CROSS-REFERENCE TO RELATED APPLICATION This application is a non-provisional of U.S. patent application Ser. No. 63/073,698, filed Sep. 2, 2020, which is incorporated herein by reference.
BACKGROUND Floating watercraft ports provide easy drive-on docking and out-of-water storage of watercraft, including personal watercraft and boats of various hull-types. Such floating watercraft ports typically include a recessed cradle formed in an upper surface of the port, and a number of rollers to receive and guide a hull of the watercraft along the cradle during entry onto and exit from the floating port. As owners purchase different watercraft, and watercraft hull designs change over time, it is advantageous for floating drive-on ports to be able to accommodate various hull sizes and shapes.
SUMMARY One example provides a wheel for conveying a watercraft on a floating drive-on watercraft port. The wheel includes a rim including a center hub having a tapered bore configured to receive an axle, the bore tapered such that a center diameter at a center circumference of the bore is less than an end diameter at bore openings at opposing ends of the bore. A tire is disposed about an outer circumference of the rim for engaging a hull of a watercraft.
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.
FIG. 1 is a perspective view of a floating watercraft port including rollers, according to one example of the present disclosure.
FIG. 2 is a top view of a floating watercraft port including rollers, according to one example of the present disclosure.
FIG. 3 is a perspective view illustrating a base portion of a floating watercraft port including rollers, according to one example of the present disclosure.
FIG. 4 is a perspective view illustrating an entrance portion of a floating watercraft port including rollers, according to one example of the present disclosure.
FIG. 5 is a perspective view of a floating watercraft port including rollers, according to one example of the present disclosure.
FIG. 6 is a perspective view of a wobble roller, according to one example.
FIG. 7 is a side view of a wobble roller, according to one example.
FIG. 8 is a perspective view of a wobble roller rim, according to one example.
FIG. 9 is a perspective view of a wobble roller assembly, according to one example.
FIG. 10 is a perspective cross-sectional view of a wobble roller assembly, according to one example.
FIG. 11 is a cross-sectional view of a wobble roller hub, according to one example.
FIG. 12 is a cross-sectional view of a wobble roller assembly, according to one example.
FIG. 13 is a cross-sectional view of a wobble roller assembly, according to one example.
FIG. 14 is a cross sectional view of an alternative implementation comprising a bushing that fits inside the hub that allows transverse articulation perpendicular to changing hull pitch. The bushing can be manufactured in a way that a lubricant can be added to the molded bushing that would otherwise interfere with adhesion from wheel hub to over-mold substrate.
FIG. 15 is a cross sectional view of an alternative implementation comprising a gradual curved pitch to transfer weight load evenly at any angle.
FIG. 16 is a cross sectional view of an alternative example of the overmold in which suspension holes have a gradual wall thickness change the employs greater force to compress in “0” degrees and gradually reduces force required to compress suspension holes towards the outer edge of the wheel.
FIG. 17 is a cross sectional view of an alternative example of the over-mold in which suspension holes have a one sided taper suspension hole to gain less suspension travel on one side vs. other. In this embodiment user can change wheel orientation around to accommodate a tailored compression assembly.
FIG. 18 is a cross sectional view of an alternative example of the over-mold in which suspension holes have a symmetrical suspension hole that reduces weight needed to compress on both sides equally.
FIG. 19 is a cross sectional view of an alternative example of the over-mold in which a symmetrical tapered suspension hole allows for greater force requirement in the middle and gradually needs less force toward outside edges to compress suspension holes.
FIGS. 20 and 21 are cross sectional views of an alternative embodiment of a hub bushing that snap fits inside the hub and allows for articulation of the wobble wheel while still allowing up to 10 degrees of articulation. Said embodiment also allows bushing polymer to hinge radially while spinning. Embodiment can employ a low friction additive for lower desired coefficient of friction. This is accomplished by eliminating the lubricant from interrupting the chemical bond of compatible hub and substrate materials. Such bushing materials that could be used to accomplish this would be a engineered polymer such as Hytrel(PET), PEEK or Acetal(POM) all which are compatible with an internal molded lubricant. This embodiment also allows axle pin to stay concentric and supported with bushing during articulated rotation. This embodiment also will maintain a home position of 0 degrees until articulation force is applied and will return to home position after wheel weight is eliminated.
FIG. 22 is a perspective view illustrating a bowtie roller, according to one example.
FIG. 23 is a side view illustrating a bowtie roller, according to one example.
FIGS. 24A and 24B are perspective views illustrating a rim of a shoulder roller, according to one example.
FIGS. 25A and 25B are perspective views illustrating a tire of a shoulder roller, according to one example.
FIG. 26A is a perspective view illustrating a rim of a center roller, according to one example.
FIG. 26B is a perspective view illustrating a tire of a center roller, according to one example.
FIG. 27 is a cross-sectional view generally illustrating portions of a bowtie roller, according to one example.
DETAILED DESCRIPTION In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise.
FIGS. 1 and 2 are perspective and top views, respectively, illustrating an example of a floating drive-on watercraft port 10 including rollers to assist in guiding a watercraft on/off and along watercraft port 10, in accordance with the present disclosure, such as wobble wheels 60 and bowtie rollers 70. The example watercraft port 10 includes a base section 12, and an entrance, or tail, section 14, which are hinged together so that base section 12 and tail section 14 can pivot or articulate relative to one another about an axis 16 to assist on/off-loading of a watercraft to/from port 10. In examples, base section 12 and tail section 14 comprise rotationally molded shells of high-density polyethylene filled with a marine-grade expanded polystyrene (EPS) foam.
FIGS. 3 and 4 respectively illustrate perspective views of base section 12 and tail section 14 when separated from one another. With reference to FIG. 4, base section 12 includes a pair of hinge knuckles 15a and 15b defining apertures 15c. Hinge knuckles 15a and 15b insert into corresponding hinge pockets in the bottom of tail section 14 (not illustrated), such that apertures 15c align with corresponding apertures 16a in tail section 14. Hinge pins (not illustrated) are inserted through apertures 15c, 16a to pivotally join tail section 14 to base section 12.
With reference to FIGS. 1-4, in one example, a first end 18 of base section 12 includes a pair of hinge knuckles 20a, 20b extending therefrom which enable base section 12 to be pivotally connected (e.g., via pins) to another structure, such as a dock (e.g., a floating dock). An opposing second end 22 of base section 12 is non-linear in plan-view and has an inset region 22a that mates with a tongue-like extension 24a of a first end 24 of tail section 14. An opposing second end 26 of tail section 14 defines an inlet or mouth 28 for receiving and directing a bow of watercraft onto/off of floating watercraft port 10.
A top surface 30 of base section 12 and a top surface 32 of tail section 14 together form a top surface 34 of watercraft port 10. A hull depression 36 is molded into top surface 34 and is symmetrical about a longitudinal axis or centerline 38 of watercraft port 10, with hull depression 36 being shaped to receive a hull of a watercraft. In one example, hull depression 36 includes a tapered bow region 40, an entrance region 42, and a center region 44 extending there between, and includes port and starboard sidewalls 46a and 46b which curve upwardly from a central channel 48 toward top surface 34. Port and starboard sidewall 46a and 46b of entrance region 42 are flared outwardly between port and starboard sides 49a and 49b of watercraft port 10, and downwardly towards a bottom surface 35 so as to form a funnel-like ramp which directs a watercraft hull upwardly along centerline 38 toward center region 44 of hull depression 36.
In one example, a number of recessed roller pockets 50 are formed in port and starboard sidewalls 49a and 49b of hull depression 36 along centerline 38 between bow region 40 and entrance region 42. In one example, opposing rows 52a, 52b and 54a, 54b of recessed roller pockets 50 are symmetrically disposed along opposite sides of central channel 48 of hull depression 36 at different lateral distances (port and starboard) from centerline 38. In one example, a series of wobble wheels 60, which will be described in greater detail below, are symmetrically mounted within roller pockets 50 on opposing sides of enteral channel 48 to form guide tracks to engage and direct a boat hull along centerline 36 while on/off-loading a watercraft to/from watercraft port 10. In one example, as will be described in greater detail below, an axle of wobble wheel 60 is mounted within axle sockets 51a and 51b on opposing sides of each roller pocket 50 (see FIG. 4), such that an axis of rotation of wobble wheels 60 is orthogonal to central axis 36.
An entrance roller 70 is mounted within an entrance roller pocket 68 disposed at a base of tapered mouth 28 of entrance region 42. In one example, as will be described in greater detail below, the entrance roller comprises a bowtie roller 70, in accordance with the present disclosure, which serves as a both as a shock absorber to lessen impact to both watercraft port 10 and a bow of a watercraft upon initial contact during docking, and to direct the bow of a watercraft toward centerline 38. In one example, as will be described in greater detail below, an axle of bowtie roller 70 is mounted within axle sockets 69a and 69b of roller pocket 68 (see FIG. 4), such that an axis of rotation of bowtie roller 70 is orthogonal to central axis 36.
In one example, as illustrated by FIGS. 1 and 2, wobble wheels 60 are mounted within roller pockets 50 of opposing rows 52a and 52b closest to centerline 36. In another example, as illustrated by the perspective view of watercraft port 10 of FIG. 5, a first portion of wobble wheels 60 are mounted in roller pockets 50 of opposing rows 52a and 52b of tail section 14 closest to centerline 36, and a second portion of wobble wheels 60 are mounted in roller pockets 50 of opposing rows 54 and 54b of base section 12 furthest away from centerline line 60. By mounting wobble wheels 60 in portions of both inner and outer rows 52a/52b and 54a/54b of roller pockets 50, wobble wheels 60 mounted in tail section 14 initially engage and guide the bow of a watercraft, which is typically narrower than other portion of the hull, onto watercraft port 10 and along centerline 36, while wobble wheels 60 mounted in base section 12 engage and guide wider portions of the watercraft hull as the watercraft is further loaded onto watercraft port 10 while also providing stability to a watercraft when docked.
FIGS. 6 and 7 respectively illustrate perspective and side views of wobble wheel 60, in accordance with one example of the present disclosure. Wobble wheel 60 includes a rim 80 having a central hub 82 defining a bore 84 configured to receive an axle (see FIGS. 9-13), an outer barrel 86, and a number of spokes 88 extending between central hub 82 and in inner surface 86a of outer barrel 86. A tire 90 is disposed about the exterior surface of outer barrel 86. In one example, tire 90 includes a plurality of through-holes 92 extending through tire 90 between opposing sidewalls 94, where through-holes 92 assist tire 90 in absorbing kinetic energy from a watercraft hull during docking by enabling tire 90 to better deflect relative to a solid tire. In one example, as illustrated, spokes 88 have a non-linear, curved shape which enable spokes 88 and outer barrel 86 to more easily flex (to further absorb kinetic energy) without fracturing (e.g., cracking) relative to straight/linear spokes.
In one example, rim 80 and tire 90 each comprise single-piece, molded copolymer materials, such as thermoplastic elastomers (TPE) and thermoplastic rubbers (TPR), for example. In one example, tire 90 is over-molded onto rim 80. With reference to FIG. 8, which is a perspective view of rim 80, according to one example, outer surface 86b of outer barrel 86 includes a number of depressions 87 formed therein about its circumference (e.g., scallop-like depressions) which assist in securing tire 90 to rim 80 when over-molded thereon. In one example, tire 90 is formed with a copolymer material having a medium-soft durometer rating in a range from 55-75 so as to absorb shock and not damage a watercraft hull, but with a low compression set so as to return-to-shape (and not have a “flat spot”) after supporting a watercraft for long periods of time.
With reference to FIG. 9, as described above, bore 84 of central hub 82 receives an axle 98 which passes there through, about which wobble wheel 60 is free to rotate. A longitudinal axis of axle 98 represents an axis of rotation 99 of wheel 60. Together, wobble wheel 60 and axle 98 represent a wobble wheel assembly 100, where with opposing ends 98a and 98b of axle 98 are seated within axle sockets 51a and 51b when wobble wheel assembly 100 is mounted within a recessed roller pocket 50. In one example, bushings or spacers 102 are disposed on axle 98 on both sides of wobble wheel 60 so as to retain wheel 60 on axle 98 and to space wheel 60 within roller pocket 50 so as to prevent contact with sidewalls thereof
FIG. 10 is a perspective, cross-sectional view of wheel assembly 100 of FIG. 9. In one example, as illustrated in greater detail below by FIG. 11, central bore 84 is outwardly tapered so as to be flared or fluted such that a diameter of central bore 84 increases from a central diameter to an outer diameter at the openings to central bore 84 at opposing ends thereof
FIG. 11 is a cross-sectional view illustrating central bore 84 in greater detail. In one example, sidewall portions 110a-110d of bore 84 are angled outwardly from a center circumference of bore 84 at a transverse centerline 112 thereof (which coincides with a transverse centerline of rim 80), such that a diameter of bore 84 increases from a diameter dC at center circumference of bore 84 at transverse centerline 112, to a diameter dO at opposing openings 84a and 84b of bore 84. In one example, the diameter of bore 84 increases linearly from diameter dC to diameter dO with the internal sidewall of bore 84, as illustrated at 110a-110d, forming an angle, θ, with an axial centerline 114 of bore 84 (which coincides with an axial centerline of rim 80, and with the axis of rotation 99). In one example, values of θ are in a range from 5 to 10 degrees. In one example, θ has a value of 10 degrees.
The tapered shape of central bore 84 allows wobble wheel 60 to “wobble” or articulate from side-to-side on axle 98 as wheel 60 freely rotates about axle 98 when engaging a hull of a watercraft being driven onto or off of watercraft port 10. By allowing wobble wheels 60 to rotate from side-to-side, wobble wheels 60 are able to adjust to the position and size of the hull, and are thereby better able to maintain alignment of the hull with centerline 36, and are better able to maintain a broad surface contact with the hull so as to avoid damage thereto. In one example, as illustrated, the surface of tire 90 is crowned (has a radius) so as to maintain broad surface contact with a watercraft hull at different angles.
FIGS. 12 and 13 are cross-sectional views of wheel assembly 100 respectively illustrating wobble wheel 60 tipped to the left and to the right. With sidewalls 110a-110d being at angle, θ, relative to axial centerline 114 of bore 84 (see FIG. 11), the transverse axis 112 of wobble wheel 60 is able to tilt at angle, θ, to the left of vertical 113 (see FIG. 12), and at angle, θ, to the right of vertical 113 (see FIG. 13), for a range of motion equal to 2×θ. In one example, if angle, θ, has a value of 10-degrees, wobble wheel 60 has a range of motion of 20-degrees (i.e., +/− 10-degrees from vertical). By articulating to both the left and right, wobble wheel assembly 100 can be universally mounted within roller pockets 50 in any direction on either side of centerline 36. Although the range of angle, θ, of sidewalls 110a-110d of bore 84 is described as being in a range from 5 to 10 degrees, other angles may be employed. However, it is noted that rotation of wobble roller 60 will be inhibited when tipped if angle, θ, is too large.
FIG. 14 is a cross sectional view of an alternative implementation comprising a bushing that fits inside the hub that allows transverse articulation perpendicular to changing hull pitch. The bushing can be manufactured in a way that a lubricant can be added to the molded bushing that would otherwise interfere with adhesion from wheel hub to over-mold substrate.
FIG. 15 is a cross sectional view of an alternative implementation comprising a gradual curved pitch to transfer weight load evenly at any angle.
FIG. 16 is a cross sectional view of an alternative example of the overmold in which suspension holes have a gradual wall thickness change the employs greater force to compress in “0” degrees and gradually reduces force required to compress suspension holes towards the outer edge of the wheel.
FIG. 17 is a cross sectional view of an alternative example of the over-mold in which suspension holes have a one sided taper suspension hole to gain less suspension travel on one side vs. other. In this embodiment user can change wheel orientation around to accommodate a tailored compression assembly.
FIG. 18 is a cross sectional view of an alternative example of the over-mold in which suspension holes have a symmetrical suspension hole that reduces weight needed to compress on both sides equally.
FIG. 19 is a cross sectional view of an alternative example of the over-mold in which a symmetrical tapered suspension hole allows for greater force requirement in the middle and gradually needs less force toward outside edges to compress suspension holes.
FIGS. 20 and 21 are cross sectional views of an alternative embodiment of a hub bushing that snap fits inside the hub and allows for articulation of the wobble wheel while still allowing up to 10 degrees of articulation. Said embodiment also allows bushing polymer to hinge radially while spinning. Embodiment can employ a low friction additive for lower desired coefficient of friction. This is accomplished by eliminating the lubricant from interrupting the chemical bond of compatible hub and substrate materials. Such bushing materials that could be used to accomplish this would be a engineered polymer such as Hytrel(PET), PEEK or Acetal(POM) all which are compatible with an internal molded lubricant. This embodiment also allows axle pin to stay concentric and supported with bushing during articulated rotation. This embodiment also will maintain a home position of 0 degrees until articulation force is applied and will return to home position after wheel weight is eliminated.
FIGS. 22 and 23 respectively illustrate perspective and side views of bowtie roller 70, according to one example of the present disclosure. Although illustrated primarily herein as being employed as an entrance roller, bowtie roller 70 may be used for other purposes and in other locations with floating watercraft ports. In the illustrated example, bowtie roller 70 includes a pair of shoulder rollers 120, illustrated as shoulder rollers 120a and 120b, and a center roller 140, with each of the rollers being disposed on a same axle 160, with each roller able to spin freely and independently from one another about axle 160. Each shoulder roller 120 includes a rim 122 including a center hub 124 defining a bore 126 to receive axle 160 (see FIGS. 24A and 24B below for further detail), and a tire 130 disposed on rim 122. In examples, bushings (not illustrated) may be disposed on axle 160 adjacent to each shoulder roller 120 to maintain positions of shoulder rollers 120 and center roller 140 on axle 160.
With reference to FIG. 23, tire 130 of shoulder roller 120 includes an inner tire portion 132 and an outer tire portion 134, with shoulder roller 120 positioned on axle 160 such that inner tire portion 132 faces center roller 140. In one example, a diameter of outer tire portion 134 of tire 130 decreases from a diameter D1 at an outer sidewall 136a opposite inner tire portion 132 to a diameter D2 where outer tire portion 134 transitions to inner tire portion 132, such that outer tire portion 134 has a first angle of depression, α1, relative to an axis of rotation 164 of bowtie roller 70 (which coincides with the longitudinal axis of axle 160) from outer sidewall 136a toward inner tire portion 132. Similarly, a diameter of inner tire portion 132 decreases from diameter D2 at the transition with outer tire portion 134 to a diameter D3 at an inner sidewall 136b, such that inner tire portion 132 has a second angle of depression, α2, relative to the axis of rotation 164. In one example, as illustrated, second angle of depression, α2, is greater than first angle of depression, α1. In one example, the diameter of center roller 140 matches the diameter, D3, at inner sidewall 136b of tire 130.
FIGS. 24A and 24B are perspective views illustrating hub 122 of shoulder rollers 120, according to one example. Hub 122 includes a first hub portion 150, corresponding to outer tire portion 134, and a second hub portion 152 corresponding to inner tire portion 132 of tire 130. First hub portion 150 includes center hub 124 defining bore 126, an outer barrel 154 having an inner surface 154a and an outer surface 154b, and a number of spokes 156 extending between center hub 124 and inner surface 154a of outer barrel 154. In one example, outer surface 154b includes scallop-like depressions 158 to interlock with outer tire portion 134 of over-molded tire 130. Second hub portion 152 tapers downward from first hub portion 150 and has an outer surface 170 including a plurality of outwardly radiating ribs 172 to interlock inner tire portion 132 of with over-molded tire 130.
FIGS. 25A and 25B are perspective views illustrating tire 130, according to one example. In one example, outer tire portion 134 includes a number of tapered openings 180 extending partially through tire 130 from outer sidewall 136a. Openings 180 enable compression of otherwise solid tire 130 (similar to through-holes 92 of wobble wheel 60) to provide absorption of kinetic energy by shoulder rollers 120 when contacted by a watercraft hull. In one example, an outer surface of outer tire portion 134 includes a tread 182 to shed water from shoulder rollers 120.
In one example, rim 122 and tire 130 of shoulder roller 120 each comprise single-piece, molded copolymer materials, such as thermoplastic elastomers (TPE) and thermoplastic rubbers (TPR), for example. In one example, tire 130 is over-molded onto previously molded rim 120. With reference to FIGS. 24A and 24B, scallop-like depressions 158 and raised ribs 172 formed about the circumferential surface of hub 122 assist in securing tire 130 to rim 122 when tire 130 is over-molded thereon. In one example, tire 130 is formed with a copolymer material having a medium-soft durometer rating in a range from 55-75 so as to absorb shock and not damage a watercraft hull, but with a low compression set so as to return-to-shape (and not have a “flat spot”) after supporting a watercraft for long periods of time.
FIGS. 26A and 26B respectively illustrate perspective views of a rim 190 and a tire 200 of center roller 140, according to one example. Rim 190 includes an outer barrel 192 defining bore 126 through which axle 160 passes. An outer surface 192 of barrel 192 includes a number of depressions 194 to assist in interlocking hub 190 with tire 200 which is over-molded thereon. A plurality of through-holes 202 extend through tire 200 between opposing sidewall 204a and 204b to enable compression of otherwise solid tire 200 (similar to through-holes 92 of wobble wheel 60) to provide absorption of kinetic energy by center roller 140 when contacted by a watercraft hull.
In one example, rim 190 and tire 200 of center roller 140 each comprise single-piece, molded copolymer materials, such as thermoplastic elastomers (TPE) and thermoplastic rubbers (TPR), for example. In one example, tire 200 is over-molded onto previously molded rim 190. With reference to FIG. 26A, depressions 194 in outer surface 192a of hub 190 assist in securing tire 200 to rim 190 when tire 200 is over-molded thereon. In one example, tire 200 is formed with a copolymer material having a medium-soft durometer rating in a range from 55-75 so as to absorb shock and not damage a watercraft hull, but with a low compression set so as to return-to-shape (and not have a “flat spot”) after supporting a watercraft for long periods of time.
With reference to FIGS. 1-2, bowtie roller 70 is positioned within entrance roller pocket 68, with opposing ends 162a and 162b of axle 160 being mounted within axle sockets 69a and 69b.
As described above, shoulder rollers 120a, 120b and center roller 140 each spin independently about axle 160. When driving a watercraft onto watercraft port 10, tapered mouth 28 of entrance section 14 directs a bow of the watercraft to bowtie (entrance) roller 70. Upon initial contact, openings 180 within tire 130 of shoulder rollers 120a and 120b, through-holes 202 extending through tire 200 of center roller 140, and the elastic characteristics of the material from which tires 130 and 200 are formed, absorb a portion of kinetic energy of the watercraft rather than transferring such kinetic energy into the watercraft port 10 and the watercraft hull, thereby reducing a “jarring” effect of initial contact. As the watercraft is driven onto watercraft port 10, the independent spinning of each roller, and the downward angle of each shoulder roller 120a, 120b toward center roller 140 cause the watercraft hull to self-align with the longitudinal centerline 36 of watercraft port 10. Similarly, bowtie roller 70 functions to assist in maintain central alignment of a watercraft hull when the watercraft is being driven off of watercraft port 10. As described above, center rollers 140 of different widths may be employed to adjust an overall width of bowtie roller 170 to accommodate watercraft hulls of different widths.
FIG. 27 is a simplified cross-sectional view generally illustrating portions of a bowtie roller 70, according to one example of the present disclosure. According to the example of FIG. 27, inner tire portions 132 of shoulder rollers 120a and 120b each include a circular extension 196 extending from inner sidewall 136b and forming a cylindrical roller pocket 198 which is coaxial with bore 126. As illustrated, opposing ends of center roller 140 are disposed within cylindrical roller pockets 198 of shoulder rollers 120a and 120b. Disposing opposing ends of center roller 140 within roller pockets 198 prevents objects (including keels of boat hulls and pontoons) from becoming wedged between the ends of center roller 140 and shoulder rollers 120a and 120b.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described herein without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.
