail  122  are configured to be slidably connected to first and second ends of battery  106 , respectively. The apparatus also comprises an MEH rail apparatus comprising first MEH frame rail  116  substantially vertically oriented within submersible craft  100  and second MEH frame rail  118  substantially vertically oriented within submersible craft  100 , wherein first MEH frame rail  116  is positioned on a first side of submersible craft  100  and second MEH frame rail  118  is positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . First MEH frame rail  116  and second MEH frame rail  118  are configured to be slidably connected to first and second ends of MEH  104 . 
         [0040]    In one embodiment, a system for selectively positioning battery  106  and MEH  104  within submersible craft  100  is provided, the system comprising: battery  106 ; a battery rail apparatus comprising first battery frame rail  120  configured to be substantially vertically oriented within submersible craft  100  and second battery frame rail  122  configured to be substantially vertically oriented within submersible craft  100 , wherein first battery frame rail  120  is configured to be positioned on a first side of submersible craft  100  and second battery frame rail  122  is configured to be positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . A first end of battery  106  is slidably connected to first battery frame rail  120  and a second end of the battery is slidably connected to second battery frame rail  122 . The apparatus also includes MEH  104 ; an MEH rail apparatus comprising first MEH frame rail  116  configured to be substantially vertically oriented within submersible craft  100  and second MEH frame rail  118  configured to be substantially vertically oriented within submersible craft  100 , wherein first MEH frame rail  116  is configured to be positioned on a first side of submersible craft  100  and second MEH frame rail  118  is configured to be positioned on a second side of submersible craft  100  substantially opposite the first side of submersible craft  100 . A first end of MEH  104  is slidably connected to first MEH frame rail  116  and a second end of MEH  104  is slidably connected to second MEH frame rail  118 . Battery  106  comprises a substantially negative buoyancy and MEH  104  comprises a substantially positive buoyancy. 
         [0041]    In another embodiment, an apparatus for selectively positioning battery  106  and MEH  104  within submersible craft  100  is provided, the apparatus comprising: battery  106 ; a battery rail apparatus substantially vertically oriented within submersible craft  100 , wherein the battery rail apparatus includes first battery rail  112  and second battery rail  114 , and wherein first battery rail  112  and second battery rail  114  are slidably connected to submersible craft  100 . The apparatus also includes MEH  104 ; an MEH rail apparatus substantially vertically oriented within submersible craft  100 , wherein the MEH rail apparatus includes first MEH rail  108  and second MEH rail  110 , and wherein first MEH rail  108  and second MEH rail  110  are slidably connected to submersible craft  100 . Battery  106  comprises a substantially negative buoyancy and MEH  104  comprises a substantially positive buoyancy. 
         [0042]      FIG. 2  illustrates a top plan view of an example arrangement of a submersible craft  200  configured to selectively invert. Submersible craft  200  includes a frame  202 , an MEH  204 , and a battery  206 . MEH  204  includes an MEH rail apparatus including a first MEH rail  208  and a second MEH rail  210 . Battery  206  includes a battery rail apparatus including a first battery rail  212  and a second battery rail  214 . In one embodiment, frame  202  further includes a first MEH frame rail  216 , a second MEH frame rail  218 , a first battery frame rail  220 , and a second battery frame rail  222 . 
         [0043]      FIG. 3  illustrates a perspective view of an example arrangement of a submersible craft  300  configured to selectively invert. Submersible craft  300  includes a frame  302 . In one embodiment, frame  302  further includes a first MEH frame rail  316 , a second MEH frame rail  318 , a first battery frame rail  320 , and a second battery frame rail  322 . 
         [0044]      FIG. 4  illustrates a perspective view of an example arrangement of battery  406  in a submersible craft configured to selectively invert (not shown). Battery  406  includes a battery rail apparatus including a first battery rail  412  and a second battery rail  414 . In one embodiment, battery  406  includes a first battery rail attachment  424  and a second battery rail attachment  426 . First battery rail attachment  424  and second battery rail attachment  426  may be configured to attach battery  406  to first battery rail  412  and second battery rail  414 , respectively. In another embodiment, first battery rail attachment  424  and second battery rail attachment  426  may be removably or integrally connected to a battery cradle (not shown), which is configured to contain and support battery  406 . The battery cradle may comprise at least one of a metal, a polymer, or a composite material. In one embodiment, a battery cradle is removably or integrally connected to at least one of first battery rail  412  and a second battery rail  414 . In another embodiment, a battery cradle is slidably connectable to at least one of a first battery frame rail (not shown) and a second battery frame rail (not shown). 
         [0045]    In operation, submersible craft  100 ,  200 , and  300  may include a sonar device configured to direct sonar out of a single side of the craft (e.g., port side only). When it is desired to direct sonar out of the opposite side of submersible craft  100 ,  200 , and  300  (e.g., from port side to starboard side), submersible craft  100 ,  200 , and  300  may be inverted 180 degrees about the x-axis and/or z-axis, thereby causing sonar to be directed out of the opposite side of submersible craft  100 ,  200 , and  300  (e.g., the starboard side). In one embodiment, submersible craft  100 ,  200 , and  300  is symmetrical about its horizontal plane (x-z plane), such that the craft&#39;s upper portion is a mirror image of its lower portion. In such an embodiment, the symmetry of submersible craft  100 ,  200 , and  300  permits operation of submersible craft  100 ,  200 , and  300  in an inverted state that is essentially identical to its operation in a normal state. In one embodiment, submersible craft  100 ,  200 , and  300  is permeable to the liquid medium. In another embodiment, submersible craft  100 ,  200 , and  300  is configured to operate while flooded with liquid medium. 
         [0046]    Although not wishing to be bound by a particular theory, submersible craft  100 ,  200 , and  300  has a center of buoyancy and a center of gravity when submerged. A submerged craft&#39;s center of buoyancy is its immersed center of mass. Stated differently, submerged craft&#39;s center of buoyancy is the point through which the resultant force is exerted on a body by a static fluid in which it is submerged, and which is located at the centroid of displaced volume. 
         [0047]    In an embodiment where at least a portion of a submersible craft is permeable to a liquid and/or configured to operate while flooded, the various components within the submersible craft may have various centers of buoyancy. In this embodiment, the center of buoyancy of the submersible craft as a whole is the central point of the individual centers of buoyancy of the various components. The location of the center of buoyancy of the submersible craft may be calculated using vector addition and accounting for the position of the various individual centers of buoyancy, as well as the value of the buoyant force at each of the various individual centers of buoyancy. In this sense, the position of components within the submersible vehicle that have positive buoyancy have an effect on the center of buoyancy of the submersible vehicle. 
         [0048]    A submerged craft&#39;s center of gravity is the point from which the weight of the submerged craft may be considered to act. Stated alternatively, a submerged craft&#39;s center of gravity is the point in or near the craft at which the gravitational potential energy of the craft is equal to that of a single particle of the same mass located at that point and through which the resultant of the gravitational forces on the component particles of the craft acts. In this sense, the position of components within the submersible vehicle has an effect on the center of gravity of the submersible vehicle. 
         [0049]    The center of buoyancy of submersible craft  100 ,  200 , and  300  creates a force upward from submersible craft  100 ,  200 , and  300  toward the surface of the liquid medium in which it operates. The center of gravity of submersible craft  100 ,  200 , and  300  creates a force downward from submersible craft  100 ,  200 , and  300  toward the floor of the liquid medium in which it operates. If there is a differential between the center of buoyancy of submersible craft  100 ,  200 , and  300  and the center of gravity of submersible craft  100 ,  200 , and  300 , such as through a difference in position of the battery  106 ,  206 , and  406  and MEH  104  and  204 , then submersible craft  100 ,  200 , and  300  will orient itself such that its center of gravity is below its center of buoyancy. Accordingly, if battery  106 ,  206 , and  406  comprises a substantially negative buoyancy and MEH  104  and  204  comprises a substantially positive buoyancy, then shifting battery  106 ,  206 , and  406  to an upper position within submersible craft  100 ,  200 , and  300  using a battery rail apparatus and shifting MEH  104  and  204  to a lower position within submersible craft  100 ,  200 , and  300  using an MEH rail apparatus will cause the center of gravity of submersible craft  100 ,  200 , and  300  to be higher than its center of buoyancy upon replacement in a liquid medium. The result of such a relationship between the center of gravity of submersible craft  100 ,  200 , and  300  and the center of buoyancy of submersible craft  100 ,  200 , and  300  is that submersible craft  100 ,  200 , and  300  will invert when placed back in the liquid medium, so as to orient its center of gravity lower than its center of buoyancy, and its substantially negative buoyancy battery  106 ,  206 , and  406  lower than its substantially positive buoyancy MEH  104  and  204 . 
         [0050]    In another embodiment, MEH  104  and  204  can comprise a substantially negative buoyancy and battery  106 ,  206 , and  406  can comprise a substantially positive buoyancy. Accordingly, if battery  106 ,  206 , and  406  comprises a substantially positive buoyancy and MEH  104  and  204  comprises a substantially negative buoyancy, then shifting battery  106 ,  206 , and  406  to a lower position within submersible craft  100 ,  200 , and  300 , and shifting MEH  104  and  204  to an upper position within submersible craft  100 ,  200 , and  300  will cause the center of gravity of submersible craft  100 ,  200 , and  300  to be higher than its center of buoyancy. The result of such a relationship between the center of gravity of submersible craft  100 ,  200 , and  300  and the center of buoyancy of submersible craft  100 ,  200 , and  300  is that submersible craft  100 ,  200 , and  300  will invert when placed back in the liquid medium, so as to orient its center of gravity lower than its center of buoyancy. 
         [0051]      FIG. 5  is a flowchart illustrating an example method for selectively inverting a submersible craft within a liquid medium. As shown in  FIG. 5 , the example method includes providing a battery contained on a battery rail apparatus, wherein the battery rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the battery in one of a battery lower position and a battery upper position (step  500 ). An MEH is provided contained on an MEH rail apparatus, wherein the MEH rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the MEH in one of an MEH upper position and an MEH lower position (step  510 ). An external shell is provided upon the submersible craft (step  520 ). The example method further includes removing the submersible craft from the liquid medium (step  530 ) and removing the external shell (step  540 ). The battery is moved from the battery lower position to the battery upper position (step  550 ) while the MEH is moved from the MEH upper position to the MEH lower position wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy (step  560 ). Finally, the method includes replacing the external shell (step  570 ), replacing the submersible craft into the liquid medium (step  580 ), and allowing the submersible craft to invert within the liquid medium (step  590 ). 
         [0052]    In steps  540  and  570 , the external shell may be removably fixed to frame  102 ,  202 , and  302  using external shell fasteners, including for example captive screws, screws, bolts, clips, pins, straps, or cam locks. Removal and replacement of the external shell may include simply removing and replacing the external shell fasteners. 
         [0053]    In step  550 , moving battery  106 ,  206 , and  406  from a battery lower position to a battery upper position may include removing for example a captive screw, bolt, pin, clip, or strap locking battery in battery lower position, sliding battery along battery rail apparatus to battery upper position until it encounters an upper stop, and replacing a captive screw, bolt, pin, clip, or strap locking battery in battery upper position. 
         [0054]    In step  560 , moving MEH  104  and  204  from an MEH upper position to an MEH lower position may include removing for example a captive screw, bolt, pin, clip, or strap locking MEH in MEH upper position, sliding MEH along MEH rail apparatus to MEH lower position until it encounters a lower stop, and replacing a captive screw, bolt, pin, clip, or strap locking MEH in MEH lower position. 
         [0055]    In steps  530  and  580 , the removal and replacement of submersible craft  100 ,  200 , and  300  from the liquid medium may involve temporarily placing submersible craft  100 ,  200 , and  300  on the deck of a ship, on land, on a dock, or on a stationary platform above the surface of the liquid medium. In one embodiment, the liquid medium is water in a pond, lake, stream, river, or ocean. 
         [0056]    In step  590 , submersible craft  100 ,  200 , and  300  will attempt to invert without external force because it will orient its center of gravity below its center of buoyancy. However, in one embodiment it may be necessary to physically assist submersible craft  100 ,  200 , and  300  in initially inverting. 
         [0057]    In one embodiment, submersible craft  100 ,  200 , and  300  further includes an acoustic beacon and/or relocation transponder. In one embodiment, the acoustic beacon/relocation transponder must be directed toward the surface of the liquid medium. In such an embodiment, the method of inverting submersible craft  100 ,  200 , and  300  further includes adjusting the orientation of acoustic beacon/relocation transponder so it points downward during the flipping procedure. Upon replacement of submersible craft  100 ,  200 , and  300  in the liquid medium, submersible craft  100 ,  200 , and  300  will invert to orient its center of gravity below its center of buoyancy, thus causing acoustic beacon/relocation transponder to be directed upwardly toward the surface of the liquid medium after inversion of submersible craft  100 ,  200 , and  300 . 
         [0058]    In one embodiment, submersible craft  100 ,  200 , and  300  further includes a tether strain relief physically attaching submersible craft  100 ,  200 , and  300  to a host ship, dry land, a dock, or a platform above the liquid medium. Tether strain relief may be physically attached to a lower portion of frame  102 ,  202 , and  302 . In such an embodiment, the method of inverting submersible craft  100 ,  200 , and  300  further includes removing tether strain relief from submersible craft  100 ,  200 , and  300  and reattaching it toward the top of submersible craft  100 ,  200 , and  300  during the flipping procedure. Upon replacement of submersible craft  100 ,  200 , and  300  in the liquid medium, submersible craft  100 ,  200 , and  300  will invert to orient its center of gravity below its center of buoyancy, thus causing tether strain relief to be attached toward the bottom of submersible craft  100 ,  200 , and  300  after inversion of submersible craft  100 ,  200 , and  300 . 
         [0059]      FIG. 6  is a flowchart illustrating an example method for selectively inverting a submersible craft within a liquid medium. As shown in  FIG. 6  the example method includes providing a battery contained on a battery rail apparatus, wherein the battery rail apparatus is substantially vertically positioned within the submersible craft and is configured to selectively position the battery in one of a battery lower position and a battery upper position (step  600 ). An MEH is provided contained on an MEH rail apparatus, which is substantially vertically positioned within the submersible craft and is configured to selectively position the MEH in one of an MEH upper position and an MEH lower position (step  610 ). The example method further includes moving the battery from the battery lower position to the battery upper position (step  620 ) and moving the MEH from the MEH upper position to the MEH lower position wherein the battery comprises a substantially negative buoyancy and the MEH comprises a substantially positive buoyancy (step  630 ). Finally, the example method includes allowing the submersible craft to invert within the liquid medium (step  640 ). 
         [0060]      FIG. 7  is a flowchart illustrating an example method for selectively inverting a submersible craft within a liquid medium. As shown in  FIG. 7  the example method includes moving a battery contained within the submersible craft from a battery lower position to a battery upper position (step  700 ) and moving an MEH within the submersible craft from an MEH upper position to an MEH lower position (step  710 ). Finally, the example method includes allowing the submersible craft to invert within the liquid medium (step  720 ). 
         [0061]    To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage  624  (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” To the extent that the term “selectively” is used in the specification or the claims, it is intended to refer to a condition of a component wherein a user of the apparatus may activate or deactivate the feature or function of the component as is necessary or desired in use of the apparatus. To the extent that the term “operatively connected” is used in the specification or the claims, it is intended to mean that the identified components are connected in a way to perform a designated function. As used in the specification and the claims, the singular forms “a,” “an,” and “the” include the plural. Finally, where the term “about” is used in conjunction with a number, it is intended to include ±10% of the number. In other words, “about 10” may mean from 9 to 11. 
         [0062]    As stated above, while the present application has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art, having the benefit of the present application. Therefore, the application, in its broader aspects, is not limited to the specific details, illustrative examples shown, or any apparatus referred to. Departures may be made from such details, examples, and apparatuses without departing from the spirit or scope of the general inventive concept.