Abstract
A watercraft propulsion includes an elongated fin disposed below a bottom of the watercraft, the fin having a pivotal spot located closer to a forward end than to an aft end of the watercraft, a hinge attached to the bottom having a slot confining the forward end to a first vertical range of motion, a shaft passing through a hole formed in a hull of the watercraft, the shaft having a lower end below the bottom of the watercraft and an upper spot above a deck of the watercraft, the lower end pivotally engaging the fin at the pivotal spot, a first foot pedal linked to the shaft at the upper spot via a first wheel disposed below the upper spot of the shaft, and a second foot pedal linked to the shaft at the upper spot via a second wheel disposed above the upper spot of the shaft.
Claims
1. A manual propulsion system for a watercraft, the system comprising: an elongated fin disposed below a bottom of the watercraft with a fin centerline in an elongated direction of the elongated fin aligned with a centerline of the watercraft, the elongated fin having a forward end, an aft end and a pivotal spot located closer to the forward end than to the aft end; a hinge attached to the bottom of the watercraft, the hinge having a first slot confining the forward end of the elongated fin to a first vertical range of motion; a shaft freely passing through a first hole formed in a hull of the watercraft, the shaft having a lower end below the bottom of the watercraft and an upper spot above a deck of the watercraft, the lower end pivotally engaging the elongated fin at the pivotal spot; a first foot pedal linked to the shaft at the upper spot via a first wheel disposed below the upper spot of the shaft; and a second foot pedal linked to the shaft at the upper spot via a second wheel disposed above the upper spot of the shaft.
2. The system of claim 1, wherein the elongated fin has an opening at the pivotal spot and a first pin removably inserted through a body of the elongated fin into the opening and a hole formed in the lower end of the shaft for engaging the shaft to the elongated fin, wherein the first pin is positioned perpendicular to the fin centerline.
3. The system of claim 1, wherein the elongated fin has a first and second member protruding vertically from a top surface of the elongated fin at the pivotal spot, wherein the first and second member secure a removable second pin inserted in a hole formed in the lower end of the shaft for engaging the shaft to the elongated fin, wherein the second pin is positioned perpendicular to the fin centerline.
4. The system of claim 1, wherein elongated fin comprises a third pin protruding from the forward end of the elongated fin, wherein the first slot slidably accommodates a first protruding end of the third pin to confine the forward end of the elongated fin to the first vertical range of motion.
5. The system of claim 4, wherein the hinge comprises a second slot symmetrical and parallel to the first slot, wherein the second slot slidably accommodates a second protruding end of the third pin, wherein the third pin is removably inserted through a second hole formed in the forward end and perpendicular to the fin centerline with the first and second protruding end of the third pin protruding from opposite sides, respectively, of the elongated fin.
6. The system of claim 5, wherein the third pin is locked in place in the second hole by a set screw.
7. The system of claim 5, wherein the hinge is a protruding part of the hull.
8. The system of claim 1, wherein the first hole confines the shaft to a vertical motion.
9. The system of claim 8, wherein an upper end of the first hole is above a water line of the watercraft.
10. The system of claim 1, wherein the upper spot of the shaft moves between the first and second wheel with a second vertical range of motion in response to movements of the first and second foot pedal, wherein the second vertical range of motion is larger than the first vertical range of motion.
11. The system of claim 1, further comprising a first and second crank rotatable around an axle mounted on a deck of the watercraft, wherein the first foot pedal is attached to an upper end of the first crank and the second foot pedal is attached to an upper end of the second crank.
12. The system of claim 11, wherein the first foot pedal is linked to the upper spot of the shaft by a first cable with a first end attached to the first crank and a second end attached to the upper spot of the shaft, wherein the first cable loops around a lower part of the first wheel; and the second foot pedal is linked to the upper spot of the shaft by a second cable with a third end attached to the second crank and a fourth end attached to the upper spot of the shaft, wherein the second cable loops around an upper part of the second wheel.
13. The system of claim 12, wherein the upper spot of the shaft has a first and second member protruding from opposite sides of the shaft, wherein the second end of the first cable is attached to the first member and the fourth end of the second cable is attached to the second member.
14. The system of claim 12, wherein the first and second cables are of a same length.
15. The system of claim 14, wherein the length of the first or second cable is adjustable.
16. The system of claim 12, wherein the first and second cable are of one piece of cable looping from one side of the shaft to an opposite side of the shaft.
17. The system of claim 12, further comprising a first and second cover disposed over the first and second wheel, respective, wherein the first cover prevents the first cable from jumping off a first groove of the first wheel; and the second cover prevents the second cable from jumping off a second groove of the second wheel.
18. The system of claim 1, further comprising a frame mounted on a deck of the watercraft, wherein the first wheel is rotatably mounted to a lower end of the frame; and the second wheel is rotatably mounted to an upper end of the frame.
19. A method for manually propelling a watercraft, the method comprising: attaching a hinge to a bottom of the watercraft, the hinge having a first slot confining a forward end of an elongated fin to a vertical range of motion; freely passing a shaft through a hole formed in a hull of the watercraft, the shaft having a lower end pivotally engaging the elongated fin at a pivotal spot, the pivotal spot being closer to the forward end of the elongated fin than to an aft end of the elongated fin; linking a first foot pedal to an upper spot of the shaft via a first wheel disposed below the upper spot of the shaft; and linking a second foot pedal to the upper spot of the shaft via a second wheel disposed above the upper spot of the shaft.
20. The method of claim 19, wherein the hinge comprises a second slot symmetrical and parallel to the first slot, wherein the first slot slidably accommodates a first end of a pin protruding from a first side of the forward end of the elongated fin; and the second slot slidably accommodates a second end of the pin protruding from a second side of the forward end of the elongated fin, the second side being opposite to the first side.
Description
BRIEF DESCRIPTION OF THE DRAWING
[0005] FIG. 1 is a side view of personal watercraft with a flapping propulsion system according to embodiments of the present disclosure.
[0006] FIG. 2 is a perspective view of an exemplary implementation of the slotted hinge shown in FIG. 1 according to embodiments of the present disclosure
[0007] FIGS. 3A and 3B are perspective views of a forward part of the fin 110 engaging a shaft according to embodiments of the present disclosure.
[0008] FIG. 4 is a top view of the manual propulsion system shown in FIG. 1.
[0009] FIG. 5 is a flowchart illustrating a process of constructing a manual flapping propulsion system according to embodiments of the present disclosure.
[0010] The drawings accompanying and forming part of this specification are included to depict certain aspects of the disclosure. A clearer conception of the disclosure, and of the components and operation of systems provided with the disclosure, will become more readily apparent by referring to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings, wherein like reference numbers (if they occur in more than one view) designate the same elements. The disclosure may be better understood by reference to one or more of these drawings in combination with the description presented herein.
DESCRIPTION
[0011] The present disclosure relates to a flapping manual propulsion system for a personal watercraft. A preferred embodiment of the present disclosure will be described hereinafter with reference to the attached drawings.
[0012] FIG. 1 is a side view of personal watercraft with a flapping propulsion system according to embodiments of the present disclosure. The flapping propulsion system includes an elongated fin 110, a shaft 120, a slotted hinge 130, a pull-down cable 160L exemplarily attached to a left crank 180L and a pull-up cable 160R exemplarily attached to a right crank 180R. In embodiments, a centerline of the elongated fin 110 in the elongated direction is aligned with a centerline of the watercraft, so that when the elongated fin 110 makes up-and-down flapping motion, it generates a propulsion force aligned with the centerline of the watercraft.
[0013] As shown in FIG. 1, in an embodiment, both the left crank 180L and the right crank 180R are pivotally mounted to an axle 173 which is secured to a hull 102 of the watercraft by a bracket 170. A forward end of the fin 110 has a pin 117 slidably inserted in a slot 133 formed in the slotted hinge 130. A lower end of shaft 120 is pivotally attached to a pin 123 mounted to the elongated fin 110 at a pivotal spot between a forward end and an aft end of the elongated fin 110. A cross-sectional view of the elongated fin 110 in FIG. 1 shows that the pin 123 is exemplarily situated in a hole 113 in the fin 110. In embodiments, a forward distance from the pivotal spot to the forward end of the elongated fin 110 is greater than an aft distance from the pivotal spot to the aft end of the elongated fin 110. In an example, the forward distance is about one fifth of the aft distance. In another example, the forward distance is about one sixth of the aft distance. In yet another example, the forward distance is about one seventh of the aft distance.
[0014] Referring to FIG. 1 again, the slot 133 confines the pin 117 to a substantially vertical range of motion. Because the pivotal spot is closer to the forward end of the elongated fin 110, when the shaft 120 moves upward, the pin 117 along with a forward portion of the elongated fin 110 will be lifted more than an aft portion of the fin 110. Eventually, the pin 117 will be stopped by an upper limit of the slot 133. When the shaft 120 moves further upward, the aft portion of the elongated fin 110 will continue to move upward. In an embodiment, a range of the upward motion of the shaft 120 together with the upper limit of the slot 133 allows the elongated fin 110 to swing up to a first horizontal position. Conversely, when the shaft 120 moves downward, the pin 117 along with the forward portion of the fin 110 will be pushed down more than the aft portion of the fin 110. Eventually, the pin 117 will be stopped by a lower limit of the slot 133. When the shaft 120 moves further downward, the aft portion of the fin 110 will continue to move downward. In an embodiment, a range of the downward motion of the shaft 120 together with lower limit of the slot 133 allows the fin 110 to swing down to a second horizontal position. Such up-and-down swing motion by the fin 110 between the first and second horizontal position provides forward propulsion to the watercraft. In embodiments, the elongated fin 110 is made of a bendable plastic material. To accommodate the bending of the elongated fin 110, the vertical range of motion by the shaft 120 is greater than the vertical range of motion by the forward end of the fin 110.
[0015] Referring to FIG. 1 again, the shaft 120 goes through a hole 105 formed in a hull 102 of the watercraft. In embodiments, the hole 105 has enough tolerance to allow the shaft 120 to freely move up and down. The hole 105 also has enough length to restrict the shaft 120 to a vertical up and down motion. In one example, the hole 105 is approximately 10 centimeters long. In another example, the hole 105 is approximately 15 centimeters long. In embodiments, an upper end of the hole 105 is above a water line, so that the hole 105 will not let water into an interior of the watercraft.
[0016] Referring to FIG. 1 again, one end of the pull-down cable 160L is attached to the left crank 180L, and the other end of the pull-down cable 160L is attached to an upper end of the shaft 120. The pull-down cable 160L loops around a pull-down pulley wheel 146 which is rotatably fastened to a mounting frame 150 by a bracket 148. The mounting frame 150 is rigidly mounted to a deck of the watercraft 102. Similarly, one end of the pull-up cable 160R is attached to the right crank 180R, and the other end of the pull-up cable 160R is attached to the upper end of the shaft 120. The pull-up cable 160R loops around a pull-up pulley wheel 142 which is rotatably fastened to the mounting frame 150 by a bracket 144. In an embodiment shown in FIG. 1, the mounting frame 150 has holes 152 and 156 to allow the pull-up cable 160R and pull-down cable 160L, respectively, to go through. In embodiments, the left crank 180L and the right crank 180R are symmetrical. For example, a length from the axle 173 to a pivotal pin 183L of the left pedal 187L is the same as a length from the axle 173 to a pivotal pin 183R of the right pedal 187R; and an attachment point of the pull-down cable 160L on the left crank is at the same height as an attachment point of the pull-up cable 160R. As shown in FIG. 1, the pull-up pulley wheel 142 is disposed above the pull-down pulley wheel 146 by a predetermined distance, and the upper end of the shaft 120 can move up and down between the pull-up pulley wheel 142 and the pull-down pulley wheel 146. In an example, the predetermined distance is approximately ten centimeters.
[0017] Referring to FIG. 1 again, when the left crank 180L rotates counterclockwise at a pressing of a left pedal 187L by a user, the pull-down cable 160L pulls the shaft 120 along with the elongated find 110 downward. Meanwhile the downward motion of the shaft 120 pulls the pull-up cable 160R downward to cause the right crank 180R to rotate clockwise. When the right crank 180R rotates counterclockwise at a pressing of a right pedal 187R by the user, the pull-up cable 160R pulls the shaft 120 along with the elongated fin 110 upward. Meanwhile the upward motion of the shaft 120 pulls the pull-down cable 160L upward to cause the left crank 180L to rotate clockwise. In embodiments, the pull-down cable 160L and the pull-up cable 160R have the same length, so that the shaft 120 can move down and up by the same distance for a given degree of rotation for both left crank 180L and the right crank 180R. As a result, symmetrical movements of the left crank 180L and the right crank 180R causes the elongated fin 110 to flap upward and downward by the same degree of angle.
[0018] FIG. 2 is a perspective view of an exemplary implementation of the slotted hinge 130 shown in FIG. 1 according to embodiments of the present disclosure. The slotted hinge 130 includes two parallel side panels 130L and 130R and a horizontal panel 210 connecting lower ends of the side panels 130L and 130R. Upper ends of the side panels 130L and 130R are attached to a bottom surface of the watercraft hull (not shown)preferably centered on a centerline of the watercraft. In an embodiment, the side panels 130L and 130R are built in the hull of the watercraft 102 as protruding members. The horizontal panel 210 serves to enhance structural rigidity of the side panels 130L and 130R.
[0019] As shown in FIG. 2, exemplary slot openings 133L and 133R are formed in the side panels 130L and 130R, respectively, for accommodating pin 117 protruding from the forward end of the elongated fin 110 shown in FIG. 1. The slot openings 133L and 133R are of the same dimension and disposed symmetrically in reference to the centerline of the watercraft 102. In an embodiment, a vertical length of the slot opening 133L or 133R is smaller than the range of motion of the shaft 120 to account for the bending the elongated fin 110. In an embodiment, the vertical length of the slot opening 133L or 133R is determined so that the forward end of elongated fin 110 and the aft end of the elongated fin 110 are at a same horizontal plane when the shaft 120 reaches either the upper or lower limit. In an embodiment, a horizontal width of the slot opening 133L or 133R is slightly larger than a diameter of the pin 117, so that the pin 117 along with the elongated fin 110 can wiggle back and forth in the horizontal direction in response to its flapping motion.
[0020] In an embodiment, both upper end and lower end of the slot opening 133L or 133R have a soft portion (not shown in FIG. 2) to cushion the impact of the pin 117 during the flapping motion by the elongated fin 110. The soft portion may exemplarily be a rubber piece glued onto the upper or lower end of the slot opening 133L or 133R.
[0021] Although FIG. 2 illustrates that the slot 133L and 133R are through openings in the side panels 130L and 130R, respectively, in other embodiments, recessed slots formed in the side panels 130L and 130R can also accommodate the pin 117.
[0022] FIGS. 3A and 3B are perspective views of a forward part of the fin 110 engaging a shaft according to embodiments of the present disclosure. Referring to FIG. 3A, in an embodiment, the elongated fin 110 has a vertical hole 113 disposed along a centerline of the elongated fin 110 for accommodating the lower end of the shaft 120. The elongated fin 110 engages the shaft 120 by the pin 123 which is inserted in a horizontal hole 302 in the elongated fin 110 and a hole 310 at the lower end of the shaft 120. In an embodiment, the horizontal hole 302 goes from one side of the elongated fin 110 to the other side in parallel to a horizontal surface of the elongated fin 110 and perpendicular to a centerline of the elongated fin 110, so that the pin 123 is positioned perpendicular to a centerline of the elongated fin 110. In an embodiment, an inner diameter of the hole 310 has enough tolerance to accommodate the pin 123 to allow the shaft 120 to freely pivot around the pin 123.
[0023] As shown in FIG. 3A, the pin 117 perpendicularly protrudes from both side of the forward end of the elongated fin 110. In an embodiment, the pin 117 is a metal rod passing through a hole formed along the forward end of the elongated fin 110 and is locked in place by a set screw 306 through the forward end of the elongated fin 110.
[0024] FIG. 3B shows an alternative structure for engaging the elongate fin 110 and the shaft 120 according to embodiments of the present disclosure. As shown in FIG. 3B, the elongated fin 110 has a first and second member 321L and 321R protruding vertically from a top surface of the elongated fin 110 at the pivotal spot, wherein the first and second member 321L and 321R secure a removable pin 335 inserted through a hole 332 formed in the first member 321L. In operation, the removable pin 335 is inserted in the hole 310 formed at the lower end of the shaft 120. In an embodiment, the inner diameter of the hole 310 has enough tolerance to accommodate the pin 335 to allow the shaft 120 to freely pivot around the pin 335. In an embodiment, the pin 335 is positioned perpendicular to a centerline of the elongated fin 110.
[0025] FIG. 4 is a top view of the manual propulsion system shown in FIG. 1. A rod 410L protrudes from the upper end of the shaft 120 toward a left hand side of a user. A rod 410R protrudes from the upper end of the shaft 120 toward a right hand side of the user. The pull-down cable 160L connects the left crank 180L to the rod 410L via the pull-down pulley wheel 146. The pull-up cable 160R connects the right crank 180R to the rod 410R via the pull-up pulley wheel 142. In an embodiment, an end of the pull-down cable 160L forms a loop pivotably hooked to the left crank 180L by a protruding pin 421L. Similarly, an end of the pull-up cable 160R also forms a loop pivotably hooked to the right crank 180R by a protruding pin 421R.
[0026] In an embodiment, the pull-down cable 160L and the pull-up cable 160R are part of one cable that includes a section 420 that crosses from the rod 410L to the rod 410R. In an embodiment, a length of the section 420 can be adjusted. When the length of the section 420 is lengthened, a length of the pull-down cable 160L and a length of the pull-down cable 160R will be shortened, so that the foot pedals 187L and 187R can be reached by short legged person. Conversely, when the length of the section 420 is shortened, the length of the pull-down cable 160L and a length of the pull-down cable 160R will be longer, so that the foot pedals 187L and 187R can be reached by long legged person. In an embodiment, the section 420 loops around the shaft 120, so that by looping more or less rounds, the length of the section 420 can be adjusted.
[0027] In embodiments, both the pull-down pulley wheel 146 and the pull-up pulley wheel 142 are covered (not shown) to prevent the pull-down cable 160L and the pull-up cable 160R to jump off the respective groove.
[0028] The term, end as in the upper end, lower end, forward end or aft end as used herein, generally refers to a vicinity of an edge of an elongated member. For example, rod 410L or 410R may protrude from the upper end of the shaft 120 at a point one centimeter to the very end of the shaft 120.
[0029] FIG. 5 is a flowchart illustrating a process of constructing a manual flapping propulsion system according to embodiments of the present disclosure. The process begins with attaching a hinge 130 to a bottom of the watercraft 102 in block 510. The hinge 130 has a first slot 133 confining a forward end of an elongated fin 110 to a vertical range of motion.
[0030] In block 520, the process freely passes a shaft 120 through a hole 105 formed in a hull of the watercraft 102. The shaft 120 has a lower end pivotally engaging the elongated fin 110 at a pivotal spot which is closer to the forward end of the elongated fin 110 than to an aft end of the elongated fin 110.
[0031] In block 530, the process links a first foot pedal 187L to an upper spot of the shaft 120 via a first wheel 146 which is disposed below the upper spot of the shaft 120.
[0032] In block 540, the process links a second foot pedal 187R to the upper spot of the shaft 120 via a second wheel 142 which is disposed above the upper spot of the shaft 120.
[0033] Although the disclosure is illustrated and described herein as embodied in one or more specific examples, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the disclosure and within the scope and range of equivalents of the claims. Accordingly, it is appropriate that the appended claims be construed broadly and, in a manner, consistent with the scope of the disclosure, as set forth in the following claims.
