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PRIORITY CLAIM 
       [0001]    Priority to U.S. provisional patent application 61/055,294 filed May 22, 2008, which is incorporated herein in its entirety by reference, is claimed. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to devices for tethering watercraft, boats in particular, to docks. Currently, the most common way for a boat to be secured to a dock is to wrap a rope from a boat around a cleat fastened to the dock surface. A cleat is a device bolted to the surface of the dock and has two prongs extending laterally from opposing sides of the base. A rope may be looped in a figure eight pattern or lashed in some other manner around the two opposing prongs. 
         [0003]    There are several shortcomings in the use of cleats. Primarily the cleats together with a mass of rope used to tether the boat are a tripping hazard to those walking on the dock. This is ironic in view of the care generally taken on boats to eliminate tripping hazards. Also, the boat is only as secure as the extent to which the cleat is bolted to the dock. As docks weather, the security of the cleat&#39;s moorings becomes an insidious issue because the cleat looks secure but the wood holding it may have rotted. Finally, there is typically excess rope that is often casually coiled around the cleat. Thus there remains a need for a better way to tether a boat to a dock. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is a tethering device for a boat. The top surface of the tethering device is flush with the top of the dock and it is secured to the underside of the decking so that someone can walk on top of the decking without tripping. Inside the housing of the device is a retraction reel storing a sufficient length of line to provide tethering of the boat to the dock while retracting excess line for out-of-sight storage while leaving the pre-selected length of line extending from the tethering device. The housing also has a line locking mechanism to hold the pre-selected length of line and prevent the boat from drifting away taking the line with it. 
         [0005]    The present tethering device is made to be fastened to the underside of the decking of the dock rather than to the top side of the decking so the part of the decking that holds it is not the sun and rain exposed surface. Also, securement of the tethering device is spread over several decking boards to better distribute the load. 
         [0006]    The low-profile, flush upper surface of the device eliminates the tripping hazard of cleats, and the retraction reel eliminates the mass of excess line. The result is a neater appearance and certainly safer than the use of prior art cleats. 
         [0007]    The internal line locking mechanism helps to assure that the line is securely fastened and remains securely fastened to the device at the length predetermined by the user. 
         [0008]    These and other features and their advantages will be readily apparent to those skilled in the art in tethering small craft to docks and marinas from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    In the figures, 
           [0010]      FIG. 1  is a left side perspective view of a dock with a boat tethered to a tethering device, according to a preferred embodiment of the present invention; 
           [0011]      FIG. 2  is a detail of the view of  FIG. 1  with the dock board of the tethering device shown lifted to reveal the mounting plate and housing, according to a preferred embodiment of the present invention; 
           [0012]      FIG. 3  is a left side perspective, exploded view of the present tethering device according to a preferred embodiment of the present invention; 
           [0013]      FIG. 4  is a left side, cross sectional view of the tethering device with latch arm lifted, according to a preferred embodiment of the present invention; 
           [0014]      FIGS. 5A and 5B  are left side, cross sectional views of a portion of the present tethering device with latch arm in the unlatched (raised) position and in the latched (lowered) position so that the impact of the latch on the cam&#39;s ability to grip the line to the boat is apparent, according to a preferred embodiment of the present invention; and 
           [0015]      FIGS. 6A and 6B  are right side, cross sectional views of a portion of the present tethering device with latch arm in the unlatched (raised) position and in the latched (lowered) position, according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0016]    As illustrated in  FIGS. 1 and 2 , the present invention is a device  10  for tethering a boat  12  or other water craft to a dock  14 . A dock is a framework  16  covered with decking  18  and that extends from a shoreline out over the water where it may be supported by pilings  20 , as shown, or may be a floating dock, to allow those with boats floating on the water to walk between shore and boat  12  easily. Boat  12  is tethered to dock  14  so that it is kept proximate to dock  14  and does not float away. 
         [0017]    Decking  18  may be made of lumber such as 2×6 pine boards laid in parallel across framework  16  and fastened with nails or screws, or made of plastic, composite, metal, concrete or a combination of materials. The present device  10  may be incorporated into the surface of the dock or, as shown, made to replace a short section of the end of one decking board  22  and may be flush with the top of decking  18  so that it does not present a tripping hazard. Dock  14  may have several of the present devices installed along its edge  24  at intervals depending on how long dock  16  is and how many boats  12  may be tied up to dock  16 . A marina dock may have a device  10  every 20 feet for example. Each device  10  has a line  26  that may have a loop  28  formed in the running end  30  thereof, preferably a spliced line loop for use in hitching line  26  to a cleat  32  on boat  12  using, for example, a lark&#39;s head hitch as illustrated in  FIG. 1 . 
         [0018]    Device  10  is intended to provide a length of line  26  for use in tethering boat  12  to dock  14 . Device  10  may be installed into dock  14  so that it holds running end  30  of line  26  at the dock&#39;s edge  24 . The user simply unlatches a latch arm  40  on device  10  by raising it in order to release line  26 , meaning, to cause device  10  to release its hold on line  26  so that running end  30  can be pulled away from device  10 . The user may then pull a pre-selected amount of line  26  sufficient to reach boat  12  where loop  28  of the running end  30  may be attached to a cleat  32  or to another part of the boat  12 . As will be explained herein, device  10  retracts the slack in line  26 . When latch arm  40  is lowered to the latched position, device  10  grips line  26  so boat  12  cannot drift away from dock  16  beyond the pre-selected length of line  26  extending from device  10  when latch arm  40  was placed in the latched position. Latch arm  40  is shown in  FIGS. 1 and 2  in the latched position, which is flush with the top of device  10  and decking  18 . No part of device  10  extends significantly above decking  18  so as to present a tripping hazard and there is no pile of rope to clutter dock  14 . 
         [0019]    Device  10  includes a housing  42  that may have six sides defining a rectangular parallelepiped as shown in  FIGS. 2 and 3 . Housing  42  has a hole  44  formed in one side which side is designated herein for convenience as top side  46  when device  10  is oriented as shown in  FIG. 1 . Top side  46  of housing  42  opposes a bottom side  48  of housing  42 . Hole  44  will be located in top side  46  near a proximal side  50  as opposed to near a distal side  52 . Proximal side  50  is intended to be parallel to and close to edge  24  of dock  16 , when device  10  is installed in a preferred location of dock  16 , so that line  26  issues from hole  44  at a point closest to edge  24  and boat  12  to limit the amount of line  26  on decking  18 . Housing  42  has a first or left side  54  as seen in  FIGS. 1-4 , and an opposing second or right side  56 . Top side  46  has two additional holes formed therein, a first proximal hole  58  and a second distal hole  60 , the purposes of which will be explained presently. 
         [0020]    Housing  42  is supported from above by a U-shaped adaptor plate  70  that is fastened to the underside of decking  18  so that housing  42  is above the water line in order to avoid the impact of water on housing  42  and its internal structures. Top side  46  of housing  42  is formed with a flange  72  that rests on adaptor plate  70 . When housing  42  is in position on adaptor plate  70 , top side  46  is below the top surface of decking  18 . A dock board  74  is then attached to adaptor plate  70  over flange  72  using bolts. Preferably, adaptor plate  70  includes pre-attached floating nut plates  80  so that the user merely needs to drill holes through decking  18  and decking board  22  from the surface of decking  18  and decking board  22  and then install bolts through the pre-drilled holes. Holes are formed in dock board  74  ( FIGS. 2 and 3 ) and adaptor plate  70  to allow adaptor plate  70  to be secured to dock board  74  and adaptor plate  70  to decking  18 , using bolts  82  and  84 , respectively ( FIG. 4 ). Dock board  74  has a thickness and a width that matches the thickness and width of the boards that comprise decking  18  so that device  10  can be installed merely by removing a portion of one decking board  22  near edge  24 , installing adaptor plate  70  to the underside of surrounding, remaining decking  18 , positioning flange  72  of housing  42  on adaptor plate  70 , positioning dock board  74  over housing  42  and then securing dock board  74  to adaptor plate  70  with flange  72  sandwiched therebetween with bolts  82 , and decking  18  to adaptor plate  70  with bolts  84 , and the top surface of dock board  74  will be flush with the surrounding decking  18 . Preferably the fastening bolts  82 ,  84  are counter-sunk so that no part of device  10  extends above decking  18  but rather is all essentially flush with decking  18 . 
         [0021]      FIGS. 3 ,  4 ,  5 A,  5 B,  6 A and  6 B are cross sectional views of device  10 . Reference numbers used in  FIGS. 1 and 2  are used in  FIGS. 3-6  for the same components for convenience. Also, for convenience, the views in  FIGS. 3 ,  4 ,  5 A and  5 B are deemed left side views of device  10 , from the perspective of someone standing on boat  12  and looking at device  10  on dock  14 , as is the case in  FIG. 1 .  FIGS. 6A and 6B  show right side cross sectional views of device  10  from the same perspective. 
         [0022]    Referring particularly to  FIG. 3 , an exploded view of device  10 , and  FIG. 4 , a cross sectional view from the left side of device  10 , housing  42  of device  10  includes removable left side  54  for providing access to the interior of housing  42  and held in place with screws  118 . To the left of housing  42  is adaptor plate  70  that fits just under flanges  72  of housing  42 . Flanges  72  may be approximately ¼ inch wide or a little wider. Dock board  74  is attached to adaptor plate  70  from below using bolts. Inside a recess  86  formed in dock board  74  is latch arm  40  with a latch  88 . A hole  90  is formed in dock board for running end  30  of line  26  to exit device  10  and which hole  90  is in registration with hole  44  in housing  42 . Hole  90  may be beveled to reduce wear on line  26  as line  26  is pulled from and retracts back into device  10 . 
         [0023]    Two other holes are formed in dock board  74 , namely, a first hole  98  in the proximal end of recess  86  of dock board  74  that allows latch  88  on the end of latch arm  40  to communicate with the housing  42 , and a second hole  102  on the distal end of recess  86  of dock board  74  that allows latch arm  40  to communicate with the interior of housing  42 . Distal end of latch arm  40  is pivotally attached to the distal end of recess  86  of dock board  74  with a pivot pin  104 . A small strike plate  106  is attached to the proximal end of recess  86  in dock board  74  with screws  64 . A sliding catch  108  moves rearward and clear of strike plate  106  with latch  88  when latch  88  is pivoted, thereby unfastening latch  88  and latch arm  40 , allowing it to be raised by pivoting it about pivot pin  104  to the unlatched, raised position. Similarly, latching arm  40  can be pivoted down until sliding catch  108  passes strike plate  106  and latch  88  can be pivoted closed, at which point, sliding catch  108  is slid forward to catch strike plate  106  and hold latch arm  40  secure to dock board  74 . The structure and operation of latch arm  40  will be described in more detail below. 
         [0024]    Inside housing  42  is a retraction reel  120  that retracts slack in line  26 . Reel  120  has a circular cover plate  122  over a spool  124  rotatably mounted to an axle  126 . An end of line  26  is secured to spool  124  and wound therearound. Running end  30  of line  26  passes around a post  128  close to the inside surface of proximal side  50  and below hole  44 . Running end  30  extends through hole  44  and hole  90  in dock board  74 . Loop  28  in running end  30  serves to prevent line  26  from being retracted by retraction reel  120  back into housing  42 . Alternatively, a knot in running end  30  or an object to which running end  30  of line  26  is tied can serve the same purpose as long as the width of the knot or object is greater than the diameter of hole  90  so that running end  30  cannot be retracted back into device  10 . Retraction is accomplished using a power coil spring  130  inside spool  124  that is loaded by the withdrawal of a length of line  26  and relieved when allowed to retract spring back onto spool  124 . 
         [0025]    Within housing  42  is a line locking system shown in  FIG. 3  at the bottom right to allow the user to hold line  26  so that it does not retract running end  30  all the way back to dock board  74  but allows a user to pre-selected a length of line  26  to remain drawn from device  10 . The line locking system includes principally a locking arm  140  pivotally carrying a toothed cam  142  on the end thereof, as best seen in  FIGS. 3 and 4 . Cam  142  has a surface treatment to increase friction between line  26  and cam  142  such as teeth as shown or knurling.  FIGS. 5A and 5B  show left side views with latch arm in the unlatched and latched positions, respectively;  FIGS. 6A and 6B  show right side views of latch arm in the unlatched and latched positions respectively. The operation of the line locking system components except for biasing springs are best seen in  FIGS. 5A and 5B ; the biasing springs are best seen in  FIGS. 6A and 6B . 
         [0026]    Referring now to  FIGS. 5A , and  5 B, locking arm  140  is pivotally mounted to housing  42  so that its proximal end carries toothed cam  142  and its distal end is positioned just below second holes  60  and  102  in housing  42  and in recess  86  of dock board  74 , respectively. An activation rod  144  is carried by distal end of locking arm  140  so that it extends through holes  60  and  102  where latching arm  40  can engage it and, as latching arm  40  is moved from the unlatched (raised) position to the latched (lowered) position, latching arm  40  presses activation rod  144  down into housing  42  whereby it in turn pivots distal end of locking arm  140  counter-clockwise about a pivot pin  138  when viewed from the left side of device  10 . The counter-clockwise pivoting of locking arm  140  pushes toothed cam  142  against line  26  to prevent further movement of line  26  as long as latch arm  40  is latched and activation rod  144  is pressed down. A stopper  150  carried by locking arm  140  limits the ability of toothed cam  142  to back away from line  26  even when latch arm  40  is in the unlatched position and line  26  is free to retract. 
         [0027]    To assure that line  26  is always positioned so that it can be held by toothed cam  142 , an arm mount  146  is affixed to the inside surface of proximal side  50 . Arm mount  146  has two opposing flanges  148  that define a channel therebetween which channel is positioned so that line  26  runs directly through it, between opposing flanges  148 , as line  26  passes around post  128  on its way to hole  44  in housing  42 . Toothed cam  142 , when moved by the pivoting of locking arm  140  to the latched (closes) position, rotates into the channel defined by arm mount  146  and against line  26 . 
         [0028]    Referring now to  FIGS. 6A and 6B , the effect of certain biasing springs will now be described. There are two biasing springs, a return biasing spring  160  and a cam spring  162 . Return biasing spring  160  urges locking arm  140  to rotate counter-clockwise when viewed from the right side of device  10  (clockwise when viewed from the left side) so that activation rod  144  is pushed up upon movement of latch arm  40  to the unlatched position. Conversely, closing latch arm  40  loads return biasing spring. Locking arm  140 , aided by stopper  150 , causes toothed cam  142  to pivot into the channel between opposing flanges  148  and against line  26  when latch arm  140  is closed while return biasing spring  160  pivots toothed cam  142  away from line  26  when latching arm  40  is moved to the unlatched position. 
         [0029]    Return biasing spring  160  is a coiled spring with a first end  166  and an opposing second end  168  with coil  170  fixed into position by post  172  and a clevis pin  174  to hold it onto post  172 . First end  166  engages a catch  176  carried on locking arm  140  and movable therewith, so that first end  166  moves with the movement of locking arm  140 . As locking arm  140  is rotated clockwise (right view) about a pivot pin  138  by the downward movement of activation rod  144 , return bias spring  160  is loaded against catch  178  on arm mount  146 . Counter-clockwise rotation of locking arm  140  relieves return bias spring  160 . 
         [0030]    Cam spring  162  has a first end  184  and an opposing second end  186  with a coil  188  there between mounted on a post  190  and held to post  190  by a clevis pin  192 . First end  184  of cam spring  162  is also operated against catch  176  and second end  186  is applied against post  194  so that cam spring is always urging toothed cam  142  out of the arm mount channel and away from line  26 . Locking arm  140  and return biasing spring  160  ultimately control when toothed cam  142  is in channel. Also, when latch arm  40  is in the latched position, tension on line  26  will act on toothed cam  142  to further engage cam  142  against line  26 , but when latch  40  is moved to the unlatched position, and locking arm  140  is moved away from line  26 , cam spring  162  pulls toothed cam  142  from line  26 . 
         [0031]    Those familiar with docks and boating will appreciate that many modifications and substitutions can be made to the foregoing preferred embodiments of the present invention without departing from the spirit and scope of the present invention, defined by the appended claims.

Summary:
A tethering device for a boat may be mounted to a dock so that the top surface of the tethering device is flush with the top of the dock. Inside the housing is a retraction reel storing a sufficient length of line to provide tethering of the boat to the dock while retracting excess line back for out-of-sight storage but leaving the pre-selected length of line extending from the tethering device. The housing also has a line locking mechanism to hold the line at the pre-selected length so as to prevent the boat from drifting away taking line with it.