Abstract:
The present invention relates to a human-powered boat that a user can easily operate with his/her own manual power even though the boat is in a form causing large resistance to propulsion, and the human-powered boat is equipped with a propulsion apparatus that imitates the tail fin of a fish. The propulsion apparatus, in which an oscillating foil mechanism is applied to an “L-shaped oar”, enables a rider to perform forward-facing rowing and can easily change a direction and prevent damage due to a collision with an underwater obstacle. Typically, the human-powered boat of the present invention has the following three limitations in order to maximize simplicity while maintaining propulsion efficiency, compared with prior arts in the same technical field: First, a rider has a specific limitation in tilting the propulsion apparatus through an up-down movement of his/her arm. Second, the foil of the propulsion apparatus does not make contact with the longitudinal axis of the boat body in a predetermined range of motion. Third, the propulsion apparatus has a predetermined level of limitation in generating a propulsion force below the submerged portion of the boat body.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a technical field of a boat moving by rowing oars that are taken out from left and right sides of the boat body. The boat is mostly compact and uses a non-motorized propulsion apparatus, i.e., human-powered propulsion apparatus as a propulsion apparatus thereof. Here, a rider may row oars through a forward and backward movement of rider&#39;s arms. 
         [0002]    Particularly, the human-powered boat according to the present invention uses a human-powered propulsion apparatus having a mechanism that converts a forward and backward movement of a rider&#39;s arm into a left and right motion of a foil submerged under the water surface so that the boat moves while the rider faces the front that is an advancing direction of the boat. 
       BACKGROUND ART 
       [0003]    The present invention is based on technical knowledge about ‘forward-facing rowing’ and ‘oscillating foil’ so as to safely secure a front view and improve energy efficiency of propulsion when a boat is propelled by using human power. 
         [0004]    The most common example of the forward-facing rowing may be found in narrow beam boats having a sharp boat body such as a kayak or a canoe. However, in case of a wide beam boat having larger width, since a distance between its rider and the water surface outside the boat body is distant, a pivot may be positioned at a middle portion of each oar. Furthermore, since such a boat greatly undergoes propulsion resistance, the rider may generate propulsion force through a motion that pulls a handle of the oar backward than a motion that pushes the handle of the oar forward. The pulling motion may be converted in direction by the pivot, and thus, the boat may be accelerated in a direction opposite to the rider&#39;s eyes (backward-facing rowing). 
         [0005]    Thus, in order to enable the rider to have a forward-facing rowing in the wide beam boat having the large width, additional ideas are necessary in addition to the installation of the pivot. The simplest solution of the ideas may be an “L-shaped oar”, in which a middle portion of an oar&#39;s loom is bent. When the oar has a shape in which the oar extends from the handle in a width direction of the boat body to meet a side of the boat body and then extends backward in a longitudinal direction of the boat body so that the extending end is coupled to a plate-shaped foil, the forward and backward movement of the rider&#39;s arm may be converted into a left and right oscillating motion of the foil to generate propulsion force as if a fish moves a tail fin thereof. 
         [0006]    The oscillating foil may be chosen as best technology in the above-described means that is capable of “generating the propulsion force like a fish” (see Robotic Design for SHOAL—Swimming mechanism [on-line], SHOAL Project Consortium, 2012.) Explaining a configuration and operation of a basic mechanism for realizing the oscillating foil mechanism with reference to  FIG. 1 , a first pivot  11  is disposed on a front end of an oscillating crank  32  having a predetermined length, and a plate-shaped foil  12  is coupled to a rear end of the oscillating crank  32  to allow the oscillating crank  32  to oscillate about the first pivot  11 . As a result, the foil  12  pushes water backward to generate propulsion force F. 
         [0007]    In addition to these basic components, a second pivot  13  is additionally disposed on a front portion of the foil  12  to allow the foil  12  to relatively rotate with respect to the oscillating crank  32 , thereby more improving propulsion efficiency. Explaining a specific operation principle, when rotating force is applied to the first pivot  11  in a counterclockwise direction in the idle state of the oscillating crank, the foil  12  rotates about the second pivot  13  in a clockwise direction while largely moving along a rear end of the oscillating crank  32  and then is stopped at a limited angle β. Thereafter, the foil  12  obliquely pushes water until the oscillating crank  32  reaches a limited angle α. 
         [0008]    When the oscillating crank  32  switches its direction to start the rotation again in the clockwise direction, the foil  12  rotates in a counterclockwise direction and stops at a limited angle. Then, the foil  12  pushes water until the oscillating crank  32  reaches the limited angle. 
         [0009]    That is, the foil  12  primarily largely oscillates about the first pivot  11 , and simultaneously, secondarily flaps in small about the second pivot  13  to generate the propulsion force F. 
         [0010]    Here, it is preferable that the first pivot  11  and the second pivot  13  provide rotation axes that are perpendicular to the water surface to prevent the boat body from pitching due to the oscillation of the foil  12 . 
         [0011]    According to the advanced researches about an oscillating foil propulsion mechanism, propulsion efficiency can be increased by making the end portion of the foil  12  flexible. (see H. Yamaguchi et al., “Oscillating Foils for Marine Propulsion”, The 4th International Society of Offshore and Polar Engineering Conference, vol. 3, 1994, pp. 539-544.) 
         [0012]    Hereinafter, the prior arts, which are combinations of above-mentioned L-shaped oar and the oscillating foil mechanism, will be introduced using the above-mentioned terms. 
         [0013]    The most impressive technology is U.S. Pat. No. 4,867,718 (1989 Sep. 19) to Stephen Dupont. Characteristically, two hinges, a ‘sweep hinge’ that corresponds to the first pivot by providing a vertical rotation axis at the bent part of L-shaped oars and a ‘teeter hinge’ that has a horizontal rotation axis, are coupled simultaneously and the two hinges may be involved in the entire movement of the oar at the same time. Here, in a coupling structure between the oscillating crank and the foil, the position of the second pivot is retreated toward a central portion of the foil, not to the front end of the foil. By doing this, it has the effect of accelerating the secondary flapping motion of the foil. U.S. Pat. No. 4,867,719 (1989 Sep. 19) filed by the same inventor discloses a feature in which a sliding outrigger is added to the components of the foregoing invention. 
         [0014]    Thereafter, according to U.S. Pat. No. 6,964,589 (2005 Nov. 15) by Roger Lin, by transmitting the rider&#39;s arm movement to a rear side of a boat body using a power transmission device, the foil can perform flapping motion without colliding with the boat body even without an outrigger. In addition, the oscillating crank is obliquely dropped from a position higher than the water surface of the stern to minimize its submerging portion. 
         [0015]    Thereafter, Jack Parker introduced the most simplified mechanism that is imaginable in corresponding technical fields by coupling the foil directly to the first pivot through U.S. Pat. No. 7,396,267 (2008 Jul. 8). U.S. Pat. No. 8,419,487 (2013 Apr. 16) filed by the same inventor discloses a feature in which the first pivot is moved from the inside to the outside of the boat body. 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0016]    An objective of the present invention is to provide a propulsion apparatus having the most simplified structure while maintaining propulsion efficiency of oscillating foil. 
         [0017]    When disadvantages of the foregoing prior arts are discovered based on this objective and ‘adoption of ideas’ or ‘omission of ideas’ which becomes the cause of the disadvantages are analyzed and summarized, resultant features may be described as follows. 
         [0018]    In U.S. Pat. Nos. 4,867,718 and 4,867,719, a ‘teeter hinge’ is adopted for fixing an L-shaped oar, so the complexity of the propulsion apparatus increases, and simultaneously, a rotation axis of a foil cannot be vertically fixed with respect to the water surface while a boat moves, so the boat body tends to move up and down according to rider&#39;s arm movement and finally the propulsion efficiency decreases as a result. However, since the ‘teeter hinge’ enables a rider to lift the foil and load it on the boat as a boat using a general oar collects a row at anchor, if this retracting function is desired, the teeter hinge may be an idea that cannot be omitted. 
         [0019]    In U.S. Pat. No. 6,964,589, a power transmission device is adopted for transmitting the rider&#39;s arm movement to an oscillating crank that is positioned at a rear portion of the boat body, so the complexity of the propulsion apparatus increases. However, since the foil is positioned behind a stern, a space in which the foil oscillates is secured without using an outrigger as its advantage. 
         [0020]    In U.S. Pat. Nos. 7,396,267 and 8,419,487, a foil is directly coupled to the first pivot in a state which the oscillating crank is omitted in the propulsion apparatus. Since the essential components for securing effectiveness of oscillating foil mechanism is not prepared, it may be difficult to expect higher propulsion efficiency. However, in the propulsion apparatus according to the inventions, the foil can rotate at an angle of 180 degrees to generate reverse propulsion force through the same arm movement as the former arm movement (this function enables the rider to perform the forward-facing rowing and the backward-facing rowing). For this, the foil is positioned under a keel of the boat body. If an oscillating crank is added to a front portion of the foil positioned in the deep water, big resistance may occur when rowing. 
         [0021]    The problems involved in the prior arts as described above may occur by intentionally adopting or omitting a specific component in order to obtain a desirable expected effect from different perspectives. Thus, an approach for a new invention by adding a component of one prior art to another prior art cannot be effective. Thus, the geometry and mechanism of the propulsion apparatus has to be totally redesigned. 
         [0022]    The objective of the present invention is specifically described as follows: 
         [0023]    {circle around (1)} forward-facing rowing of a rider 
         [0024]    {circle around (2)} high-efficient propulsion apparatus having a simplified structure 
         [0025]    {circle around (3)} securing a space for a foil&#39;s oscillation on a side of a boat body 
         [0026]    {circle around (4)} enabling the rider to perform oval arm movement 
         [0027]    {circle around (5)} preventing a foil from being damaged by an underwater obstacle 
         [0028]    {circle around (6)} easy detachment of the propulsion apparatus from the boat body 
         [0029]    {circle around (7)} structure of the foil for reducing manufacturing costs 
       Solution to Problem 
       [0030]    To solve the foregoing problems, the present invention proposes a new solution that indirectly secures some advantages of the prior arts and resolutely abandons some preferable functions of them by totally redesigning the geometry and mechanism of the propulsion apparatus in which the oscillating foil mechanism is applied to the L-shaped oar. 
         [0031]    Particularly, a human-powered boat according to the present invention, which is capable of being propelled by rider&#39;s power and constituted by following units including a boat body having a predetermined length and width, at least one mounting means provided at a position that is away by a predetermined distance from a longitudinal axis of the boat body to at least one outside of left and right sides, and at least one propulsion apparatus coupled to the mounting means to operate by a rider&#39;s arm, wherein the mounting means provides a first rotation axis in a vertical direction. 
         [0032]    Each of the propulsion apparatuses includes a rotational post fixed in position by the mounting means to rotate about the first rotation axis, a handle crank having a predetermined length and placed in a width direction of the boat body so that an outer end thereof is coupled to an upper portion of the rotational post, an oscillating crank having a predetermined length and placed in a longitudinal direction of the boat body so that a front end thereof is coupled to the rotational post, and a rear end thereof has a height less than that of the outer end of the handle crank, and a plate-shaped foil having a predetermined length and height and coupled to the rear end of the oscillating crank in a longitudinal direction of the boat body. 
         [0033]    Thus, when the rider grasps the handle crank to alternately move forward and backward, the foil may oscillate in a left and right direction about the first rotation axis to generate propulsion force. 
         [0034]    Here, in order to maximize the simplicity of the apparatus while maintaining propulsion efficiency, the human-powered boat according to the present invention includes following three limitations.
       {circle around (1)} If the first rotation axis is not tilted, the oscillating crank is not tilted through the vertical movement of the rider&#39;s arm.   {circle around (2)} A motion range of the foil does not reach the longitudinal axis of the boat body.   {circle around (3)} The generation of the propulsion force under the portion of the boat body submerged in the water is limited to a predetermined level.       
 
         [0038]    In addition to the above constituents, in the human-powered boat according to the present invention, the oscillating crank may be spread at an angle of 5 degrees or more in its top plan view to the outside of the boat body to increase the motion range of the foil. 
         [0039]    Also, in order to effectively apply the knowledge of oscillating foil mechanism, a flapping hinge having a rotation axis in the vertical direction may be coupled to the rear end of the oscillating crank, and the foil may be coupled to the flapping hinge in a longitudinal direction of the boat body, wherein since the foil horizontally rotates at a predetermined angle about the rotation axis provided by the flapping hinge, the foil may have a specific pitch in generating propulsion force. Here, when a side surface of the foil is divided into two front and rear portions by a virtual vertical center line, the rear portion may be more flexible than the front portion. 
       Advantageous Effects of Invention 
       [0040]    In the human-powered boat according to the present invention, the L-shaped propulsion apparatus may be basically used to allow the rider to row in the moving direction of the boat (the rider rows facing forward), thereby giving the psychological stability to the rider. 
         [0041]    The unnecessary additional ideas may be eliminated to provide the propulsion apparatus having the maximally simplified structure while maintaining the high-efficient propulsion property of the oscillating foil mechanism. This may provide the effects of the easy handling and reduced manufacturing costs. 
         [0042]    Also, the motion range for generating the propulsion force at a side of the boat body may be sufficiently secured without using an outrigger to reduce the manufacturing costs and the overall width of the human-powered boat, thereby allowing the boat to be used in the crowded aquatic environments such as the public swimming pool. 
         [0043]    The rider may operate the propulsion apparatus through his/her arm movement freely without being aware of whether the propulsion apparatus is tilted or not, and also, the propulsion apparatus may be easily detached from or mounted on the boat body. 
         [0044]    A means for protecting the propulsion apparatus when colliding with the underwater obstacle may be prepared. 
         [0045]    Since the foil of the propulsion apparatus has the structure having a vertical rotation axis by itself, the injection molding may be easy, and the manufacturing costs may be reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0046]      FIG. 1  is a view illustrating a basic configuration and operation of an oscillating foil mechanism. 
           [0047]      FIGS. 2A to 2C  are views illustrating a human-powered propulsion apparatus and a geometry and mechanism of a human-powered boat using the same according to the present invention. 
           [0048]      FIG. 2D  is a photograph of a state in which a working demonstrator of the human-powered boat illustrated in  FIG. 2C  is prepared to give a demonstration according to a first embodiment of the present invention. 
           [0049]      FIGS. 3A to 3C  are views of the human-powered boat according to the first embodiment of the present invention. 
           [0050]      FIGS. 4A to 4C  are views of a human-powdered propulsion apparatus of  FIG. 3A  according to the first embodiment of the present invention. 
           [0051]      FIGS. 5A to 5G  are views illustrating a configuration and operation of the human-powered propulsion apparatus of  FIG. 4A . 
           [0052]      FIGS. 6A and 6B  are views illustrating a configuration and operation of a mounting means of  FIG. 3A . 
           [0053]      FIGS. 7A to 7E  are views of a human-powered propulsion apparatus according to a second embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0054]    Embodiments of the present invention will now be described with reference to the accompanying drawings. 
         [0055]    The present invention relates to a propulsion apparatus to which an oscillating foil mechanism is applied to an ‘L-shaped oar’ and a boat that obtains propulsion force by using the same. The L-shaped oar means an oar having a ‘loom that is bent in an L shape’ in the whole outer appearance in a top plan view. This L-shaped oar may convert rider&#39;s forward and backward arm movement that is inputted to one end of the oar into a left and right motion of the other end when setting the boat&#39;s sailing direction forward. 
         [0056]      FIG. 2A  is a schematic top plan view illustrating a human-powered propulsion apparatus and a geometry and mechanism of a human-powered boat using the same according to the present invention. A human-powered boat  100 , according to the present invention, has a structure in which two L-shaped propulsion apparatuses  35  are mounted bilaterally symmetric to each other with respect to a longitudinal axis  99  of a boat body  79  having a predetermined length and width and moving forward (M). In the present invention, a human-powered boat  100  may be a boat in a dictionary definition that is a small ship designed to be able to float while moving on water as well as a board concept including an inflatable float having various shapes in which a person rides thereon on water. In addition, it is preferable that the boat body  79  constituting the human-powered boat  100  of the present invention includes an inflatable float on at least one side of both sides thereof or the boat body is an inflatable float in itself but is not limited thereto. In detailed descriptions with respect to the position and configuration of the propulsion apparatus  35 , a first pivot  11  is positioned away by a predetermined distance outward from a longitudinal axis  99  of the boat body  79 , and the propulsion apparatus  35  oscillates about the first pivot  11 . Here, a potion at which a handle crank  31  and an oscillating crank  32 , which serve as an oar&#39;s loom in the propulsion apparatus  35 , meet approximately perpendicular to each other and then coupled to each other is fixed to the boat body  79  by the first pivot  11 . 
         [0057]    As illustrated in the drawings, the handle crank  31  has a predetermined length and is placed in a width direction of the boat body  79  so that an outer end  33  thereof is coupled to the first pivot  11 , and the oscillating crank  32  has a predetermined length and is placed in a longitudinal direction of the boat body  79  so that a front end thereof is coupled to the first pivot  11 . Here, it is preferable that the handle crank  31  and the oscillating crank  32  are coupled to each other at an angle that is approximately perpendicular to each other, but the angle may be adjusted according to a position of the rider or a structure of the boat body  79 . 
         [0058]    In addition, a plate-shaped foil  12  having a length and height is coupled to a rear end  34  of the oscillating crank  32  in a longitudinal direction of the boat body  79 . When the rider seats behind the handle crank  31  and grips it by hand and then alternately move the handle crank  31  forward and backward, the foil  12  may oscillate in a left and right direction about the first pivot  11  to generate propulsion force. This operation may correspond to forward-facing rowing in which the rider faces an advancing direction of the boat body  79  and moves the boat. 
         [0059]    Here, the propulsion apparatus  35  is illustrated in a state in which the oscillation is stopped at an angle at which propulsion resistance with respect to a flow of the water in a longitudinal direction of the boat body  79  is smallest and this state may be defined as an idle state in the present invention. 
         [0060]    To improve efficiency of the propulsion apparatus  35  according to the oscillating foil mechanism that is described above under the title of background, it is preferable that a second pivot  13  is added to a portion at which the oscillating crank  32  and the foil are coupled to each other. Here, the second pivot  13  may allow the propulsion apparatus  35  to have a specific pitch in generating the propulsion force, like a propeller, and the foil  12  may complexly oscillate about the first pivot  11  and the second pivot  13 . 
         [0061]    In the present invention, when a maximal oscillation is performed having the same left and right angle with respect to the idle state of the oscillating crank  32  to generate the propulsion force, an area on which the foil  12  is swept on a virtual plane that is parallel to the water surface and cuts a center of the foil  12  may be defined as a maximum motion range  21 . In the drawing, the area is expressed on portions of the propulsion apparatus  35 , which are symmetrically opposed to each other, due to spatial restraint. 
         [0062]      FIG. 2B  is a schematic front view of the human-powered boat  100  illustrated in  FIG. 2A .  FIG. 2B  illustrates a left side of the boat body  79 . Since the outer end  33  of the handle crank  31  is positioned in a higher portion of the boat body  79 , and the rear end  34  of the oscillating crank  32  is positioned in a lower portion of the boat body  79 , it is confirmed that a height difference H 1  is clearly generated between the outer end  33  and the rear end  34 . Further, the rear end  34  of the oscillating crank  32  is positioned higher than the lowest portion of the boat body  79 . 
         [0063]    A reason in which a distance  6  from a first rotation axis  55  provided by the first pivot  11  to a second rotation axis  66  provided by the second pivot  13  is greater than a straight-line distance L 1  from the first rotation axis  55  to the rear end  34  of the oscillating crank  32  in a longitudinal direction of the boat body  79  is for representing the technical knowledge in which the propulsion efficiency of the oscillating foil is improved when the second pivot  13  (or the second rotation axis  66 ) is positioned backward from a front portion of the foil  12  with somewhat space. 
         [0064]    Furthermore, it is preferable that the foil  12  has a height greater than a length thereof to form a shape that is elongated downward on the whole. This shape may improve the propulsion efficiency by quickly performing a flapping motion of the foil  12  together with the second rotation axis  66  moved backward. 
         [0065]    The above-described human-powered boat and human-powered propulsion apparatus may have three functional limitations in operation thereof. 
         [0066]    First, since the oscillating crank  32  oscillates about only the first rotation axis  55 , it is impossible to tilt the oscillating crank  32  through the vertical movement of the rider&#39;s arm during movement. Thus, it is difficult to adjust a depth, to which the foil is submerged in the water, by the rider as if a general oar is used. 
         [0067]    Second, since a range in which the oscillating crank moves without contacting the boat body  79 , is limited under a configuration that the first pivot  11  providing a center about which the propulsion apparatus oscillates is positioned on a side of the boat body  79 , it is difficult to allow the foil  12  to pass through the longitudinal axis of the boat body  79 . Accordingly, it is not effective to turn the angle of the foil  12  and use it as a rudder. 
         [0068]    Third, there is a limitation in moving the foil  12  under the submerged portion of the boat body  79  since the rear end of the oscillating crank  32  is positioned higher than the lowest portion of the boat body  79 . It is impossible to turn the foil  12  under the boat body  79  so as to convert the propulsion direction. 
         [0069]    In the human-powered boat  101  illustrated in  FIG. 2C , the propulsion apparatus  36  having an improved structure in which the oscillating crank  32  is spread outward to increase the motion range  21  of the foil  12  is mounted. This improvement may provide an economical effect, in which the motion range  21  is expanded, by locating the foil  12  of the propulsion apparatus farther away outward from the longitudinal axis  99  of the boat body  79 , without moving the fixed position of the first pivot  11  outward by adding an outrigger on the boat body  79 . 
         [0070]    Here, it is preferable that a ratio of a straight-line distance W 1  in a width direction of the boat body  79  to a straight-line distance L 2  in a longitudinal direction of the boat body  79  from the first pivot  11  to the end  34  of the oscillating crank has an arc tangent of 5 degrees or more. 
         [0071]      FIG. 2D  is a photograph of a state in which a working demonstrator of the human-powered boat is prepared to give a demonstration according to a first embodiment of the present invention in which various functions are added and embodied while maintaining the geometry and mechanism of the human-powered boat  101  in the top plan view illustrated in  FIG. 2C . 
         [0072]    According to results of a performance test, the human-powered boat may move at a speed that is greater than a walking speed despite the rider is a child having weak physical strength and the boat causes large propulsion resistance. It is also confirmed that previous education or practice is unnecessary when the propulsion apparatus  36  is initially used, and a reverse propulsion function is unnecessary because the boat is easily changed in direction. This may be impossible or very difficult in case where a child rows a general oar. 
         [0073]    The results of the performance test confirm that various functional limitations do not have significant effect on product value due to maximally simplified structure. Therefore, the human-powered boat and the human-powered propulsion apparatus according to the present invention may take the above-described embodied functional limitations as technical features of the present invention. 
         [0074]    The functional limitations of the human-powered boat and the human-powered propulsion apparatus according to the present invention will be described in detail as follows with reference to  FIGS. 2A to 2C . 
         [0075]    First, it is impossible to tilt the oscillating crank  32  through the vertical movement of the rider&#39;s arm without tilting the first rotation axis  55 . This may limit a motion form of the oscillating crank  32  during movement, and thus, the allowable motion may only be the oscillation about the first rotation axis  55 . 
         [0076]    Thus, since an erroneous operation of the rider (erroneous arm operation) during movement does not cause a tilting of the oscillating crank  32  (about a center line in a longitudinal direction of the boat body  79  or a center line in a width direction of the boat body  79 ), the propulsion force of the foil  12  may be generated in the uniform direction to improve the propulsion efficiency. At the same time, the rider may move freely without having a concern of the mistake thereof. 
         [0077]    Second, the maximum motion range  21  of the foil  12  does not cross the longitudinal axis  99  of the boat body  79 . Thus, the function of each of the propulsion apparatuses  35  and  36  as a static rudder may be limited. However, since the propulsion apparatus according to the present invention generates the propulsion force on the side of the boat body  79 , the direction change may be enabled by causing a difference in left and right propulsion forces of the boat body  79 . As a result, a dynamic rudder function is maintained as ever. 
         [0078]    Third, when the maximum motion range  21  of the foil  12  and ‘the area of the boat body submerged in the water (a plane of draft)’ are vertically projected onto the same virtual horizontal plane, the portion overlapped by each other may be less than 30% of the total area of the maximum motion range  21 . Thus, the range in which the propulsion force is generated may be limited in size. Here, a smaller overlapping portion is preferable, but the size percentage of overlapped portion is set under consideration of a change in draft according to loaded weight. 
         [0079]    In the second and third functions, each of the propulsion apparatuses is limited in size and capacity. If the propulsion apparatus mounted on the side of the boat body  79  operates to cross the longitudinal axis  99  of the boat body  79 , the oscillating crank  32  may be elongated, or a power transmission device may be added thereby increasing a size of the propulsion apparatus. Therefore, this functional limitation may be necessary to simplify the propulsion apparatus. Since it has a clear limitation to improve the propulsion efficiency by increasing the maximum motion range of the foil  12  under the condition in which the limited human power is used as input power, this limitation may be preferable in consideration of the ‘scale efficiency’. 
         [0080]    Also, if the propulsion apparatus widely operates under the area of the boat body  79  that is submerged in the water, the portion of the oscillating crank  32 , which is submerged in the water increases (because the depth of the boat body  79  generally increases in cross-section toward a middle portion thereof) thereby causing unnecessary propulsion resistance. Thus, this limitation may act as a direct pulse effect in improving of the propulsion efficiency. 
         [0081]    As described above, the present invention adopts the three functional limitations to maximize the simplicity of the apparatus while maintaining the propulsion efficiency and obtain the reflective improvement in performance from each of the limitations. At a word, removing unnecessary ideas may improve the values of products. 
         [0082]    The human-powered boat according to the first embodiment 101 of the present invention will be described in detail with reference to  FIGS. 3A to 3C . 
         [0083]    Referring to the perspective view of  FIG. 3A  and the top plan view of  FIG. 3B , the human-powered boat  101  according to the present invention has a structure in which two L-shaped propulsion apparatuses  36  and  36 ′ are mounted on an inflatable boat body  179  having a predetermined length and width and moving forward, and bilaterally symmetrical to each other with respect to the longitudinal axis  99  of the boat body  179 . Each of the propulsion apparatuses  36  and  36 ′ illustrated in  FIG. 3B  is in an idle state. 
         [0084]    In detailed description of position and configuration of the propulsion apparatuses  36  and  36 ′, mounting means  37  and  37 ′ may be coupled to positions that are away by a predetermined distance outward from the longitudinal axis  99  to left and right sides of the boat body  179 , and the propulsion apparatuses  36  and  36 ′ each of which has an L-shaped oar are respectively coupled to the mounting means  37  and  37 ′. Here, the mounting means  37  and  37 ′ may provide first pivots  11  and  11 ′ to the propulsion apparatuses  36  and  36 ′ coupled thereto, respectively. Thus, the propulsion apparatuses  36  and  36 ′ may overall oscillate about the first pivots  11  and  11 ′, respectively. 
         [0085]    Oars&#39; looms, which determine the whole shapes of the propulsion apparatuses in  FIG. 3B , may be formed by coupling handle cranks  31  and  31 ′ to oscillating cranks  32  and  32 ′. It is seen that the first pivots  11  and  11 ′ are positioned on places at which the handle cranks  31  and  31 ′ and the oscillating cranks  32  and  32 ′ meet to be coupled to each other. Each of the handle cranks  31  and  31 ′ has a predetermined length and is placed in a width direction of the boat body  179  so that an outer end thereof is coupled to each of the first pivots  11  and  11 ′. Also, each of the oscillating cranks  32  and  32 ′ has a predetermined length and is placed in a longitudinal direction of the boat body  179  so that a front end thereof is coupled to each of the first pivots  11  and  11 ′. 
         [0086]    Here, it is preferable that each of the handle cranks  31  and  31 ′ and each of the oscillating cranks  32  and  32 ′ are coupled to each other at an angle that is approximately perpendicular to each other. However, the angle may be adjusted according to a position of the rider or a structure of the boat body  179 . 
         [0087]    Also, each of plate-shaped foils  12  and  12 ′, each of which has a length and height, is coupled to a rear end of each of the oscillating cranks  32  and  32 ′ in a longitudinal direction of the boat body  179 . When the rider seats behind the handle cranks  31  and  31 ′ and grips them by hands and then alternately move the handle cranks  31  and  31 ′ forward and backward, the foils  12  and  12 ′ may oscillate in a left and right direction about each of the first pivots  11  and  11 ′ to generate propulsion force. This operation may correspond to forward-facing rowing in which the rider faces an advancing direction of the boat body  179  and moves the boat. 
         [0088]      FIG. 3C  illustrates a right side view of the human-powered boat according to the first embodiment of the present invention. Here, the handle crank  31  is positioned above the mounting means  37 , and the oscillating crank  32  is positioned below the mounting means  37 . As shown in the drawing, it is preferable that the oscillating crank  32  is positioned above the water surface and thus does not contact the water surface during the operation, and the whole of the foil  12  may be submerged under the water surface if possible. 
         [0089]    The human-powered propulsion apparatus according to the present invention may represent a combination of the mounting means and the propulsion apparatus. 
         [0090]      FIGS. 4A to 4C  are views of the human-powered propulsion apparatus of  FIG. 3A  according to the first embodiment of the present invention. Only the propulsion apparatus  36  mounted on the left side of the boat body  179  and operated by a left hand of the rider and the mounting means  37  fixing the propulsion apparatus  36  to the boat body  179  are illustrated. 
         [0091]    The mounting means  37  positioned on the side of the boat body  179  provides a first rotation axis  55  in a vertical direction to the propulsion apparatus  36  paired therewith. 
         [0092]    The propulsion apparatus  36  includes a rotational post  30  fixed in position by the mounting means  37  to rotate about the first rotation axis  55 , a handle crank  31  having a predetermined length and placed in a width direction of the boat body  179  so that an outer end thereof is coupled to an upper portion of the rotational post  30 , an oscillating crank  32  having a predetermined length and placed in a longitudinal direction of the boat body  179  so that a front end thereof is coupled to the rotational post  30 , and a plate-shaped foil  12  having a predetermined length and width and coupled to a rear end of the oscillating crank  32  in a longitudinal direction of the boat body  179 . When the rider grasps the handle crank  31  and alternately move forward and backward, the foil  12  oscillates about the first rotation axis  55  to generate propulsion force. 
         [0093]    Referring to the plan view of  FIG. 4B , when the position of the first rotation axis  55  is expressed as the first pivot  11 , a ratio W 1 /L 2  of a straight-line distance W 1  from the first pivot  11  to an end of the oscillating crank  32  in a width direction of the boat body  179  to a straight-line distance L 2  from the first pivot  11  to an end  34  of the oscillating crank  32  in a longitudinal direction of the boat body  179  may has an arc tangent value of 5 degrees or more. According to the geometry, a sufficient motion range  221  in which the foil  12  oscillates in the left and right directions may be secured although the mounting means  37  is closely coupled to the side of the inflatable boat body  179 . 
         [0094]    Also, if the mounting means  37  is modified in shape like an outrigger so that the first pivot  11  is positioned more away from the boat body  179 , the motion range of the foil  12  may increase without spreading a rear portion of the oscillating crank to the outside of the boat body  179 . 
         [0095]    Referring to the right side view of  FIG. 4C , a rear end  34  of the oscillating crank  32  has a height less by a predetermined height H 1  than that of an outer end  33  of the handle crank  31 . This is done because the height at which the rider easily moves an arm is higher than the water surface. 
         [0096]    Also, the rear end  34  of the oscillating crank  32  may be positioned higher than the lowest portion of the boat body  179 . This is intended to reduce the propulsion resistance during the operation by minimizing the portion of the oscillating crank  32 , which is submerged under the water surface. 
         [0097]    In addition, in the structure in which the oscillating crank  32  and the foil  12  are coupled to each other, a flapping hinge  67  having a rotation axis  66  in a vertical direction is coupled to the rear end of the oscillating crank  32 , and then, the foil  12  is coupled to the flapping hinge  67  in a longitudinal direction of the boat body  179 . 
         [0098]    Thus, since the foil  12  horizontally rotates at a predetermined angle θ about the rotation axis  66  provided by the flapping hinge  67 , the foil  12  has a specific pitch in generating propulsion force, like a propeller. Here, the rotation axis  66  provided by the flapping hinge  67  may be the same as the rotation axis provided by the second pivot  13 , which is illustrated in  FIGS. 1, 2A, 2C, and 4B . 
         [0099]    According to the above-described technical knowledge of the oscillating foil, as illustrated in  FIG. 4C , it is preferable that the foil  12  has a shape that is vertically elongated on the whole, so that the foil  12  has a height greater than a length thereof, Also, it is preferable that a rear portion of the foil  12  is more flexible than a front portion of the foil  12  when a side surface of the foil  12  is divided into two front and rear portions by using a virtual vertical center line  88 . 
         [0100]    The human-powered propulsion apparatus according to the first embodiment of the present invention will be more particularly described with reference to exploded views and operations illustrated in  FIGS. 5A to 5G . 
         [0101]    Referring to the exploded view of  FIG. 5A , in the propulsion apparatus  36  having the structure in which the rotational post  30  and the handle crank  31  are coupled to each other, a motion hinge  77  having a rotation axis  771  in a longitudinal direction of the boat body  179  is coupled to an upper portion of the rotational post  30 , and an outer end of the handle crank  31  is coupled to the motion hinge  77  in a width direction of the boat body  179 . 
         [0102]    Thus, as illustrated in the front view of  FIG. 5B , the handle crank  31  may oscillate at a predetermined angle about the rotation axis provided by the motion hinge  77 . As a result, when the rider grasps and rows the handle crank  31 , an upward and downward motion may be added to a forward and backward motion to allow the rider&#39;s hand moves along an oval path at if the rider rows a general oar. However, although the rider&#39;s arm movement is free as described above, the motion transmitted to the oscillating crank  32  in  FIG. 5A  may be only the oscillation about the first rotation axis  55 . 
         [0103]    Particularly, the motion hinge  77  may be provided by coupling a first coupling element  774  coupled to the handle crank  31  to a second coupling element  773  coupled to the rotational post  30  by inserting a hinge pin  772  having a rotation axis  771  in a longitudinal direction of the boat body  179 . 
         [0104]    As illustrated in  FIG. 5B , it is preferable that the vertical oscillating motion range of the handle crank  31  is limited from a horizontal line to a vertical line. This may be easily realized by forming an L-shaped hooking portion  775  in the second coupling element  773 . 
         [0105]    Referring to the exploded view of  FIG. 5C , in the propulsion apparatus  36  having the structure in which the oscillating crank  32  and the foil  12  are coupled to each other, a retracting hinge  78  having a rotation axis  781  in a width direction of the boat body  179  is coupled to the rear portion of the oscillating crank  32 , and the foil  12  is coupled to the retracting hinge  78  in a longitudinal direction of the boat body  179 . 
         [0106]    Thus, as the right side view illustrated in  FIG. 5D , when the foil  12  collides with an underwater obstacle  789 , the foil  12  may rotate at a predetermined angle about the rotation axis provided by the retracting hinge  78  and be lifted upward to reduce the risk of damage. Here, it is preferable that the vertical oscillating motion range of the foil  12  is limited from a vertical line to horizontal line. This may be easily realized by forming an L-shaped hooking portion  783  in a third coupling element. 
         [0107]    As described above, it is seen that two hinges such as the flapping hinge  67  and the retracting hinge  78  may be added when the oscillating crank  32  and the foil  12  of the human-powered propulsion apparatus are coupled to each other. Explaining a specific configuration, in which the two hinges are added at once, with reference to  FIG. 5C , a third coupling element  783  is coupled to the rear end of the oscillating crank  32 , and then, a fourth coupling element  784  is coupled by using a horizontal hinge pin  782  to constitute the retracting hinge  78 . 
         [0108]    Subsequently, a fifth coupling element  674  is coupled to a rear portion of the fourth coupling element  784  by using a vertical hinge pin  672  to constitute the flapping hinge  67 . The foil  12  is coupled to a rear portion of the fifth coupling element  674  in a longitudinal direction of the boat body  179 . 
         [0109]    Here, the fourth coupling element  784  includes at least one or more rings  785  that are spaced away at a predetermined distance from each other along the second rotation axis  66  provided by the vertical hinge pin  672 , and the fifth coupling element  674  includes at least one or more rings  675  that are disposed to miss the rings of the fourth coupling element. Thus, when the fourth coupling element  784  and the fifth coupling element  674  are coupled to each other, the rings  786  and  675  respectively provided at the elements may be engaged with each other like gears and then strung downward from top to bottom in a line by using the vertical hinge pin  672  and fixed in position. 
         [0110]    In the coupling structure as described above, two hinge&#39;s function may be realized at the same time with small number of components. Also, since it is impossible to disassemble the flapping hinge  67  without withdrawing the hinge pin  782  constituting the retracting hinge  78 , the flapping hinge  67  that has to endure vibrations may be improved in durability. 
         [0111]    Here, at least one stopping protrusion  786  is disposed on each of left and right sides of the fourth coupling element  784 , and at least one stopping protrusion  676  is disposed on each of left and right sides of the fifth coupling element  674 . Since the stopping protrusions  786  and  676  are positioned at the same height when being coupled, if the foil  12  starts to rotate in one direction from the idle state illustrated in  FIG. 5E  (a rear view) with respect to the oscillating crank  32 , the rotation stops when the stopping protrusions  786  and  676  meet together, so that the maximum rotation range of the fin is defined. 
         [0112]    The oscillation of the foil  12  with respect to the oscillating crank  32  is illustrated in the top plan view of  FIG. 5G . Here, the second rotation axis  66  provided by the flapping hinge  67  may be the same as the second pivot  13  on the drawing. Angles β and β′ at which the foil rotates in a left or right direction with respect to the idle state may be different from each other. In this case, it is preferable that the internal angle positioned closer to the boat body  179  is greater than another angle (β&gt;β′). 
         [0113]    In the human-powered propulsion apparatus according to the first embodiment of the present invention, since the oscillating crank  32  is coupled to a lower portion of the rotational post  30 , it is difficult to detach or mount the propulsion apparatus  36  from or to the mounting means  37 . 
         [0114]    However, in case of that the boat body  179  is inflatable as described in the human-powered boat according to the first embodiment of the present invention, or a potion of the boat body  179 , on which the mounting means is fixed, is provided as an inflatable float, if the mounting means  37  may be divided into at least two components  371  and  372  by using at least one vertical cross-section as illustrated in the perspective view of  FIG. 6A , contact surfaces of at least two components constituting the mounting means  37  may be spread to easily detach the propulsion apparatus  36  from the mounting means  37  in a state in which air within the boat body  179  may be discharged to reduce an internal pressure as illustrated in  FIG. 6B . 
         [0115]    As described above, the vertically divided mounting means  37  may be manufactured through injection molding by using a simple mold and thus reduced in manufacturing costs. 
         [0116]    In the human-powered boat according to the first embodiment of the present invention, the boat body is for a one-seater boat and two propulsion apparatuses  36  and  36 ′ positioned bilaterally symmetrical to each other are mounted on the boat body. In case of a two or more-seater boat on which two or more persons may ride side by side at left and right sides, each of the propulsion apparatuses may be asymmetrically disposed on left and right sides one another. Thus, regarding the mounting of the propulsion apparatuses, the symmetrical feature of the propulsion apparatuses may be flexibly applicable. 
         [0117]    In some cases, the present invention may include a structure in which only one propulsion apparatus is mounted on one side of the boat body  179 , and the general oar is rowed at an opposite side. 
         [0118]      FIGS. 7A to 7E  are views of a human-powered propulsion apparatus according to a second embodiment of the present invention. Referring to  FIG. 7A , in a human-powered propulsion apparatus  336  according to a second embodiment of the present invention, it is confirmed that an oscillating crank  322  is coupled to an upper portion of a rotational post  30 , unlike the propulsion apparatus  36  according to the foregoing first embodiment. Referring to  FIG. 7B , the oscillating crank  322  gradually decreases in height from a portion thereof coupled to the rotational post  30  to a rear of a boat body  179  and then is coupled to a foil  12 . A shape in which the oscillating crank  322  is inclined backward and downward may provide an effect in which energy loss is less because a portion of the oscillating crank  322 , which is submerged under the water, is reduced even though the boat body  179  is deeply submerged under the water surface due to the large loadage. 
         [0119]    Also, the largest advantage of the propulsion apparatus  336  having the geometry is that the propulsion apparatus  336  may be easily lifted and detached from the boat body  179  as illustrated in  FIG. 7C . Of course, even when being mounted again, the rotational post  30  may be simply inserted into the mounting means  37  to mount the propulsion apparatus  336  on the boat body  179 . 
         [0120]    Furthermore, in the propulsion apparatus  336  having the structure in which the rotational post  30  and the oscillating crank  322  are coupled to each other, a folding hinge  56  having a rotation axis  561  in a width direction of the boat body  179  is added to the coupled portion between the rotational post  30  and the oscillating crank  322 . Referring to  FIG. 7D , the folding hinge  56  includes a sixth coupling element  562  coupled to the rotational post  30 , and a seventh coupling element  563  inserted into the folding hinge  56  to rotate at a fixed angle about the rotation axis  561  in a width direction of the boat body  179  and coupled to a front end of the oscillating crank  322 . 
         [0121]    The sixth coupling element  562  and the seventh coupling element  563  do not have to be separated from each other during the operation of the propulsion apparatus  336  and have to provide a function that restricts the oscillating crank  322  so that the oscillating crank  322  stops to rotate downward at a specific angle. Since this is capable of being secured through a simple design change of the folding hinge  56 , such as adding of a predetermined locking means operable by a rider&#39;s hand and a modification of contact surfaces of the two coupling elements  562  and  563  into uneven surfaces, its detailed description will be omitted in the present invention. 
         [0122]    Due to the effect through the adding of the folding hinge  56 , the propulsion apparatus  336  may be reduced in overall volume because the oscillating crank  322  rotates upward at a predetermined angle about the rotation axis  561  provided by the folding hinge  56  and then is lifted. 
         [0123]    Referring to  FIG. 7E , the propulsion apparatus  336  is detached from the boat body  179 , and then, a handle crank  31  is folded upward with respect to a motion hinge  77 . Then, the oscillating crank  322  is folded upward with respect to the folding hinge  56 , and then, a foil  12  is folded upward with respect to a retracting hinge  78  to reduce the overall volume. Therefore, the propulsion apparatus  336  may be easily carried and stored. 
         [0124]    Of cause, the folding hinge  56  provides the same effect when the folding hinge  56  is applied to the human-powered propulsion apparatus  36  according to the first embodiment. 
         [0125]    The handle cranks  31  and  31 ′ and the oscillating cranks  32 ,  32 ,′ and  322  of the human-powered propulsion apparatus according to the present invention have to be changed in length according to the boat body  179  or a body size of the rider. For example, when the boat body  179  increases in width thereby increasing a distance from the rider&#39;s position to the mounting means, it is necessary to increase a length of each of the handle cranks  31  and  31 ′. Also, the increase in length of each of the oscillating cranks  32 ,  32 ′ and  322  may be effective as a method for expanding the motion range of each of the foils  12  and  12 ′. 
         [0126]    Thus, in the human-powered propulsion apparatus according to a third embodiment of the present invention, each of the handle cranks  31  and  31 ′ or the oscillating cranks  32 ,  32 ′ and  322  may have a telescopic tube structure that is adjustable in length. Since this structure is commonly found from an umbrella to a smartphone antenna, the structure will be omitted in the drawings. 
         [0127]    However, the telescope tube structure may include a stopping means for fixing the telescopic tube such after a length of the telescope tube is adjusted as a screw. Or, a constituent for remotely adjusting a length of each of the oscillating cranks  32 ,  32 ′ and  322  by using a string may be added. Since these constituents are commonly adopted to operate a sail or rudder in the small-sized boat technical fields, their detailed descriptions will be omitted. 
         [0128]    The human-powered boat according to the second embodiment of the present invention may represent a human-powered boat in which the human-powered propulsion apparatus according to the second embodiment is mounted on the boat body  179  of the human-powered boat according to the first embodiment. Similarly, the human-powered boat according to the third embodiment of the present invention may represent a human-powered boat in which the human-powered propulsion apparatus according to the third embodiment is mounted on the boat body  179  of the human-powered boat according to the first embodiment. Thus, drawings with respect to the human-powered boats according to the second and third embodiments will be omitted. 
         [0129]    Various features according to each of the embodiments of the present invention may be mutually applied to each other. For example, the telescope tube structure of the human-powered propulsion apparatus according to the third embodiment may be applied to the handle crank of the human-powered propulsion apparatus according to the second embodiment, and the folding hinge of the human-powered propulsion apparatus according to the second embodiment may be applied to the human-powered boat according to the first embodiment. Also, the structure in which the mounting means of the human-powered boat according to the first embodiment is divided into at least two components may be applied to the human-powered boat according to the second or third embodiment. 
       INDUSTRIAL APPLICABILITY 
       [0130]    The present invention relates to the non-motorized movable human-powered boat and the human-powered propulsion apparatus thereof. Particularly, the present invention may be applied to the structure in which the rider rows the oar through the forward and backward movement of the rider&#39;s arm while facing the advancing direction of the boat.