Abstract:
An apparatus for varying the dimensions of a hull of a vessel comprising an arcuate truss assembly having a plurality of members pivotally joined. The arcuate truss assembly is operatively arranged to form a portion of the hull. The assembly is operatively arranged to extend and retract to vary the dimensions of the hull when the plurality of members are pivoted with respect to one another. The members of the arcuate truss assembly pivot in a plane substantially coplanar with the portion of the vessel hull.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/442,129, filed Jan. 24, 2003. 

   FIELD OF THE INVENTION 
   This invention relates to the construction of vessels. More specifically it relates to an apparatus for the construction of vessels having variable sized hulls. Even more specifically, the present invention relates to a vessel having a hull whose size and shape can be modified without refitting the vessel. 
   BACKGROUND OF THE INVENTION 
   Waterborne and submersible vessels are typically constructed having a hull of fixed dimensions. This fixes various characteristics of the vessel, such as the capacity, maneuverability, and stability of the vessel. If a vessel owner wishes to modify any of these characteristics, a major overhaul is typically required. This typically involves significant cost in resources and time. 
   Clearly, then, there is a longfelt need for a vessel having a hull with variable dimensions. 
   SUMMARY OF THE INVENTION 
   The present invention broadly comprises a method and apparatus for varying the dimensions of a vessel hull comprising an assembly having a plurality of members pivotally joined. The assembly is operatively arranged to form a portion of the vessel hull. The assembly is operatively arranged to extend and retract to vary the dimensions of the hull when the plurality of members are pivoted with respect to one another. 
   A general object of the present invention is to provide an apparatus for varying the dimensions of a vessel hull. 
   Another object of the present invention is to change the carrying capacity, buoyancy, maneuverability, stability, and/or resistance of the vessel. 
   These and other objects, features and advantages of the present invention will become readily apparent to those having ordinary skill in the art upon a reading of the following detailed description of the invention in view of the drawings and claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
       FIG. 1  is a perspective view of a first embodiment of the present invention installed integral with a vessel hull of a floatable vessel; 
       FIG. 2  is a side view of the present invention installed integral with a hull of a floatable vessel; 
       FIG. 3A  is a side view of the present invention, mounted on a portion of a hull of a floatable vessel, in a retracted configuration; 
       FIG. 3B  is a side view of the present invention, mounted on a portion of a hull of a floatable vessel, in an extended configuration; 
       FIG. 4A  is a side view of the assembly of the present invention in a retracted configuration; 
       FIG. 4B  is a side view of the assembly of the present invention in an extended configuration, having a membrane attached to an inner portion; 
       FIG. 4C  is a side view of the assembly of the present invention in an extended configuration; 
       FIG. 4D  is a side view of the assembly of the present invention in an extended configuration, covered by a membrane; 
       FIG. 5A  is a top view of a second embodiment of the present invention, in a fully extended configuration; 
       FIG. 5B  is a top view of the second embodiment of the present invention, in a partially extended configuration; 
       FIG. 5C  is a top view of the second embodiment of the present invention, in a fully retracted configuration; 
       FIG. 6A  is a top view of a third embodiment of the present invention covered by a membrane, in a fully extended configuration; 
       FIG. 6B  is a top view of the third embodiment of the present invention covered by a membrane, in a partially extended configuration; 
       FIG. 6C  is a top view of the third embodiment of the present invention covered by a membrane, in a fully retracted configuration; 
       FIG. 7A  is a top view of a fourth embodiment of the present invention covered by a plurality of plates, in a fully extended configuration; 
       FIG. 7B  is a top view of the fourth embodiment of the present invention covered by a plurality of plates, in a partially extended configuration; 
       FIG. 7C  is a top view of the fourth embodiment of the present invention covered by a plurality of plates, in a fully retracted configuration; 
       FIG. 8A  is a side view of the fourth embodiment of the present invention mounted on a portion of a floatable vessel hull and fully extended; 
       FIG. 8B  is a side view of the fourth embodiment of the present invention mounted on a portion of a floatable vessel hull and fully extended; 
       FIG. 9A  is a side view of a fifth embodiment of the present invention mounted on a portion of a floatable vessel hull and fully extended; 
       FIG. 9B  is a side view of the fifth embodiment of the present invention mounted on a portion of a floatable vessel hull and fully extended; 
       FIG. 10  is a side view of a sixth embodiment of the present invention mounted on a portion of a hull of a submersible vessel; 
       FIG. 11  is a side view of the sixth embodiment with the assemblies of the present invention fully retracted; 
       FIG. 12  is a rear view of a seventh embodiment of the present invention mounted on a portion of a hull of a submersible vessel, showing the assemblies fully extended; 
       FIG. 12A  is a side view of the seventh embodiment of the present invention, showing the assemblies fully extended; 
       FIG. 13  is a rear view of the seventh embodiment of the present invention, showing the assemblies fully retracted; 
       FIG. 14  is a front view of an eighth embodiment of the present invention mounted on a portion of a hull of a submersible vessel, showing the spherical assembly fully extended; and, 
       FIG. 15  is a front view of the eighth embodiment of the present invention, showing the spherical assembly fully retracted; 
       FIG. 16A  is a detail of the assembly shown in  FIG. 4B , showing a pneumatic or hydraulic extension and retraction means in a retracted configuration; 
       FIG. 16B  is a detail of the assembly shown in  FIG. 4A , showing a pneumatic or hydraulic extension and retraction means in an extended configuration; 
       FIG. 16C  is a detail of the assembly shown in  FIG. 4B , showing a microelectromechanical extension and retraction means with the assembly extended; and 
       FIG. 16D  is a detail of the assembly shown in  FIG. 4A , showing a microelectromechanical extension and retraction means with the assembly retracted. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   It should be appreciated that, in the detailed description of the invention which follows, like reference numbers on different drawing views are intended to identify identical structural elements of the invention in the respective views. 
   A first embodiment of the present invention is shown in  FIG. 1  and designated  10 . The invention comprises an assembly for changing the dimensions of a vessel hull. The assembly may be a radial extension/retraction truss structure as disclosed by U.S. Pat. No. 5,024,031 (Hoberman), incorporated by reference herein. As shown in  FIG. 1 , the assemblies are mounted on hull sections  12 ,  14 ,  18 , and  20  of vessel  16 . The assemblies are covered by membrane  40 , and are not visible in  FIG. 1 .  FIG. 4B  shows assembly  38  in an extended configuration with the membrane not shown.  FIG. 4D  shows extended assembly  38  beneath a cutaway of membrane  40 . 
   It should be readily apparent to one skilled in the art that the assemblies of the present invention can be extended and retracted by pneumatic, hydraulic, microelectromechanical systems (MEMS), or any other means known in the art. Assemblies actuated by any means known in the art are intended to be within the spirit and scope of the invention as claimed. 
     FIG. 2  shows portion  22  of a hull of a vessel having hull extension  24 . Apparatus  10  is located on the forward section of hull extension  24 . Membrane  40  is shown covering the assembly of the present invention. The membrane is shown in solid lines for a fully retracted configuration of the assembly and in broken lines for a fully extended configuration of the assembly. 
     FIGS. 3A and 3B  illustrate the buoyancy gain realized by the vessel when the membrane is sealed to the hull with a watertight seal. Membrane  40  is shown covering the assembly in the fully retracted position in  FIG. 3A . Membrane  40  is connected to hull portion  34 . The waterline  32  is relatively high with respect to hull  30 .  FIG. 3B  shows membrane  40  covering the assembly in a fully extended configuration. The expansion of the vessel volume below the waterline  32  increases the buoyancy of the vessel. This leads to the vessel rising in the water. Thus, waterline  32  is relatively lower on hull  30 . 
   In addition, the expansion and contraction of the assembly will change the magnitude of the wave-making drag created by the hull moving through the water (corresponding to the change in the Froude number). Thus, in some applications, the extent to which the assembly is extended or contracted may be determined by the optimal Froude number (the Froude number resulting in minimum drag for a desired speed) resulting from the assembly size, rather than the buoyancy created by the assembly size. 
   The watertight embodiment shown in  FIGS. 3A and 3B  may also be used to compensate for vessel internal (payload) or external environmental moments by extending the different assemblies shown in  FIG. 1  to different configurations. If each assembly is extended to a different configuration, each of the assemblies creates a different amount of buoyancy. This allows the operator of the vessel to rebalance the vessel for loading or unloading, passenger crowding, turning, wind, and icing, for example. 
     FIGS. 3A and 3B  show an embodiment that varies the hull geometry while maintaining a watertight seal, thus changing the buoyancy of the hull. However, a watertight seal is not necessary. The apparatuses  10  in  FIG. 1  may be mounted on watertight hull portions, which would fix the buoyancy of the vessel. A membrane or plurality of plates would still be necessary to substantially inhibit the free flow of fluid through the apparatus  10 . In this case, the extension and contraction of the assembly would serve only to change the Froude number, changing the magnitude of the drag created. In this case, the configuration of the assembly would be determined solely by the optimal Froude number (the Froude number that minimizes drag at the desired speed). Configurations of the present invention either with a watertight seal or without a watertight seal are both within the spirit and scope of the invention as claimed. 
     FIGS. 1–3  show a membrane covering the assembly of the present invention. However, the membrane may be connected to an inner portion of the assembly, exposing the assembly to the water. In either case, the membrane may be connected to the hull with a watertight seal.  FIG. 4A  shows assembly  38  in a retracted position. In one embodiment, membrane  40  is connected to an inner portion of assembly  38 , such that it expands as assembly  38  extends (shown in  FIG. 4C ). It should be readily apparent to one skilled in the art that a membrane may be located within the assembly, covering the assembly, or a membrane may be located both inside the assembly and covering the assembly, and these modifications are intended to be within the spirit and scope of the invention as claimed. 
   A second exemplary embodiment of the present invention is shown in  FIGS. 5A–5C  and designated  110 . This embodiment is an assembly similar in operation to a diaphragm shutter on a camera. This assembly covers an aperture in the hull when fully extended, and exposes the aperture in the hull when fully retracted.  FIG. 5A  shows assembly  38  in a fully extended configuration.  FIG. 5B  shows the assembly in a partially extended configuration.  FIG. 5C  shows the assembly in a fully retracted configuration. 
   The assembly may be covered by a flexible membrane, as illustrated in  FIGS. 6A–6C .  FIG. 6A  shows embodiment  210  comprising fully extended assembly  38  covered by membrane  40 . Membrane  40  has an aperture  42  in the center, which is substantially closed when the assembly is fully extended.  FIG. 6B  shows assembly  38  partially retracted, opening aperture  42 .  FIG. 6C  shows assembly  38  fully retracted, opening aperture  42  to its widest extent. 
   In embodiment  310 , a non-circular assembly  74  is covered with plates as shown in  FIGS. 7A–7C .  FIG. 7A  shows embodiment  310  comprising fully extended assembly  74  partially covered by a plurality of plates  44 . When assembly  74  is retracted, plates  44  are also retracted, forming an aperture.  FIG. 7B  shows assembly  74  partially retracted, with the plurality of plates partially retracted.  FIG. 7C  shows assembly  74  fully retracted, retracting plates  44  to their greatest extent. As should be readily apparent to one skilled in the art, other means of covering a diaphragm shutter assembly are possible, and these modifications are intended to be within the spirit and scope of the invention as claimed. For example, the plates or membrane may or may not be watertight when the assembly is fully extended. A watertight seal is not required for an aperture such as a bow thruster, as there is a watertight seal within the aperture. The present invention would serve to decrease drag when it is fully extended and the vessel is moving. However, the present invention could serve to both reduce drag and provide a watertight seal for an aperture in a vessel hull. 
     FIG. 8A  shows a diaphragm shutter assembly mounted on hull portion  78  of hull  76 .  FIG. 8B  shows assembly  74  fully retracted, forming aperture  75 . Aperture  75  faces the forward direction of the hull. This embodiment may be used to cover, for example, a torpedo tube. However, any aperture in a hull may be covered in this manner. 
     FIGS. 9A and 9B  illustrate a fifth exemplary embodiment of the present invention. Hull  76  comprises apparatus  310 . Apparatus  310  is a diaphragm shutter assembly covered by plates  44 . Apparatus  310  covers an aperture in hull  76  containing bow thruster  90 . When bow thruster  90  is needed to maneuver the vessel, apparatus  310  is retracted to reveal aperture  75 . When the bow thruster is no longer needed, apparatus  310  is extended to cover aperture  75 , reducing the drag that would result from exposing aperture  75  during normal travel. An aperture for a water-jet, turbine, or any other aperture in a hull may be covered by apparatus  310  in a similar fashion. 
   It should be readily apparent to one skilled in the art that the present invention may be used to vary the geometry of hulls of both waterborne and submersible vessels. Variable hulls for both waterborne and submersible vessels are intended to be within the spirit and scope of the invention as claimed. In addition, the invention could be used to vary the geometry of aircraft, including, for example, airships.  FIGS. 10–15  illustrate the use of the present invention to vary the dimensions of aircraft. 
     FIG. 10  shows vessel  412  having passenger compartment  414 . A variable hull section  410  is connected to the front and the back of the vessel. Assembly  438  (shown beneath a cutaway) is covered by flexible membrane  440 . Assembly  438  expands and contracts to change the dimensions of the hull of the vessel. (Both front and rear assemblies are shown fully extended in  FIG. 10 .) Fins  416 ,  420 , and  418  are constructed to allow assembly  438  to expand and contract while the fins are moved to any position. Vessel  412  can be an airship or a submersible. 
     FIG. 11  shows the front and rear assemblies fully contracted. This reduces the displacement of fluid by the vessel. As with the previously discussed embodiments, there can be a flexible membrane over the assembly, within the assembly, or both over the assembly and within the assembly. The membrane may be used to contain a fluid less dense than the intended environment, or may simply bound the interior of the vessel. (In the latter case, a less dense internal fluid is held in containers within the hull of the aircraft.) All of the above embodiments are within the spirit and scope of the invention as claimed. 
     FIGS. 12 ,  12 A, and  13  show a vessel  512  having an ellipsoidal assembly  538  that extends and retracts conformally.  FIG. 12  is a rear view of vessel  512  with assembly  538  (shown beneath a cutaway of membrane  540 ) in a fully expanded configuration. Passenger compartment  514  is connected to the lower portion of the airship. Horizontal stabilizers  520  and vertical stabilizers  516  are connected to the assembly, and move relative to the passenger compartment when the assembly extends or retracts. Fins  518  may be fixed in size or also composed of assemblies  538 . They are free to move throughout the desired dynamic range regardless of the extent to which the hull assemblies are extended or retracted. As stated above, a flexible membrane covers the assemblies, is within the assemblies, or both. The membranes may be tight, allowing the less dense fluid to be bounded by the membrane(s), or the less dense fluid may be held in containers within the membrane(s). Vessel  512  can be an airship or a submersible. 
     FIGS. 14 and 15  show vessel  612  comprising a spherical hull  610 . The spherical hull is an assembly  638  (shown beneath a cutaway of membrane  640 ) covered by membrane  640 . Passengers may be carried within compartment  614 . As with previous embodiments, the less dense fluid may be contained within fluid tight membranes covering, within, or both covering and within the assembly. The less dense fluid may instead be held within containers within the hull. Vessel  612  can be an airship or a submersible. 
   The truss assemblies shown in  FIGS. 1–15  form arcuate shapes. In particular, the truss assemblies shown in these figures form a curved shape in two mutually orthogonal planes. Not only is the membrane  40  curved, but the assembly  38 , beneath the membrane  40 , is curved. For example,  FIGS. 4A–4D  show that assembly  38  forms, in an elevation plane, a curved surface. The profile ranges from elliptical to semi-circular, depending on the extent to which assembly  38  is retracted or extended.  FIGS. 5A–5C  and  6 A– 6 C show that the assemblies are substantially curved in plan view also.  FIGS. 7A–7B  show the assemblies curved in a perspective view. 
   In general, the members forming a present invention truss assembly pivot in respective planes substantially coplanar with the portion of a vessel hull formed by the assembly. For example, in  FIGS. 4A–4D , the members forming truss  38  rotate about truss joints  802 . At each joint  802 , the members connected to the joint rotate in a plane that is substantially planar with the surface formed by truss  38 . This coplanar rotation also is shown in  FIGS. 7A–7C . In particular, the members are shown rotating “beneath” respective plates  44 , that is, in substantially the same planes as respective plates  44 . Plates  44 , in turn, substantially form the planar surface of embodiment  310 . 
     FIGS. 16A and 16B  show an extension and retraction means  700  for the truss assembly shown in  FIGS. 4B and 4A , respectively, connected to a truss segment  702  of assembly  38 . Means  700  includes a cylinder and piston arrangement  704 . Arrangement  704  can be a pneumatic system or a hydraulic system. For the sake of clarity, the ancillary components of arrangement  704 , such as fluid reservoirs, piping, and valves are not shown. In some embodiments, arrangement  704  is connected to truss segment  702  at pins  706  and  708 . In some embodiments (not shown), truss segment  702  is connected to structural elements, such as element  710 . In  FIG. 16A , means  700  is retracted, which results in the extended configuration of assembly  38  shown in  FIG. 4B . In  FIG. 16B , means  700  is extended, which results in the retracted configuration of assembly  38  shown in  FIG. 4A . 
     FIGS. 16C and 16D  show an extension and retraction means  800  for the truss assembly shown in  FIGS. 4B and 4A , respectively, associated with a truss joint  802  of assembly  38 .  FIGS. 16C and 16D  show one possible embodiment of a MEMs actuator. However, it should be understood that other types of MEMs actuators, including, but not limited to, linear MEMs actuators, for example, are included within the spirit and scope of the claims. Means  800  is a MEMS actuator. MEMS actuator  800  includes hub  804  and variable pole element  806 . As shown in  FIGS. 16C and 16D , hub  804  has a fixed north and south magnetic pole configuration. However, the magnetic configuration of element  806  is defined by the direction of electrical current flow as controlled by a switch (not shown). In  FIGS. 16C and 16D , the current directions are reversed, resulting in the “flipping” of the north and south magnetic poles in element  806 . In  FIG. 16C , the north and south poles of hub  804  and the south and north poles, respectively, of element  806  are mutually attracted, causing element  806  to assume the position shown. When the switch is flipped to reverse the direction of the electrical current, element  806  assumes the magnetic configuration shown in  FIG. 16D . Reversing the magnetic configuration of element  806  in  FIG. 16C  causes a magnetic torque  808  as shown in  FIG. 16D . For example, switching from the magnetic polarity shown in  FIG. 16C  to the magnetic polarity shown in  FIG. 16D  causes the north poles of hub  804  and element  806 , which are aligned, to push away from each other, causing element  806  to rotate counterclockwise. At the same time, the mutual attraction of the respective north and south poles of hub  804  and element  806  also causes element  806  to rotate counterclockwise. Thus, element  806  rotates from the position shown in  FIG. 16C  to the position shown in  FIG. 16D . By reversing the direction of the electrical current flow again, element  808  can be made to rotate clockwise from the position shown in  FIG. 16D  to the position shown in  FIG. 16C . By reversing the direction of the electrical current flow again, element  808  can be made to rotate clockwise from the position shown in  FIG. 16D  to the position shown in  FIG. 16C . 
   Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, and these modifications are intended to be within the spirit and scope of the invention as claimed.