Abstract:
A swimmer propulsion device includes a harness with attached frame and resilient tail assembly. A foot-operated driver on the frame rotates and forces an apex member against the fluked tail assembly, while tensioning propulsion bands. As the apex member rotates beyond perpendicular, the band snaps the upwardly displaced tail assembly downwardly, thus thrusting the swimmer forward. The tail assembly has a spine with resilient vertebrae and a resilient portion that are all deformed as the tail assembly is displaced upwardly by the apex member. As the tail assembly moves downwardly, the resilient portion and the vertebrae return to the undeformed state, thus adding thrust to that provided by the bands. Interchangeable drivers and propulsion bands are provided that adjusts the amount of thrust provided by the system. Interchangeable flukes and dorsal fins are also provided. A single piece tail assembly is also provided as an alternate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to devices for propelling a swimmer through water using body strength. 
     2. Description of the Prior Art 
     There have been propulsion devices available for several years that have several common features in that fin-like members are used to propel the device. 
     Keivanjah (U.S. Pat. No. 4,642,056) provides a water craft in which the operator is seated. Fins on an H-shaped frame are cam actuated to propel the craft. 
     Hildebrandt (U.S. Pat. No. 943,074) discloses a boat propeller that includes a cam mounted on a rotary shaft that causes a vertically positioned caudal fin to move from side to side. 
     Gongwer (U.S. Pat. No. 3,204,699) includes a swimmer propulsion device that attaches to the swimmers lower legs. A leg plate is straddled by the swimmer, from which a curved rod extends forwardly. A pair of oscillating fins is pivotally attached to the curved rod, the fins being positioned beneath the swimmer&#39;s lower torso, when the swimmer is horizontal. 
     Baulard-Caugan (U.S. Pat. No. 4,193,371) provides a swimmer propulsion device with a vertically oriented fish tail member on two arms that are in turn mounted on two additional arms, to which are attached foot stirrups. Pushing one of the stirrups causes the arm linkage to push the tail in one direction, and pushing the other stirrup causes the arm linkage to push the tail in the other direction. 
     McGowan (U.S. Pat. No. 3,440,994) includes a swimmer propulsion device having a vertically positioned tail fin that is pushed left and right by using alternate feet to push on opposite ends of a pivot bar that is rigidly attached to the tail fin. 
     Coulter (U.S. Pat. No. 227,491) discloses a sculling-propeller for boats that provides hand operated controls for moving a rear-mounted fin-like blade. 
     Only some of the foregoing are for swimmers, and of those that are for swimmers, the devices require large structures with a large number of parts in relatively complicated arrangements. None provides a swimming device that has a high-degree of integration with the contours of the swimmer&#39;s body, nor do any provide an unobtrusive, yet effective means of oscillating horizontally positioned flukes. Furthermore, no prior art devices allow the swimmer&#39;s feet to simultaneously contribute to the means for moving the flukes. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention is a swimmer propulsion device that is streamlined in shape for integration with the contours of the swimmer&#39;s body, the device including an unobtrusive and effective means of oscillating horizontally positioned flukes, using the combined force of both the swimmer&#39;s feet. 
     The device includes a harness for the swimmer that has a flexible tail assembly and a frame with ratcheting pedals that simultaneously rotate a driver. This rotation causes one of three driver apexes to be forced against, and to displace, the tail assembly while simultaneously tensioning a propulsion band. The propulsion band snaps the tail assembly downward when the driver apex continues to move such that it is no longer displacing the tail assembly. This downward movement of the tail assembly and its flukes propels the swimmer forward. 
     A flexible spine is included in the tail assembly, with the individual vertebra in the spine being resilient, such that the displacement of the tail assembly by the driver apex deforms the vertebrae. Upon release the vertebrae return to the undeformed shape, thus adding to the downward force on the tail assembly. 
     A swimmer propulsion device is provided, comprising: a harness to be affixed to the body of the swimmer; a frame extending from the harness toward the feet of the swimmer; a tail assembly having: a flexible spine; and a tail member; a foot-powered driving assembly having: at least one foot pedal to be attached to the swimmer&#39;s foot, the at least one foot pedal having a forward position and a rearward position; and a driver rotatably attached to the frame and ratchetably rotated by a rearward push on the at least one foot pedal, the driver having at least three apex members, the driver being spaced from the tail assembly such that two of the apex members are proximate the tail assembly; and at least one resilient propulsion member attached to the tail assembly and the frame, such that, as the at least one foot pedal is being pushed rearwardly, the driver is rotated causing one of the apex members to singularly bear upon the tail assembly, the single apex member displacing the tail assembly such that the tail member moves from a first position to a second position, the displacement of the tail assembly placing the at least one propulsion member in tension, the continued rotation of the driver causing the single apex member to rotate beyond the perpendicular position against the tail assembly, the propulsion member tension then causing the at least one propulsion member to contract and pull the tail assembly such that the tail member is brought from the second position to the first position, the at least one foot pedal being ratchetably movable to the forward position. 
     In one embodiment, each apex member has a roller, the roller being the portion of the apex member that bears upon the tail assembly. 
     In one embodiment, the tail assembly has a generally longitudinal groove, the groove receiving and laterally constraining the single apex member as the single apex member bears upon the tail assembly. 
     In one embodiment, the number of pedals is two and the number of propulsion members is two, the pedals being attached for simultaneous movement from the forward to the rearward position. 
     In one embodiment, the number of pedals is two, each pedal being independently ratchetable and pushable, such that the driver is rotated by pushing either of the pedals. 
     In one embodiment, the number of pedals is one, the pedal being adapted for simultaneous pushing by both swimmer feet. 
     In one embodiment, the spine further comprises a first vertebra and a plurality of vertebrae, each of the vertebrae plurality being successively and partially encompassed by another of the vertebrae, and a resilient cord extending through the vertebrae such that the vertebrae are aligned and secured, the vertebrae being resilient such that, as the tail assembly is displaced by the single apex member, the vertebrae are deformed, and as the single apex member rotates beyond the perpendicular position against the tail assembly, the vertebrae return to the undeformed state, thus causing a displacement of the tail assembly such that the tail member is moved toward the second position. 
     In one embodiment, the vertebrae having decreasing widths in a direction horizontally perpendicular to the longitudinal axis of the tail assembly. 
     In one embodiment, the vertebrae having decreasing heights in a direction vertically perpendicular to the longitudinal axis of the tail assembly. 
     In one embodiment, the harness has at least one dorsal fin. 
     In one embodiment, the at least one dorsal fin is detachable. 
     In one embodiment, the tail assembly has at least one dorsal fin. 
     In one embodiment, the at least one dorsal fin is detachable. 
     In one embodiment, the tail member has at least one dorsal fin. 
     In one embodiment, the at least one dorsal fin is detachable. 
     In one embodiment, the tail member is flexible. 
     In one embodiment, the tail member has two flukes. 
     In one embodiment, the tail member flukes have at least one thickened edge. 
     In one embodiment, the tail member flukes have at least one reinforced edge. 
     In one embodiment, the harness further comprises a first back member and a second back member, the second back member being coupled to the first back member, the frame being attached to the harness second back member. 
     In one embodiment, the second back member is slidably coupled to the first back member. 
     In one embodiment, the harness further comprises a first back member and a second back member, the second back member being coupled to the first back member, the tail assembly being attached to the harness second back member. 
     In one embodiment, the second back member is slidably coupled to the first back member. 
     In one embodiment, the tail member further comprises lateral stabilizers. 
     In one embodiment, the tail member further comprises at least one thickened outer edge. 
     In one embodiment, the tail member further comprises at least one reinforced outer edge. 
     In one embodiment, the device further comprises a second driver to be interchanged with the driver, the second driver having longer apexes than the driver. 
     In one embodiment, the device further comprises a second driver to be interchanged with the driver, the second driver having shorter apexes than the driver. 
     In one embodiment, the device further comprises a second driver, interchangeable with the driver, the second driver having more apexes than the driver. 
     In one embodiment, the device further comprises a second driver, interchangeable with the driver, the second driver having less apexes than the driver, but at least three apexes. 
     In one embodiment, the tail assembly further comprises a resilient portion, the driver single apex bearing upon such resilient portion during rotation such that the portion is deformed as the single apex member rotates, and returns to the undeformed state when the single apex member rotates beyond the perpendicular position against the portion, thus causing a displacement of the tail assembly such that the tail member is moved toward the second position. 
     In one embodiment, the resilient portion has a generally longitudinal groove, the groove receiving and laterally constraining the single apex member as the single apex member bears upon the resilient portion. 
     In one embodiment, the device further comprises a second propulsion member, interchangeable with the at least one propulsion member, the second propulsion member requiring a different amount of force for tensioning. 
     In one embodiment, the tail member further comprises a central stabilizer. 
     In one embodiment, the tail member further comprises a tail member top and a substantially rigid member positioned proximate the tail member top, such that as the tail member is forced back to the first position, the tail member top is forced against the rigid member, the rigid member then at least partially impeding the further deformation of the tail member. 
     In one embodiment, the tail member is removably attached. 
     In one embodiment, the device further comprises a second tail member, interchangeable with the tail member. 
     There is provided a swimmer propulsion device, comprising: a harness to be affixed to the body of the swimmer; a frame extending from the harness toward the feet of the swimmer; a tail assembly having: a flexible spine; and a tail member; means for moving the tail member from a first position to a second position using footpower; and means for forcing the tail member from the second position to the first position. 
     In one embodiment, the tail member further comprises means for lateral stabilization. 
     In one embodiment, the tail member further comprises means for central stabilization. 
     In one embodiment, the means for forcing the tail member from the second position to the first position further comprises means for varying the rate at which the tail member is forced back to the first position. 
     In one embodiment, the means for moving the tail member from the first position to the second position further comprises means for varying the distance between said positions. 
     A swimmer propulsion device is provided, comprising: a harness to be affixed to the body of the swimmer, the harness further comprising a first back member and a second back member, the second back member being slidably coupled to the first back member; a frame extending from the harness second back member toward the feet of the swimmer; a tail assembly extending from the harness second back member having: a flexible spine, the spine further comprising a first vertebra and a plurality of vertebrae, each of the vertebrae plurality being successively and partially encompassed by another of the vertebrae, and a resilient cord extending through the vertebrae such that the vertebrae are aligned and secured; a resilient portion, having a generally longitudinal groove; and a tail member; a foot-powered driving assembly having: a pair of foot pedals to be attached to the swimmer&#39;s feet, the pedals having a forward position and a rearward position; and a driver rotatably attached to the frame and ratchetably rotated by a rearward push on the foot pedals, the driver having three apex members, each apex member having a roller, the driver being spaced from the tail assembly such that two of the apex member rollers are proximate the tail assembly resilient portion longitudinal groove; and a pair of resilient propulsion members attached to the tail assembly and the frame, such that, as the foot pedals are being pushed rearwardly, the driver is rotated causing one of the apex member rollers to singularly bear upon the resilient portion longitudinal groove, the single apex member roller displacing the tail assembly such that the tail member moves from a first position to a second position, the displacement of the tail assembly placing the propulsion members in tension, the continued rotation of the driver causing the single apex member roller to rotate beyond the perpendicular position against the tail assembly, the propulsion member tension then causing the propulsion members to contract and pull the tail assembly such that the tail member is brought from the second position to the first position, the foot pedals being ratchetably movable to the forward position. 
     The foregoing and other advantages will appear from the description to follow. In the description reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     Various other objects, features and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views. 
     FIG. 1 is a side view of the device in use, where the swimmer has ratcheted the pedals forward in preparation for a rearward push. 
     FIG. 2 is a side view of the device in use, where the swimmer has pushed rearwardly to the point where the driver has tensioned the propulsion band as the driver apex is forced against the tail assembly. 
     FIG. 3 is a side view of the device, without the swimmer, with driver in the same position as in FIG.  2 . 
     FIG. 4 is a top view of the harness with the backplate removed. 
     FIG. 5 is a side view of the harness with the backplate removed. 
     FIG. 6 is a top view of the device in use. The vertebrae shown have a substantially constant width. 
     FIG. 7 is an oblique view of the backplate showing the portion that receives the forwardmost vertebra. 
     FIG. 8 is a side view of the backplate showing the cord path and cord hook. 
     FIG. 9 is a top view of the frame and driver assembly. 
     FIG. 10 is an oblique view of a vertebra. 
     FIG. 11 is an exploded top view of alternate vertebrae that have decreasing width. 
     FIG. 12 is a top view of the cord hook. 
     FIG. 13 is an oblique view of the thruster and fluke assembly. 
     FIG. 14 is a sectional rear view along cutting plane  14 — 14  as shown on FIG.  13 . 
     FIG. 15 is an oblique view of the fluke assembly. 
     FIGS. 16-24 are top views of alternate fluke assemblies. 
     FIG. 25 is a top view of an alternate tail assembly. 
     FIG. 26 is a side view of the alternate tail assembly portion of FIG.  25 . 
     FIG. 27 is a rectangular box indicating an interchangeable alternate driver. 
     FIG. 28 is a perspective view of the cord. 
    
    
     DESCRIPTION OF THE REFERENCED NUMERALS 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the figures illustrate the swimmer propulsion device of the present invention. With regard to the reference numerals used, the following numbering is used throughout the various drawing figures. 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 20 
                 swimmer 
               
               
                 21 
                 swimmer torso 
               
               
                 22 
                 swimmer arms 
               
               
                 23 
                 swimmer legs 
               
               
                 24 
                 swimmer feet 
               
               
                 30 
                 swimmer propulsion device of the present invention 
               
               
                 32 
                 vest 
               
               
                 34 
                 vest shoulder strap 
               
               
                 36 
                 vest shoulder strap latch members 
               
               
                 38 
                 vest torso belt 
               
               
                 40 
                 torso belt latch members 
               
               
                 42 
                 backplate 
               
               
                 44 
                 backplate attachment member 
               
               
                 46 
                 backplate attachment member runner slots 
               
               
                 48 
                 backplate runners 
               
               
                 50 
                 backplate dorsal fin 
               
               
                 52 
                 backplate side holes 
               
               
                 54 
                 fasteners 
               
               
                 60 
                 frame 
               
               
                 62 
                 frame front members 
               
               
                 64 
                 frame rear members 
               
               
                 70 
                 driver 
               
               
                 72 
                 axle 
               
               
                 74 
                 first apex member 
               
               
                 76 
                 second apex member 
               
               
                 78 
                 third apex member 
               
               
                 80 
                 first apex member roller 
               
               
                 82 
                 second apex member roller 
               
               
                 84 
                 third apex member roller 
               
               
                 86 
                 foot pedal 
               
               
                 87 
                 pedal straps 
               
               
                 88 
                 foot pedal arms 
               
               
                 90 
                 ratchet gear 
               
               
                 100 
                 vertebra 
               
               
                 102 
                 vertebra forward portion 
               
               
                 104 
                 vertebra upper extensions 
               
               
                 106 
                 vertebra lower extensions 
               
               
                 108 
                 vertebra hole 
               
               
                 110 
                 cord 
               
               
                 112 
                 cord front loop 
               
               
                 114 
                 cord rear loop 
               
               
                 120 
                 backplate upper extensions 
               
               
                 122 
                 backplate lower extensions 
               
               
                 124 
                 backplate hole 
               
               
                 126 
                 backplate slot 
               
               
                 130 
                 hook member 
               
               
                 132 
                 hook member bar 
               
               
                 134 
                 hook member loop 
               
               
                 140 
                 thruster 
               
               
                 142 
                 thruster forward extensions 
               
               
                 144 
                 thruster rearward extensions 
               
               
                 146 
                 thruster slots 
               
               
                 147 
                 thruster groove 
               
               
                 148 
                 thruster front portion 
               
               
                 150 
                 thruster rear portion 
               
               
                 152 
                 thruster hole 
               
               
                 154 
                 thruster rear slot 
               
               
                 156 
                 thruster dorsal fin 
               
               
                 158 
                 bar 
               
               
                 160 
                 pin 
               
               
                 162 
                 pin latches 
               
               
                 164 
                 pin hole 
               
               
                 166 
                 fluke assembly 
               
               
                 168 
                 flukefront portion 
               
               
                 170 
                 fluke pin hole 
               
               
                 172 
                 thruster rear upper extensions 
               
               
                 174 
                 thruster rear lower extensions 
               
               
                 176 
                 flukes 
               
               
                 178 
                 fluke thickened edges 
               
               
                 180 
                 fluke central stabilizer 
               
               
                 182 
                 orca whale fluke shape 
               
               
                 184 
                 alternate fluke shape 
               
               
                 186 
                 alternate fluke shape 
               
               
                 188 
                 alternate fluke shape 
               
               
                 190 
                 alternate fluke shape 
               
               
                 192 
                 alternate fluke shape 
               
               
                 193 
                 alternate fluke shape 
               
               
                 194 
                 alternate fluke shape 
               
               
                 195 
                 alternate fluke shape 
               
               
                 196 
                 frame extensions 
               
               
                 200 
                 propulsion band 
               
               
                 230 
                 resilient member 
               
               
                 250 
                 alternate vertebrae 
               
               
                 252 
                 alternate driver 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings in more detail, in which similar reference characters denote similar elements throughout the several views, FIGS. 1-25 and illustrate the swimmer propulsion device of the present invention indicated generally by the numeral  30 . 
     The device  30  is shown in use by a swimmer  20  in FIGS. 1-2 and the vest  32  is specifically depicted in FIGS. 4-5. In donning the device  30 , the swimmer  20  places the vest  32  about his torso  21  by latching the shoulder straps  34  about his arms  22  using latch members  36 , and by latching the vest torso belt  38  using latch members  40 . The swimmer&#39;s legs  23  and feet  24  are not encompassed by the vest  32 . 
     When properly fitted to the swimmer  20 , the vest  32  is positioned for receiving a backplate  42 , the backplate  42  being shown specifically in FIGS. 7-8. The vest  32  positions a backplate attachment member  44 , having three female runner slots  46 , with the open end of the slots  46  pointed forwardly. Three male runners  48  on the backplate  42  are closely received by the runner slots  46  as the backplate  42  is brought rearward while directing the runners  48  into the runner slots  46 . A detachable dorsal fin  50  extends from the backplate  42 . It can be replaced with fins of varying shapes and sizes. 
     Along both sides of the backplate  42  are holes  52  for receiving fasteners  54 , the fasteners  54  attaching a frame  60 , by fastening frame forward members  62  to the backplate  42 , as shown in FIGS. 7-9. The backplate  42  can be constructed from typical rigid plastics or other materials. 
     As shown in FIG.  1  and FIG. 9, the frame forward members  62  extend rearwardly where they descend and join. As the frame  60  extends rearwardly it forks into frame rear member  64 . Positioned on the frame rear members  64  for rotation is a driver  70  mounted on an axle  72 . The driver  70  has a first, second and third apex member  74 , 76 , 78 , each apex member  74 , 76 , 78  having a roller  80 , 82 , 84 . Foot pedals  86 , with conventional straps  87 , are mounted on pedal arms  88 , which are, in turn, attached to the axle  72 . A ratchet gear  90  allows the pedal  86  to move free of the axle  72  when rotated in the clockwise direction, as viewed on FIG.  1 . When the pedals  86  are rotated in the counter-clockwise direction (as viewed on FIG. 1) the driver  70  is rotated as well. Various rigid materials, including plastics and metals can be used for the frame  60 , driver  70 , pedals  86 , axle  72 , and pedal arms  88 . 
     An extended assembly of vertebrae  100  also extend from the backplate  42 , as shown in FIGS. 1,  6 ,  10  and  11 . Each vertebra  100  has a curved forward portion  102  that is partially encompassed by upper vertebrae extensions  104  and lower vertebrae extensions  106 , when the forward portion  102  is inserted into the extensions  104 , 106  of another vertebrae  100 . Each vertebrae  100  has a hole  108  through which a resilient cord  110  is run, the cord  110  extending along the length of the “spine.” The cord  110  has a front loop  112  and a rear loop  114 , as shown in FIG.  29 . As shown in FIG. 6, the vertebrae  100  are substantially the same lateral width, but have a constantly decreasing vertical width, as shown in FIG.  1 . The vertebrae  100  can be constructed from numerous resilient plastic materials. 
     The frontmost vertebra  100  is inserted among backplate upper extensions  120  and lower extensions  122  and is partially encompassed therein in a similar fashion as the other vertebrae  100 . As shown in FIG. 8, the backplate  42  has a hole  124  and a slot  126  coincident with the hole  124 , the hole  124  aligning with the vertebrae holes  108 , allowing the cord  110  to extend into the backplate  42 . 
     As the cord  110  passes through the backplate hole  124 , a hook member  130  is used to secure the cord  110 . The hook member  130  is shown separately in FIG. 12, and in place in FIG.  8 . The hook member  130  has a hooked bar  132  and a loop  134 . The bar  132  is inserted into the cord front loop  112 , and as the cord  110  is pulled rearwardly through the vertebrae  100 , the bar  132  is drawn into, and closely received by, the slot  124 . This prevents the cord front loop  132  from being pulled back through the backplate hole  124 . 
     Hook member loop  134  is provided for screwdriver insertion at a subsequent disassembly of the “spine.” 
     Referring now to FIG. 13, wherein a thruster  140  is depicted. The thruster  140  has a pair of forward extensions  142  extending from the sides, a pair of rearward extensions  144  also extending from the sides, but at a more rearward point, and slots  146  extending through the thruster  140  from top to bottom. The thruster  140  also has a downwardly facing groove  147 , as shown in FIG.  14 . 
     The thruster  140  also has a dorsal fin  156  that is detachable and replaceable with fins of various sizes and shapes. The thruster  140  can be constructed from various resilient plastics, including fiberglass reinforced plastics. 
     The thruster  140  has a rounded front portion  148  that mates with, and is partially encompassed by the last vertebra  100  to the rear of the vertebrae  100  assembly. As shown in FIG. 14, the thruster  140  also has a rear portion  150 . Extending through the thruster  140  is a hole  152  that aligns with the vertebrae holes  108  such that the cord rear loop  114  can be pulled through the thruster rear portion  150 . The thruster hole  152  has a coincident slot  154 . A bar  158  is inserted into the cord rear loop  114  and is drawn into, and closely received by the slot  154  to secure the cord  110 . During assembly the cord rear loop  114  is so secured in the thruster rear portion slot  154 , the cord  110  is routed through the vertebrae  100  and through the backplate hole  124 , where the hook member  130  is inserted while the cord  110  is in tension. 
     As shown in FIGS. 13-15, the thruster  140  has a pin  160 , pin latches  162  and a pin hole  164  proximate the thruster rear portion  150 . A fluke assembly  166  has a front portion  168  that is received by the thruster rear portion  150 . The fluke front portion  168  has a pin hole  170  that aligns with the thruster rear portion pin hole  164 , for insertion of the pin  160 . The pin  160  is held in place by the pin latches  162 . 
     The fluke front portion  168  is firmly mated with the thruster  140  by the restraining function of thruster rear upper extensions  172  and thruster rear lower extensions  174  that partially encompass the fluke front portion  168 . 
     The fluke assembly  166  includes two flukes  176 . The flukes  176  have thickened outer edges  178  that stiffen and laterally stabilize the flukes  176 . The fluke assembly  166  also includes a central stabilizer  180  in the form of an upswept portion overlying part of the flukes  176 . The central stabilizer  180  also stiffens and stabilizes the flukes  176 , when the flukes  176  are moving downwardly. As shown in FIGS. 15-24, the flukes  176  can be shaped in accordance with the known flukes of dolphins  166 , and orca whales  182 , and in other designer shaped flukes  184 , 186 , 188 , 190 , 192 , 193 , 194 , 195 , 196 . The fluke assembly  166  can be constructed from various plastics, including fiberglass reinforced-plastics. As shown further in FIG. 26, the fluke assembly portion of the tail member further comprises a tail member top and a substantially rigid member  181  positioned proximate the tail member top, such that as the tail member is forced back to the first position, the tail member top is forced against the rigid member, the rigid member then at least partially impeding the further deformation of the fluke assembly portion of the tail member. 
     As shown in FIGS. 1-2, the frame  60  has a pair of extensions  196 . A pair of resilient propulsion bands  200  connect the thruster rearward extensions  144  and the frame extensions  196 . FIG. 1 depicts the swimmer&#39;s knees in a bent position  23  after the swimmer  20  has ratcheted the foot pedals  86  forward. Prior to pushing rearwardly on the pedals  86 , the third apex member roller  84  and the first apex member roller  80  are both adjacent the thruster  140 , the roller  80  being laterally constrained within the thruster groove  147 . As the swimmer  20  pushes on the pedals  86 , the pedal arms  88  engage the driver  70  through ratchet gear  90 . As the driver  70  is forced into counter-clockwise rotation, first apex member roller  80  is forced against the thruster  140 , moving the thruster  140  upwardly, while simultaneously creating tension in the propulsion bands  200  as they are stretched. FIG. 2 depicts the stretched propulsion band  200  and the third apex member roller  80  at the point of maximum thruster  140  displacement, that is when the third apex member is perpendicular to the thruster  140 . At this point the flukes  176  have been raised and the propulsion bands  200  have been significantly tensioned. Also, the vertebrae  100  assembly has been bent causing an elastic deformation within the individual vertebra  100 . 
     By following through with the rearward push, the pedal arms  88  force the driver  70  beyond the point shown in FIG. 2, and the tension in the propulsion bands  200  and the elastic deformation of the vertebrae  100  is released. When released from tension and deformation both the propulsion bands  200  and the vertebrae  100  force the flukes  176  sharply downward, thus thrusting the swimmer  20  forward. 
     After this release the first apex member roller  80  and the second apex member roller  82  are then adjacent the thruster  140 . For the next thrusting event, the swimmer  20  again ratchets the foot pedals  86  forward and then pushes rearwardly. In this event, the second apex member roller  82  will be forced against the thruster  140 , and laterally constrained within the thruster groove  147 , with analogous stretching of the propulsion bands  200  and deformation of the vertebrae  100 . 
     The thruster  140  is also resilient and deforms as it is borne upon by the apex member rollers  80 , 82 , 84 . As it returns to the undeformed shape it adds additional thrust to that provided by the propulsion bands  200  and vertebrae  100 . 
     The present invention also encompasses various combinations of propulsion bands  200  (of varying length and tensions) and thruster rearward and forward extensions  142  and  144  (placed at varying positions along the thruster  140 ). Such combinations allow alternate propulsion ban  200  configurations on the available extensions  142 , 144 , and variations in the amount of thrust and the force necessary to push the pedals  86  to vary. 
     Similarly, the present invention also encompasses drivers with varying numbers of apexes, and with apexes of various heights. This will allow a varying thruster vertical response, thus varying the amount of thrust. It will also allow varying force requirements for pushing the pedals  86 . For example FIG. 27 depicts an alternate embodiment of a driver with more apexes than driver  70 . 
     The present invention also encompasses a single pedal embodiment, where the current pedals are replaced by a single member that moves both pedal arms. 
     In FIG. 1, pedal  86  also depicts the single pedal embodiment. Similarly, the number of pedal arms and propulsion bands can be reduced to one. In another embodiment, each pedal arm can ratchet independently of the other, while each rotates the driver during its rearward push. 
     In another embodiment, the rollers  80 , 82 , 84  are eliminated. 
     In another embodiment, fluke outer edges are reinforced with stiffeners, such as fiberglass, or metal rods. 
     In another embodiment, the flukes are substantially rigid. 
     In another embodiment, the backplate, vertebrae, thruster, and fluke assembly are replaced by a single, resilient member  230 . This embodiment is shown in FIGS. 25-26. 
     In another embodiment, shown in FIG. 11, the vertebrae  250  have constantly decreasing lateral widths. 
     Although particular types of materials and particular dimensions have been discussed herein, other types and sizes of materials can also be used, all in accordance with the present invention, and as determined by the intended end use for the overall device, as will occur to those of skill in the art upon review of the present disclosure. In particular, further flukes and/or other tail members of various sizes and shapes, and various cooperations with different spines may be envisioned with in the scope of the present invention. Accordingly, the preceding description and figures are illustrative only and are not to be considered as limitations on the scope of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various swimming applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.