Abstract:
An adjustable swivel base assembly and track for swivel mounting fishing boat downrigger or planar board masts, including a planar mounting base plate, a pair of stationary riser supports on the base plate, and a planar bottom bearing plate stationarily supported on the upper ends of the supports. Vertically spaced planar bottom and top bearings are stationarily affixed to the bearing plate and a planar swivel top plate is supported on and sandwiched slidably between the bearings, and is adapted to carry and swivel the mast load. An indexable locking system selectively locks the swivel plate in any one of a plurality of angularly spaced positions. A track is mounted on a fishing boat and has side edge flanges with mutually facing in-turned lips that overlap opposite side edges of the base plate when slidably and releasably mounted in the track.

Description:
This is a United States regular utility patent application filed pursuant to 35 U.S.C. §111(a) and claiming the benefit of the priority application under 35 U.S.C. §119(e)(1) of U.S. provisional application Ser. No. 60/445,978 filed Feb. 7, 2003. 

   FIELD OF THE INVENTION 
   This invention relates primarily to fishing equipment designed for trolling from a moving boat, primarily for use in deep water sport and commercial fishing, and more particularly to devices for holding down rigger masts and planer board masts used for fishing that allows these masts to be swiveled in a full circle and locked at selected angularly spaced increments. 
   BACKGROUND OF THE INVENTION 
   Fishing is one of the oldest vocations and avocations. In the last fifty years or so the equipment and fishing techniques have evolved into increasingly sophisticated products and strategies for catching fish. Bait fish seek water at a certain temperature and water depth. The big fish follow them to feed on them. Numerous electronic devices have been provided to detect water temperature variations at different depths, to locate schools of fish at different locations and to provide a read-out of underwater topography where fish congregate. Modern trolling motors allow both large and small fishing and commercial boats to move at slow and controlled trolling speeds through the water. 
   It is preferred to equip trolling boats with the ability to fish with more than one fishing rod at a time in order to multiply the number of possibilities for catching fish simultaneously or in close sequence to thereby increase the chances of catching fish. Fishing boats are often equipped with mounting tracks along their port and starboard gunnels and across the transom top board to thereby enable fishermen to use more than one fishing rod, because many rod holders will fit into the track. Usually the track is mounted to the boat permanently. 
   Down riggers add another dimension to trolling fishing by allowing fishermen to fish at a controlled depth. Being able to fish with more than one down rigger at a time is another strategy that increases the chances of catching fish. Down riggers have a long boom with a heavy-duty aircraft cable line to which a heavy sinker is attached. The heavy-duty line and sinker are necessary to keep the fishing line at a controlled or constant depth at trolling speeds. To maximize the performance of down rigger, they need to be mounted on a swivel mechanism that is easy to swivel and easy to lock and unlock. With multiple down riggers deployed it is necessary to be able to adjust the down rigger masts by swiveling them so that their lines will not interfere with each other. In addition, as the boat navigates a turn in its course, being able to swivel down riggers helps keeps the fishing lines from fouling the propellers. Other and different fishing techniques, such as planer board fishing, are also enhanced by mounting the associated rods on swivel bases. 
   Although hitherto a variety of different types of swivel bases for mounting down rigger masts and planer board masts have been provided in an attempt to accommodate most, if not all, of the aforementioned usage parameters, there remains much room for improvement in such devices. For example, there is a need to improve the ease of which the swivel base can be locked and unlocked to permit the desired swivel action. There is also a need for improvement in the locking system provided in the adjustable swivel base from the standpoint of strength, elimination of play or “slop” in the various locked positions of the device, reduction in manufacturing costs, and ability to smoothly operate under heavy applied loads that are exerted by the cantilever action of the down rigger and planer board masts on the mounting base. 
   With all these needs, there still remains an overall need that such particular needs be met with an improved adjustable swivel base mechanism able to take the extreme loads of big fish and heavy sinkers on the fishing lines even when trolling at relatively fast deep sea sport and commercial fishing speeds. 
   OBJECTS OF THE INVENTION 
   Accordingly, among one or more objects of the present invention are to provide an improved adjustable swivel base for holding down rigger masts and planer board masts that satisfies all of the foregoing needs with a strong, corrosion-resistant structure that is economical to manufacture and assemble, that is readily adjustable to provide a variety of selected angularly spaced positions of operable and stored repose of the down rigger mast or planer board mast mounted on the base, that is securely but releasably lockable in any one of the angular locking positions of the swivel base and that is designed to compensate for wear of the locking mechanism parts and to eliminate play in locked positions, that is readily adapatable to being track mounted and locked in selected positions along the track, that enables the base to be removed, after use, along with the down rigger or planer board mast attached to it, and then stored on the boat in a secure location out of the weather, and which is simple in construction, compact, easy to mount and easy to operate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing, as well as further objects, and also features and advantages of the present invention, will become apparent from the following detailed description of the best mode presently known to the inventors of making and using the invention, as well as from the accompanying drawings (which are drawn to engineering scale unless otherwise indicated), wherein: 
       FIG. 1  is a perspective view (looking down from above and from the front) of a presently preferred but exemplary embodiment of an improved adjustable swivel base assembly of the present invention mounted on a track (shown in phantom) and adapted for mounting thereon on a conventional down rigger mast or planer board mast (not shown). 
       FIG. 2  is a perspective view of the adjustable swivel base assembly of  FIG. 1  (looking up from below and from the front), i.e., as viewed generally looking in the direction and location of the arrow  2  of  FIG. 1 , the swivel base assembly being shown by itself separate from the track of  FIG. 1 . 
       FIG. 3  is an exploded perspective view of the adjustable swivel base assembly of  FIGS. 1 and 2  to better illustrate the construction and assembly of its component parts as used in the preferred form of  FIGS. 1 and 2 . 
       FIG. 4  is a top plan view of the swivel base assembly of  FIGS. 1–3  with the base assembly top plate rotated out of parallelism with the base track-mounting plate and with a portion of the top plate broken away to illustrate interior details. 
       FIG. 5  is a fragmentary cross sectional view taken on the line  5 — 5  of  FIG. 4  and enlarged thereover. 
       FIG. 6  is bottom plan view of the top plate of the swivel base assembly shown by itself. 
       FIG. 7  is a fragmentary cross sectional view taken on the line  7 — 7  of  FIG. 1  and enlarged thereover. 
       FIG. 8  is a top plan view of the bottom bearing of the base swivel mechanism shown by itself. 
       FIG. 9  is a side elevation view of the bottom bearing of  FIG. 8 . 
       FIG. 10  is a bottom plan view of the top bearing of the base swivel mechanism shown by itself. 
       FIG. 11  is a side elevation view of the top bearing of  FIG. 10 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring in more detail to the accompanying drawings,  FIG. 1  illustrates a presently preferred but exemplary embodiment of an improved adjustable swivel base assembly  20  of the invention as releasably and adjustably mounted to a mounting track  22 . Track  22  may be of conventional construction and in turn is mounted by suitable fasteners (not shown) to a gunnel, transom rail or other suitable mounting area of an associated fishing boat (not shown). 
   Track  22  has a pair of opposed upright side flanges, only one of the flanges  24  being shown, each having an in-turned lip  26  overlying the bed or upper surface of track  22 . Base assembly  20  has a rectangular mounting base plate  30  having width and height dimensions such that the base plate sits closely but slidably between the side flanges of track  22  and underlies the overlapping flange lips  26  on each side of the track to thereby capture the base plate against liftoff from the track. To lock the base plate  30  on the track the base plate is provided with a plurality (preferably three) of thumb screws  32 . The threaded shank  34  of each thumb screw is threadably engaged in an associated one of three threaded through-holes  36 ,  38  and  40  ( FIG. 2 ) provided in plate  30  and oriented as shown in  FIG. 2 . Screwing down these thumb screws  32  lifts base plate  30  against the underside of flange lips  26  and develops a strong frictional clamping force for holding the base assembly  20  from movement along the length of track  22 . 
   A pair of obround risers  42  and  44  are symmetrically mounted to plate  30  with an angled orientation relative to one another as shown in  FIGS. 1 ,  2 ,  3  and  4 , such that their flat facing side surfaces  46  and  48  define an included angle therebetween of about 40°. Each riser  42 ,  44  is preferably made as an aluminum extrusion having a cross sectional contour that is seen in  FIGS. 3 and 4 , namely an “obround” contour such that riser  42  has parallel flat side walls  46  and  50  merging with semicircular end walls  52  and  54 . Likewise, riser  44  has parallel flat sidewalls  48  and  56  merging with semicircular end walls  58  and  60 . 
   The interior surface of each of the curved riser end walls  52 ,  54 ,  58  and  60  has an individually associated integral, longitudinally extending screw boss  62 ,  64 ,  66  and  68  respectively. Each screw boss defines an interior channel with a circular wall surface encompassing about 270° and having a diameter for slidably receiving therethrough an associated mounting screw. Two of such mounting screws  70  and  72  are shown fragmentarily in  FIG. 3  inserted respectively in associated screw bosses  66  and  68  of riser  44 . Identical mounting screws  74  and  76  ( FIG. 2 ) extend respectively through the screw bosses  62  and  64  of riser  42 . Plate  30  is provided with suitable through-holes that are beveled on the underside to individually receive the flat heads of the mounting screws  70 – 74  ( FIG. 2 ). The threaded upper ends of mounting screws  70 – 74  individually threadably engage threaded through-holes  80 ,  82 ,  84  and  86  respectively provided in a bottom bearing plate  90  of base assembly  20  ( FIG. 3 ). Plate  90  is thus fixedly and securely screw-mounted on and supported by risers  42  and  44  which in turn are securely screw-affixed to and supported by mounting base plate  30 . 
   Base assembly  20  further includes a rotatable top plate  100  journaled for rotation on and between a bottom bearing  102  and a top bearing  104  that are stationarily affixed to bottom bearing plate  90  by a top bearing cover plate  106  carrying four threaded studs  108 ,  110 ,  112  and  114  ( FIGS. 3 ,  4  and  7 ). These studs  108 – 114  extend through mating holes  115 ,  117 ,  119  and  121  in top bearing  104  ( FIGS. 10 and 11 ), through registering holes  116 ,  118 ,  120  and  122  in bottom bearing  102  ( FIGS. 8 and 9 ), and thence through registering holes  124 ,  126 ,  128  and  130  in bottom bearing plate  90  ( FIG. 3 ). As shown in  FIG. 2 , the lower ends of studs  108 – 114  project from the underside of plate  90  and receive thereon locking hex nuts  132 ,  134 ,  136  and  138  respectively. 
   As best seen in  FIGS. 3 ,  6  and  7 , top plate  100  has a central through-hole defined by a bearing bore  150  extending upwardly from the plane of under face  152  of plate  100  to a junction at annular shoulder  154  with a bearing counterbore  156  in turn opening to the top face  158  of plate  100 . Bottom bearing  102  has a raised circular central bearing boss  160  (see also  FIGS. 8 and 9 ) received with a close clearance sliding fit in bearing bore  150 . The bottom face  152  of plate  100  rides slidably on the upper surface  162  of bottom bearing  102  that encircles boss  160 . As best seen in  FIG. 7 , the top bearing  104  also has a bearing boss portion  164  that fits slidably within plate bearing bore  150 , and has a radially extending marginal flange portion  166  that rides slidably on plate shoulder  154 . Plate  100  is thus clamped by top bearing  104  and bottom bearing  102 , both of which are in turn held fixed by studs  110 – 114  to bottom bearing plate  90 . 
   It will be seen that bearings  102  and  104 , in accordance with one of the features of the invention, thus provide a special heavy duty bearing system featuring large swivel-bearings for both the top and bottom of plate  100  to enable 360° rotatable mounting of plate  100  on base assembly  20  while heavily loaded. This is important because the loads of the down rigger mast to be mounted on plate  100  often are extreme cantilever loads as well as thrust and axial gravitational loads. With this type of loading, there is a need for the large bearing surfaces of both top and bottom bearings  104  and  102  in order to obtain a smooth, low force swivel action. It will be seen from  FIGS. 6–11  that the bearing system of the present invention is well designed to withstand such heavy cantilever loads that apply force to the top, bottom and sides of the bearings. Note that both the top and bottom bearings  104  and  102  are flanged to take such loads. The materials employed in bearings  102  and  104  may be Delrin®, nylon or preferably ultra-high molecular weight (UHMW) polyethylene. Note that these plastic bearing plates  102  and  104  are backed up with metal plates top and bottom, i.e., top bearing cover plate  106  and bottom bearing plate  90 . The four fasteners  108 ,  110 ,  112  and  114  that bolt through the bearing assembly are tensioned to a predetermined torque to minimize play or a loose fit between the moving swivel parts and yet still allow plate  100  to swivel freely relative to the remaining base components. 
   It will also be noted that top plate  100  is provided with a predetermined “universal” pattern of threaded through-holes  170 – 190  on the right hand side of plate  100  (as viewed in  FIG. 6 ), as well as a mirror image symmetrical array of similar mounting holes on the left hand side of plate  100  (as viewed in  FIG. 6 ). These threaded holes are pre-determined by design to match up with the mounting bolt pattern of the most popular models of down rigger mounting platforms that are to be removably attached to plate  100  by mounting threaded fastener, thumb screw or the like. 
   In order to maximize operational performance of down riggers they need to be mounted on a swivel mechanism that is easy to swivel while being capable of taking the heavy cantilever loads. It will be seen that base assembly  20  achieves this result. It is also necessary, in order to maximize the performance of down riggers, that the swivel base be easy to lock and unlock with a positive, reliable, strong and rugged locking system. Swivel base  20  of the invention also provides this feature, thereby enhancing the performance of down riggers and other trolling equipment via swivel mounting and locking at selected spaced angular increments about a 360° swivel traverse. 
   Thus, in accordance with this locking system feature of the present invention the adjustable swivel base assembly  20  is provided with an improved gear-like lock system. As best seen in  FIG. 6 , and in assembly (in phantom) in  FIG. 4 , this locking system includes a “negative” gear-like profile either molded or machined into the underface  152  of top plate  100 . This gear profile includes an annular cavity defined by a top wall  200  and bounded on its inner diameter by a cylindrical wall  202  concentric with and of larger diameter than bore wall  160 . Wall  200  is bounded on its outer periphery by equally angularly spaced tooth peak surfaces  204  that define an interrupted cylindrical surface of larger diameter than, and concentric with, wall surface  202 . A plurality of equally angularly spaced teeth root cavities  206  extend generally radially outwardly from wall  200 , one cavity between each pair of tooth peaks  204 . Each tooth peak  204  terminates circumferentially at relatively sharp or small radius corners  208  and  210 . 
   The locking system also includes a cylindrical locking pin  220  mounted on one end of a locking lever  222  that is pivotally mounted to bottom bearing plate  90  flush against its underface  224  ( FIG. 5 ). Pin  220  extends upwardly through a specially formed arcuate slot  226  in bottom bearing plate  90  and further upwardly through a registering arcuate slot  228  formed in bottom bearing  102  ( FIGS. 3 ,  4  and  8 ). The upper end of pin  220  enters the aforementioned annular cavity defined by cylindrical wall  202 , top wall  200 , the teeth apexes  204  and negative tooth root spaces  206 . 
   Lever  222  is pivotally attached to bottom bearing plate  90  by a threaded stud  230  ( FIGS. 2 ,  3 ,  4  and  5 ) press fitted at its upper end in plate  90  and protruding downwardly therefrom past the lower surface  232  of lever  222 . An internally threaded bearing sleeve  234 , having a hex nut  236  integrally formed at its lower end, is threadably received on stud  230  to thereby both attach lever  222  to plate  90  as well as to form the pivot bearing surface for pivotal swinging motion of lever  222  about the pivot axis of pin  230  (as indicated by arrow P in  FIGS. 1 ,  2  and  4 ). The opposite end of lever  222  remote from locking pin  220  is provided with a downwardly extending handle  240 . Preferably this handle comprises a threaded stud  242  press fit at its upper end into an opening at the handle end of lever  222  and receiving a plastic sleeve  244  thereon that is free to rotate thereon and held on the stud by a lock nut  246  threaded onto the lower end of stud  242 . Lever  222  is spring biased toward a locking position, preferably by a tension coil spring  250  having one end tang  252  hooked into a hole  254  drilled into sidewall  48  of riser  44 , and having its other end tang  256  hooked around the shank  258  of a rivet  260  that extends through lever  222 . Thus, as indicated in  FIG. 4 , lever  22  is normally spring biased to pivot in a direction to drive locking pin  220  toward the root or bottom of whichever negative tooth recess  206  it is selectively registered. 
   In operation, in order to release top plate  100  for swivel motion of the same, along with whatever down rigger or planer board mast load is mounted thereon, the operator merely manually grips handle  240  and pulls it outwardly away from the base assembly  20 . This pivotally rotates lever  222  in a clockwise direction as viewed in  FIGS. 1 ,  2  and  4 , thereby forcing locking pin  220  to travel radially inwardly of the plate gear profile and in a slightly arcuate path that is accommodated by the arcuate guide and pin-bracing slot  226  in plate  90  and slot  228  in bearing  102 . When lever  222  is pulled outwardly to the full limit of its pivotal travel clockwise, pin  220  will be registering with the annular space between cylindrical wall  202  and the teeth apexes  204 , i.e., out of registry with the negative locking teeth in plate  100  (solid line position of pin  220  in  FIG. 6 ). When locking handle is pulled to this full release position, top plate  100  is free to swivel about the axis of the bearings  102  and  104 . 
   Once unlocking force is removed from lever  222  by releasing handle  240  and initial swivel motion is imparted to plate  100 , spring  250  will bias lever  222  counterclockwise as viewed in  FIG. 4 , thereby forcing locking pin  220  against whichever tooth apex  204  it may be registered. Further swivel motion of plate  100  will register pin  220  with the next adjacent tooth cavity  206  and spring bias on lever  222  will snap force pin  220  into such cavity. It will be seen that in the preferred embodiment there are twelve tooth cavities  206 , thereby providing locking positions at 30° angular increments for a full 360° swivel traverse of plate  100 . It is to be noted that the corners  208  and  210  at the circumferentially opposite ends of each tooth apex  204  are relatively sharp and have a small radius dimension. This geometry has been found to produce a snap action drop in of locking pin  220  as spring  250  pulls lever  222  counterclockwise as viewed in  FIG. 4 . This positive snap action seating of locking pin  220  is considered a desirable safety feature in the mode of operation of base assembly  20 . 
   In accordance with another feature of the present invention, the negative tooth recesses  206  are generated on a longitudinal center line that is curved with the same radius as the arcuate path of travel of locking pin  220 . This is perhaps best seen in  FIGS. 4 and 6 . The range of travel of locking pin  220  is indicated in  FIG. 6  where the fully unlocked position of pin  220  is shown in solid lines and the fully locked position of pin  220  is shown in broken lines. This curvature of each tooth recess  206  allows a quick drop in action of pin  220  upon being initially registered with a tooth recess under the biasing force of spring  250 , and with lever  222  released. It is also to be noted that the sidewalls  207  and  209  ( FIG. 6 ) of each tooth recess  206  are tapered so as to converge slightly radially outwardly toward the associated tooth root surface  211 . Sidewalls  207  and  209  reach a transverse dimension less than the diameter of locking pin  220  at a point in the travel path of pin  220  such that the locking pin cannot touch the bottom of root surface  211  of tooth recess  206 . Hence, the locking pin  220  seats, in locked position, against the sidewalls  207  and  209  of the associated tooth recess  206  without bottoming in the same. 
   Because pin  220  so engages the sidewalls of the associated gear recess  206 , there is little play when in swivel lock up because pin  220  tends to lock up when gripped by the tapered sidewalls as it reaches the center of the profile of the gear recess. Also, because the pin does not bottom out in the associated gear profile recess  206 , if the sidewalls  207  and  209  wear with use, pin  220  will just seat a little deeper in the gear profile, thereby providing compensation for wear in the system. In addition, because the curved walls  207  and  209  follow the arcuate path of travel of locking pin  220  in its operative range of lock-unlock motion (see  FIGS. 4 and 6 ), top plate  100  can be unlocked readily by pulling outwardly on handle  240  without having to exert force on the swivel top plate, and/or down rigger mounted thereon, in order to engage and disengage the locking pin from the gear profile recess  206 . 
   As indicated previously, the small radius corners  208 ,  210  of each gear apex  204  cause locking pin  220  to accelerate more rapidly when registering and going into a gear profile pocket or recess  206 . This in turn gives a desirable snap action mode of operation. 
   As another safety feature, the lever operating handle  240  extends downwardly from lever  222 , thereby eliminating a potential pinch point for the operator relative to plate  90 . Also, the unlocking mode is a pull-out action on handle  240  relative to the base assembly. This is a further safety feature that keeps the swivel base  20  from being inadvertently unlocked, as what might happen if the operator were required to push in the handle in order to unlock the swivel plate  100 . 
   The mounting of the two obround extrusions  42  and  44  at the aforementioned 40° included angle relative to one another angle provides structural rigidity and is compact enough to enable base  20  fit into a six inch track. The obround extrusions  42  and  44  have the built in screw bosses  62 ,  64 ,  66  and  68  integrally formed during the extrusion of the part as a cost saving. By making the risers  42  and  44  as extrusions, they can be cut to different lengths and thereby allow different heights of risers to be easily used in the production of different height models of adjustable swivel base assemblies  20 . Note that the bottom plate  90  is made slightly oval, as seen in  FIG. 4 , to make the adjustable swivel base  20  better fit into a six inch wide track  22 . 
   It will also be evident from the foregoing description and drawings that the adjustable swivel base assembly  20  of the invention is constructed with rugged dimensional relationships, and when constructed to the scale of the drawings provides a swivel locking mechanism that is strong enough to take the heavy loads of big fish and heavy sinkers tugging on fishing lines, as well as the loads of planer boards and other large cantilever mast loads. 
   The anti-wear feature provided by designing locking pin  220  to lock in the center of the selected tooth space  206 , such that the locking pin cannot engage the bottom or root face  211  between the tooth recess sidewalls  207  and  209 , insures minimum swivel rotational movement or “play” of the swivel base assembly when in locked condition. Wear compensation is also thereby achieved, because locking pin  220  will lock up in a non-bottoming range of tooth sidewall engagement positions even if the sidewalls of the gear teeth and/or pin surface erode from wear over a prolonged usage period. 
   From the foregoing description it also will now be evident that the novel principles of construction and operational mode of the invention can be advantageously employed in other mechanisms, besides as an adjustable swivel base for a down rigger mast or a planer board mast, that advantageously require rotational locking and unlocking action about a vertical axis or other axis about which swivel motion is desired, such as in various seating applications such as seat swivels, platform swivels and the like. Accordingly, the invention is not intended to be limited to the particular embodiments disclosed and is intended to cover equivalent structures and mechanisms that may be beyond the literal scope of the present preferred embodiments as illustrated and disclosed herein; but yet within the spirit and intent of the present invention, as limited only by the lawfully applicable prior art.