Patent Publication Number: US-11390361-B2

Title: Personal watercraft

Description:
BACKGROUND 
     Technical Field 
     An aspect of the present disclosure relates to a personal watercraft. 
     Description of the Related Art 
     A personal watercraft includes a straddle seat which is located rearward of a handle and on which a user sits in a straddling position (see U.S. Pat. No. 10,227,110 B  1 , for example). Different users have different physical characteristics, and it is desired that such a seat be adjustable to offer improved ride comfort to every user. 
     SUMMARY 
     A personal watercraft according to an aspect of the present disclosure includes: a watercraft body; a handle located above the watercraft body; a seat assembly including at least one straddle seat located rearward of the handle; and at least one mounting adjuster configured to mount the straddle seat on the watercraft body and allow the straddle seat to be positionable on the watercraft body in a plurality of mounting positions arranged in a front-rear direction. 
     In the above configuration, the position of the straddle seat on the watercraft body can be changed in the front-rear direction by the mounting adjuster for mounting the straddle seat on the watercraft body. Thus, different seating positions can be provided by the use of one and the same seat, and seat adjustment can be made depending on the user&#39;s physical characteristics or the user&#39;s preferences such as a preferred seating posture. This makes it possible to offer good seat comfort to various users. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left side view illustrating a personal watercraft according to an exemplary embodiment and showing a part of the personal watercraft in cross-section. 
         FIGS. 2A and 2B  illustrate the seat position adjustment of the personal watercraft of  FIG. 1 . 
         FIG. 3  is a rear left perspective view of a part of the personal watercraft of  FIG. 1  with a seat assembly removed. 
         FIG. 4  is a plan view of the personal watercraft of  FIG. 2  with a closure panel removed. 
         FIG. 5  is a vertical cross-sectional view of a part of the personal watercraft of  FIG. 1  as seen from the left. 
         FIG. 6  is a front perspective view of front and rear seats of  FIG. 5 . 
         FIG. 7  is a rear left perspective view of a part of the personal watercraft of  FIG. 1  with the rear seat removed. 
         FIG. 8A  illustrates the position adjustment of the front seat of  FIG. 5 .  FIG. 8B  illustrates the position adjustment of the rear seat of  FIG. 5 . 
         FIG. 9  is a vertical cross-sectional view of a mounting adjuster of  FIG. 7  as seen from the left. 
         FIG. 10  is a horizontal cross-sectional view of the mounting adjuster of  FIG. 9 . 
         FIG. 11  illustrates the operation of the mounting adjuster of  FIG. 10 . 
         FIG. 12A  is a perspective view of a first variant of the front and rear seats of  FIG. 6 . 
         FIG. 12B  is a perspective view of a second variant of the front and rear seats of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, exemplary embodiments will be described with reference to the drawings. 
       FIG. 1  is a left side view illustrating a personal watercraft  1  according to an exemplary embodiment and showing a part of the personal watercraft  1  in cross-section. Referring to  FIG. 1 , the personal watercraft  1  (hereinafter referred to as “PWC”) includes a watercraft body  2 , and the watercraft body  2  includes a hull  11  and a deck  12  covering the hull  11  from above. The interior of the watercraft body  2  includes an engine room R, in which an engine E serving as a prime mover is accommodated. The engine E includes an output shaft connected to a propeller shaft  3  extending rearward. The rear end of the propeller shaft  3  is connected to a pump shaft  4   a  of a water jet pump  4  located in the rear of the hull  11 . An impeller  4   b  is mounted on the pump shaft  4   a . A stator vane  4   c  is located rearward of the impeller  4   b . A pump casing  4   d  is located radially outward of the impeller  4   b  and encloses the impeller  4   b.    
     A water inlet  11   a  opens at the bottom of the hull  11 . The water inlet  11   a  and the pump casing  4   d  are in communication via a water passage  11   b . The pump casing  4   d  is provided with a pump nozzle  4   e  facing rearward of the watercraft body  2 . The pump nozzle  4   e  decreases in diameter from front to rear, and an ejection orifice opens at the rear end of the pump nozzle  4   e . To the ejection orifice of the pump nozzle  4   e  is connected a steering nozzle  5  which is swingable in the left-right direction. A bowl-shaped reverse bucket  6  is located in proximity to the steering nozzle  5 . The reverse bucket  6  is pivotally supported by the hull  11  and pivotable between an advanced position where the reverse bucket  6  covers the ejection orifice of the steering nozzle  5  from behind to cause water ejected from the pump nozzle  4   e  to be redirected forward and a retracted position where the reverse bucket  6  allows the ejection orifice of the steering nozzle  5  to be open in the rearward direction. 
     In the PWC  1 , water drawn into the hull  11  through the water inlet  11   a  located at the bottom of the hull  11  is pressurized and accelerated by rotational power of the impeller  4   b  of the water jet pump  4  driven by the engine E. The flow of water is conditioned by the stator vane  4   c  and ejected rearward through the ejection orifice of the pump nozzle  4   e  and the steering nozzle  5  to produce propulsion power. A bar-shaped handle  7  is located above the front of the deck  12  and rotatably supported by the deck  12 . When the operator tilts the handle  7  to the left or right, the steering nozzle  5  swings to the left or right in conjunction with the tilting movement of the handle  7 . 
     The deck  12  includes a seat support  21  and a pair of foot rests  22 . The seat support  21  is located rearward of the handle  7  and projects upward from a deck floor of the deck  12 . The deck floor is a floor on which users can walk. The foot rests  22  are located to the left and right of the seat support  21 , respectively. The foot rests  22  constitute a part of the deck floor. The seat support  21  supports a seat assembly  8  from below. The seat assembly  8  includes a front seat  15  and a rear seat  16  located adjacent to and rearward of the front seat  15 . 
     The seat assembly  8  is removable from the watercraft body  2 . In the present embodiment, the front and rear seats  15  and  16  are independent of each other. The front and rear seats  15  and  16  are straddle seats on which users sit in a straddling position. The front seat  15  is a seat on which at least the operator sits. In the present embodiment, the front seat  15  is configured to allow two persons to sit thereon. Specifically, the operator and a first passenger located adjacent to and rearward of the operator can sit on the front seat  15 . The rear seat  16  is configured to allow a second passenger to sit thereon. The second passenger is a person who is located adjacent to and rearward of the first passenger. 
       FIGS. 2A and 2B  illustrate the seat position adjustment of the PWC  1  of  FIG. 1 . As shown in  FIG. 2A , the positions of the front and rear seats  15  and  16  mounted on the watercraft body  2  can be collectively shifted rearward. Conversely, the mounting positions of the front and rear seats  15  and  16  can be collectively shifted forward. Thus, the positions of the front and rear seats  15  and  16  mounted on the watercraft body  2  can both be changed in the same direction, namely in the forward or rearward direction. As shown in  FIG. 2B , the positions of the front and rear seats  15  and  16  mounted on the watercraft body  2  can be changed in such a manner that the front and rear seats  15  and  16  are moved away from each other in the front-rear direction. Conversely, the mounting positions of the front and rear seats  15  and  16  can be changed in such a manner that the front and rear seats  15  and  16  are moved toward each other in the front-rear direction. Thus, the front and rear seats  15  and  16  can be position-adjusted in a multistep fashion independently of each other. The seat assembly  8  may be configured such that the front and rear seats  15  and  16  are not independent of each other and position-adjusted together. 
       FIG. 3  is a rear left perspective view of a part of the PWC  1  with the seat assembly  8  removed.  FIG. 4  is a plan view of the PWC  1  with a closure panel  13  removed. In  FIG. 4 , a recess  41   b  of the closure panel  13  and some other portions are omitted. Referring to  FIGS. 3 and 4 , the seat support  21  includes a peripheral wall  21   a  projecting upward from the foot rests  22  and an upper wall  21   b  connected to the upper edge of the peripheral wall  21   a . The upper wall  21   b  of the seat support  21  is provided with an engine room opening Q 1  and a pair of duct openings Q 2 . 
     The engine room opening Q 1  and duct openings Q 2  allow the engine room R to be open to the outside of the deck  12 . In plan view, the engine room opening Q 1  overlaps the engine E. In plan view, the engine room opening Q 1  overlaps both of the front and rear seats  15  and  16 . The duct openings Q 2  are located between the rear edge of the upper wall  21   b  and the engine room opening Q 1  in the front-rear direction. The duct openings Q 2  are aligned in the left-right direction. Into the duct openings Q 2  are inserted ventilation ducts  9  for allowing the engine room R to be open to the atmosphere. Positioning projections  71  of a pair of rear mounting adjusters  20  described later project upward from that portion of the upper wall  21   b  of the seat support  21  which is posterior to the ventilation ducts  9 . 
     The watercraft body  2  includes the closure panel  13  mounted on top of the deck  12 . The closure panel  13  is removably secured to the seat support  21  by fixing elements  14 . The closure panel  13  closes the engine room opening Q 1 . The closure panel  13  is located forward of and spaced from the duct openings Q 2 . The closure panel  13  is located below and faces both of the front and rear seats  15  and  16 . 
     The closure panel  13  includes a panel body  31  and an inspection cover  32 . The panel body  31  includes an upper plate  41 , a side plate  42 , and insertion holes  43 . The upper plate  41  closes the engine room opening Q 1 . The upper plate  41  is placed on top of a portion of the upper wall  21   b  of the seat support  21 . The side plate  42  projects downward from the side edges of the upper plate  41 . The side plate  42  extends along the peripheral wall  21   a  of the seat support  21 . The closure panel  13  need not include the side plate  42 . The insertion holes  43  are located forward of and above the upper plate  41 . The insertion holes  43  are open at least toward the rear of the watercraft body. In the present embodiment, each insertion hole  43  is open at both ends in the front-rear direction of the watercraft body. 
     The upper plate  41  is provided with an inspection opening Q 3 . In plan view, the inspection opening Q 3  overlaps an inspection-requiring portion which is related to the engine E and which is frequently inspected (e.g., a portion for oil check). The inspection opening Q 3  is closed from above by the inspection cover  32 . The inspection cover  32  includes a plate portion  32   a  that closes the inspection opening Q 3  and grip portions  32   b  provided on the upper surface of the plate portion  32   a . The inspection cover  32  is mounted on the panel body  31  to close the inspection opening Q 3  and is removable to uncover the inspection opening Q 3 . 
     The upper surface of the panel body  31  of the closure panel  13  includes a top surface  41   a  and a recess  41   b . The recess  41   b  extends downward from the top surface  41   a  and defines a space S. At least a portion of the bottom of the recess  41   b  is a horizontal surface  41   bb  which extends in a horizontal direction when the PWC  1  is at rest on the water. The front edge of the horizontal surface  41   bb  is smoothly continuous with the top surface  41   a . The recess  41   b  includes an inclined surface  41   ba  adjacent to and rearward of the horizontal surface  41   bb . The inclined surface  41   ba  is inclined upward from front to rear when the PWC  1  is at rest on the water. That is, the normal to the inclined surface  41   ba  extends upward and forward. A positioning projection  71  of a front mounting adjuster  10  described later projects upward from the inclined surface  41   ba  of the recess  41   b.    
       FIG. 5  is a vertical cross-sectional view of a part of the PWC  1  of  FIG. 1  as seen from the left.  FIG. 6  is a front perspective view of the front and rear seats  15  and  16  of  FIG. 5 .  FIG. 7  is a rear left perspective view of a part of the PWC  1  of  FIG. 1  with the rear seat  16  removed.  FIG. 8A  illustrates the position adjustment of the front seat  15  of  FIG. 5 .  FIG. 8B  illustrates the position adjustment of the rear seat  16  of  FIG. 5 . Referring to  FIG. 5 , the front seat  15  includes a front cushion  51  and a front bottom plate  52 . The rear seat  16  includes a rear cushion  61  and a rear bottom plate  62 . In plan view, a rear end portion of the front seat  15  and a front end portion of the rear seat  16  overlap the closure panel  13  regardless of in which position the seat assembly  8  is mounted. The rear seat  16  covers the ventilation ducts  9  from above. There is a gap between the rear seat  16  and the ventilation ducts  9 . 
     Referring to  FIGS. 5 and 6 , the front cushion  51  includes a front bottom support  51   a , a hip support  51   b , and a rear bottom support  51   c . The front bottom support  51   a  is a front part of the front cushion  51  and supports the hips of the operator from below. The hip support  51   b  is configured to support the hips of the operator from behind when the operator sits on the front bottom support  51   a . Specifically, the hip support  51   b  is adjacent to and rearward of the front bottom support  51   a  and projects upward from the rear end of the front bottom support  51   a . The front cushion  51  as viewed in the front-rear direction is in the shape of an upwardly convex arch. In the thus shaped front cushion  51 , the hip support  51   b  projects upward with respect to the front bottom support  51   a  and exhibits an arch shape. 
     When the PWC  1  is at rest on the water, the difference between the vertical height of a portion of the front bottom support  51   a  that is immediately adjacent to the hip support  51   b  and the vertical height of the hip support  51   b  is, for example, in the range of 5 to 20 cm and preferably in the range of 10 to 15 cm, although the difference between the vertical heights is not limited to these ranges. 
     The rear bottom support  51   c  is a seat portion which is adjacent to and rearward of the hip support  51   b  and which has a lower height than the hip support  51   b . The rear bottom support  51   c  located adjacent to and rearward of the operator supports the hips of the first passenger from below. The rear end portion of the rear bottom support  51   c  is inserted into a space beneath the rear seat  16  through the front opening of the space. Specifically, both in plan view and in side view, the arched rear edge of the front seat  15  is covered by the arched front end portion of the rear seat  16 . The seat assembly  8  may be configured such that the front end portion of the rear seat  16  is inserted into a space beneath the front seat  15  through the rear opening of the space. 
     The front bottom plate  52  is located below and secured to the front cushion  51 . The front bottom plate  52  is located above and faces the closure panel  13 . Ahead of the front bottom plate  52  are located engaging projections  53  extending forward. The engaging projections  53  are formed integrally with the front bottom plate  52  by one-piece molding. To the rear end portion of the front bottom plate  52  is secured a receiver  72  of the front mounting adjuster  10 . The engaging projections  53  of the front seat  15  are inserted into the insertion holes  43  of the closure panel  13  through the rear openings of the insertion holes  43 , and thus the receiver  72  of the front mounting adjuster  10  is connected to the watercraft body  2 , so that the front seat  15  is secured to the watercraft body  2 . As seen from  FIG. 5 , if the rear seat  16  is removed from the watercraft body  2 , a user operable structure  79  of the front mounting adjuster  10  is exposed toward the rear of the watercraft body  2 . The details of the configuration of the front mounting adjuster  10  will be described later. 
     The rear cushion  61  includes a front hip support  61   a , a bottom support  61   b , and a rear hip support  61   c . The front hip support  61   a  is configured to support the hips of the first passenger from behind when the first passenger sits on the rear bottom support  51   c  of the front seat  15 . Specifically, the front hip support  61   a  is an upwardly projecting front end portion of the rear cushion  61  and is adjacent to and rearward of the rear bottom support  51   c  of the front seat  15 . The front hip support  61   a  as viewed in the front-rear direction is arched and projects upward with respect to the rear bottom support  51   c.    
     When the PWC  1  is at rest on the water, the difference between the vertical height of a portion of the rear bottom support  51   c  that is immediately adjacent to the front hip support  61   a  and the vertical height of the front hip support  61   a  is, for example, in the range of 3 to 15 cm and preferably in the range of 5 to 10 cm, although the difference between the vertical heights is not limited to these ranges. 
     The bottom support  61   b  is a seat portion which is adjacent to and rearward of the front hip support  61   a  and which has a lower height than the front hip support  61   a . The bottom support  61   b  supports the hips of the second passenger from below. The rear hip support  61   c  is configured to support the hips of the second passenger from behind when the second passenger sits on the bottom support  61   b . Specifically, the rear hip support  61   c  is adjacent to and rearward of the bottom support  61   b  and projects upward from the rear end of the bottom support  61   b . When the PWC  1  is at rest on the water, the difference between the maximum vertical height of the bottom support  61   b  and the maximum vertical height of the rear hip support  61   c  is, for example, in the range of 2 to 10 cm and preferably in the range of 4 to 8 cm, although the difference between the maximum vertical heights is not limited to these ranges. 
     The rear bottom plate  62  is located below and secured to the rear cushion  61 . The rear bottom plate  62  is located above and faces the closure panel  13  and the ventilation ducts  9 . A hand grip  64  is secured to the rear bottom plate  62 . The hand grip  64  projects rearward beyond the rear cushion  61 . The hand grip  64  can be held by a user when the user moves on the deck  12  or when the user gets onto the watercraft body  2  from the water. The hand grip  64  is U-shaped. The two front ends of the hand grip  64  are secured to the rear bottom plate  62 , and the arched portion of the hand grip  64  extends rearward. Ahead of the rear bottom plate  62  is located an engaging projection  63  extending forward. The engaging projection  63  is formed integrally with the rear bottom plate  62  by one-piece molding. To the rear end portion of the rear bottom plate  62  are secured receivers  72  of the pair of rear mounting adjusters  20 . The rear mounting adjusters  20  are spaced apart from each other in the left-right direction. 
     The engaging projection  63  of the rear seat  16  is inserted into the space beneath the front bottom plate  52  of the front seat  15  through the rear opening of the space, and thus the receivers  72  of the rear mounting adjusters  20  are connected to the watercraft body  2 , so that the rear seat  16  is secured to the watercraft body  2 . The user operable structures  79  of the rear mounting adjusters  20  are exposed toward the rear of the watercraft body  2  to which the rear seat  16  has been secured (see  FIG. 7 ). The configuration of the rear mounting adjusters  20  is the same as the configuration of the front mounting adjuster  10  which will be described later. Thus, a particular description of the configuration of the rear mounting adjusters  20  will not be given. 
     Referring to  FIG. 8A , the front mounting adjuster  10  is configured to allow the front seat  15  to be mountable on the watercraft body  2  in a plurality of mounting positions (e.g., three mounting positions) arranged in the front-rear direction. Referring to  FIG. 8B , the rear mounting adjusters  20  are configured to allow the rear seat  16  to be mountable on the watercraft body  2  in a plurality of mounting positions (e.g., three mounting positions) arranged in the front-rear direction. Thus, the mounting position of the front seat  15  and the mounting position of the rear seat  16  are changeable independently of each other. Combinations of the mounting positions provided by the front mounting adjuster  10  and the mounting positons provided by the rear mounting adjusters  20  include a first combination in which the front seat  15  and the rear seat  16  are maximally close to each other and a plurality of second combinations other than the first combination. 
     When mounted using any of the second combinations, the front and rear seats  15  and  16  are spaced by a gap G. The front end portion of the rear cushion  61  is shaped to cover the gap G formed between the front and rear seats  15  and  16  mounted using the second combination. Specifically, when the front and rear seats  15  and  16  are mounted using any of the second combinations, the rear end portion of the front cushion  51  is inserted into the space beneath the rear seat  16  through the front opening of the space. Thus, both in plan view and in side view, the rear edge of the front seat  15  is covered by the front end portion of the rear seat  16 . When mounted using the first combination, the front and rear seats  15  and  16  may be in contact without any gap G or spaced by a gap G in the front-rear direction. 
       FIG. 9  is a vertical cross-sectional view of the mounting adjuster  10  of  FIG. 7  as seen from the left.  FIG. 10  is a horizontal cross-sectional view of the mounting adjuster  10  of  FIG. 9 .  FIG. 11  illustrates the operation of the mounting adjuster  10  of  FIG. 10 . The front mounting adjuster  10  and rear mounting adjusters  20  have the same configuration. Hereinafter, the configuration of the front mounting adjuster  10  will be descried. Referring to  FIGS. 9 and 10 , the front mounting adjuster  10  includes the positioning projection  71  and the receiver  72 . The positioning projection  71  is secured to the bottom surface of the recess  41   b  of the closure panel  13  and projects upward toward the front seat  15  (see  FIG. 5 ). The positioning projection  71  is, for example, substantially in the shape of a circular cylinder. The positioning projection  71  includes an engagement receiving structure  71   a . The engagement receiving structure  71   a  is, for example, an annular recess formed in the outer circumferential surface of the positioning projection  71  and extending around the axis of the positioning projection  71 . 
     The receiver  72  is secured to the front seat  15 . The receiver  72  is located above and faces the positioning projection  71 . The receiver  72  includes a housing  73 , a plurality of engaging structures  74 , a plurality of support shafts  75 , a coupling structure  76 , a spring  77 , a drive force conversion structure  78 , and a user operable structure  79 . The housing  73  includes a first positioning space  73   a , a second positioning space  73   b , a third positioning space  73   c , and a shared space  73   d . The first to third positioning spaces  73   a  to  73   c  are separate spaces arranged in the front-rear direction and divided from one another. The shared space  73   d  is adjacent to all of the first to third positioning spaces  73   a  to  73   c  in the left-right direction and is in communication with each of the first to third positioning spaces  73   a  to  73   c.    
     The bottom of the housing  73  is provided with first to third positioning holes H 1  to H 3  arranged in the front-rear direction. The first positioning hole H 1  allows the first positioning space  73   a  to open downward. The second positioning hole H 2  allows the second positioning space  73   b  to open downward. The third positioning hole H 3  allows the third positioning space  73   c  to open downward. The positioning projection  71  is inserted from below into a hole arbitrarily selected from the first to third positioning holes H 1  to H 3 , so that the position of the front seat  15  in the horizontal direction is fixed on the watercraft body  2 . 
     The number of the engaging structures  74  and the number of the support shafts  75  are the same as the number of the first to third positioning holes H 1  to H 3 . The three sets of the engaging structure  74  and the support shaft  75  are associated with the first to third positioning holes H 1  to H 3 , respectively. The engaging structure  74  is, for example, an engaging rod. The engaging structure  74  is swingable about the support shaft  75  provided in the housing  73 . The coupling structure  76  is located in the shared space  73   d . The coupling structure  76  is, for example, a coupling rod. The coupling structure  76  is pivotally connected to the proximal ends of the three engaging structures  74 . 
     Referring to  FIGS. 10 and 11 , when the coupling structure  76  moves to one side in the front-rear direction, the three engaging structures  74  swing together in a first direction about the support shafts  75 , and the distal ends of the three engaging structures  74  move to engagement positions. As a result, one of the three engaging structures  74  is engaged with the engagement receiving structure  71   a  of the positioning projection  71  to block the front seat  15  from moving upward away from the watercraft body  2  (the front seat shown in  FIGS. 6 and 7  is in this engaged state). When the coupling structure  76  moves to the opposite side in the front-rear direction, the three engaging structures  74  swing together in a second direction about the support shafts  75 , and the distal ends of the three engaging structures  74  move to disengagement positions. As a result, all of the three engaging structures  74  are disengaged from the engagement receiving structure  71   a  of the positioning projection  71 . The engaging structures  74  are biased by the spring  77  toward the engagement positions. 
     The user operable structure  79  is located rearward of the housing  73 . The user operable structure  79  is configured to transmit a drive force to the coupling structure  76  through the drive force conversion structure  78 . The user operable structure  79  is swingably connected to the housing  73  so that the rear end portion of the user operable structure  79  is movable in the up-down direction. The drive force conversion structure  78  converts swinging motion of the user operable structure  79  in the up-down direction to linear motion of the coupling structure  76  in the front-rear direction. The drive force conversion structure  78  may be, for example, a cam structure in which the front end surface of the user operable structure  79  is in contact with the rear end surface of the coupling structure  76 . The drive force conversion structure  78  need not necessarily be used. The user operable structure  79  may be configured to move linearly, and the linear motion of the user operable structure  79  may be transmitted directly to the coupling structure  76 . 
     When the user operable structure  79  is moved upward by a hand, the coupling structure  76  moves in the front-rear direction against the spring  77 , and the three engaging structures  74  move together to the disengagement positions. As a result, one of the engaging structures  74  which had been engaged with the engagement receiving structure  71   a  becomes disengaged from the engagement receiving structure  71   a.    
     The positioning projection  71  and the first to third positioning holes H 1  to H 3  constitute a positioner  70  of the mounting adjuster  10 . The positioner  70  is configured to place the front seat  15  on the watercraft body  2  in a mounting position selected from three mounting positions arranged in the front-rear direction. The engagement receiving structure  71   a , engaging structures  74 , support shafts  75 , coupling structure  76 , spring  77 , drive force conversion structure  78 , and user operable structure  79  constitute a lock  80  of the mounting adjuster  10 . The lock  80  is configured to switch between a state where the front seat  15  is locked to the watercraft body  2  and a state where the front seat  15  is unlocked from the watercraft body  2 . 
     When the positioning projection  71  is inserted into the first positioning hole H 1  and the associated engaging structure  74  is engaged with the engagement receiving structure  71   a , the front seat  15  is mounted on the watercraft body  2  in a foremost mounting position. When the positioning projection  71  is inserted into the third positioning hole H 3  and the associated engaging structure  74  is engaged with the engagement receiving structure  71   a , the front seat  15  is mounted on the watercraft body  2  in a rearmost mounting position. When the positioning projection  71  is inserted into the second positioning hole H 2  and the associated engaging structure  74  is engaged with the engagement receiving structure  71   a , the front seat  15  is mounted on the watercraft body  2  in a middle mounting position intermediate between the foremost mounting position and the rearmost mounting position. Thus, the front mounting adjuster  10  allows the mounting position of the front seat  15  on the watercraft body  2  to be changeable in the front-rear direction. The rear mounting adjusters  20  operate on the same principle as the front mounting adjuster  10  to allow the mounting position of the rear seat  16  on the watercraft body  2  to be changeable in the front-rear direction. 
     In the configuration described above, the positions of the seats  15  and  16  on the watercraft body  2  can be changed in the front-rear direction. Thus, different seating positions can be provided by the use of one and the same seat, and seat adjustment can be made depending on the user&#39;s physical characteristics or the user&#39;s preferences such as a preferred seating posture. This makes it possible to offer good seat comfort to various users. Additionally, since changes of the positions of the seats  15  and  16  are accompanied by changes of the positions of the hip supports  51   b ,  61   a , and  61   c , good seat comfort can be reliably provided. 
     Since the position of the front seat  15  on which at least the operator sits can be changed in the front-rear direction, good seat comfort can be offered to the operator. Since the front and rear seats  15  and  16  can be position-adjusted independently of each other, both the seat comfort experienced by the operator and first passenger sitting on the front seat  15  and the seat comfort experienced by the second passenger sitting on the rear seat  16  can be optimized. 
     The rear end portion of the front cushion  51  or the front end portion of the rear cushion  61  is shaped such that when the front and rear seats  15  and  16  are spaced by the gap Gin the front-rear direction, the rear or front end portion covers the gap G. Thus, the gap G is inconspicuous even if the mounting positons of the front and rear seats  15  and  16  are changed to those where the front and rear seats  15  and  16  are spaced by the gap G. While an engine room opening of a conventional PWC is sealed by a seat serving as a lid, the engine room opening Q 1  is closed by the closure panel  13 . This eliminates the need for endowing the seat assembly  8  with a sealing function. Thus, the seat assembly  8  can be provided with a slide mechanism without having to complicate the configuration of the seat assembly  8 . 
     The closure panel  13  includes the panel body  31  provided with the inspection opening Q 3  and the inspection cover  32  removably mounted to close the inspection opening Q 3 . Thus, when inspection work for the engine E (such as oil check) is performed, the entire closure panel  13  need not be removed, and only the inspection cover  32  has to be removed to access the engine E through the inspection opening Q 3 . As such, both watertightness and ease of inspection can be ensured. 
     Since the front mounting adjuster  10  is located in the space S defined by the recess  41   b  of the closure panel  13 , the size of the space beneath the seat assembly  8  can be reduced to prevent a size increase of the seat assembly  8  in the up-down direction. The recess  41   b  of the closure panel  13  has the horizontal surface  41   bb  smoothly continuous with the top surface  41   a , and thus water entering the recess  41   b  is easily discharged outside (forward from) the recess  41   b.    
     Since the positioner  70  of each of the mounting adjusters  10  and  20  provides for a plurality of mounting positions, each of the seats  15  and  16  is mountable on the watercraft body  2  in a plurality of positions arranged in the front-rear direction. Since the positioning projection  71  of each of the mounting adjusters  10  and  20  is provided with the engagement receiving structure  71   a , the positioning projection  71  can serve as a component of both the positioner  70  and the lock  80 , and this allows for a simplified configuration of the mounting adjusters  10  and  20 . Since the engaging structures  74  and the user operable structure  79  are provided in the seats  15  and  16 , the watercraft body  2  can be simplified, and large areas can be allocated to the cushion portions of the seats  15  and  16 . 
     The user operable structure  79  causes the plurality of engaging structures  74  to move together; that is, one user operable structure  79  is sufficient to move the plurality of engaging structures  74 . This allows for simplification of the configuration and enables the user to disengage the engaging structures  74  by operating one and the same user operable structure  79  regardless of the changes of the mounting positions of the seats  15  and  16 . Thus, the user friendliness is improved. 
     Since the hand grip  64  is secured to the rear seat  16  rather than to the watercraft body  2 , there is no need for changing the position of the hand grip  64  when changing the mounting position of the rear seat  16  on the watercraft body  2 . The two rear mounting adjusters  20  for the rear seat  16  with the hand grip  64  secured thereto are spaced apart from each other in the left-right direction. Thus, the rear seat  16  mounted on the watercraft body  2  can be stably held in place even when a load acting leftward or rightward is applied to the hand grip  64 . 
       FIG. 12A  is a perspective view of a first variant of the front and rear seats shown in  FIG. 6 . Referring to  FIG. 12A , the front and rear seats  115  and  116  are shaped such that the rear edge of the front seat  115  covers the front end portion of the rear seat  116  in plan view and that the gap G between the front and rear seats  115  and  116  is open in the left-right direction in side view. The front and rear seats  115  and  116  may be shaped such that the front edge of the rear seat  116  covers the rear end portion of the front seat  115  in plan view and that the gap G between the front and rear seats  115  and  116  is open in the left-right direction in side view. 
       FIG. 12B  is a perspective view of a second variant of the front and rear seats shown in  FIG. 6 . Referring to  FIG. 12B , the front and rear seats  215  and  216  are shaped such that the front edge of the rear seat  216  covers the rear end portion of the front seat  215  in side view and that the gap G between the front and rear seats  215  and  216  is open in the upward direction in plan view. The front and rear seats  215  and  216  may be shaped such that the rear end portion of the front seat  215  covers the front edge of the rear seat  216  in side view and that the gap G between the front and rear seats  215  and  216  is open in the upward direction in plan view. 
     Many modifications and other embodiments of the present invention will be apparent to those skilled in the art from the foregoing description. Accordingly, the foregoing description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the invention. The details of the structure and/or function may be varied substantially without departing from the scope of the invention. 
     While in the above embodiment the positioner  70  includes a plurality of positioning holes H 1  to H 3  and one positioning projection  71 , the positioner  70  may include one positioning hole and a plurality of positioning projections. One of the front and rear seats  15  and  16  may be capable of position adjustment in the front-rear direction, while the other of the front and rear seats  15  and  16  may be incapable of position adjustment in the front-rear direction. The PWC  1  may be a two-seater PWC in which each of the front and rear seats  15  and  16  is configured for seating of one person. In this case, for example, one of the hip support  51   b  and the front hip support  61   a , in particular the hip support  51   b , need not be provided. 
     The seat assembly  8  may include only one straddle seat. The front end portion of the rear cushion  61  may be inserted into the space beneath the rear end portion of the front cushion  51 . In this case, the rear end portion of the front cushion  51  may cover the front end portion of the rear cushion  61 . The male-female relationship in fitting of the engagement structures  74  and the engagement receiving structure  71   a  may be reversed. The configurations of the positioner  70  and the lock  80  are not limited to those described above, and any other known configurations may be used. The mounting adjusters  10  and  20  are not limited to those of the embodiment described above, and may be rails capable of sliding in the front-rear direction and being held in a fixed position in the front-rear direction.