Abstract:
A controllable fin surface configuration positionable on the underwater surface of a craft having a bow and a stern, the craft having a direction of travel defined from the stern to the bow, the configuration comprising: at least one hinge adapted to mechanically support the fin surface configuration; and at least one fin surface mechanically attached to the hinge and having a range of motion definable from a closed state to an open state; wherein the closed state is defined by the fin surface configuration offering minimal resistance to relative water movement opposing the direction of travel and the open state is defined by the fin surface configuration offering maximum resistance to relative water movement in the direction of travel.

Description:
BENEFIT OF PRIOR APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/224,971, filed Jul. 13, 2009 whose disclosure is incorporated herein by reference. 
     
    
     FIELD AND BACKGROUND OF THE INVENTION 
       [0002]    The current invention relates to a controllable fin surface configuration for watercraft and specifically a fin surface configuration to enhance watercraft stability and movement. More specifically, embodiments of the present invention relate to a fin surface configuration and method to enhance stability and movement of a surf board and similar type watercraft. 
         [0003]    In the specification and claims which follow, the term “watercraft” is meant to mean any boat or recreational craft meant to move above or partially submerged in the water. Salient examples of watercraft include but are not limited to: a surfboard; a wind surfboard; and a light boat propelled by oars and/or motors. 
         [0004]    There are many kinds of watercraft utilizing unnecessary energy to overcome water resistance while moving through water. While many watercraft utilize a vertically configured stabilizer on the underside of the watercraft, one or more additional surfaces could have the potential to enhance watercraft stability and movement. 
         [0005]    An example of prior art related to such vertically-configured stabilizer surfaces on the underside of the watercraft surfaces is US Patent Application Publication 2007/0093154 to Simpson, whose disclosure is incorporated herein by reference. Simpson describes a fin for use on a surfboard and other watercraft of a low-drag, high lift, and high aspect ratio, among other characteristics, to make the surfboard or watercraft more maneuverable and to stabilize the surfboard or watercraft. 
         [0006]    Another example is U.S. Pat. No. 4,733,496 by Wallner et al., whose disclosure is incorporated herein by reference. Wallner likewise describes a fin for surfboards and watercraft, his fin including a pivoting rudder like section that swings out when a turn is commenced, enhancing the maneuverability of the surfboard. The fin described includes a stationary section with a pivoting blade section that can be mechanically adjusted. 
         [0007]    A third example of a vertically configured stabilizer on the underside of the watercraft is that of Johnson, in U.S. Pat. No. 3,890,661, whose disclosure is incorporated herein by reference. In the referenced publication, a surfboard is steered by a fin that functions as a rudder in response to force due to gravity of the surfer&#39;s body. A vertical shaft connects the rudder-fin to the surfboard body. A lever arm adjustable in length is provided between the shaft and body of the surfboard to vary steerability characteristics. 
         [0008]    The cited prior art hereinabove are representative of primarily single vertical fin configurations and they are directed at enhancing maneuverability of a surfboard or other craft. A fin configuration that has a horizontal component is described by Harper in U.S. Pat. No. 4,077,077, whose disclosure is incorporated herein by reference. Harper describes a stabilizer keel for water surface vehicles. The keel includes a pair of pivoted keel plates that are pivoted on a stationary base member by an integral hinge. The plates are urged apart from the axis of the hinge by a spring to normally form a V-configuration for the purpose of stabilizing the object to which the keel is mounted; for example a water ski. The hinge axis is inclined so the plates, when in the open V-configuration, will lift upwardly against the ski upon movement of the skin a forward direction. As forward velocity is increased, pressure against the plates also increases, causing them to swing inwardly against the resistance of the spring. At relatively high speeds, the pates come together to form a substantially standard shape keel. 
         [0009]    Harper&#39;s stabilizer keel can be effective when used in a water ski and/or a watercraft which is powered by propeller or towed at higher speeds. However the “normally open” configuration of Harper&#39;s stabilizer keel ensures high resistance at relatively slow speeds, which could be disadvantageous, for example, with only human power especially when considering the case of a surfboard. 
         [0010]    In surfing, a surfer wishing to leave the beach and go out to surf on a wave must first “power” his surfboard away from the beach to deeper water by paddling with his hands/arms. Paddling the surfboard against incoming waves involves strength, and the keel or other prior art surfaces described hereinabove offer little advantage or perhaps a serious disadvantage to the surfer. Likewise, when a surfer is preparing to catch a wave, he must quickly paddle towards the beach to increase his speed, with the prior art surfaces described above hardly serves any advantage, if at all. 
         [0011]    In both cases of paddling out to sea or paddling to catch a wave, there is a need for a fin configuration that can be easily adapted to watercraft to stabilize the watercraft, and in the case of a surfer, to assist his efforts, especially at low speed. 
       SUMMARY OF THE INVENTION 
       [0012]    According to the teachings of the present invention there is provided a controllable fin surface configuration positionable on the underwater surface of a craft having a bow and a stern, the craft having a direction of travel defined from the stern to the bow, the configuration comprising: at least one hinge adapted to mechanically support the fin surface configuration; and at least one fin surface mechanically attached to the hinge and having a range of motion definable from a closed state to an open state; wherein the closed state is defined by the fin surface configuration offering minimal resistance to relative water movement opposing the direction of travel and the open state is defined by the fin surface configuration offering maximum resistance to relative water movement in the direction of travel. 
         [0013]    Preferably, the range of motion is from substantially 0 degrees in the closed state to as much as substantially 90 degrees in the open state. Most preferably, the hinge is configurable substantially perpendicular to the underwater surface and the configuration further comprises at least 2 fin surfaces. Typically, the fin surfaces are in the closed state when substantially parallel to each other. Most typically, the hinge is configurable substantially perpendicular to the direction of travel and substantially flush with the underwater surface. Preferably, the configuration further comprises a plurality of hinges, each of the plurality of hinges having at least one fin surface. 
         [0014]    According to further teachings of the present invention there is provided a method for positioning a controllable fin surface configuration on the underwater surface of a craft having a bow and a stern, the craft having a direction of travel defined from the stern to the bow, the method comprising the steps of: locating a hinge to mechanically support the fin surface configuration; attaching at least one fin surface to the hinge, the at least one fin surface having a range of motion definable from a closed state to an open state; defining the closed state as the fin surface configuration offering minimal resistance to relative water movement opposing the direction of travel; and defining the open state as the fin surface configuration offering maximum resistance to relative water movement in the direction of travel. Preferably, the range of motion is from substantially 0 degrees in the closed state to as much as substantially 90 degrees in the open state. Most preferably, the hinge is configurable substantially perpendicular to the underwater surface and the configuration further comprises at least 2 fin surfaces. Typically, the fin surfaces are in the closed state when substantially parallel to each other. 
         [0015]    Preferably, the hinge is configurable substantially perpendicular to the direction of travel and substantially flush with the underwater surface. Most preferably, the configuration further comprises a plurality of hinges, each of the plurality of hinges having at least one fin surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS AND APPENDICES 
         [0016]    The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a pictorial view of an under water surface of a craft showing a controllable fin surface configuration in an open state, in accordance with an embodiment of the current invention; 
           [0018]      FIGS. 2 and 3  are pictorial representations of the craft as it begins to ride a wave and as the craft goes out against a wave, respectively, with the controllable fin surface configuration in an open state, in accordance with embodiments of the current invention; 
           [0019]      FIG. 4  is a pictorial view of an under water surface of a craft showing a controllable fin configuration, in accordance with an embodiment of the current invention; 
           [0020]      FIGS. 5A , B, C, and  5 D are detailed pictorial views of the controllable fin configuration of  FIG. 4 , in various closed and open configurations, in accordance with an embodiment of the current invention; 
           [0021]      FIG. 6  is a pictorial view of an under water surface of a craft showing an alternative of controllable fin configuration in an open state, in accordance with an embodiment of the current invention; and 
           [0022]      FIG. 7  is a pictorial view of an under water surface of a craft showing an alternative of controllable fin configuration in an open state, in accordance with an embodiment of the current invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    The current invention relates to a controllable fin surface configuration for watercraft and specifically a fin surface to enhance watercraft stability and movement. More specifically, embodiments of the present invention relate to a fin surface configuration and method to enhance stability and movement of a surf board and similar type watercraft. 
         [0024]    Reference is presently made to  FIG. 1 , which a pictorial view of a watercraft (or “craft”)  6  having an underwater surface  8  and a controllable fin surface configuration  10  in an open state, in accordance with an embodiment of the current invention. Craft  6  typically has a bow  11  (ie a forward or leading end) and a stern  12  (ie a trailing end). A direction of travel of the craft is defined from the stern to the bow. The controllable fin surface configuration includes a controllable fin  13  attached to surface  8  near the stern, by a hinge  14 , where the hinge is oriented substantially perpendicularly to the direction of travel of craft  6 . Two vertically-oriented fins  18 , representing conventional stabilizing craft  6 —stabilizing fins, are optionally mounted on either side of controllable fin  13 . It should be noted that while the controllable fin surface is shown in  FIG. 1  and in subsequent figures is shown near the stern, the controllable fin surface may be optionally or alternatively positioned near the bow or between the bow and stern to accomplish its functioning, as described hereinbelow. 
         [0025]    The fin is hinged and free to move, so that when craft  6  moves forward in the water and/or when water moves in the direction from the bow to the stern more quickly than the forward movement of the craft, the relative water movement serves to create a force on controllable fin  13  to bias it to close against surface  8  (not shown in the figure)—yielding a “closed state”. However, when the watercraft advances more slowly than the surrounding water and/or when water moves from the stern to the bow more quickly than the forward movement of the craft, the relative water movement serves to create a force on controllable fin  13  to bias it to open away from surface  8 , yielding an “open state” of controllable fin configuration  10 , as shown in  FIG. 1 . The range of movement of the controllable fin is substantially from 0 degrees (in line and parallel with surface  8 , ie. closed state) to as much as 90 degrees (perpendicular to surface  8 , ie. open state), although the open state may be represented by a value less than 90 degrees, dependent on specific design of the fin configuration. 
         [0026]    A “braking effect” (braking backward movement of the craft) described hereinabove is further illustrated by referring to  FIGS. 2 and 3 , which are pictorial representations of the craft as it moves away from the beach and against a wave  20 , and the craft as it is about to ride the wave, respectively, with controllable fin surface configuration  10  in an open state, in accordance with embodiments of the current invention. The dark arrow in both figures emphasizes the relative water direction as described hereinabove. The concept of relative water direction/movement is central in understanding embodiments of the current invention, as described hereinbelow. 
         [0027]    Essentially, controllable fin surface  13  alternately assumes an open state (as shown in  FIGS. 2 and 3 ) and a closed state, as described hereinabove. As such, the controllable fin surface, in its open state, acts to assist the surfer in the two situations shown in  FIGS. 2 and 3 , namely to brake backward movement of the craft, such as when going against waves out to sea, and to aid in acceleration and “catching” a wave when surfing back towards the beach. The open state is characterized by an increase of surface area of controllable fin configuration  10  against the water, thereby yielding a resultant force on the craft, the force having a direction from the stern of the craft towards its bow. 
         [0028]    Reference is now made to  FIGS. 4 ,  5 A,  5 B,  5 C, and  5 D which is a pictorial view of a craft  6  having an underwater surface  8  showing controllable fin configuration  110  and detailed pictorial views of controllable fin configuration  110  in various closed and open configurations, respectively, all in accordance with an embodiment of the current invention. Craft  6  is essentially similar to craft  6  of  FIGS. 1-3  and in structure and function, apart from the differences noted hereinbelow. Craft  6  has an imaginary centerline (not indicated in the figures) running from the leading edge of the bow to stern  12 . Controllable fin configuration  110  includes two stationary supports  220 , mounted perpendicularly to surface  8  and located near the stern and symmetrically spaced about the imaginary centerline, each support having a hinge  222  which connects two controllable fins  224  and  226  to the respective support, allowing the controllable fins to move away from each other in an “open state” ( FIG. 5C ), a nearly open state ( FIGS. 4 and 5D ), and a “closed state” (FIGS.  5 A and  5 B)—all as shown. Controllable fins  224  and  226  each have a range of movement ranging from 0 degrees (in line with support  220 ) to substantially 90 degrees (perpendicular to support  220 ). 
         [0029]    Each fin is hinged and free to move within the range of movement, so that when craft  6  moves forward in the water (and/or when water moves in the direction from the bow to the stern) the relative movement of the water relative to the craft serves to create a force on fins  224  and  226  to bias them to close against each other yielding the closed state. However, when the watercraft advances more slowly than the surrounding water (and/or when water moves from the stern to the bow) the relative movement of the water serves to create a force on fins  224  and  226  to bias the fins away from each other, yielding an open state of controllable fin configuration  10 . In this way, controllable fin configuration  110  serves to assist the surfer in much the same way as controllable fin configuration  10  does in the two situations shown in the  FIGS. 2 and 3 , namely to brake backward movement of the craft, such as when going against waves out to sea, and to aid in acceleration and “catching” a wave when surfing back towards the beach. 
         [0030]    Reference is now made to  FIG. 6 , which is pictorial view of the under water surface of craft  6  showing an alternative controllable fin configuration  410  in an open state, in accordance with an embodiment of the current invention. Controllable fin configuration  410  is a combination of controllable fin configuration  10  of  FIGS. 1 ,  2 , and  3  and controllable fin configuration  310  of  FIGS. 4-6B  and the numerals used to express components of  FIG. 7  are meant to be similar in structure and function as noted in the previous figures. In controllable fin configuration  410 , however, conventional fins  18  have been replaced with controllable fin configuration  310 . As noted hereinabove, while the controllable fin configurations shown in  FIG. 6  and in previous figures have been located nearer to the stern of craft  6 , the controllable fin surface configuration may be optionally or alternatively positioned near the bow or between the bow and stern to accomplish its functioning, as described hereinabove. Furthermore, the controllable fin surface configuration may include not only 1, 2, or 4 fin surfaces as shown in previous figures and described hereinabove, but it may include a plurality of fin surfaces approaching/approximating a configuration associated with scales on a fish, as described hereinbelow. 
         [0031]    Reference is presently made to  FIG. 7 , which is a pictorial view of an under water surface of craft  6  showing a controllable fin configuration  510  in an open state, in accordance with an embodiment of the current invention. Controllable fin configuration  510  includes a plurality of individual fin configurations  511  similar in structure, but smaller in scale, and similar in function to fin configuration  10  of  FIGS. 1 ,  2 ,  3 , and  6 , except as noted hereinbelow. Individual fin configurations  511  includes surface  513  connected to hinge  514 , similar in structure and function to surface  13  and hinge  14  of  FIG. 1 , inter alia. As can be seen in  FIG. 7 , individual fin configurations  511  are scaled smaller than fin configuration  10 . The individual fin configuration individually and collectively serve to brake and assist the craft in a manner similar to that described for configuration  10 . 
         [0032]    It may be furthermore understood that scaled-down configurations of fin configuration  110  (as shown in  FIG. 4 ) and/or scaled-down configurations of fin configuration  410  (as shown in  FIG. 6 ) may be likewise distributed on the under water surface of craft  6 , similar to that described for configuration  510  hereinabove. 
         [0033]    It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.