Abstract:
An amphibious small boat, including rowing/fishing/motor/sailing boats, canoes and kayaks has a removable, retractable wheeled undercarriage enabling the craft to be trailered or managed singlehandedly on the ground; or the undercarriage retracted inboard. The canoe and kayak undercarriage is easily removed. Working loads are distributed to the fabric of the craft. The boat undercarriage can be manually lever-controlled and the lever anchors the undercarriage. A motorized actuator is also given. An elevated towing hitch is used with all embodiments, and includes a safety, breakaway link for highway needs. Signal/running lights are included with the small boat embodiments.

Description:
RELATED APPLICATION(S) 
     This application is a continuation of U.S. application Ser. No. 12/379,271 filed Feb. 18, 2009, now U.S. Pat. No. 8,091,501; and this application claims the benefit of Canadian Patent application number 2,653,882, filed Feb. 12, 2009, each of which is incorporated by reference in its entirety herein. 
    
    
     BACKGROUND 
     This invention is directed to small boats equipped with retractable undercarriages, suited for being towed behind a vehicle, and for use as watercraft. 
     Boats in a wide range of sizes are conventionally mounted upon a trailer, for land transportation. In addition to the costs of a trailer there are a number of drawbacks to this procedure. In the case of canoes and kayaks, these also may be carried in trailers, but are frequently mounted upon the roofs of vehicles. 
     In the case of small powerboats with inboard or outboard motors, fishing boats, sail boats and rowboats, these additional drawbacks include: the initial mounting of the boat to the trailer, which normally requires at least two people; securing the boat to the trailer; wading the trailer in order to disembark the boat; parking the vehicle/trailer combination during the use of the boat; and reversing these procedures at termination of use of the boat. The roof-mounting of canoes and kayaks frequently requires two persons, and necessitates securely lashing the craft to the vehicle. 
     Many attempts have been made in the past to provide retractable undercarriages, including retractable undercarriages for small boats. However, for a wide variety of reasons, none of these earlier attempts appear to have achieved commercial success, and a practical solution to this problem does not appear to be commercially available. 
     One difficulty that has to be overcome, particularly in the case of small boats having lightweight aluminum hulls, is the problem of attaching undercarriage components in such a fashion as to permit trailering of the boat without distorting or damaging the hull structure. In the case of canoes and kayaks, the nature of their structures, and their inherent flexibility make them unsuited to the addition of extraneous add-on structures. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an amphibious small watercraft having a hull, a towing hitch mounted at the bow of the craft, a wheeled undercarriage adjustably secured to the hull, having a first, retracted, position and a second, deployed, position; the undercarriage having a curved spring support arm with a wheel located at the end of the support arm, the arm being located in a concave-upward trailing mode when in its second, deployed position; and locking means securing the undercarriage in its second position, in use to enable vehicular towing and single-handed transfer of the watercraft. 
     The invention provides the small watercraft as set forth above, including reinforcement means connecting the undercarriage with the hull of the craft. 
     The small watercraft as set forth above, wherein the watercraft is selected from the group comprising rowing/motor/sailing boats, canoes and kayaks. 
     The subject small watercraft comprising a rowing/motor/sailing boat, wherein the undercarriage is a duplex undercarriage that includes two of the support arms, each having a wheel attached thereto; the locking means comprising a control lever having one end of the arm connected in torque transfer relation with the two support arms; the other end of the control lever being secured in immobilized, load transfer relation with the hull of the boat. 
     The subject small watercraft, being a canoe or a kayak, and having an undercarriage that consists of a single support arm and an attached wheel, the locking means including an anchor plate secured to the hull of the canoe, the plate having one end of the arm pivotally attached to it, for pivotal displacement from its first, retracted position to its second, deployed position; and abutments projecting from the plate to locate the arm in a selected one of its two positions. 
     The subject small watercraft, having a duplex undercarriage; wherein the torque arm is releasably secured to the boat hull, and is manually moveable from a second position securing the undercarriage in a deployed position, to a first position wherein the undercarriage is retracted from its second position to an inoperative position above the hull. 
     The subject small watercraft with duplex undercarriage has an option wherein the control lever is secured to the boat hull; in this option the undercarriage has a reduction gear secured by the control lever to the boat hull; wherein operation of the reduction gear in a first direction displaces the undercarriage from a second deployed position to a first retracted inoperative position above the hull, and reverse operation of the gear deploys the undercarriage. The reduction gear may be hand or motor operated. 
     The subject small watercraft, wherein the reduction gear is supportedly connected by a supplemental support arm to the hull of the boat, to maintain a housing portion of the reduction gear immobile during the trailering of the boat, and during the operation of the reduction gear. 
     The subject reduction gear, when hand-operated may include a locking pin to lock the gear operating handle, particularly when the undercarriage is deployed for trailering use, thereby locking the undercarriage in its deployed position. 
     Another embodiment may rely at least in part upon its reduction gear ratio being sufficiently high, in use to prevent overhauling of the gear under loads applied to the undercarriage during trailering of the boat. 
     The subject small boat&#39;s retractable duplex undercarriage has a pair of journal boxes mounted upon and located intermediate the ends of gunnel portions of its hull; and hull reinforcement members connecting the journal boxes to the hull in load transfer relation. 
     The subject small watercraft with duplex undercarriage has a towing hitch secured to the bow, with reinforcement means transferring loading forces to the hull. 
     For both the canoe and kayak, the undercarriage locking means includes a withdrawable abutment pin selectively attachable to the anchor plate, to immobilize the arm in abutting relation with a selected one of the abutments in a selected one of the two positions of the arm. 
     Also, for both the canoe and the kayak, a towing hitch located at the bow of the canoe/kayak, for attachment to a towing hitch of a vehicle, is of a polarized nature such that in use the combined vehicle/craft hitches restrict the towed watercraft from lateral toppling (tilting) displacement relative to the vehicle, permitting only relative vertical and left/right turning displacement. 
     For the canoes and kayaks, the hull reinforcement means consists of a unitary spine member extending from bow to stern of the craft, and following the lower profile of the hull. The towing hitch and the undercarriage are secured to the respective ends of the spine member, in load transfer relation with the hull. 
     In the case of the small boats, signal/running lights may be permanently attached, including a connection for attachment to the lighting system of the towing vehicle, while for canoes and kayaks a removable wiring harness and a lightweight frame for the signal/running lamps can be provided. 
     The subject boat undercarriage may have an intermediate axle of predetermined stiffness extending laterally across the boat securing the axle portions in mutually spaced, laterally aligned relation; the intermediate axle having a control lever projecting therefrom, in use to enable rotation of the intermediate axle, the projecting axle portions and the attached wheels from a second, secured condition wherein the wheels are deployed downwardly a predetermined distance, to extend below the boat hull; to a first, retracted condition whereat the attached wheels are in an elevated position sufficient to clear the surface of a supporting body of water on which the boat may float. The control lever may be adjustably secured to the intermediate axle, to enable it to be selectively repositioned transversely across the width of the boat. 
     The boat has a lever attachment fitting secured to the boat hull, for releasably immobilizing the lever when the wheels are in their second, deployed condition. 
     The boats also have hull reinforcement structure secured to the hull in supporting relation with the aforesaid lever attachment. 
     In a second aspect of the deployment/retraction provisions for the subject boat, the intermediate axle that extends laterally across the boat is connected at its centre to the gear wheel of a worm reduction gear. The gear box containing the worm/reduction gear is attached to the hull of the boat. An alternative arrangement has a pair of half axles located within the two halves of the intermediate axle, the half axles being driven by the gear wheel of the worm reduction gear; and having their outer ends attached in controlling relation with the journal box axle portions. In this alternative arrangement, the intermediate axle inner ends are secured to the side walls of the gear box. 
     The inner ends of the half axles are connected to a pinion wheel within a housing containing a helical worm drive. The hand-operated worm drive version has a cranked handle, the rotation of which serves to reposition the undercarriage from its deployed position to its retracted position, and vice versa. The intermediate axle and the worm drive gear box are preferably secured in a fixed position by a lever securing them to the hull of the boat, to provide the torsional force required, primarily to withstand the loads applied against the undercarriage when deployed. 
     In canoe and kayak embodiments the undercarriage has a single wheel, mounted at the rear of the craft, with hull bending reinforcement provided in the form of a central spine extending the length of the hull, along the craft centerline. The characteristic longitudinal flexibility of the canoe/kayak hulls is compensated for by the addition of this auxiliary, built-in spine extending along the bottom of the craft, to stiffen the craft longitudinally, while providing a rigid sub-structure, which enables an undercarriage with a wheel or wheels to be secured at the rear of the hull, and a towing hitch to be secured to the nose of the hull, without unduly stressing the fabric of the craft. 
     In all embodiments, the stability of the undercarriage is enhanced by the form of the wheel suspension arm, when deployed, as an upwardly concave flat section leaf spring, the transverse dimension of which provides tremendous stability to the axle of the supported wheel, so that wheel alignment remains true. 
     The boats, canoes and kayaks may also include undercarriage immobilization means secured to the craft, in use to secure the wheels/wheel in their elevated position. 
     For the boat embodiments this undercarriage immobilization means may comprise a toggle linkage adjustably and removably secured to the boat hull and having a movable head portion, the toggle linkage having a first, retracted condition, with the head in non-contacting relation with the undercarriage, and a second, actuated condition of the toggle linkage, with the head releasably locked in immobilizing contact with the undercarriage, when the wheels are in a fully retracted, elevated condition. For this embodiment, the toggle immobilization means may also include an outboard platform portion to receive a portion of the undercarriage in supported relation thereon. 
     For the canoe/kayak embodiments, the undercarriage arm with its attached wheel may be readily removed, for storage such as in the towing vehicle, or elsewhere. 
     For the canoe and kayak embodiments, the hitch connecting the craft to the towing vehicle is ‘polarized’, so as to permit the craft only pivotal up-and-down displacement. 
     In the preferred embodiment, this ‘polarized’ hitch is a simple pinned arrangement, having a horizontally oriented pin that inhibits lateral canting of the craft. 
     While the preferred mode of trailering a boat is bow-first, it will be understood that the reverse may apply, within the ambit of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Certain embodiments of the invention are illustrated, by way of example, without limitation of the invention thereto, other than as set forth in the accompanying claims; it being understood that further embodiments may be derived by one skilled in the art. Reference is made to the accompanying drawings, wherein: 
         FIG. 1  is a side view of a subject amphibious boat afloat, showing retracted and deployed positions of the undercarriage; 
         FIG. 2  is a three-quarter perspective view, at the stern end of a subject boat, with the undercarriage deployed; 
         FIG. 3  is a side view of a subject boat afloat, having the undercarriage partially retracted; 
         FIG. 4A  is a localized view, in perspective, showing the control lever locked for the undercarriage deployed condition; 
         FIG. 4B  is a view similar to  FIG. 4A  of a further embodiment having a hand-cranked worm gear undercarriage retraction mechanism; 
         FIG. 4C  is a section view of the worm-gear gear box, taken at C-C of  FIG. 4B ; 
         FIG. 4D  is a plan view of a motor-driven worm-gear box; 
         FIG. 5  is a side perspective view of a toggle link clamp for the retracted undercarriage; 
         FIG. 6  is a side view of a towing vehicle with a subject towing hitch, and the bow portion of a subject amphibious boat; 
         FIGS. 7 ,  8  and  9  are respectively side, plan and end views of a subject elevated towing hitch for the subject amphibious boats; 
         FIG. 10  is a side view of a subject canoe embodiment in accordance with the present invention secured by an elevated hitch to a towing vehicle, with the canoe undercarriage deployed; 
         FIG. 11  is a rear-end view of the canoe of  FIG. 10 ; 
         FIG. 12  is a mid-length cross section of the canoe hull showing its inbuilt auxiliary spine; 
         FIG. 13  is an enlarged side view of a portion of  FIG. 10 , showing details of the vehicle towing hitch and the canoe/kayak hitch attachment; 
         FIG. 14  is a side view of a subject kayak embodiment in accordance with the present invention secured by an elevated hitch to a towing vehicle, with the kayak undercarriage deployed; 
         FIG. 15  is a rear-end view of the kayak of  FIG. 14 ; 
         FIG. 16  is a mid-length cross section of the kayak hull, taken at A-A of  FIG. 14  showing its inbuilt auxiliary spine; 
         FIG. 17  is an enlarged view of the undercarriage portion of  FIG. 10 ; 
         FIG. 18  is similar to  FIG. 17 , including the undercarriage in its retracted position; and, 
         FIG. 19  is a rear-end view of the undercarriage portions of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 ,  2  and  3 , a small boat  12  of the type used for rowing, fishing or use with an outboard motor, has a hull  14  with gunnels  16  extending along the two sides of the hull  14 . At the bow  18  a towing hitch  20  is secured, mounted on plate  21  that forms part of a bow reinforcement structure ( FIG. 2 ). Attached at midships is a retractable undercarriage  22  having wheels  24  mounted upon wheel support arms in the form of spring steel trailing support arms  26  having an oblong cross-section, curved concave-upward. 
     It will be understood that the boat illustrated is of the sheet aluminum type. 
     In  FIG. 1  the undercarriage  22  is shown in its fully retracted position, with its deployed position illustrated in phantom.  FIG. 1  also shows the boat  12  with an outboard motor  28  attached to its transom  30 . 
     In the  FIG. 2  embodiment, traffic lights  32  are shown, mounted on the transom  30 . A wiring harness (not shown) extends the length of the boat to a plug-in connection  33  located at the bow (see  FIG. 6 ), for connection of the boat lights to the signal/lighting system of a towing vehicle. 
     The undercarriage  22  has an intermediate axle  34  located in the boat mid section and extending laterally at right angles to the boat&#39;s longitudinal axis (not shown). This intermediate axle  34  interconnects two axle portions  36  that are rotatably secured in journal boxes  38  that are transversely mounted upon the gunnels  16 . 
     A hull reinforcement includes web  40 , to which the journal boxes  38  are attached, and which reinforcement with web  40  distributes to the boat hull  14  a significant portion of the undercarriage loading forces acting on the journal boxes  38 . 
     The axle portions  36  extend outboard, beyond the boat hull  14 , and have the undercarriage arms  26  of spring steel secured thereto. 
     A stub axle  42  secured to the remote, distal end of each arm  26  projects outwardly (away from the boat), each stub axle  42  having a wheel  24  rotatably mounted thereon. 
     An undercarriage control lever  44  is attached to the intermediate axle  34 , the control lever  44  being illustrated as being located centrally upon the axle  34 . 
     Also shown are a pair of undercarriage immobilization toggle clamps  46 , mounted upon gunnels  16  and located forward of the journal boxes  38 . The clamps are adjustably/removably mounted to the gunnels. 
     On a hull strake  48  on each side of the boat  12  are located two strong points  50 , to which the hull reinforcement  39  that includes web  40 , is bolted (see  FIG. 4A ). Two additional strong points are positioned along the keel section, longitudinally coincident with the hull reinforcement  39 , of which web  40  forms a part. 
     In  FIGS. 1 and 3  a boat  12  is shown afloat,  FIG. 3  demonstrating undercarriage retraction when the boat  12  is afloat, where the occupant of the boat can readily unlock and raise the undercarriage control lever  44  to raise the undercarriage  22  from its deployed condition to its retracted, stowed position. 
     In use, the undercarriage may remain deployed during initial operations in water, to safeguard an outboard motor from bottoming damage in shallow water or rocky beach. 
     The toggle clamps  46 ,  46  are shown in their retracted condition. 
     In the fully retracted position of the undercarriage  22 , the end of the control lever  44  is positioned pointing downward and located closely adjacent to the bottom of the boat, to position the wheels  24  in their illustrated retracted condition. 
     In this position of the undercarriage  22 , one or both of the toggle clamps  46  may be actuated, to bring the moveable heads of clamps  46  outboard and down in releasable clamping relation with the undercarriage  22 . This precludes accidental deployment of the undercarriage  22  when the boat is underway. The end of control lever  44  may also be secured to the hull of the boat  12  for that purpose. 
     Referring to  FIG. 4A , this partial (scrap) view shows the control lever  44  in its rearward, clamped condition, securing the undercarriage  22  (not shown) in its fully deployed condition (see  FIG. 2 ), with the wheels deployed to make ground contact. The control lever  44  provides torque to counter those forces acting on the undercarriage  22  when it is supporting the weight of the boat and its contents, including impact forces acting on the undercarriage when the boat is being trailered. 
     When afloat in shallow water the partial support of the boat by the still-deployed undercarriage  22  can serve to keep the propeller of an outboard motor from grounding or fouling on small rocks etc. 
     The control lever  44  is anchored by way of an angle bracket  54 , secured to the rearward face  56  of a reinforcing cross tube  58  that forms part of the hull reinforcement structure  39 , of which web  40  and brace  41  also form a part. 
     As stated above, the hull reinforcement  39  is through-bolted in place to four strong points  50  on the hull, at the hull strakes  48  (see  FIG. 2 ) and two strong points, outboard along the keel, beneath brackets  54  and  54 A, and serves to safely distribute boat/boat load and trailering forces that may act upon the undercarriage  22 , when the undercarriage is deployed. 
     It will be noted that the reinforcement parts  40 ,  41  and  58  are perforated for weight saving and for drainage purposes, to minimize pooling in the bottom of the boat. 
     A tongue portion  60  of control lever  44  is entered beneath angle bracket  54 , and secured in place by control lever pin  62 . A slight transverse flexing of the lever  44  enables the tongue portion  60  to be inserted beneath the angle bracket  54 , for insertion of the pin  62  in interlocking, securing engagement therewith. 
     In the  FIG. 4B  embodiment the manual deployment and retraction of the undercarriage  22  is effected by a reduction gear  45 . The manual gear  45  ( FIG. 4C ) has a worm  47  and pinion wheel  49 , to which axle portions  36  are connected by half axles  51  located within the intermediate axle  34 . In this arrangement the two halves of the intermediate axle  34  are secured to the housing side walls of the reduction gear  45 . The half axles  51  are keyed to the pinion wheel  49 . 
     A crank  53  is used to manually drive the worm gear  47 , and has a locking pin  53 A to secure it in position, when the undercarriage is deployed or retracted. 
     In the  FIG. 4D  power-driven embodiment, a battery-driven electric motor  46 B is mounted upon the reduction gear  45 , being controlled by a three-position switch  46 A, illustrated as ‘D’ (DEPLOY), ‘O’ (OFF) and ‘R’ (RETRACT). A cylindrical rechargeable battery B is readily withdrawn and safely pocketable, to positively immobilize the gearbox  45  during trailering, so as to prevent accidental undercarriage retraction. 
     Alternatively, the intermediate axle  34  may itself be keyed to, and driven by the pinion wheel  49 ; the axle  34  being supported in bearings in the housing side walls of reduction gear  45 . 
     In the case of the reduction gear embodiments, the control lever  44  is used as a fixed torsion arm, to counter the turning moments (both clockwise and counterclockwise) that act upon the reduction gear, both in its displacement of the undercarriage  22 , and when the undercarriage  22  is deployed and supports the weight of the boat and its contents. 
     A supplemental support arm  55  is also illustrated, secured by bracket  54 A to the exterior keel strong points (not shown) to minimize the bending moments acting on the reduction gear  45  and its attached axle components, detailed above. 
     Turning to  FIG. 5 , a toggle clamp  46  is shown bolted down to a composite bracket assembly  64  which enables clamp  46  to be readily relocated along the gunnel, or removed. 
     The toggle clamp  46  is shown in its deactivated condition, having its elastomeric head portion  68  raised above and inboard of the gunnel  16 . 
     The component parts of bracket assembly  64  are bolted together in sandwiching relation with the gunnels  16 , and the assembly  64  includes an outboard platform portion  66 . 
     The platform portion  66  receives a distal end portion of the undercarriage  22 , namely the end of support arm  26 , and stub axle  42 , in supported relation thereon, when the undercarriage is fully retracted. 
     The bracket assembly  64  serves to distribute and harmlessly transfer to the hull of the boat the weight of the retracted undercarriage  22  and those forces acting upon the toggle clamp  46 . 
     At this juncture the inboard handle  67  of toggle clamp  46  is depressed, swinging the elastomeric head portion  68  outboard and down onto the undercarriage, immobilizing the undercarriage and holding it down onto the bracket platform portion  66 . 
     It will be understood that with the undercarriage fully retracted, and the control lever  44  in its forward position, immobilization may also be achieved by tying down or otherwise immobilizing control lever  44 . 
       FIG. 6  shows a bow portion of a rowing/fishing/sailing/outboard type boat  12 , the boat  12  being hitched to the back  70  of a towing vehicle, by way of an elevated vehicle hitch  72 , to which the towing hitch  20  (of boat) is secured. 
     The reinforcement plate  21  (see also  FIG. 2 ), connects the towing hitch  20  (of boat) to the boat bow, in load dispersive relation. 
     Turning also to  FIGS. 7 ,  8  and  9 , the elevated vehicle hitch  72  has a hollow base member  74  of square section that is sized for insertion as the male member within the towing tube of a heavy-duty vehicular towing hitch, being secured in entered, pinned relation to that hitch by way of hitch pin  75  ( FIG. 8 ). 
     The elevated vehicle hitch  72  has an inclined mast portion  76  of square section, welded to the base member  74 , and having a platform portion  78  surmounted by a hitch ball  80  bolted to platform  78 . The mast portion  76  has an inclined brace member  82  welded to it, the bottom end portion of brace member  82  being welded to the top surface of base member  74 . 
     A rearwardly extending plate  84  supports a windlass  86  ( FIGS. 6 and 7 ). A windlass cable  88  is secured by way of a spring-loaded catch to an eye  90 , attached to the bow of the boat  12 . The windlass  86  serves in handling the boat  12 , as in winding it up/down a slipway or loading ramp; and in its fully retracted condition the windlass  86  and cable  88  serve as an emergency tether, to meet highway safety requirements, when being trailered. 
     The high gearing ratio of the windlass  86  (and its somewhat low efficiency) prevents the cable  88  from overhauling the windlass, in the event of a towing breakaway of the boat from its hitch. 
     Turning to  FIGS. 10 to 13 , a canoe  94  is attached by a hitch  96  located on the bow of the canoe to an elevated vehicle hitch  72 A attached to a towing vehicle. The elevated vehicle hitch  72 A has an upstanding bifurcated hitch post  97  rotatably mounted upon bearings  99  that permit free total rotation of the hitch post  97 , while precluding any tilting of the post  97 , relative to the elevated vehicle hitch  72 A and its vehicle. 
     The canoe/kayak towing hitch  96  is welded to the spine  100 / 112  of the craft, the craft spine  100  being integrally moulded into the hull of the canoe (as is also the case for the kayak). 
     The towing hitch  96  (of canoe/kayak) with its vertical sides  96 A is a close sliding fit within the vertical slot of bifurcated hitch post  97 , to substantially preclude lateral tilting of the canoe  94  or kayak  111  in relation to the elevated vehicle hitch  72 A. 
     The towing hitch  96  is pinned to elevated vehicle hitch  72 A by a withdrawable, horizontal pin  101 , giving the towing hitch  96  limited freedom to pivot vertically, up and down, the horizontal pin  101  being secured by a cotter pin  103 . The vertical pivoting motion accommodates changes in elevation and climbing/descending attitude between the towing vehicle and the trailered canoe/kayak craft. 
     The flat, vertical sides  96 A of the towing hitch  96  and the vertical slot of the bifurcated hitch post  97  serve to ‘polarize’ the towing hitch (of boat) in a vertical plane, to permit changes in elevation between the towing vehicle and the canoe, while the rotatable, bifurcated hitch post  97  of elevated vehicle hitch  72 A ensures tracking of the canoe behind its towing vehicle, while the ‘polarization’ of the hitch prevents any lateral, capsize movement of the canoe  94  upon its hitch, thereby maintaining the plane of wheel  98  substantially parallel with the plane of the wheels of the towing vehicle. 
     The spine  100 ,  112  of aluminum tube, common to both canoe  94  and kayak  111 , is moulded in the fabric of the hull of the craft (see  FIG. 12 ), and extends from bow to stern of the respective craft  94 ,  111  being shown in phantom in  FIG. 10  and a bow portion in  FIG. 13 . It will be understood that alternative forms of craft stiffening may be adopted. 
     In  FIG. 11  a detachable stainless steel tether wire  102  connects the wheel  98  to the hull of the canoe  94 , in order to meet highway safety requirements. A similar provision is made in the case of the kayak  111 . 
       FIG. 14  shows a kayak  111  in accordance with the present invention, having a stiff ‘spine’  112  of aluminum tube moulded in the fabric of its hull (see  FIG. 16 ), which spine  112  extends from bow to stern of the kayak  111 , being shown in phantom in  FIG. 14 . 
     In the case of both kayak  111  and canoe  94 , the two spine ends both protrude upwardly above the fabric of the craft, and have elements of the hitch (at the bow) and the undercarriage (at the stern) attached to the respective protruding spine portions, so as to transfer the associated loadings in dispersed relation to the fabric of the craft. It will be understood that due to the substantial longitudinal symmetry of the respective craft “bow” and “stern” may be readily interchanged. 
     The provisions for mounting and locking in place the support arm  26 A and wheel  98  that comprise the kayak  111  undercarriage are substantially the same as for the canoe  94 , (see below re  FIGS. 17 ,  18  and  19 ), together with the stainless steel (safety) tether cable  102 , as detailed above. 
       FIG. 15  shows the kayak  111  having the wheel  98  and support arm  26 A in the deployed condition. 
       FIG. 16  shows the tubular aluminum spine  112  integrated into the fabric of the kayak  111 . 
     Turning to  FIGS. 17 ,  18  and  19  it will be noted that, while illustrating the undercarriage and mounts for a canoe  94 , the same principles apply for a kayak  111 , although dimensions and proportions may vary. 
     In  FIG. 17  the aft end a canoe  94  with an imbedded spine  100  has an undercarriage mounting plate  113  welded thereto (shown cross-hatched in  FIG. 19 , for clarity). 
     The curved (concavely upward when deployed) support arm  26 A is bolted by bolts  116  ( FIG. 17 ) to a base plate  118  that is secured to the mounting plate  113 . 
     A pivot eye-bolt  120  secures the base plate  118  to the mounting plate  113 , in pivotal relation therewith. Use of an eye-bolt  120  greatly facilitates removal of the support arm/wheel  26 A/ 98  assembly. 
     A removable sheer pin  122  ( FIG. 19 ) secures the base plate  118  and attached support arm  26 A in the illustrated deployed position ( FIG. 17 ) or in its upward, retracted position (with support arm  26 A shown ‘solid’) in  FIG. 18 . 
     By removing the sheer pin  122  and the pivot eye-bolt  120 , the wheel  98 , the support arm  26 A, along with base plate  118  can all be readily and rapidly removed from the craft, for storage elsewhere, such as in the towing vehicle. 
     It should be noted that there are a number of unobvious advantages to providing an amphibious watercraft with a trailing undercarriage having upwardly concave curved wheel attachment arms of predetermined flexibility. When under tow, the occurrence of a major impact with a road obstacle or pothole can only result in flexure of the boat suspension, with little tendency for the undercarriage curved arm to act as a rigid strut that could transmit serious impact damage to the hull of the craft, at the undercarriage attachment point/points. 
     When backing-up a craft behind a vehicle, the upwardly concave curved flexible arm is capable of flexure, if the wheel encounters a serious obstacle, and is much less likely to cause damage to the craft than would a straight trailing link arrangement that could act as a rigid strut, with disastrous consequences for the craft. 
     Also, in the case of a boat attached to a towing hitch of a parked vehicle and inundated by rainwater under storm conditions, filling of the boat at a rate greater than the stern drain can handle can result in the undercarriage ‘kneeling’ to the point where the stern becomes supported on the ground, and the transference of loading to the boat hull from the undercarriage becomes stable, as the hull per se assumes much of the dead-load of the boat and its contents, while the undercarriage serves to relieve some of the deadload from off the hitch. 
     The resilience of the undercarriage suspension, in the case of the fishing boat embodiment, includes the flexibility of the trailing support arms  26 , together with the torsional flexure of the intermediate axle, and the bending flexibility of the control lever, all of which flexibilities contribute to the total flexure energy capacity of the undercarriage and its securement system, and the durability of the total system. 
     In the case of the canoe and kayak embodiments, the use of a plate spring trailing arm suspension affords resilience and great lateral stability, while the incorporation of an inbuilt spine, that enables the craft to be trailered with fore and aft suspensions, has virtually no effect on the dynamics of handling in the water, and the curved trailing spring arm and ‘polarized’ hitch ensures secure trailing characteristics, while the low mass of the undercarriage has little effect on normal handling of the craft on the water. 
     It should also be noted that the subject amphibious boat, canoe and kayak embodiments are suited for operation by a single individual, and do not require undue strength in order to make full use of all their functions.