Stand-up paddleboard

Abstract

This stand-up paddleboard minimizes the effects of waves while effectively generating and utilizing the vertical rebound force of the tail section to improve straight-line stability and propulsion, efficiently converting paddling motion into straight-line energy for high-speed and long-duration sailing. [Solution] The stand-up paddleboard 1 of this disclosure includes a hull body 10, a fin 50 disposed at the rear end of the hull body 10 extending vertically downward from the bottom surface of the hull body 10, and a tail portion 40 which is the rear part of the hull body 10. The tail portion 40 extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface 42 at its rear end that extends in both the vertical and width directions of the hull body 10. The lower side edges 41 of the tail portion 40 are formed in a sharp edge shape.

Description

【Technical Field】 【0001】 The present invention relates to a stand-up paddle board. 【Background Art】 【0002】 Conventional stand-up paddle (SUP) boards (hereinafter also referred to as "SUP boards") have one fin to ensure straight-ahead stability (see, for example, Non-Patent Documents 1 to 3). 【0003】 Competitive SUP boards have specific structural features in order to optimize propulsion efficiency and maneuverability on water. Generally, competitive SUP boards have an elongated shape compared to other types of SUP boards, with the front (nose part) tapering and the rear (tail part) being slightly wider than the nose part. In particular, race boards are made thinner with an emphasis on straight-ahead performance and speed. 【0004】 The bottom board surface structure (hull) mainly includes two types: displacement hull and planning hull. The displacement hull is designed to cut through water, has a V-shaped bottom surface, and is excellent in straight-ahead stability. On the other hand, the planning hull has a flat bottom surface and is designed to glide on the water surface. Competitive boards often adopt a hybrid hull that combines these characteristics. 【0005】 Also, a fin for ensuring straight-ahead performance and directional stability is attached to the rear of the bottom of the board (the bottom surface of the tail), and in particular, a single large fin (single fin) is arranged in race boards. 【Prior Art Documents】 【Patent Documents】 【0006】 【Non-Patent Document 1】 REI “How to Choose a Stand Up Paddle Board (SUP)” (accessed October 1, 2025), https: / / www.rei.com / learn / expert-advice / how-to-choose-a-stand-up-paddleboard.html [Non-Patent Document 2] GILI SPORTS “How to Choose a Stand Up Paddle Board” (accessed October 1, 2025), https: / / www.gilisports.com / blogs / sup-expert-advice / how-to-choose-a-stand-up-paddle-board [Non-Patent Document 3] BOTE BOARD Journal, "Choose Your Hull: A Look at Hull Design" (Accessed October 1, 2025), https: / / www.boteboard.com / blogs / experience / hull-design [Overview of the Initiative] [Problems that the invention aims to solve] 【0007】 However, a structure that relies on only one fin is susceptible to the effects of waves, raising concerns about the rear of the board tending to drift sideways. Especially in rough water conditions, it does not have sufficient resistance to the lateral forces caused by waves, requiring the SUP paddler to expend extra effort to maintain their course. 【0008】 Furthermore, the tail section of conventional competition SUP boards is generally wide and thin (relatively flat). As a result, while buoyancy is generated when the SUP board sinks into the water, the rebound force from this buoyancy is not sufficiently obtained, and it cannot be efficiently utilized for propulsion. The inefficiency of energy conversion is particularly pronounced when the tail section is wide and thin. It is presumed that this structure prevents the energy generated by paddling from being effectively converted into propulsion, making efficient propulsion difficult, especially for long-distance riding and competitive use. In addition, the conventional tail section structure has poor rebound characteristics in the vertical direction, which may also reduce energy efficiency when riding over waves. 【0009】 Furthermore, conventional SUP boards are typically designed with rounded edges (R-curves) on both sides of their bottom surface. This rounding allows water to escape laterally (to the sides), resulting in insufficient directionality for the water flow in the forward direction. Consequently, the SUP board lacks stability at the rear (the so-called "locking feeling"), and propulsion energy is dispersed laterally. This dispersion makes yaw motion (side-to-side sway) more likely in waves, leading to a decrease in propulsion efficiency and long-distance sailing performance. 【0010】 In this respect, it can be said that conventional SUP boards had room for improvement. 【0011】 This invention has been made in view of the circumstances described above, and its purpose is to provide a stand-up paddleboard that minimizes the effects of waves, effectively generates and utilizes the vertical rebound force of the tail to improve straight-line stability and propulsion, and efficiently converts paddling motion into straight-line energy to achieve high-speed and long-duration sailing. [Means for solving the problem] 【0012】 The aforementioned objectives of the present invention are achieved by the configuration described below. [1] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail section extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface at its rear end that extends in both the vertical and width directions of the hull body. The lower side edges of the tail portion are formed in a sharp, edge-like shape. Stand-up paddleboard. [2] When viewed from the side, if the front edge of the root of the fin is used as the reference point and the front side is designated as the first region and the rear side as the second region, The portion of the second region described above is the tail portion, The lower side edges of the tail portion are formed in a sharper, more angular shape compared to the lower side edges of the hull body in the first region. [1] Stand-up paddleboard. [3] The widthwise edges and lower edge of the flat surface are formed in a sharp, angular shape compared to the side edges on the underside of the hull body in the first region. [2] Stand-up paddleboard. [4] The tail section periodically sinks into the water surface in response to the paddling motion of the rower, thereby periodically generating a vertical rebound force. This repulsive force assists the forward propulsion of the hull body. A stand-up paddleboard as described in any one of [1] to [3]. [5] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail portion extends from the front to the rear while maintaining its thickness in a side view, and has a flat surface extending in both the vertical and width directions of the hull body at its rear end, and is box-shaped. The tail portion periodically generates a vertical repulsive force by periodically sinking into the water surface according to the paddling motion of the paddler. The forward propulsion force of the hull body is assisted by the repulsive force. Stand-up paddle board. [6] Both side surfaces in the width direction of the tail portion are formed in an inclined surface shape so as to approach each other in the width direction as going backward. The stand-up paddle board according to [1] or [5]. [7] The standing position portion of the paddler is set behind the center of gravity position of the hull body. The stand-up paddle board according to [1] or [5]. 【0013】 It is preferable to adopt the configuration of [1]. In this case, by the tail portion maintaining its thickness from the front to the rear, the vertical restoring force (repulsive force) against the sinking during the paddling motion increases, and the propulsion efficiency can be improved. Also, since the flat surface at the rear end of the tail portion extends in both the vertical and width directions,the contact area with water (such as seawater, etc.) is optimized during the periodic sinking due to the paddling motion, and the repulsive force can be adaptively generated. Furthermore, by forming both side edges on the lower side of the tail portion in a sharp edge shape, the water flow can be controlled, unnecessary lateral water flow can be suppressed, and the straight-ahead stability can be enhanced. By combining these elements, it is less affected by waves, and the paddling energy can be efficiently converted into forward motion, and as a result, the high-speed and long-time navigation performance by the paddler can be realized. It is preferable to adopt the configuration of [2]. In this case, by dividing the front and rear sides with reference to the leading edge at the base of the fin, the functional areas of the hull can be clearly defined, and optimal shape designs can be applied to each of the first area and the second area. In particular, by defining the second area as the tail part and forming the side edges on both lower sides of this tail part into a more acute edge shape compared to the first area, the controllability of the water flow in the rear part can be enhanced. This more acute edge structure can suppress not only the influence of transverse waves but also the lateral dispersion of water generated during the paddling operation, and can concentrate the propulsive force more in the straight-ahead direction. It is preferable to adopt the configuration of [3] above. In this case, the controllability of the water flow at the rear end of the tail part can be further enhanced. It is preferable to adopt the configuration of [4] above. In this case, in each cycle of the paddling operation by the paddler, when the whole hull repeats periodic forward and backward and up and down movements due to the paddle operation of the paddler, the tail part sinks into and contacts the water surface, thereby periodically generating a repulsive force in the vertical direction. At the same time, the water flow is controlled by the edge shape of the tail part, and the repulsive force against the sinking is efficiently converted into a forward propulsive force. As a result, the paddling energy of the paddler can be utilized to the maximum extent, and an additional propulsive force that cannot be obtained with a normal flat board shape can be generated. This effect is particularly remarkable in long-distance races or navigation on a wavy water surface (such as the sea surface), and it is possible to achieve faster and more sustainable navigation with the same paddling effort. Furthermore, the generation of this periodic repulsive force also contributes to reducing the fatigue of the paddler and leads to an overall improvement in competitive performance. It is preferable to adopt the configuration of [5] above. In this case, the tail section maintains its thickness from front to rear, increasing the vertical restoring force (rebound force) against sinking during paddling, thereby improving propulsion efficiency. Furthermore, the shape of the flat surface at the rear end of the tail section, which extends both vertically and horizontally, increases the three-dimensional contact area with water (such as seawater) during periodic sinking caused by paddling, generating a greater rebound force. Moreover, in each cycle of paddling by the rower, as the entire hull repeatedly undergoes periodic forward and backward and up and down movements due to the rower's paddle operation, the tail section contacts the water surface and sinks, periodically generating a vertical rebound force. Here, because the tail section has a large volume with thickness maintained from front to rear, it has the characteristic of easily sinking in water and simultaneously easily floating up. Due to this characteristic, when the tail section sinks in water, the rebound force against sinking is efficiently converted into forward propulsion force. At the same time, the board temporarily lifts out of the water and bounces upward, drastically reducing wave resistance and frictional resistance instantaneously. This phenomenon is fundamentally similar to how flying fish and dolphins experience less resistance when leaping out of the water than when swimming. As a result, the paddler's paddling energy is utilized to its fullest potential, efficiently generating additional forward propulsion that cannot be obtained with a normal flat board shape. This effect is particularly noticeable in long-distance races and when navigating on wavy waters (such as the ocean), allowing for faster and more sustained navigation with the same paddling effort. Furthermore, the generation of this periodic rebound force and reduction of resistance also contribute to reducing paddler fatigue, thereby improving overall competitive performance. The configuration described in [6] above is preferable. In this case, by making the tail section tapered in plan view (top view), it is possible to facilitate sinking into the water during the periodic up-and-down motion of paddling, while simultaneously suppressing water resistance when surfacing. This makes it possible to efficiently generate a rhythmic rocking motion on the water surface (for example, the sea surface). As a result, it is possible to improve the performance of movements such as bouncing using the propulsion force associated with paddling, and to further reduce the wave resistance and frictional resistance acting on the hull when bouncing. It is possible to achieve a light and agile propulsion force, much like that of a flying fish or dolphin leaping out of the water. The configuration described in [7] above is preferable. In this case, the paddler's weight is applied to the rear of the hull, which promotes interaction between the tail and the water surface (e.g., the sea surface). This allows the tail to sink appropriately into the water during the up-and-down motion of the hull accompanying paddling, efficiently converting its rebound force into propulsion. Furthermore, this standing position improves the stability of the hull against waves and water resistance from the front, optimizing the balance between straight-line tracking and maneuverability, especially in competitive applications. Moreover, by positioning the paddler behind the center of gravity of the hull, the synergistic effect with the forward-leaning posture during paddling enables energy-efficient propulsion, which can also reduce paddler fatigue during long paddling sessions. [Effects of the Invention] 【0014】 According to the present invention, while minimizing the effects of waves, the vertical rebound force of the tail section is effectively generated and utilized to improve straight-line stability and propulsion, and the paddling motion is efficiently converted into straight-line energy, enabling high-speed and long-duration navigation. 【0015】 The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by referring to the accompanying drawings and reading through the embodiments for carrying out the invention described below (hereinafter referred to as "embodiments"). [Brief explanation of the drawing] 【0016】 [Figure 1] Front top perspective view illustrating an example of the appearance of a SUP board according to the first embodiment of the present invention. [Figure 2] Rear lower perspective view illustrating an example of the appearance of a SUP board shown in Figure 1. [Figure 3] A plan view illustrating an example of the appearance of a SUP board shown in Figure 1. [Figure 4] A side view illustrating an example of the appearance of the SUP board shown in Figure 1. [Figure 5] Figure 4 is a side view enlarged illustrating an example of a SUP board with fins attached. [Figure 6] Figure 1 shows a bottom view illustrating an example of the appearance of a SUP board. [Figure 7] Rear upper perspective view illustrating an example of the external shape of the tail section shown in Figure 1. [Figure 8] Rear lower perspective view illustrating an example of the tail section shown in Figure 1 with fins attached. [Figure 9] Rear view illustrating an example of the external shape of the tail section shown in Figure 1. [Figure 10] A series of photographs showing the actual paddling action using the SUP board according to the present invention. [Figure 11] Figure 10 shows a series of photographs illustrating the paddling motion after the initial photograph. [Figure 12] Figure 11 shows a series of photographs illustrating the paddling motion after the initial photograph. [Figure 13] Figure 12 shows a series of photographs illustrating the paddling motion after the initial photograph. [Figure 14] Figure 13 shows a series of photographs (5) illustrating the paddling motion after the initial photograph. [Figure 15] Figure 14 shows a series of photographs (6) illustrating the paddling motion after the initial photograph. [Figure 16] Figure 15 shows a series of photographs (7) illustrating the paddling motion after the initial photograph. [Figure 17] Figure 16 shows a series of photographs (8) illustrating the paddling motion after the initial photograph. [Figure 18]Figure 17 shows a series of photographs (9) illustrating the paddling motion after the initial photograph. [Figure 19] Figure 18 shows a series of photographs illustrating the paddling motion after the initial photograph. [Modes for carrying out the invention] 【0017】 Hereinafter, embodiments specifically disclosing the stand-up paddleboard according to the present invention will be described in detail with reference to the attached drawings as appropriate. 【0018】 However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. Furthermore, each of the attached drawings should be viewed according to the orientation of the reference numerals. 【0019】 Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure, and are not intended to limit the subject matter described in the claims. 【0020】 <Explanation of Terms> The terms "including" or "characterized by," which are synonymous with "containing" and "containing," are to be interpreted in an inclusive or open sense and do not exclude additional, unlisted elements or steps of the method. "Including" is a technical term used in the language of the claims and means that the named claim elements are mandatory, but other claim elements may be added to further form components within the scope of the claims. The terms "equipped with" and "having" are similarly intended to be non-exclusive and mean that there may be additional elements beyond those listed. 【0021】 Furthermore, as used herein, the phrase "consisting of" excludes any element, step, or component not specified in the claim. Where the phrase "consisting of (or a variation thereof)" appears in a section of the body of the claim rather than immediately following the preamble, it limits only the elements indicated in that section, and does not exclude other elements from the claim as a whole. As used herein, the phrase "essentially consisting of" limits the scope of the claim to those that do not substantially affect the main components and novel features (singular or plural) of the claimed subject matter, in addition to the specified elements or method steps. 【0022】 With respect to the terms “contains,” “consistes of,” and “essentially consists of,” if any of these three terms is used herein, the subjects disclosed and claimed in this invention may also include the use of any of the other two terms. Thus, in some embodiments not expressly noted as otherwise, any instance of “contains” may be replaced by “consistes of” or “essentially consists of.” 【0023】 The terms “process” or “step” may be used explicitly or implicitly in relation to the characteristics of a process or method. However, unless otherwise specified, the order or procedure between such explicit or implicit processes or steps is not limited. 【0024】 <First Embodiment> A first embodiment of the stand-up paddleboard 1 (hereinafter also referred to as "SUP board") according to the present invention will be described based on Figures 1 to 9. The SUP board 1 in this embodiment is for competition use and is configured with a structure optimized to achieve both high speed and stability in racing competitions, as described later. The SUP board 1 is used on water surfaces such as the sea, lakes, or ponds. The fin 50 (see below) is detachable, and for the sake of explanation, the fin 50 is not shown in Figures 1, 4, 6, 7, and 9. 【0025】 [About the basic configuration] The basic configuration of the SUP board 1 according to this embodiment will be described with reference to Figures 1 to 6. Figure 1 is a front top perspective view illustrating an example of the appearance of the SUP board 1 according to this embodiment. Figure 2 is a rear-bottom perspective view illustrating an example of the appearance of the SUP board 1 shown in Figure 1. Figure 3 is a plan view illustrating an example of the external appearance of the SUP board 1 shown in Figure 1. Figure 4 is a side view illustrating an example of the appearance of the SUP board 1 shown in Figure 1. Figure 5 is a side view enlarged illustrating an example of the SUP board 1 shown in Figure 4 with the fin 50 attached. Figure 6 is a bottom view illustrating an example of the external appearance of the SUP board 1 shown in Figure 1. 【0026】 As shown in Figures 1 to 6, the SUP board 1 of this embodiment is configured to have a hull body 10 that extends in an elongated shape in the front-rear direction, and fins 50 attached to the bottom surface of the hull body 10. 【0027】 (• Hull body 10) The hull body 10 is a main body portion that extends in a plate-like shape in the longitudinal direction. The hull body 10 is formed by using a foamed resin material such as EPS foam, which has water resistance and sufficient buoyancy, as the core material, and laminating and hardening fiber-reinforced plastic (FRP), carbon fiber, or glass fiber around its outer circumference. This molding process results in a structure that is lightweight yet highly rigid for a SUP board 1. 【0028】 The hull body 10 is composed of a nose section 20 which is the front part of the hull body 10, a tail section 40 which is the rear part of the hull body 10, and a deck section 30 (central section) which is positioned between the nose section 20 and the tail section 40. A fin 50 is provided on the rear bottom surface of the hull body 10, i.e., the tail section 40. 【0029】 Next, we will describe the configuration of the nose section 20, deck section 30, fin 50, and tail section 40. 【0030】 (Nose section 20) As shown in Figures 1 to 4 and Figure 6, the nose section 20 is positioned at the front end of the hull body 10, and its tip is formed to be asymptotically tapered in the width direction, narrowing (pointing) and having a water-cutting shape. This water-cutting shape allows the nose section 20 to efficiently distribute and minimize resistance to the water surface (including the sea surface), thereby increasing propulsion efficiency when moving in a straight line, enabling it to cut through waves and move straight. 【0031】 Furthermore, the bottom of the tip of the nose section 20 is slightly curved upwards, specifically forming a curved shape that gradually and asymptotically rises slightly from the rear upwards when viewed from the side (see Figure 4). This curved shape allows the SUP board 1 of this embodiment to navigate stably even on wavy waters (for example, the sea), and in particular reduces resistance when facing headwinds. 【0032】 Furthermore, both of the widthwise edges of the bottom of the nose section 20 are formed as gently curved convex surfaces (R-surfaces) (see Figures 1, 2, 4, and 6). These convex surfaces extend continuously along their longitudinal direction from the nose section 20 to the central part of the hull body 10, and play a role in efficiently guiding the water flow to the sides of the hull. This improves straight-line stability and increases propulsion efficiency during paddling. 【0033】 With this configuration of the nose section 20, the SUP board 1 of this embodiment achieves an excellent balance of straight-line stability and maneuverability through a synergistic effect with the tail section 40, which will be described later, and can exhibit high performance, especially in competitive applications. 【0034】 (Deck section 30) As shown in Figures 1, 3, and 4, a deck section 30 is provided on the upper central part of the hull body 10, on which a competitor can board and maintain an upright posture. The deck section 30 is provided as a recessed (concave) central upper surface (see Figures 1 and 3). 【0035】 The deck section 30 is composed of a front inclined surface 31, a rear inclined surface 32, a flat surface 33 (an example of a "standing position"), and a pair of side wall sections 34. The combination of these components provides a stable footing for the paddler and enables efficient center of gravity shifting during paddling. 【0036】 The front inclined surface 31 of the deck section 30 is located in the front part of the deck section 30 and is formed to slope upward from the rear to the front. In addition, the front inclined surface 31 of the deck section 30 has a roughly triangular shape with its apex facing forward in a plan view (top view, see Figure 3). The rear inclined surface 32 of the deck section 30 is located in the rear part of the deck section 30 and is formed to slope upward from the front to the rear, and is also formed to be roughly rectangular in a plan view. 【0037】 The flat surface 33 of the deck section 30 is positioned between the front inclined surface 31 and the rear inclined surface 32, providing the main standing position for the rower. This flat surface 33 of the deck section 30 is appropriately wide and has an anti-slip surface to allow the rower to maintain a stable posture. In this embodiment, the center position of the flat surface 33 of the deck section 30 is set behind the center of gravity of the hull body 10. As a result, the rower's load is applied behind the center of gravity of the hull body 10. Consequently, when the rower is on the hull body 10, that is, when viewed as the entire system of the rower and the hull body 10, the overall center of gravity is positioned towards the rear in the fore-aft direction, in relation to the mass of the rower and the hull body 10. 【0038】 The pair of side walls 34 of the deck section 30 extend and stand along both side edges 41 of the deck section 30, defining the recessed shape of the deck section 30 in the width direction of the hull body 10. Furthermore, the front ends of each of the pair of side walls 34 of the deck section 30 are formed to be inclined so that they approach each other from rear to front in a plan view. As a result, the pair of side walls 34 of the deck section 30 are formed to form a roughly V shape in a plan view, corresponding to the roughly triangular shape of the front inclined surface 31 of the deck section 30. These pair of side walls 34 of the deck section 30 prevent the rower's feet from slipping laterally (in the width direction), and particularly assist in maintaining balance in unstable water conditions. In addition, each of the pair of side walls 34 of the deck section 30 has a drain hole 35 (see Figures 1, 2, and 4). Each of the drainage holes 35 is formed along the width direction of the hull body 10, connecting the inside of the deck section 30 with the outside of the hull body 10, and draining seawater and other fluids that accumulate in the deck section 30 to the outside. 【0039】 Furthermore, the deck section 30 may be fitted with PU reinforcing material (such as polyurethane) to increase the overall rigidity of the hull. This suppresses hull deflection caused by the weight of the competitor and paddling movements, ensuring stability and propulsion efficiency. It is also possible to enhance the anti-slip effect by attaching deck pads or applying anti-slip treatments to the surface of the deck section 30. 【0040】 (• Fin 50 configuration) As shown in Figures 2 and 5, a fin 50 is provided on the bottom surface of the rear end of the hull body 10 to provide straight-line stability. The fin 50 is shaped like the dorsal fin of a dolphin or orca and is positioned at the rear end of the hull body 10, extending vertically downward from the bottom surface of the hull body 10. The fin 50 is provided to ensure the straight-line stability of the SUP board 1 and enhance directional stability in the water. The fin 50 is formed from the same material as the hull body 10, or is appropriately molded from a highly rigid resin material or the like. 【0041】 Furthermore, the fins 50 are detachably attached to the hull 10 and can be replaced as appropriate according to competition conditions or the user's (rower's) preference. The structure of the fins 50 is generally a single-fin 50 structure with one fin in the center, but in some cases, a tri-fin 50 structure with auxiliary fins 50 on the left and right in addition to the central fin 50, or a quad-fin 50 structure with four fins 50 can also be adopted as appropriate. The fins 50 ensure the straight-line movement of the hull 10 (boat) and function as an axis point during turns. 【0042】 Furthermore, as shown in Figures 2 and 5, in this embodiment, when viewed from the side, the front side is defined as the first region A1 and the rear side as the second region A2, with the front end edge of the root of the fin 50 as the reference (boundary). The portion located in the second region A2 is configured as the tail section 40, and the portion located in the first region A1 corresponds to the aforementioned nose section 20 and central section (including the deck section 30). 【0043】 Furthermore, fins 50 can be appropriately selected in various shapes, sizes, thicknesses, and weights depending on the competition conditions, user preferences, and sea conditions. There are many different shapes of fins 50, from those that prioritize straight-line tracking to those that prioritize maneuverability, and these types of fins 50 are appropriately selected according to their purpose and can be attached and detached. The SUP board 1 of this embodiment can be used in combination with fins 50 of any shape. 【0044】 (Tail section 40) As shown in Figures 1 to 6, the tail section 40 is the rear portion of the hull body 10, that is, the second region A2 of the hull body 10 as described above. The tail section 40 extends from front to rear while maintaining its thickness in a side view (see Figures 4 and 5). In addition, the tail section 40 has a flat surface 42 at its rear end that extends in both the vertical and width directions of the hull body 10 (see Figures 2 to 6). In this way, the tail section 40 is formed in an overall box shape. The specific configuration of the tail section 40 will be described later. 【0045】 [Regarding the structure of the tail section 40] The specific configuration of the tail section 40 will be explained with reference to Figures 7 to 9. Figure 7 is a rear top perspective view illustrating an example of the external shape of the tail section 40 shown in Figure 1. Figure 8 is a rear-lower perspective view illustrating an example of the tail section 40 shown in Figure 1 with the fins 50 attached. Figure 9 is a rear view illustrating an example of the external shape of the tail section 40 shown in Figure 1. 【0046】 As shown in Figures 7 to 9, the tail section 40 extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface 42 at its rear end that extends in both the vertical and width directions of the hull body 10. In other words, unlike conventional thin and flat tail sections 40, the tail section 40 is formed in a box shape with a certain volume. Furthermore, each of the two widthwise sides of the tail section 40 is formed as an inclined surface that approaches each other in the width direction as it moves towards the rear. 【0047】 This box-like structure increases the three-dimensional contact area of ​​the tail section 40 with the water, enabling efficient generation of propulsion during paddling. Furthermore, the inclined surface formation on both sides of the tail section 40 in the width direction facilitates the sinking of the tail section 40 into the water and, as will be described later, makes it easier to obtain a large rebound force when sinking. 【0048】 In this embodiment, when the rower performs a paddling motion, the hull body 10 experiences periodic changes in velocity in the forward and backward directions. In the tail section 40 of this embodiment, this change causes the tail section 40 to periodically sink into the water. 【0049】 When the tail section 40 sinks into the water, its box-like structure increases the overall and three-dimensional contact area with the water due to its volume. This increase in contact area generates a large vertical rebound force (restoring force) in the tail section 40 relative to the water surface. This vertical rebound force occurs periodically in sync with each paddling stroke. This periodic rebound force enhances the forward propulsion force of the SUP board 1. In other words, as the tail section 40 sinks into the water and bounces back repeatedly, the periodically generated rebound force, in addition to the force of the paddler's paddling, is converted into forward propulsion force, generating even more forward momentum. This rebound force assists the forward propulsion force of the hull body 10. 【0050】 In this embodiment, the lower (bottom) side edges 41 of the tail section 40 are formed in a sharp edge shape. That is, the lower side edges 41 of the tail section 40 are formed in a sharper edge shape compared to the lower side edges of the hull body 10 in the first region A1, i.e., the nose section 20 and the central section. Specifically, while the lower side edges of the hull body 10 in the first region A1 (i.e., the nose section 20 and the central section) are formed with a relatively gentle curvature, the lower side edges 41 of the tail section 40 are formed at a steeper angle in comparison, and for example, have a sharp edge in cross-sectional view. 【0051】 Furthermore, the widthwise edges and lower edge of the flat surface 42 formed at the rear end of the tail section 40 are similarly formed in a sharp edge shape. Specifically, the widthwise edges and lower edge of the flat surface 42 of the tail section 40 are similarly formed at a steeper angle compared to the lower side edges of the hull body 10 in the first region A1, and have, for example, acute edges in cross-sectional view. 【0052】 The configuration of the tail section 40, which has such sharp, edge-shaped edges, allows for efficient control and regulation of water flow during paddling. Specifically, as mentioned above, when a rower paddles, the hull 10 undergoes periodic changes in speed in the forward and backward directions. When the tail section 40 sinks into the water due to these changes, the sharp, edge-shaped side edges 41 accurately capture the water flow and restrict the movement of the hull 10 in the width direction. This allows it to perform a function similar to that of a fin 50, and together with the aforementioned fin 50, it creates an effect as if there were effectively three fins 50. 【0053】 These sharp, edgy edges control the water flow as the tail section 40 sinks into the water, supporting the generation of appropriate rebound force and effective propulsion during paddling. The sharp, edgy edges 41 are formed by intersecting at a steep angle from the underside to the sides of the tail section 40, playing a role in efficiently directing the water flow. 【0054】 Furthermore, the lower side edges 41 of the tail section 40, and the widthwise edges and lower edge of the flat surface 42 of the tail section 40 are preferably set at approximately right angles (90°), but this set angle can be adjusted or changed as appropriate depending on the usage conditions or the user's skill. 【0055】 With this configuration of the tail section 40, the SUP board 1 of this embodiment is able to generate efficient propulsion when the tail section 40 interacts with the water surface during paddling. In particular, during each cycle of paddling, as the entire hull repeatedly undergoes periodic up-and-down motion due to the paddler's weight shift and paddle operation, the tail section 40 contacts the water surface and sinks, generating a vertical rebound force. This rebound force is efficiently converted into forward propulsion by the box shape and sharp, edge-shaped side edges 41 of the tail section 40. Furthermore, the sharp, edge-shaped side edges 41 accurately capture the water flow and suppress the movement of the hull body 10 in the width direction, so that the aforementioned rebound force is converted into forward propulsion without waste. 【0056】 In this embodiment, the width of the rear end of the tail section 40, that is, the width dimension of the flat surface 42 of the tail section 40, is set to be about one-third the width of the central part of the hull body 10. 【0057】 [Features and advantages of this embodiment] / / [1] As described above, the stand-up paddleboard 1 of this embodiment includes a hull body 10, a fin 50 that extends vertically downward from the bottom surface of the hull body 10 at the rear end of the hull body 10, and a tail portion 40 which is the rear part of the hull body 10. The tail portion 40 extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface 42 at its rear end that extends in both the vertical and width directions of the hull body 10. The lower side edges 41 of the tail portion 40 are formed in a sharp edge shape. 【0058】 As a result, the tail section 40 maintains its thickness from front to rear, increasing the vertical restoring force (rebound force) against sinking during paddling, thereby improving propulsion efficiency. Furthermore, the shape of the flat surface 42 at the rear end of the tail section 40, which extends in both the vertical and width directions, optimizes the contact area with water (e.g., seawater) during periodic sinking caused by paddling, allowing for adaptive generation of rebound force. In addition, the sharp edges 41 on both sides of the lower part of the tail section 40 control the water flow, suppressing unnecessary lateral water flow and improving straight-line stability. The combination of these elements makes the paddler less susceptible to wave effects, efficiently converts paddling energy into forward motion, and as a result, enables high-speed and long-duration navigation by the paddler. 【0059】 / / [2] Furthermore, according to the stand-up paddleboard 1 of this embodiment, when viewed from the side, if the front side is designated as the first region A1 and the rear side as the second region A2, with respect to the front end edge of the base of the fin 50, the portion of the second region A2 is designated as the tail section 40. The lower side edges 41 of the tail section 40 are formed in a sharp-angled edge shape compared to the lower side edges of the hull body 10 in the first region A1. 【0060】 This allows for a clear definition of the functional areas of the hull by dividing it into front and rear sections based on the front edge of the fin base 50, enabling optimal shape design for each of the first and second areas A1. In particular, defining the second area A2 as the tail section 40 and forming the lower side edges 41 of this tail section 40 into sharper edges compared to the first area A1 enhances the controllability of water flow in the rear section. This sharper edge structure not only reduces the effects of transverse waves but also suppresses the lateral dispersion of water generated during paddling, allowing the propulsion force to be concentrated more in the straight direction. 【0061】 / / [3] Furthermore, according to the stand-up paddleboard 1 of this embodiment, both ends and the lower end of the flat surface 42 (of the tail section 40) in the width direction are formed in a sharp-angled edge shape compared to both lower side edges of the hull body 10 in the first region A1. 【0062】 This further improves the controllability of water flow at the rear end of the tail section 40. 【0063】 / / [4] Furthermore, according to the stand-up paddleboard 1 of this embodiment, the tail section 40 periodically sinks into the water surface in response to the paddling motion of the paddler, thereby periodically generating a vertical repulsive force. This repulsive force assists in the forward propulsion of the hull body 10. 【0064】 As a result, in each cycle of paddling by the rower, as the entire hull repeatedly performs periodic forward and backward and up and down movements due to the rower's paddle operation, the tail section 40 sinks into the water and makes contact, periodically generating a vertical rebound force. At the same time, the edge shape of the tail section 40 controls the water flow, and the rebound force against sinking is efficiently converted into forward propulsion. This allows the rower's paddling energy to be utilized to the fullest extent, generating additional propulsion that cannot be obtained with a normal flat board shape. This effect is particularly noticeable in long-distance races or when navigating on choppy waters (e.g., the open sea), enabling faster and more sustained navigation with the same paddling effort. Furthermore, the generation of this periodic rebound force also contributes to reducing rower fatigue, leading to an overall improvement in competitive performance. 【0065】 / / [5] Furthermore, according to this embodiment of the stand-up paddleboard 1, the boat includes a hull body 10, a fin 50 that extends vertically downward from the bottom surface of the hull body 10 at the rear end of the hull body 10, and a tail section 40 which is the rear part of the hull body 10. The tail section 40 extends from front to rear while maintaining its thickness in a side view, and has a box shape with a flat surface 42 at its rear end that extends in both the vertical and width directions of the hull body 10. The tail section 40 periodically sinks into the water surface in response to the paddling motion of the rower, periodically generating a vertical repulsive force. This repulsive force assists in the forward propulsion of the hull body 10. 【0066】 As a result, the tail section 40 maintains its thickness from front to rear, increasing the vertical restoring force (rebound force) against sinking during paddling, thereby improving propulsion efficiency. Furthermore, the shape of the flat surface 42 at the rear end of the tail section 40, which extends in both the vertical and width directions, increases the three-dimensional contact area with water (e.g., seawater) during periodic sinking caused by paddling, generating a greater rebound force. Moreover, in each cycle of paddling by the rower, as the entire hull repeatedly undergoes periodic forward and backward and up and down movements due to the rower's paddle operation, the tail section 40 contacts the water surface and sinks, periodically generating a vertical rebound force. Here, because the tail section 40 has a large volume with thickness maintained from front to rear, it has the characteristic of easily sinking in water and simultaneously easily floating up. Due to this characteristic, when the tail section 40 sinks in water, the rebound force against sinking is efficiently converted into forward propulsion force. At the same time, the board temporarily lifts out of the water and bounces upward, drastically reducing wave resistance and frictional resistance instantaneously. This phenomenon is fundamentally similar to how flying fish and dolphins experience less resistance when leaping out of the water than when swimming. As a result, the paddler's paddling energy is utilized to its fullest potential, efficiently generating additional forward propulsion that cannot be obtained with a normal flat board shape. This effect is particularly noticeable in long-distance races and when navigating on wavy waters (such as the ocean), allowing for faster and more sustained navigation with the same paddling effort. Furthermore, the generation of this periodic rebound force and reduction of resistance also contribute to reducing paddler fatigue, thereby improving overall competitive performance. 【0067】 / / [6] Furthermore, according to the stand-up paddleboard 1 of this embodiment, each of the two sides of the tail section 40 in the width direction is formed as an inclined surface so that they get closer to each other in the width direction as they move towards the rear. 【0068】 This design, with its tapered tail section 40 in a plan view (top view), facilitates sinking into the water during the periodic up-and-down motion of paddling, while simultaneously suppressing water resistance during ascent. This allows for efficient generation of rhythmic rocking motions on the water surface (e.g., the sea surface). As a result, it enhances performance in actions such as bouncing using the propulsion force associated with paddling, and further reduces wave resistance and frictional resistance acting on the hull body 10 during bouncing. This enables the creation of a nimble propulsion force, much like that of a flying fish or dolphin leaping out of the water. 【0069】 / / [7] Furthermore, according to the stand-up paddleboard 1 of this embodiment, the flat surface 33 of the deck section 30 (an example of the "rower's standing position") is set further back than the center of gravity of the hull body 10. 【0070】 This allows the paddler's weight to load the rear of the hull, promoting interaction between the tail section 40 and the water surface (e.g., the sea surface). As a result, during the up-and-down movement of the hull 10 accompanying paddling, the tail section 40 sinks appropriately into the water, efficiently converting its rebound force into propulsion. Furthermore, this standing position improves the stability of the hull against waves and water resistance from the front, optimizing the balance between straight-line tracking and maneuverability, especially in competitive applications. Moreover, by positioning the standing position behind the center of gravity of the hull 10, the synergistic effect with the forward-leaning posture during paddling enables energy-efficient propulsion, which can also reduce paddler fatigue during long paddling sessions. [Examples] 【0071】 The usefulness of the present invention will be described in more detail with reference to one or more examples (tests). However, the examples described herein are merely technical information to aid in understanding the technical content of the present invention, and the subject matter described herein is not intended to be limited by this description of the examples. 【0072】 To confirm the usefulness of the SUP board according to the first embodiment of the present invention (1, hereinafter also referred to as "this embodiment"), a demonstration test was conducted by floating this embodiment on the actual surface of the sea. In this test, the actions of the paddler operating this embodiment by paddling were recorded in a series of photographs, and the relationship between the movements of the paddler and the embodiment was analyzed based on these records. 【0073】 Figures 10 to 19 are sequential photographs recorded during this test. Figure 10 is a series of photographs showing the actual paddling action using the SUP board (1) according to the present invention. Figure 11 is a sequence of photographs (2) showing the paddling motion after the photograph shown in Figure 10. Figure 12 is a sequence of 3 photographs showing the paddling motion after the photograph shown in Figure 11. Figure 13 is a sequence of photographs (4) showing the paddling motion after the photograph shown in Figure 12. Figure 14 is a sequence of 5 photographs showing the paddling motion after the photograph shown in Figure 13. Figure 15 is a sequence of 6 photographs showing the paddling motion after the photograph shown in Figure 14. Figure 16 is a series of 7 photographs showing the paddling motion after the photograph shown in Figure 15. Figure 17 is a sequence of photographs (8) showing the paddling motion after the photograph shown in Figure 16. Figure 18 is a sequence of photographs showing the paddling motion after the photograph shown in Figure 17. Figure 19 is a series of 10 photographs showing the paddling motion after the photograph shown in Figure 18. 【0074】 As shown in the sequential photographs in Figures 10 to 19, the test results confirmed that when the rower paddled at a constant rhythm, the tail section (40, the rear part of the hull (10), the second region (A2) of the hull (10)) periodically sank to the water surface, generating a vertical repulsive force, and that this force showed a high correlation with the paddling cycle. 【0075】 Specifically, it was observed that when the tail section (40) periodically sinks into the water surface in accordance with the paddling motion, the water mass trapped (pushed vertically downward) by the box-shaped structure (rear volume) of the tail section (40) is pushed backward in conjunction with the paddler's paddling motion, generating a forward propulsive force for the hull (10). Furthermore, it was observed that as this water mass is periodically pushed backward, the tail section (40) rises upward due to the continuous paddling motion, based on the law of action and reaction, resulting in a smooth continuity that leads to the next cycle. It was also observed that this phenomenon is enhanced by setting the center of gravity towards the rear of the hull (10) when considering the entire system of the paddler and the hull (10). 【0076】 Furthermore, in this phenomenon, the sharp edge-like shape of both lower edges (41) of the tail section (40) directs the water flow generated by the push-out appropriately, thereby increasing the efficiency of conversion into forward thrust. This edge-like structure functions as a hydrodynamically optimized shape, appropriately directing the water flow and increasing the efficiency of conversion into forward thrust. 【0077】 Thus, this test confirmed that when a paddler performs a paddling motion, the tail section (40) periodically sinks into the water surface, generating a periodic vertical repulsive force, which is converted into forward propulsion. This conversion showed a high correlation with the paddling cycle. Specifically, it was observed that the water mass captured by the box-shaped structure of the tail section (40) is pushed backward, generating forward propulsion, and based on the law of action and reaction, the tail section (40) rises, smoothly leading to the next cycle. Furthermore, it was inferred that the sharp edge-like structure of the lower side edges (41) of the tail section (40) appropriately directs the water flow, increasing the efficiency of conversion to forward propulsion. As a result, the SUP board (1) having the tail section (40) of the present invention has improved propulsion efficiency, and it was demonstrated that the box-shaped structure of the tail section (40) and the shape of the sharp edge-like side edges (41) efficiently convert the vertical repulsive force into forward propulsion. The usefulness of the present invention was confirmed by this test. 【0078】 <Finally> This concludes the description of specific embodiments and examples. However, the embodiments of the present invention are not limited to these embodiments and examples, and modifications and improvements can be made as appropriate. 【0079】 In other words, it is clear to those skilled in the art that various examples of modifications, alterations, substitutions, additions, deletions, and equivalents can be conceived within the scope of the claims, and these are naturally understood to fall within the technical scope of this disclosure. Furthermore, the components of the embodiments described above may be combined in any way without departing from the spirit of the present invention. 【0080】 Furthermore, when the specification and claims of this patent are translated into English or other languages, several terms will be referenced, and these terms will be interpreted as having the following meanings. 【0081】 The singular forms "a," "an," and "the" include multiple references unless explicitly indicated otherwise in the context. 【0082】 "Optional" or "optionally" means that the event or situation described afterward may or may not occur, and the description includes examples of the event occurring and examples of the event not occurring. 【0083】 The linguistic approximations used throughout this specification and claims may be applied to modify any quantitative expression that may change to an acceptable degree without altering the underlying function of the expression. That is, values ​​modified by terms such as “about,” “approximately,” and “substantially” are not limited to the specified exact value. In at least some examples, the approximating language may correspond to the precision of an instrument used to measure a value. Throughout this specification and claims, limitations on ranges may be combined and / or interchanged. Such ranges are specified and include all subranges contained therein unless the context or language indicates otherwise. 【0084】 <Note> Furthermore, the features of the stand-up paddleboard (1) according to one or more embodiments and examples described above are briefly summarized below in [1] to [7]. 【0085】 [1] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail section extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface at its rear end that extends in both the vertical and width directions of the hull body. The lower side edges of the tail portion are formed in a sharp, edge-like shape. Stand-up paddleboard. [2] When viewed from the side, if the front edge of the root of the fin is used as the reference point and the front side is designated as the first region and the rear side as the second region, The portion of the second region described above is the tail portion, The lower side edges of the tail portion are formed in a sharper, more angular shape compared to the lower side edges of the hull body in the first region. [1] Stand-up paddleboard. [3] The widthwise edges and lower edge of the flat surface are formed in a sharp, angular shape compared to the side edges on the underside of the hull body in the first region. [2] Stand-up paddleboard. [4] The tail section periodically sinks into the water surface in response to the paddling motion of the rower, thereby periodically generating a vertical rebound force. This repulsive force assists the forward propulsion of the hull body. A stand-up paddleboard as described in any one of [1] to [3]. [5] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail section extends from front to rear while maintaining its thickness in a side view, and has a box-like shape with a flat surface at its rear end that extends in both the vertical and width directions of the main hull. The tail section periodically sinks into the water surface in response to the paddling motion of the rower, thereby periodically generating a vertical rebound force. This repulsive force assists the forward propulsion of the hull body. Stand-up paddleboard. [6] Each of the two sides of the tail section in the width direction is formed in an inclined shape so that they become closer to each other in the width direction as they move towards the rear. A stand-up paddleboard as described in [1] or [5]. [7] The rower's standing position is set aft of the center of gravity of the hull. A stand-up paddleboard as described in [1] or [5]. [Industrial applicability] 【0086】 The present invention is useful as a stand-up paddleboard 1 that minimizes the effects of waves while improving straight-line stability and propulsion, and efficiently converts paddling motion into straight-line energy, enabling high-speed and long-duration sailing. [Explanation of Symbols] 【0087】 1: SUP board (Stand Up Paddleboard) 10: Main hull 20: Nose section 30: Deck section 31: Front slope 32: Rear inclined surface 33:Flat surface 34: Side wall section 35: Drainage hole 40: Tail section 41: Both edges 42:Flat surface 50: Finn A1: First area A2: Second area

Claims

[Claim 1] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail section extends from front to rear while maintaining its thickness in a side view, and is formed in a box shape with a flat surface at its rear end that extends in both the vertical and width directions of the hull body. The lower side edges of the tail section are formed in a sharp, edge-like shape. The tail section periodically sinks into the water surface in response to the rower's paddling motion, periodically generating a vertical repulsive force. As the tail section repeatedly sinks into the water surface and bounces back, the periodically generated repulsive force is converted into forward propulsion, and this repulsive force assists the forward propulsion of the hull. Stand-up paddleboard. [Claim 2] When viewed from the side, if the front edge of the base of the fin is used as the reference point and the front side is designated as the first region and the rear side as the second region, The portion of the second region is the tail portion, The lower side edges of the tail portion are formed in a sharper, more angular shape compared to the lower side edges of the hull body in the first region. The stand-up paddleboard according to claim 1. [Claim 3] The widthwise edges and lower edge of the flat surface are formed in a sharp-angled edge shape compared to the side edges on the lower side of the hull body in the first region. The stand-up paddleboard according to claim 2. [Claim 4] The main hull and A fin is provided at the rear end of the hull body, extending vertically downward from the bottom surface of the hull body, The tail section, which is the rear part of the hull body, The tail section extends from front to rear while maintaining its thickness in a side view, and has a box-like shape with a flat surface at its rear end that extends in both the vertical and width directions of the main hull. The tail section periodically sinks into the water surface in response to the rower's paddling motion, periodically generating a vertical repulsive force. As the tail section repeatedly sinks into the water surface and bounces back, the periodically generated repulsive force is converted into forward propulsion, and this repulsive force assists the forward propulsion of the hull. Stand-up paddleboard. [Claim 5] Each of the two sides of the tail section in the width direction is formed in an inclined shape so that they become closer to each other in the width direction as they move towards the rear. The stand-up paddleboard according to claim 1 or 4. [Claim 6] The rower's standing position is set aft of the center of gravity of the hull. The stand-up paddleboard according to claim 1 or 4.

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