STARTING ASSIST DEVICE

Abstract

The invention provides a versatile starting assist device. A starting assist device is a starting assist device mounted on a starting block having a platform on which a swimmer in a swimming competition climbs up. The starting assist device includes a foot plate that is arranged along a wall surface of a swimming pool and supports a foot of a backstroke swimmer when a competition starts, a pair of belt parts connected with the foot plate, and a supporting part that supports the pair of belt parts. The supporting part is fixed to a back end part of the platform.

Description

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-040573 filed on Mar. 2, 2015, the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

(i) Technical Field

The invention relates to a starting assist device.

(ii) Related Art

Conventionally, a starting assist device for backstroke swimming is mounted on a starting block for swimming competition.

For example, a starting assist device described in Patent Literature U.S. 2014/0165282 has a foot plate arranged along a wall surface of a swimming pool, a pair of connecting parts connected with both end parts of the foot plate, respectively, and a supporting part that supports the pair of connecting parts, and the supporting part is mounted on a base part that supports a platform of a starting block.

SUMMARY OF THE INVENTION

However, in general, a shape of a base part of a starting block is changed so as to meet specifications of a swimming pool (for example, a shape of a poolside) where the base part is installed. Therefore, the structure of the above-mentioned starting assist device needs to be changed to meet the shape of the base part on which the starting assist device is mounted. Hence, there has been a problem that versatility of the conventional starting assist device is low.

Thus, the invention provides a versatile starting assist device.

A starting assist device according to the invention is a starting assist device that is mounted on a staring block having a platform on which a swimmer in a swimming competition climbs up. The starting assist device includes a foot plate that is arranged along a wall surface of a swimming pool and supports a foot of a backstroke swimmer when a competition starts, a pair of connecting parts connected with the foot plate, and a supporting part that supports the pair of connecting parts. The supporting part is fixed to one end part of the platform on an opposite side of the swimming pool side.

In general, a shape of a base part of a starting block is changed to meet specifications of a swimming pool (for example, a shape of a poolside) in which the base part is installed. On the contrary, shape, structure, and so on of a platform mounted on an upper part of the base part are standardized. According to the invention, since the supporting part of the starting assist device is mounted on the standardized platform, it is possible to use the same shape and mounting structure for the supporting part regardless of the specifications of the swimming pool where the starting assist device is installed. Therefore, it is possible to mount the starting assist device on the starting block without changing the design of the starting assist device as appropriate to meet the specifications of the swimming pool where the starting assist device is installed, thereby making the starting assist device versatile.

Further, since the supporting part of the starting assist device is fixed to the one end part of the platform on the opposite side of the swimming pool, a swimmer is able to use the entire upper surface of the platform. Therefore, when a swimmer stands on the platform and dives into the swimming pool, the supporting part is not in the way. Therefore, during a medley relay, for example, after a backstroke swimmer starts a competition, it is not necessary to remove the starting assist device from the starting block before a swimmer who uses the starting block next stands on the platform. Therefore, it is possible to make the starting assist device easy to use.

In the foregoing starting assist device, it is preferred that the starting block has a footrest for placing a foot of a swimmer, the footrest being arranged on the upper surface of the platform, and the supporting part is arranged on the opposite side of the swimming pool through the footrest.

According to the invention, since the supporting part is arranged on the opposite side of the swimming pool through the footrest, it is possible to prevent the supporting part from standing in the way of a swimmer who stands on the platform. Thus, even in a case where the starting block has the footrest, it is not necessary to remove the starting assist device from the starting block after a backstroke swimmer starts a competition until a swimmer who uses the starting block next stands on the platform. Therefore, it is possible to realize the easily used and versatile starting assist device that can be mounted on the starting block having the footrest.

In the foregoing starting assist device, it is preferred that an arrangement position of the footrest is adjustable so that the footrest is closer to or separated from the swimming pool, and the supporting part is arranged at a position separated from the swimming pool more than the footrest that is fixed to the farthest position from the swimming pool.

According to the invention, the supporting part is arranged at a position separated from the swimming pool more than the footrest fixed to the farthest position from the swimming pool. Therefore, at whichever position the footrest is arranged, it is possible to prevent the supporting part from being in the way of a swimmer who stands on the platform. Therefore, even when the arrangement position of the footrest is adjustable, it is not necessary to remove the starting assist device from the starting block after a backstroke swimmer starts a competition until a swimmer who uses the starting block next stands on the platform. Therefore, it is possible to realize the starting assist device that is easily used and versatile.

In the foregoing starting assist device, it is preferred that the supporting part is detachably fixed to the platform through an attachment provided in the one end part of the platform.

According to the invention, since the supporting part is detachably fixed to the platform, it is possible to remove the starting assist device from the starting block easily when, for example, the starting assist device is not used for a long period of time.

In the foregoing starting assist device, it is preferred that the supporting part has a handle part.

According to the invention, since the supporting part has the handle part, it is possible to make it easy to carry, attach and detach the starting assist device.

In the foregoing starting assist device, it is preferred that the foot plate has a non-slip part on a surface that faces the wall surface of the swimming pool.

According to the invention, since the foot plate has the non-slip part on the surface that faces the wall surface of the swimming pool, it is possible to increase friction force between the wall surface of the swimming pool and the foot plate. Therefore, when a backstroke swimmer kicks the foot plate at the start of a competition, it is possible to prevent the foot plate from being dislocated with respect to the wall surface of the swimming pool.

According to the invention, since the supporting part of the starting assist device is mounted on the standardized platform, it is possible to use the same shape and mounting structure for the supporting part regardless of the specifications of the swimming pool where the starting assist device is installed. Therefore, it is possible to mount the starting assist device on the starting block without changing the design of the starting assist device as appropriate to meet the specifications of the swimming pool where the starting assist device is installed, thereby making the starting assist device versatile.

Moreover, since the supporting part of the starting assist device is fixed to the one end part of the platform on the opposite side of the swimming pool, a swimmer is able to use the entire upper surface of the platform. Therefore, when a swimmer stands on the platform and dives into the swimming pool, the supporting part is not in the way. Therefore, during a medley relay, for example, after a backstroke swimmer starts a competition, it is not necessary to remove the starting assist device from the starting block before a swimmer who uses the starting block next stands on the platform. Therefore, it is possible to make the starting assist device easy to use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a starting block and a starting assist device;

FIG. 2 is a side view of the starting block and the starting assist device;

FIG. 3 is a front view of the starting block and the starting assist device;

FIG. 4 is a perspective view of the starting block;

FIG. 5 is a perspective view of the starting assist device; and

FIG. 6 is a perspective view of the starting assist device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the invention is explained below based on the drawings. First of all, explanation is given regarding a starting block 10 on which a starting assist device 30 according to the embodiment is mounted.

FIG. 1 is a perspective view of a starting block and a starting assist device. FIG. 2 is a side view of the starting block and the starting assist device. FIG. 3 is a front view of the starting block and the starting assist device.

As shown in FIG. 1, pool facility P includes a water storage part 1 (herein below, referred to as a “swimming pool 1”) surrounded by a wall surface 2, and a poolside 3 provided in a periphery of the swimming pool 1. In the following explanation, a direction in which a swimmer standing on a platform 17 of a starting block 10 dives towards the swimming pool 1 is defined as the front, and the opposite direction is defined as the back. A direction orthogonal to a front-back direction and a vertical direction is defined as a horizontal direction.

The starting block 10 is arranged in the poolside 3 provided in the periphery of the swimming pool 1. The starting block 10 has a base part 11 fixed to an upper surface 3a of the poolside 3, the platform 17 that is fixed to an upper part of the base part 11 and allows a swimmer in a swimming competition to climb up on it, and a footrest 20 that is fixed to an upper surface 17a of the platform 17 for placing a foot of a swimmer.

The base part 11 has legs 12, a handrail 13, and side plates 16.

The legs 12 are bar-shaped members formed from, for example, stainless steel, the plurality of (in this embodiment, four) legs 12 is arranged along the vertical direction. A lower end part of each of the legs 12 is fixed to the upper surface 3a of the poolside 3. The legs 12 include a pair of front side legs 12A and a pair of back side legs 12B (see FIG. 4).

Similarly to the legs 12, the handrail 13 is a bar-shaped member formed from, for example, stainless steel. The handrail 13 has a U-shaped body part 14 that is open upwardly when viewed in the front-back direction. The body part 14 includes a first grip part 14a extending in a lower part of the body part 14 along the horizontal direction, a pair of front side connecting parts 14b extending upwardly from both end parts of the first grip part 14a, respectively, and a pair of upper side connecting parts 14c extending to the back from upper end parts of the front side connecting parts 14b, respectively. The body part 14 is formed by bending a single bar-shaped member. The first grip part 14a is arranged in front of the pair of front side legs 12A. A length of the first grip part 14a is equal to a clearance between the pair of front side legs 12A (see FIG. 3). The upper side connecting parts 14c are fixed to upper end parts of the front side legs 12A and the back side legs 12B from outside by using fastening members such as bolts. A second grip part 15 is provided above the first grip part 14a. The second grip part 15 extends along the horizontal direction. Both end parts of the second grip part 15 are connected with the pair of front side connecting parts 14b, respectively

The plurality of (in this embodiment, four) side plates 16 is arranged between each of the neighboring legs 12. Each of the side plates 16 is a plate-shaped member formed from, for example, stainless steel. The side plates 16 are fixed to the upper surface 3a of the poolside 3. It is possible to house instruments in a space surrounded by each of the side plates 16.

The platform 17 is a rectangular plate-shaped member, the longitudinal direction of which is the front-back direction in a plan view. The upper surface 17a of the platform 17 is formed to become flat. The upper surface 17a of the platform 17 is inclined so as to become lower from the back towards the front. Non-slip treatment is performed on the upper surface 17a of the platform 17 by coating the upper surface 17a with paint containing particles.

In both side surfaces of the platform 17, which face the horizontal direction, guide holes 18 are formed. As shown in FIG. 2, the guide hole 18 is formed as a long hole extending along the upper surface 17a of the platform 17 in a view from the horizontal direction. A plurality of cutouts 18a, which is cut downwardly, is formed at an interval along the direction in which the guide hole 18 extends. Later-described shafts 21 provided in the footrest 20 are inserted into the guide holes 18.

FIG. 4 is a perspective view of the starting block from the back.

As shown in FIG. 4, a pair of connecting members 22 (corresponding to an “attachment” in claims) is provided in a back end part 17b of the platform 17 at an interval in the horizontal direction. Each of the connecting members 22 has a pair of metal fittings 22a equally extending along a normal direction L1 of the upper surface 17a of the platform 17. The pair of metal fittings 22a is erected from the back end part 17b of the platform 17 towards the back and a distal end part of each of the metal fittings 22a is bent in a direction to be closer to each other. The distal end parts of the pair of metal fittings 22a are separated from each other. An engaging projection 41 of the starting assist device 30 described later is engaged with each of the connecting members 22.

As shown in FIG. 1, a pair of connecting plates 19 is provided in a lower part of the platform 17 so as to project downwardly. Each of the connecting plates 19 is a plate-shaped member extending in the front-back direction, and arranged at an interval in the horizontal direction. Each of the connecting plates 19 is fixed to the front side legs 12A and the back side legs 12B of the base part 11 by fastening members such as bolts. The platform 17 is mounted on the base part 11 through the pair of connecting plates 19.

The footrest 20 is a block-shaped member extending in the horizontal direction. As shown in FIG. 2, the footrest 20 is formed into a triangle shape in a view from the horizontal direction. A front surface 20a of the footrest 20 is inclined so as to become lower from the back towards the front. An inclination angle of the front surface 20a of the footrest 20 with respect to a horizontal plane is larger than an inclination angle of the upper surface 17a of the platform 17 with respect to the horizontal plane.

The pair of shafts 21 extending in the horizontal direction is mounted on a lower part of the footrest 20. Both of the pair of shafts 21 are inserted through the pair of guide holes 18 formed on both left and right side surfaces of the platform 17. The footrest 20 is able to slide to the front and back along the upper surface 17a of the platform 17 by moving the shafts 21 inside the guide holes 18. By allowing the shafts 21 to enter the cutouts 18a, the footrest 20 is engaged at a position corresponding to the positions of the cutouts 18a. Thus, it is possible to adjust an arrangement position of the footrest 20 so that the footrest 20 is closer to or separated from the swimming pool 1.

Next, a starting assist device 30 according to this embodiment is explained.

As shown in FIG. 1, the starting assist device 30 is mounted on the starting block 10. The starting assist device 30 includes a foot plate 31 arranged along the wall surface 2 of the swimming pool 1, a pair of belt parts 35 (corresponding to a “connecting part” in claims) connected with the foot plate 31, and a supporting part 37 that supports the pair of belt parts 35. In the following explanation regarding the starting assist device 30, the starting assist device 30 in a state of being mounted on the starting block 10 is explained unless otherwise specified.

FIG. 5 is a perspective view of the starting assist device, and is a perspective view mainly showing a foot plate seen from the back.

As shown in FIG. 5, the foot plate 31 is used to support a foot of a backstroke swimmer at the start of a competition. The foot plate 31 is formed into a triangular prism shape extending along the horizontal direction. The foot plate 31 includes a back surface 31 a that faces the wall surface 2 of the swimming pool 1 (see FIG. 1), a front surface 31b connected with an upper end side of the back surface 31a, and a lower surface 31c orthogonally connected with a lower end side of the back surface 31a. A crossing angle between the back surface 31a and the front surface 31b is about 10□. A width of the lower surface 31c is, for example, about 20 mm.

A first non-slip part 32 (corresponding to a “non-slip part” in claims) is provided on the back surface 31a of the foot plate 31. The first non-slip part 32 has, for example, a number of projections and recesses. Thus, friction force increases between the wall surface 2 of the swimming pool 1 and the back surface 31a of the foot plate 31, thereby preventing the foot plate 31 from being dislocated with respect to the wall surface 2 of the swimming pool 1 when a backstroke swimmer kicks the foot plate 31 at the start of a competition.

As shown in FIG. 1, a second non-slip part 33 is provided on the front surface 31b of the foot plate 31. The second non-slip part 33 has, for example, a number of projections and recesses like the first non-slip part 32. Thus, a foot of a backstroke swimmer is prevented from slipping off from the foot plate 31 when the backstroke swimmer kicks the foot plate 31 at the start of a competition.

It is preferred that the pair of belt parts 35 is formed from a material that is freely deformable and has low elasticity. A suitable example is a belt-shaped member formed from, for example, polypropylene or polyethylene. End parts of the pair of belt parts 35 on one side are connected with both left and right end parts of the foot plate 31, respectively. The pair of belt parts 35 extends upwardly from end parts of the foot plate 31 along the wall surface 2 of the swimming pool 1, bent to the back at an edge of the upper surface 3a of the poolside 3, and connected with the supporting part 37.

The supporting part 37 has a main shaft part 38, a cylindrical part 39 that pivotally supports the main shaft part 38, and a pair of drum parts 40 provided in both end parts of the main shaft part 38.

The main shaft part 38 is a bar member that extends along the horizontal direction and has a circular shape in a sectional view. A length of the main shaft part 38 is larger than a width of the platform 17 of the starting block 10 in the horizontal direction.

The cylindrical part 39 is fitted onto a center part of the main shaft part 38. A length of the cylindrical part 39 is equal to a width of the platform 17 of the starting block 10 in the horizontal direction. The cylindrical part 39 is arranged coaxially with the main shaft part 38.

FIG. 6 is a perspective view of the starting assist device, and a perspective view mainly showing the supporting part from the front.

As shown in FIG. 6, the pair of engaging projections 41 projecting towards the platform 17 is provided in the cylindrical part 39. Each of the engaging projections 41 is formed into a T shape in which a distal end is wider than a base end in a view from the normal direction L1 of the upper surface 17a of the platform 17 (see FIG. 4). The distal ends the engaging projections 41 can be inserted into the pair of connecting members 22 (see FIG. 4), respectively. Thus, the supporting part 37 is detachably fixed to the platform 17 through the connecting members 22. As shown in FIG. 1 and FIG. 4, since the connecting members 22 are provided in the back end part 17b of the platform 17, the supporting part 37 is arranged on the opposite side of the swimming pool 1 through the footrest 20 in a state where the supporting part 37 is mounted on the platform 17. Moreover, the supporting part 37 is arranged on the back of the footrest 20 that is fixed to a backmost part.

As shown in FIG. 6, a handle part 42 is provided in an upper part of the cylindrical part 39. The handle part 42 is formed into a U shape that is open downwardly in a view from the front-back direction. Lower end parts on both left and right sides of handle part 42 are connected with the cylindrical part 39. The handle part 42 projects in the normal direction L1 of the upper surface 17a of the platform 17 in a state where the supporting part 37 is mounted on the platform 17. Connecting positions between the handle part 42 and the cylindrical part 39 generally coincide with connecting positions between the engaging projections 41 and the cylindrical part 39 in the horizontal direction. When removing the starting assist device 30 from the starting block 10, it is only necessary to grip the handle part 42 and slide the supporting part 37 in the normal direction L1 of the upper surface 17a of the platform 17, thereby realizing a structure in which the starting assist device 30 is removed easily.

Each of the pair of drum parts 40 includes a winding drum 40a and flange parts 40b provided on both ends of the winding drum 40a. An end part of each of the belt parts 35 on the other side is connected with each of the drum parts 40, thereby making it possible to wind the belt part 35. Each of the drum parts 40 is arranged coaxially with the supporting part 37 and is fixed to the supporting part 37.

The supporting part 37 is provided with a position adjustment mechanism 45 for adjusting a position of the foot plate 31. The position adjustment mechanism 45 includes an energizing member 46 and a lock mechanism 47. The energizing member 46 is, for example, a spring, and arranged on an inner side of one end part of the cylindrical part 39. The energizing member 46 energizes the main shaft part 38 with respect to the cylindrical part 39 towards an outer side (one side) of the one end part of the cylindrical part 39 in an axis direction (horizontal direction) of the main shaft part 38. The lock mechanism 47 is provided on the other end side of the cylindrical part 39. The lock mechanism 47 is able to change a state of the main shaft part 38 between a state where the main shaft part 38 is allowed to rotate with respect to the cylindrical part 39 (herein below, referred to as a “rotating state”) and a state where the main shaft part 38 is fixed with respect to the cylindrical part 39 (herein below, referred to as a “fixed state”). Specifically, the lock mechanism 47 allows the main shaft part 38 to be in the fixed state when the main shaft part 38 is pressed by the energizing member 46 with respect to the cylindrical part 39 towards one side in the axis direction of the main shaft part 38. The lock mechanism 47 allows the main shaft part 38 to be in the rotating state when the main shaft part 38 is pulled by an operator and so on with respect to the cylindrical part 39 towards the other side in the axis direction of the main shaft part 38.

The pair of drum parts 40 rotates in conjunction with rotation of the main shaft part 38 that is allowed to be in the rotating state by the position adjustment mechanism 45. In other words, as the position adjustment mechanism 45 allows the main shaft part 38 to be in the rotating state so that the pair of drum parts 40 rotates, it is possible to wind and rewind the belt part 35. Thus, as shown in FIG. 1, a clearance between the foot plate 31 and the supporting part 37 is adjusted, thereby adjusting a position (height) of the foot plate 31 that is arranged along the wall surface 2 of the swimming pool 1.

As stated so far, the starting assist device 30 according to the embodiment includes the foot plate 31, which is arranged along the wall surface 2 of the swimming pool 1 and supports a foot of a backstroke swimmer when a competition starts, the pair of belt parts 35 connected with the foot plate 31, and the supporting part 37 that supports the pair of belt parts 35. The supporting part 37 is fixed to the back end part 17b of the platform 17.

Generally, the shape of the base part 11 of the starting block 10 is changed to meet specifications of the swimming pool 1 (for example, the shape of the poolside 3) where the base part 11 is installed. On the contrary, the shape, structure, and so on of the platform 17 mounted on the upper part of the base part 11 are standardized. According to the invention, since the supporting part 37 of the starting assist device 30 is mounted on the standardized platform 17, it is possible to use the same shape and mounting structure for the supporting part 37 regardless of the specifications of the swimming pool 1 where the starting assist device 30 is installed. Therefore, it is possible to mount the starting assist device 30 on the starting block 10 without changing the design of the starting assist device 30 as appropriate to meet the specifications of the swimming pool 1 where the starting assist device 30 is installed, thereby making the starting assist device 30 versatile.

Further, since the supporting part 37 of the starting assist device 30 is fixed to the back end part 17b of the platform 17, a swimmer is able to use the entire upper surface 17a of the platform 17. Therefore, when a swimmer stands on the platform 17 and dives into the swimming pool 1, the supporting part 37 is not in the way. Therefore, during a medley relay, for example, after a backstroke swimmer starts a competition, it is not necessary to remove the starting assist device 30 from the starting block 10 before a swimmer who uses the starting block 10 next stands on the platform 17. In other words, it is only necessary to take out the foot plate 31 from the water, allow the foot plate 31 to pass through the upper surface 17a of the platform 17, and place the foot plate 31 on the upper surface 3a of the poolside 3, and it is not necessary to remove the starting assist device 30 from the starting block 10. Therefore, it is possible to make the starting assist device 30 easy to use.

Since the supporting part 37 is arranged on the opposite side of the swimming pool 1 through the footrest 20, it is possible to prevent the supporting part 37 from being in the way of a swimmer who stands on the platform 17. Thus, even in the case where the starting block 10 has the footrest 20, it is not necessary to remove the starting assist device 30 from the starting block 10 after a backstroke swimmer starts a competition until a swimmer who uses the starting block 10 next stands on the platform 17.

Further, the supporting part is arranged on the back of the footrest 20 that is fixed on the backmost part. Therefore, at whichever position the footrest 20 is arranged, it is possible to prevent the supporting part 37 from being in the way of a swimmer who stands on the platform 17. Thus, even if the arrangement position of the footrest 20 is adjustable, it is not necessary to remove the starting assist device 30 from the starting block 10 after a backstroke swimmer starts a competition until a swimmer who uses the starting block 10 next stands on the platform 17. Therefore, it is possible to realize the easily used and versatile starting assist device that can be mounted on the starting block 10 having the footrest 20.

Moreover, since the supporting part 37 is detachably fixed to platform 17, it is possible to remove the starting assist device 30 from the starting block 10 easily when, for example, the starting assist device 30 is not used for a long period of time.

Also, since the supporting part 37 has the handle part 42, it is possible to make it easy to carry, attach, and detach the starting assist device 30.

Therefore, even in a case of, for example, a medley relay, where the starting assist device 30 is removed from the starting block 10 after a backstroke swimmer starts a competition until a swimmer who uses the starting block 10 next stands on the platform 17, the competition is not interfered because the starting assist device 30 is attached and detached easily.

The invention is not limited to the foregoing embodiment described with reference to the drawings, and various modified examples are considered within the technical scope of the invention.

For example, in the foregoing embodiment, the foot plate 31 and the supporting part 37 are connected with each other by the pair of deformable belt parts 35. However, the invention is not limited to this, and the foot plate 31 and the supporting part 37 may be connected with bar-shaped members formed from, for example, a metal material.

In the foregoing embodiment, the supporting part 37 is mounted on the platform 17 through the connecting members 22. However, the invention is not limited to this, and the supporting part may be mounted directly on the platform by fixing and fastening.

Other than above, it is possible to replace the components of the foregoing embodiment as appropriate with known components without departing from the gist of the invention.

Claims

1. A starting assist device that is mounted on a staring block having a platform on which a swimmer in a swimming competition climbs up, comprising:

a foot plate that is arranged along a wall surface of a swimming pool and supports a foot of a backstroke swimmer when a competition starts;

a pair of connecting parts connected with the foot plate; and

a supporting part that supports the pair of connecting parts, wherein

the supporting part is fixed to one end part of the platform on an opposite side of the swimming pool side.

2. The starting assist device according to claim 1, wherein

the starting block has a footrest for placing a foot of a swimmer, the footrest being arranged on an upper surface of the platform, and

the supporting part is arranged on the opposite side of the swimming pool through the footrest.

3. The starting assist device according to claim 2, wherein

an arrangement position of the footrest is adjustable so that the footrest is closer to or separated from the swimming pool, and

the supporting part is arranged at a position separated from the swimming pool more than the footrest that is fixed to a farthest position from the swimming pool.

4. The starting assist device according to claim 1, wherein the supporting part is detachably fixed to the platform through an attachment provided in the one end part of the platform.

5. The starting assist device according to claim 1, wherein the supporting part has a handle part.

6. The starting assist device according to claim 1, wherein the foot plate has a non-slip part on a surface that faces the wall surface of the swimming pool.