US20230159145A1

US20230159145A1 - Surfboards moved by user power

Info

Publication number: US20230159145A1
Application number: US17/597,278
Authority: US
Inventors: Jae Geun Shin; Jong Ha SHIN; Chae Won Shin
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-11
Filing date: 2020-12-18
Publication date: 2023-05-25
Also published as: WO2022034994A1; KR102178902B1

Abstract

Surfboards moved by user power comprises: a surfboard body streamlined, when viewed from a plan view, concave grooves are formed on both sides, respectively; a propulsion body including: a first propulsion body formed with a first propulsion unit that is hinged to one side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and a second propulsion body formed with a second propulsion unit that is hinged to the other side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and a direction change unit including: a rotating shaft passing through the surfboard body; a handle disposed on an upper end of the surfboard body of the rotating shaft to rotate the rotating shaft; and a direction change key that is disposed on a lower part of the surfboard body of the rotating shaft and rotates together with the rotating shaft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT International Application No. PCT/KR2020/018682 filed on Dec. 18, 2020, which application claims priority to Korean Patent Application No. 10-2020-0100622 filed on Aug. 11, 2021, the entire disclosures of which are expressly incorporated herein by reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

Technical Field

The present invention relates to a surfboard, and more particularly, to a surfboard that can be moved by a user's power on a calm shore without waves and whose direction also can be changed by using user's hands during movement.

Background Art

In general, surfing is a marine sport that competes for height, speed, and skill by riding a surfboard up and down the slope surface of sea waves, and it is a sport that requires a high sense of balance and precise timing.
To enjoy surfing, there must be waves, and if there are no waves in the sea, you cannot enjoy surfing.
For enjoying surfing in the sea without waves, in Korean Patent Publication No. 2003-0067609, Motor Surfing Board (published on Aug. 14, 2003), a technology that allows you to enjoy surfing in a place where there is no wind or waves by attaching a power device that uses a motor to the surfboard has been disclosed.
However, when a motor and the like is mounted on a surfboard to enjoy surfing in a place where there is no wind or waves, since in addition to the motor, various components such as a battery that delivers power to run the motor must be mounted on a very small surfboard, it is not easy to implement and has a problem in that the manufacturing cost is excessively increased.

BRIEF SUMMARY

Technical Subject

The present invention provides surfboards moved by user power that can be moved by a user's power on a shore without winds or waves and whose direction also can be easily changed by using user's hands during movement, and after use, each part is folded to enhance the convenience of movement and minimize the storage volume.

Technical Solution

As an embodiment, surfboards moved by user power comprise: a surfboard body streamlined, when viewed from a plan view, concave grooves are formed on both sides, respectively; a propulsion body including: a first propulsion body formed with a first propulsion unit that is hinged to one side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and a second propulsion body formed with a second propulsion unit that is hinged to the other side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and a direction change unit including: a rotating shaft passing through the surfboard body; a handle disposed on an upper end of the surfboard body of the rotating shaft to rotate the rotating shaft; and a direction change key that is disposed on a lower part of the surfboard body of the rotating shaft and rotates together with the rotating shaft.
It further comprises: an overturn prevention body having a first prevention body hinged to one side of the front end part of an upper surface of the surfboard body of the surfboards moved by user power and at a different height from the first propulsion body; and a second overturn prevention body hinged to the other side of a front end part at a different height from the first propulsion body, wherein the first and second overturn prevention bodies are coupled to the upper surface of the surfboard body, and wherein the first and second propulsion bodies are formed at the same height as the side surface of the surfboard body.
The first and second propulsion bodies of the surfboard moved by user power are hinged in a ball-socket joint method that freely moves with respect to the surfboard body, and through holes are formed in the first and second overturn prevention bodies, and the through holes are inserted into the protrusions protruding from the upper surface of the surfboard body so that the first and second overturn prevention bodies are rotated in a direction parallel to the upper surface of the surface board body.
The direction change unit of surfboards moved by user power comprises: a through hole passing through the surfboard body; a rotating member inserted into the through hole and rotated in a direction parallel to the surfboard body; a first folding part coupled to the rotating shaft on an upper portion of the rotating member to fold the rotating shaft; and a folding unit having a second folding part for folding the direction change key on a lower portion of the rotating member.
A first coupling portion that is separated or coupled to the side of the surfboard body is formed in the first and second propulsion bodies of surfboards moved by user power, a second coupling portion separated or coupled to the first coupling portion is formed on the side of the surfboard body, a third coupling portion coupled to the upper surface of the surfboard body is formed in the first and second overturn prevention bodies, a fourth coupling portion coupled to the third coupling portion is formed on the upper surface of the surfboard body.
The overturn prevention body of surfboards moved by user power further comprises: a third overturn prevention body that is hinged at a different height from the first propulsion body on one side of the rear end part opposite to the front end part of the upper surface of the surfboard body; and an overturn prevention body having a fourth overturn prevention body hinged to the other side of the rear end part at a different height from the first propulsion body, wherein through holes are formed in the third and fourth overturn prevention bodies, and the through holes are inserted into the protrusions protruding from the upper surface of the surfboard body, and the third and fourth overturn prevention bodies are rotated in a direction parallel to the upper surface of the surfboard body.

Advantageous Effects

The surfboards moved by user power according to the present invention can be moved by the user's power on the coast where there are no winds or waves, and the direction can be easily changed using the user's hand during movement, and have an effect that after use, each part can be folded to enhance the convenience of moving and minimize the storage volume.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:

FIG. 1 is an external perspective view of surfboards moved by user power according to an embodiment of the present invention.

FIG. 2 is a front view in the A direction of FIG. 1 .

FIG. 3 is a cross-sectional view illustrating a ball socket joint of the first and second propulsion bodies illustrated in FIG. 1 .

FIG. 4 is a cross-sectional view illustrating a direction change unit.

FIG. 5 is a cross-sectional view illustrating the coupling of an overturn prevention body and a surfboard body according to an embodiment of the present invention.

FIG. 6 is an external perspective view of surfboards moved by user power according to another embodiment of the present invention.

DETAILED DESCRIPTION

The present invention described hereinafter can apply various transformations and can have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description.
However, this is not intended to limit the present invention to specific embodiments, and it should be understood that all modifications, equivalents and substitutes included in the spirit and scope of the present invention are included. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.
The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, it should be understood that terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but this does not preclude the possibility of addition or existence of one or more other features or numbers, steps, operations, components, parts, or combinations thereof.
In addition, terms such as first, second, and the like may be used to distinguish and describe various components, but the components should not be limited by the above terms. The above terms are used only for the purpose of distinguishing one component from another.
In addition, when at least two different embodiments are described in the present application, all or part of the components may be used by merging and interchangeably using with each other, even if there is no particular description within the scope not departing from the technical spirit of the present invention.
FIG. 1 is an external perspective view of surfboards moved by user power according to an embodiment of the present invention. FIG. 2 is a front view in the A direction of FIG. 1 .
Referring to FIGS. 1 and 2 , a surfboard 600 includes a surfboard body 100, a propulsion body 200, and a direction change unit 300. In addition to this, the surfboard 600 may further include an overturn prevention body 400.
The surfboard body 100 serves as a base for supporting or fixing the propulsion body 200, the direction change unit 300 and the overturn prevention body 400.
The surfboard body 100 may be made of a variety of highly rigid materials so as to be floated in water.
The surfboard body 100 may be formed, for example, in a streamlined shape, a spindle shape, an aerodynamic shape, or a rectangular shape, and the like, and concave grooves 110 may be formed on both sides of the surfboard body 100, respectively.
In one embodiment of the present invention, the shape of the concave grooves 110 respectively formed on both sides of the surfboard body 100 may be formed in a shape corresponding to the propulsion body 200, which will be described later, when viewed in a plan view.
The propulsion body 200 is coupled to the surfboard body 100. The propulsion body 200 makes it possible to move the surfboard body 100 by purely using the user's power, not the power generated by a motor.
The propulsion body 200 includes a first propulsion body 210 and a second propulsion body 260.
The first propulsion body 210 is formed in a rectangular shape, the first propulsion body 210 is disposed in a concave groove 110 formed on the side of the surfboard body 100, and the first propulsion body 210 is formed in a shape in close contact with a groove 110.
The first propulsion body 210 may, for example, be formed in a rectangular shape or a streamlined shape, and the first propulsion body 210 may be formed in a width suitable for placing a user's foot.
A strap 215 for preventing the user's feet from being separated may be formed on the upper surface of the first propulsion body 210, and an anti-slip pad and the like for preventing the user's feet from slipping may be placed on the upper surface of the first propulsion body 210. Unlike this, a concave separation prevention groove may be formed in a portion of the upper surface of the first propulsion body 210 corresponding to the strap 215 so that the user's foot does not slip.
In one embodiment of the present invention, preventing the user's foot from being separated from the upper surface of the first propulsion body 210 is because propulsion force is generated through a motion in which the user spreads or narrows the first propulsion body 210 in the horizontal direction on the water surface, a motion in which the first propulsion body 210 is elevated and descended up and down with respect to the surfboard body 100, and a motion in which the first propulsion body 210 is rotated from left to right with respect to the surfboard body 100, and the like, and at this time, the user's foot can be easily separated from the first propulsion body 210.
In one embodiment of the present invention, a ball 216 is formed at the front end portion of the first propulsion body 210 to enable the user to perform the motion of widening or narrowing the first propulsion body 210 in the horizontal direction on the water surface, the motion of elevating the first propulsion body 210 up and down with respect to the surfboard body 100, and the motion of rotating the first propulsion body 210 left and right with respect to the surfboard body 100.
FIG. 3 is a cross-sectional view illustrating a ball socket joint of the first and second propulsion bodies illustrated in FIG. 1 .
Referring to FIGS. 1 to 3 , a concave groove 112 in which the ball 216 is accommodated is formed in the surfboard body 100, and the ball 216 is accommodated inside the groove 112. Then, in order to prevent the ball 216 from being separated from the groove 112, an anti-separation cover 217 is coupled to the surfboard body 100 so that the first propulsion body 210 is coupled to the surfboard body 100 in a ball-socket joint method.
As the first propulsion body 210 is coupled to the surfboard body 100 in a ball-socket joint manner, the surfboard body 100 is enabled to perform the motion of widening or narrowing the first propulsion body 210 in the horizontal direction on the water surface, the motion of elevating the first propulsion body 210 up and down with respect to the surfboard body 100, and the motion of rotating the first propulsion body 210 left and right with respect to the surfboard body 100.
Meanwhile, a first propulsion unit 220 is formed in the first propulsion body 210 in order to generate propulsion force in the first propulsion body 210 by moving the user's feet. The first propulsion unit 220 is formed on the lower surface of the first propulsion body 210, the first propulsion unit 220 is formed in a thin plate shape, and the first propulsion unit 220 is formed inclinedly with respect to the lower surface of the first propulsion body 210. In one embodiment of the present invention, the first propulsion unit 220 may be formed in a shape tilted with respect to the axial direction of the first propulsion body 210 when viewed in a plan view.
On the lower surface of the first propulsion body 210 on which the first propulsion unit 220 is formed, an accommodating unit for accommodating the first propulsion unit 220 by folding may be formed when the surfboard 600 is not in use.
The second propulsion body 260 is formed in a rectangular shape, the second propulsion body 260 is disposed in a concave groove 110 formed on the other side of the surfboard body 100, and the second propulsion body 260 is formed in a shape in close contact with the groove 110.
In one embodiment of the present invention, the second propulsion body 260 may be formed in substantially the same shape and the same size as the first propulsion body 210.
The second propulsion body 260 may be formed, for example, in a rectangular shape or a streamlined shape, and the second propulsion body 260 may be formed in a width suitable for placing a user's foot.
On the upper surface of the second propulsion body 260, a strap 265 for preventing the user's feet from being separated may be formed, and on the upper surface of the second propulsion body 260, an anti-slip pad and the like for preventing the user's feet from slipping may be disposed. Unlike this, a concave separation prevention groove may be formed in a portion of the upper surface of the second propulsion body 260 corresponding to the strap 265 so that the user's foot does not slip.
In one embodiment of the present invention, a ball 266 is formed at the front end portion of the second propulsion body 260 to enable the user to perform the motion of widening or narrowing the second propulsion body 260 in the horizontal direction on the water surface, the motion of elevating the second propulsion body 260 up and down with respect to the surfboard body 100, and the motion of rotating the second propulsion body 260 left and right with respect to the surfboard body 100.
Meanwhile, the surfboard body 100 is formed with a concave groove 114 in which the ball 266 is accommodated, and the ball 266 is accommodated inside the groove 114. Then, to prevent the ball 266 from being separated from the groove 114, an escape prevention cover 267 is coupled to the surfboard body 100, so that the second propulsion body 260 is coupled to the surfboard body 100 in a ball-socket joint manner.
As the second propulsion body 260 is coupled to the surfboard body 100 in a ball-socket joint manner, the surfboard body 100 is enabled to perform the motion of widening or narrowing the second propulsion body 260 in the horizontal direction on the water surface, the motion of elevating the second propulsion body 260 up and down with respect to the surfboard body 100, and the motion of rotating the second propulsion body 260 left and right with respect to the surfboard body 100.
Meanwhile, a second propulsion unit 270 is formed in the second propulsion body 260 in order to generate propulsion force in the second propulsion body 260 by moving the user's feet. The second propulsion unit 270 is formed on the lower surface of the second propulsion body 260, the second propulsion unit 270 is formed in a thin plate shape, and the second propulsion unit 270 is formed inclinedly with respect to the lower surface of the second propulsion body 260.
In one embodiment of the present invention, the second propulsion unit 270 may be formed in a shape tilted with respect to the axial direction of the second propulsion body 260 when viewed in a plan view.
On the lower surface of the second propulsion body 260 on which the second propulsion unit 270 is formed, an accommodating unit for accommodating the second propulsion unit 270 by folding may be formed when the surfboard 600 is not in use.
When the user moves the first propulsion body 210 and the second propulsion body 260 connected to the surfboard body 100 with their feet, the surfboard body 100 can be advanced even without wind or waves, and in one embodiment of the present invention, the direction change unit 300 is coupled to the surfboard body 100 so that the user can change the direction of the surfboard body 100 that is being advanced by using the hand.
The direction change unit 300 comprises a rotating shaft 310, a handle 320, and a direction change key 330. In one embodiment of the present invention, the direction change unit 300 may further include, as illustrated in FIG. 4 , a folding unit 340 that allows the rotating shaft 310 and the direction change key 330 to be folded.
FIG. 4 is a cross-sectional view illustrating a direction change unit.
Referring to FIG. 4 , the folding unit 340 comprises a through hole 342 penetrating through the surfboard body 100, a rotating member 344, a first folding part 346, and a second folding part 348.
The rotating member 344 is formed in a cylindrical block shape, being rotated inside the through hole 342, and of course, the rotating member 344 has a structure not to be separated out of the through hole 342.
A first folding part 346 coupled to the rotating shaft 310 is formed on the upper surface of the rotating member 344. The first folding part 346 includes plates formed to stand up as a pair on the upper surface of the rotating member 344, and a rotating shaft 310, which will be described later, is inserted between the first folding parts 346, and the first folding part 346 and the rotating shaft 310 are coupled by a hinge pin.
The rotating shaft 310 is, for example, formed in a cylindrical shape, and the rotating shaft 310 is hinge-coupled to a hinge pin in a state disposed between the first folding parts 346.
When the rotating shaft 310 is twisted while the rotating shaft 310 is coupled to the hinge pin, the rotating member 344 is rotated by the torsional moment of the rotating shaft 310. Meanwhile, the rotating shaft 310 may be folded in a vertical state or a horizontal state with respect to the surfboard body 100 by a hinge pin.
The handle 320 is coupled to the upper end of the rotation shaft 310, and the handle 320 allows the user to change the direction by twisting the rotation shaft 310 with a less force.
The direction change key 330 is coupled to the lower surface of the rotating member 344 by a second folding part 348, and the direction change key 330 can be folded vertically or horizontally with respect to the surfboard body 100 by the second folding part 348.
Meanwhile, the direction change key 330 is rotated together with the rotating member 344, the rotating member 344 is rotated by the rotating shaft 310, and since the rotation shaft 310 is rotated by the handle 320, as the user rotates the handle 320, the direction change key 330 is also rotated with the handle 320 so that the user can change the direction of the surfboard body 100 by hand.
Referring back to FIG. 1 , in one embodiment of the present invention, the upper surface of the surfboard body 100 may be formed with a groove 120 formed in a shape and size corresponding to the direction change unit 300, and as a result, the direction change unit 300 is accommodated in the groove 120 while being folded, thereby preventing an increase in volume due to the direction change unit 300.
Referring back to FIGS. 1 and 2 , the overturn prevention body 400 prevents the surfboard body 100 from being overturned and allows the user to more easily maintain the balance. In the case of the skilled, it is not necessary to deploy the overturn prevention body 400, but in the case of a beginner or intermediate user, it is possible to prevent falling down on the water surface by deploying the overturn prevention body 400.
The overturn prevention body 400 is hinged coupled to the front end part of the upper surface of the surfboard body 100 at a different height from the first and second propulsion bodies 210 and 260 so that the interference with the first and second propulsion bodies 210 and 260 can be prevented.
For example, the overturn prevention body 400 is disposed on the upper surface of the surfboard body 100, and the first and second propulsion bodies 210 and 260 may be disposed at positions corresponding to the sides of the surfboard body 100.
Although in one embodiment of the present invention, the overturn prevention body 400 disposed on the upper surface of the surfboard body 100 is illustrated and described, but unlike this, the overturn prevention body 400 may be disposed on the lower surface of the surfboard body 100.
The overturn prevention body 400 may include a first overturn prevention body 410 and a second overturn prevention body 420.
The first overturn prevention body 410 formed in a rectangular shape is deployed to one side of the surfboard body 100, and the second overturn prevention body 420 formed in a rectangular shape is deployed to the other side facing the one side of the surfboard body 100.
FIG. 5 is a cross-sectional view illustrating the coupling of an overturn prevention body and a surfboard body according to an embodiment of the present invention.
Referring to FIG. 5 , the front end part of the first and second overturn prevention bodies 410 and 420 of the overturn prevention body 400 is formed with a through hole, the front end part of the surfboard body 100 has a pair of protrusions 102 formed to be spaced apart are formed. The first and second through holes formed at the ends of the overturn prevention bodies 410 and 420 are inserted into the protrusions 102, due to this, the first and second overturn prevention bodies 410 and 420 are rotated in the horizontal direction with respect to the surfboard body 100.
Referring back to FIG. 1 , in order to minimize the volume of the propulsion body 200 to facilitate storage and transport when the surfboard 600 is not in use, a first coupling portion 218 that is separated or coupled to the side of the surfboard body 100 is formed in the first and second propulsion bodies 210 and 260, and a second coupling portion 103 coupled to the first coupling portion 218 is formed in the surfboard body 100.
For example, the first coupling part 218 may be a protrusion, and the second coupling part 103 may be a groove into which the protrusion is inserted and fitted.
Meanwhile, in order to minimize the volume of the overturn prevention body 400 to facilitate storage and transport when the surfboard 600 is not in use, a third coupling part 402 that is separated or coupled to the to the upper surface of the surfboard body 100 is formed, and a fourth coupling part 105 coupled to the third coupling part 402 is formed on the upper surface of the surfboard body 100.
For example, the third coupling part 402 may be a protrusion, and the fourth coupling part 105 may be a groove coupled to the third coupling part 402.
FIG. 6 is an external perspective view of surfboards moved by user power according to another embodiment of the present invention. The surfboard moved by user power illustrated in FIG. 6 has substantially the same configuration as the surfboard moved by user power illustrated and described in FIGS. 1 to 5 except for the third and fourth overturn prevention bodies 430 and 440. Therefore, duplicate descriptions of the same components will be omitted, and the same names and reference numerals will be given to the same components.
Referring to FIG. 6 , the overturn prevention body 400 of the surfboard moved by user power according to another embodiment of the present invention may include a third overturn prevention body 430 and a fourth overturn prevention body 440.
The third overturn prevention body 430 and the fourth overturn prevention body 440 are hinge-coupled at a different height from the first and second propulsion bodies 210 and 260 on one side and the other side of the rear end part of the upper surface of the surfboard body 100 so that it is possible to prevent interference with the first and second propulsion bodies 210 and 260.
For example, the third overturn prevention body 430 and the fourth overturn prevention body 440 are disposed on the upper surface of the surfboard body 100, and the first and second propulsion bodies 210 and 260 may be disposed at positions corresponding to the sides of the surfboard body 100.
Although in one embodiment of the present invention, the third overturn prevention body 430 and the fourth overturn prevention body 440 disposed on the upper surface of the surfboard body 100 are illustrated and described, but unlike this, the third overturn prevention body 430 and the fourth overturn prevention body 440 may be disposed on the lower surface of the surfboard body 100.
The third overturn prevention body 430 formed in a rectangular shape is deployed to one side of the surfboard body 100, and the fourth overturn prevention body 440 formed in a rectangular shape is deployed to the other side facing the one side of the surfboard body 100.
A through hole is formed in the front end part of the third and fourth overturn prevention bodies 430 and 440, and a pair of protrusions 102 spaced apart from each other is formed at the rear end part facing the front end part of the surfboard body 100 is formed. The through holes formed in the front end part of the third and fourth overturn prevention bodies 430 and 440 are inserted into the protrusions 102, and due to this, the third and fourth overturn prevention bodies 430 and 440 are rotated in the horizontal direction with respect to the surfboard body 100.
Meanwhile, to minimize the volume of the overturn prevention body 400 to facilitate storage and transport when the surfboard 600 is not used, a third coupling part 402 that is separated or coupled to the upper surface of the surfboard body 100 is formed in the third and fourth overturn prevention bodies 430 and 440, and a fourth coupling part 105 coupled to the third coupling part 402 is formed on the upper surface of the surfboard body 100.
For example, the third coupling part 402 is a protrusion, and the fourth coupling part 105 may be a groove coupled to the third coupling part 402.
The third and fourth overturn prevention bodies 430 and 440 prevent the surfboard body 100 and the user from overturning backwards and make it easier for users to balance. In particular, when all of the first to fourth overturn prevention bodies 410, 420, 430, and 440 are used, it is possible to easily maintain a balance on the water surface, so even beginners in surfing can easily enjoy surfing.
In particular, the user can selectively deploy and use the first to fourth overturn prevention bodies 410, 420, 430, and 440 according to the user's skill level. For example, only the first and second overturn prevention bodies 410 and 420 coupled to the front end part of the surfboard body 100 or the third and fourth overturn prevention bodies 430 and 440 coupled to the rear end part of the surfboard body 100 can also be optionally deployed and used.
According to the detailed description above, it is possible to move by the user power on a sea coast where there are no winds or waves, direction can be easily changed by using user's hands while moving, and there is an effect that each part can be folded to improve the convenience of moving and minimize the storage volume.
Meanwhile, the embodiments disclosed in the drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is obvious to those of ordinary skill in the art to which the present invention belongs that other modified embodiments based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims

What is claimed is:

1. Surfboards moved by user power comprising:

a surfboard body streamlined, when viewed from a plan view, concave grooves are formed on both sides, respectively;

a propulsion body including:

a first propulsion body formed with a first propulsion unit that is hinged to one side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and

a second propulsion body formed with a second propulsion unit that is hinged to the other side groove of the surfboard body and is formed inclined with respect to the surfboard body on a lower surface to generate propulsion force according to the movement of the user's feet; and

a direction change unit including:

a rotating shaft passing through the surfboard body;

a handle disposed on an upper end of the surfboard body of the rotating shaft to rotate the rotating shaft; and

a direction change key that is disposed on a lower part of the surfboard body of the rotating shaft and rotates together with the rotating shaft,

wherein the direction change unit of surfboards moved by user power comprises a through hole passing through the surfboard body, a rotating member inserted into the through hole and rotated in a direction parallel to the surfboard body, a first folding part coupled to the rotating shaft on an upper portion of the rotating member to fold the rotating shaft, and a folding unit having a second folding part for folding the direction change key on a lower portion of the rotating member.

2. The surfboards moved by user power according to claim 1, further comprising:

an overturn prevention body having a first prevention body hinged to one side of the front end part of an upper surface of the surfboard body of the surfboards moved by user power and at a different height from the first propulsion body; and

a second overturn prevention body hinged to the other side of a front end part at a different height from the first propulsion body,

wherein the first and second overturn prevention bodies are coupled to the upper surface of the surfboard body, and wherein the first and second propulsion bodies are formed at the same height as the side surface of the surfboard body.

3. The surfboards moved by user power according to claim 2, wherein the first and second propulsion bodies of the surfboard moved by user power are hinged in a ball-socket joint method that freely moves with respect to the surfboard body, and

wherein through holes are formed in the first and second overturn prevention bodies, and the through holes are inserted into the protrusions protruding from the upper surface of the surfboard body so that the first and second overturn prevention bodies are rotated in a direction parallel to the upper surface of the surface board body.

4. The surfboards moved by user power according to claim 2, wherein a first coupling portion that is separated or coupled to the side of the surfboard body is formed in the first and second propulsion bodies of surfboards moved by user power, and a second coupling portion separated or coupled to the first coupling portion is formed on the side of the surfboard body, and

wherein a third coupling portion coupled to the upper surface of the surfboard body is formed in the first and second overturn prevention bodies, and a fourth coupling portion coupled to the third coupling portion is formed on the upper surface of the surfboard body.

5. The surfboards moved by user power according to claim 1, further comprising:

an overturn prevention body including a third overturn prevention body that is hinge-coupled at a different height from the first propulsion body on one side of the rear end part facing the front end part of the upper surface of the surfboard body and a fourth overturn prevention body hinged to the other side of the rear end part at a different height from the first propulsion body,

wherein through holes are formed in the third and fourth overturn prevention bodies, and the through holes are inserted into the protrusions protruding from the upper surface of the surfboard body so that the third and fourth overturn prevention bodies are rotated in a direction parallel to the upper surface of the surfboard body.