Abstract:
The invention relates to a water sport device having a sitting or standing surface ( 2 ) for a person practicing water sports, a jet drive ( 8 ) and a pivotable nozzle ( 13 ), wherein a fin ( 23 ) is disposed at the nozzle ( 13 ) and is arranged in a fixed position relative to said nozzle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is for entry into the U.S. National Phase under §371 for International Application No. PCT/DE2014/100314 having an international filing date of Sep. 2, 2014, and from which priority is claimed under all applicable sections of Title of the United States Code including, but not limited to, Sections 120, 363, and 365(c), and which in turn claims priority under 35 USC 119 to German Patent Application No. 20 2013 103 977.2 filed on Sep. 4, 2013. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a water sport device having a sitting or standing surface for a person practising water sports, a jet drive and a pivotable nozzle. 
     Description of the Related Art 
     Water sport devices having a jet drive and a pivotable nozzle in the form of jet skis or surfboards are known, the latter for example from DE 20 2011 051 071. The controllable surfboard shown in the last-mentioned utility model document has a surfboard that has a jet drive integrated therein. The jet drive is provided with a pivotable nozzle for water sucked in at an underwater surface of the surfboard. By pivoting the nozzle, the surfboard can be manoeuvred to go around a right-hand or a left-hand bend. The control of the nozzle can be carried out via a controller held in the hand of the person practising water sports or by means of a gyro sensor provided in the surfboard. In the latter case, the forward feed is controlled by means of a manual controller. 
     What is of disadvantage in the known water sport device is the fact that whilst bending, control is no longer possible if the forward feed of the jet drive is too low or is switched off. In this case, the water sport device will then only carry out a lateral drifting movement. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to provide a water sport device of the type mentioned in the beginning that allows improved cornering. 
     The object is achieved by means of a water sport device mentioned in the beginning having the characterising features of claim  1 . 
     The invention utilises the idea of providing, in addition to the jet drive that during operation allows cornering by pivoting the nozzle, a pivotable fin that allows cornering even if the jet drive is not in operation or is not sufficiently strongly in operation and no water is sprayed out of the nozzle of the jet drive. 
     Advantageously, an axis of rotation is provided, about which the nozzle is arranged to be pivotable and about which the fin is also arranged to be pivotable. The fin and the nozzle are advantageously connected to each other so as to be fixed relative to each other, and a pivoting unit of the nozzle is also the pivoting unit of the fin. During operation, the fin is submerged in the water. Even if no propulsion by the nozzle takes place, the fin submerged in the water can still be used to steer the water sport device. 
     In a preferred embodiment of the invention, a standing or sitting surface for a person practising water sports is provided, and the axis of rotation is disposed to be perpendicular to the standing or sitting surface. A sitting or standing surface is here generally to be understood to be a unit on which a person practising water sports stands while practising the sport. 
     The invention relates to water sport devices in general having a jet drive. This may be understood to mean surfboards that have a jet drive integrated therein, but also conventional jet skis having a jet drive. 
     In a further preferred embodiment of the invention, the fin has a rear control surface that is provided behind the axis of rotation in the direction of movement of the water sport device and a front control surface that is mounted in front of the axis of rotation in the direction of movement. Together, the two control surfaces form the control surface of the fin. As a result of the fact that the axis of rotation does not extend along outer edges or completely outside of the control surface, but is passed through the control surface of the fin at an inward distance from the outer edges of the fin, the control surfaces each have a torque applied to them that cancel each other out when the fin is turned crosswise, so that the force acting on the pivot control of the fin and the nozzle is minimised. 
     Advantageously, the fin is fixed to a water side of the nozzle by means of nylon screws. On the one hand, the fin is fixed directly to the axis of rotation by means of a nylon screw and on the other hand it is fixed directly to the water side of the nozzle using a further nylon screw. Nylon screws can be obtained at low cost and can, even if they should break, be quickly and easily replaced. The nylon screws are designed as it were as predetermined breaking points of the fin, so that even if the water sport device is pulled across sand with its underwater surface or moves in very shallow waters and the fin should break, the fin itself is not damaged but breaks off from the nozzle at the two nylon screws which can be replaced at low cost. 
     The invention will be described by means of an embodiment example in three figures, wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a top view of a surfboard according to the invention, 
         FIG. 2  shows a bottom view of the surfboard in  FIG. 1 , 
         FIG. 3  shows a sectional view of the rear of the surfboard in  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention will be described by means of the surfboard  1 , however it is not limited to a surfboard. It is also conceivable to transfer the invention to other water sport devices, in particular to jet skis. 
     In  FIG. 1 , the surfboard  1  according to the invention is shown with a standing surface  2  for a person practising water sports, which surface is horizontally orientated during operation. On a nose  3  of the surfboard  1 , which in  FIG. 1  is on the right-hand side, an eyelet  4  for a leash  6  is provided. One end of the leash  6  is tied in a knot to the eyelet  4 . On another end of the leash  6 , a controller  7  is tied in a knot. The controller  7  comprises a wireless radio link or a Bowden cable or a connection with a cable to a drive  8  integrated in the surfboard. The radio link is indicated by the dotted line. Further, a foot strap  9  is fastened to the standing surface  2  of the surfboard  1 . For practising the sport, a person practising water sports can insert their foot into the foot strap  9  and can grasp and hold the controller  7  with one hand and can get additional hold on the surfboard  1  by the leash  6 . In this case, the controller  7  is merely used for controlling the force of the propulsion of the surfboard, i.e. the speed of the surfboard  1 . The controller may have a gyroscope function, so that the propulsion is modified via a tilting movement, or is implemented as a lever, a type of joystick. 
     A gyro sensor  11  is provided in the surfboard, which registers tilting movements about a longitudinal direction L of the surfboard  1 . The gyro sensor  11  is linked to a pivoting device  12 ,  17 ,  18  that acts on the nozzle  13  mounted in the tail  14  and pivots the nozzle  13  in a plane that is parallel to the standing surface  2 . 
     The pivot drive comprises an arm  17  provided on the nozzle  13 , which has an actuator rod  18  articulated thereto. The actuator rod  18  is linked to a servomotor  12 . The servomotor  12  allows the actuator rod  18  to be extended and retracted, so that a pivoting movement of the nozzle  13  can be carried out via the arm  17  in the plane of the drawing in  FIG. 1 . 
       FIG. 2  shows the surfboard  1  in  FIG. 1  in a view from the bottom. In  FIG. 2 , an underwater surface  16  of the surfboard  1  is shown. The underwater surface  16  has an inlet  19  for the water. For generating propulsion, according to  FIG. 3  water is sucked to the underwater surface  16  of the surfboard  1  and is accelerated by means of a propeller  21  and is ejected from the nozzle  13 . Depending on which position the nozzle  13  has been pivoted to, the surfboard  1  can negotiate a right-hand or a left-hand bend. 
       FIG. 3  shows the tail  4  of the surfboard  1  in  FIGS. 1 and 2  in a sectional view. During operation, water is sucked in through the inlet  19  on the underwater surface  16 , is accelerated by the propeller  21  provided in a water channel between the inlet  19  and the nozzle  13  and is pushed out of the nozzle  13 . The propulsion of the surfboard  1  consists of the repulsion generated as a result of the ejection. The nozzle  13  is mounted to be pivotable about the axis of rotation D on the tail  14  of the surfboard  1  and terminates the water channel on the tail side. On the water side of the nozzle  13 , a fin  23  is fixed to the nozzle  13 . The fin  23  can be pivoted with the nozzle  13 . The fin  23  is on the one hand screwed onto the axis of rotation D of the nozzle  13  by means of a nylon screw  22   a , and on the other hand it is screwed to a water side of the nozzle  13  at a further point using a further nylon screw  22   b . The axis of rotation D is perpendicularly oriented to the standing surface  2 . 
     The fin  23  carries out the pivoting movement of the nozzle  13  about the same axis of rotation D as the nozzle  13 . The nozzle  13  has a rear control surface  23   a  provided behind the axis of rotation D in the direction of movement of the surfboard  1  and a front control surface  23   b  provided in front of the axis of rotation D in the direction of movement. The two control surfaces  23   a ,  23   b  form the entire control surface of the fin  23 . When the fin  23  is positioned at an angle in the water whilst cornering, a force is thus applied both onto the rear  23   a  and the front  23   b  control surfaces, and the torques on the axis of rotation D that form as a result substantially completely cancel each other out. As a result, the servo motor  12  carrying out the pivoting movement needs to exert less force in order to carry out the pivoting movement. 
     The fin  23  allows controlled cornering, even if the jet drive does not generate any propulsion, i.e. if no water is sprayed out of the nozzle  13 . 
     According to  FIG. 2 , the fin  23  is supported by two further fins  24   a ,  24   b  which additionally stabilise the movement of the surfboard  1  and, due to their outwardly bent shape, generate additional propulsion. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  Surfboard 
           2  Standing surface 
           3  Nose 
           4  Eyelet 
           6  Leash 
           7  Controller 
           8  Drive 
           9  Foot strap 
           11  Gyro sensor 
           12  Pivoting unit servomotor 
           13  Nozzle 
           14  Tail 
           16  Underwater surface 
           17  Arm of the pivoting unit 
           18  Actuating rod of the pivoting unit 
           19  Inlet 
           21  Propeller 
           22   a  Nylon screw 
           22   b  Further nylon screw 
           23  Fin 
           23   a  Rear control surface 
           23   b  Front control surface 
           24   a  Further fin 
           24   b  Further fin 
         L Longitudinal direction 
         D Rotary axis