Patent Application
20180140959
The invention relates to an apparatus for gliding over a body of flowing water, in particular for surfing, water-skiing, kiteboarding and/or wakeboarding, according to the preamble of claim 1 and to the preamble of claim 8.
River surfing, as an example for gliding over a body of flowing water, is a form of wave riding where standing waves or, more rarely, tidal waves are surfed using a surfboard. A standing wave is generated on the surface of a flowing body of water if the water flows over an obstacle. This can be a rock or a step in the river bed. The difference to wave riding on the sea is substantially in that in the case of river surfing, the water flows through under the surfer, i.e. the surfer more or less stands on the spot, whereas when surfing on the sea the wave pushes the surfer from behind. When river surfing, the surfer moves against the direction of flow of the river, when surfing on the sea the wave and the surfer move in the same direction. When surfing on standing waves, the (counter) current of a river is consequently exploited.
So that a river can be utilized, however, for river surfing, the standing wave has to reach a certain size, has to be as consistent as possible and have a sufficient depth of water. This, in turn, is dependent on the amount of water and the flow speed of the river. Non-breaking waves are preferably used.
Said conditions are only obtained at very few places, however, in nature. In the majority of cases, said conditions are created by human intervention such as, for example, in the case of a concrete basin or a weir. In German-speaking countries, Eisbach in Munich is known for its facilities for river surfing on a standing wave.
Also associated with river surfing, consequently, is bungee-boarding, also called bungee-surfing, which can be applied on rivers where the abovementioned conditions for surfing on a standing wave, in particular a sufficient flow speed of the river, are not provided. In this connection, a resilient cable is fastened by way of one cable end on the bank or on a stationary structure such as, for example, a bridge and the surfer holds the other end of the resilient cable in his hands or fastens it on the surfboard. Then the surfer, by exploiting the flow resistance of his surfboard, can allow himself to drift with the river, i.e. he directs his surfboard by way of the surface into the river current such that the flow resistance of the surfboard is increased and the cable can clearly be tensioned. Once the cable is sufficiently tensioned, the river surfer abandons the resistance against the river current and is catapulted by the retracting cable over the surface of the water in the direction of the cable fastening means. The necessary relative speed for generating the buoyancy for the surfboard can be generated as a result of said pulling movement against the river current in order to be able to surf on the river which is otherwise unsuitable for river surfing.
A disadvantage, in this connection, is that bungee-boarding can be dangerous for the surfer. The catapult-like movement is not able to be steered or controlled in this way such that there is the risk here of the surfer being pulled against an obstruction such as, for example, the bridge or objects floating in the river and not being able either to brake nor evade said obstructions. In addition, after the end of the catapult-like movement the surfer can become entangled in the resilient cable which then runs with the river and can drown as a result.
It is also disadvantageous that as a result of the catapult-like movement of the surfboard, there is a very quick but generally really brief movement which results in a correspondingly brief enjoyment for the surfer. The catapult-like movement can also be difficult for beginners to control such that the enjoyment of river surfing by means of bungee-boarding can only be experienced after a good deal of practice and perhaps not even then. In addition, the speed of the surfboard reached is largely inconsistent.
An object of the present invention is to provide an alternative possibility for gliding over a body of flowing water such as, for example, for river surfing, which can also be applied in the case of bodies of flowing water which do not meet the conditions for gliding such as, for example, surfing on a standing wave. In particular, an alternative possibility for gliding such as, for example, for river surfing, is to be provided which is safer and/or simpler and/or longer-lasting and/or more consistent than bungee-boarding.
The object is achieved according to the invention by the features of the characteristic part of claim 1 and of claim 8. Advantageous further developments are described in the subclaims.
Consequently, the present invention relates to an apparatus for gliding over a body of flowing water such as, for example, a river, in particular for surfing, water-skiing, kiteboarding and/or wakeboarding, having a first buoyancy body such as, for example, a surfboard, a single water ski, a pair of water skis, a kiteboard or a wakeboard.
The apparatus additionally comprises according to the invention a second buoyancy body which can be, for example, a second surfboard etc. The second buoyancy body is preferably a flat and thin body produced from resilient material, the flow resistance of which, with regard to the body of flowing water, is able to be increased and reduced in as simple a manner as possible. In particular, the flow resistance can become as small as possible as a result of straightening the second buoyancy body on the surface of the water and as large as possible as a result of pressing the second buoyancy body into the body of flowing water.
The two buoyancy bodies can be connected together by means of a cable, the cable (static cable) comprising as small an amount of extensibility (resilience) as possible in order to avoid the cable extending or stretching during use. The connection can be realized in each case on the buoyancy body by a fastening means of the cable end or as a result of a person holding the respective cable end directly or by means of a handle or the like in their hands and being situated on the buoyancy body, in particular being able to stand on said buoyancy body.
The cable can run through a pulley mechanism between the two buoyancy bodies, said pulley mechanism being able to be connected to a first stationary object such as, for example, a first bridge pillar, a bridge parapet or also a fixedly anchored floating body or a floating body which is fixedly positioned in another manner such as a boat or raft. Consequently, the two buoyancy bodies are able to be moved relative to one another by means of the cable as the cable can comprise a fixed hold by means of the fastening means on the first stationary object.
According to the invention, it is possible in this manner for the first buoyancy body and the second buoyancy body to be able to carry out movements over the body of flowing water with respect to one another in substantially opposing directions by means of the pulley mechanism which is run through by the cable. This can be achieved as a result of both buoyancy bodies being able to drift away from said pulley mechanism as a result of the current of the body of flowing water until they are held by the then tensioned non-resilient cable. In this case, the two buoyancy bodies, however, can be movable relative to one another by means of the pulley mechanism as the pulley mechanism is held on the first stationary object.
If then, for example, the flow resistance of the second buoyancy body is increased relative to the flow resistance of the first buoyancy body, the second buoyancy body is made to drift downriver by the current of the body of flowing water and by means of the rigid cable connection and the pulley mechanism, the first buoyancy body is pulled against the direction of flow of the body of flowing water as a result. The relative speed between the first buoyancy body and the body of flowing water can be increased in this way such that when the relative speed is sufficiently high, it is possible to glide such as, for example river surfing, over bodies of flowing water where this would otherwise not be possible.
Once the first buoyancy body has moved as close as possible to the first stationary object or to the second buoyancy body, the flow resistances of the two buoyancy bodies can be adjusted in an opposite manner such that the first buoyancy body then drifts with the river current and the second buoyancy body is able to be pulled against the direction of flow of the body of flowing water. It is then possible to glide or rather surf on the second buoyancy body, if it is realized for this purpose.
In the simplest case, the pulley mechanism comprises for this purpose only a first guide roller which can be connected to the first stationary object by means of a fastening means such that the cable is able to run from the first buoyancy body by means of the first guide roller to the second buoyancy body.
The pulley mechanism preferably comprises a mechanical gear ratio such that one buoyancy body, preferably the first buoyancy body, is able to experience greater speed than the other buoyancy body as a result of the relative movement of the other buoyancy body. A high mechanical gear ratio is particularly preferred, such as, in particular, a tenfold gear ratio or even greater, such that one buoyancy body is able to experience a clearly faster speed than the other buoyancy body.
It is also advantageous in this connection for said apparatus to be able to be operated by two persons. In this way, gliding such as, for example, river surfing, can become a team sport. In addition, the safety of using said apparatus can be increased because both persons are able to monitor and, where applicable, help one another.
It is also advantageous in this connection for the velocity of the relative speed, which provides the gliding or surfing speed, of the one buoyancy body to be able to be influenced by the measure of the flow resistance of the other buoyancy body which is drifting at that moment. The flow resistance, in this case, can be influenced as a result of how far said buoyancy body is put under water. In this way, a lower gliding or surfing speed can be chosen, for example for inexperienced gliders or river surfers.
It is also advantageous that in the case of substantially constant flow speed of the body of flowing water, the relative speed of the other buoyancy body can be held substantially constant as a result of a substantially constant flow resistance of the buoyancy body which is drifting at that moment. This can make gliding simpler for inexperienced users such as, for example, river surfing for inexperienced river surfers. In addition, the duration of the gliding or surfing movement can also be designed to last for longer as a result.
It is also advantageous in this connection for the start of the gliding or surfing movement to be able to be carried out in a less jerky manner, i.e. less catapult-like, because the relative speed is able to be influenced by the extent of the change in the flow resistance.
According to one aspect of the present invention, the pulley mechanism comprises a first guide roller which can be connected to the first stationary object by means of a fastening means, a second guide roller which can be connected to the second buoyancy body by means of a fastening means, and a cable end fastening means which can be connected to the first stationary object or to a further stationary object such that the cable is able to run from the first buoyancy body by means of the first guide roller and by means of the second guide roller to the cable end fastening means.
In this way, a mechanical gear ratio is realized between the two buoyancy bodies, as a result of which the relative speed between the two buoyancy bodies is able to be increased in favor of the first buoyancy body. Thus, the second buoyancy body can serve substantially for increasing the relative speed of the first buoyancy body, on which the actual gliding or river surfing can take place, whilst the second buoyancy body, as a result of the gear ratio to slow, can be pulled against the current of the body of flowing water in order to be able to practice gliding or river surfing.
In addition, the connection between the cable end fastening means and a further stationary object such as, for example, a second bridge pillar, provides the possibility of allowing the two buoyancy bodies to carry out their movements side by side and parallel to one another in order to be able to avoid mutual interference.
According to a further aspect of the present invention, the pulley mechanism comprises a first guide roller which can be connected to the first stationary object by means of a fastening means, a second guide roller which can be connected to the second buoyancy body by means of a fastening means, a third guide roller which can be connected to the first stationary object or to a further stationary object by means of a fastening means, and a cable end fastening means which can be connected to the second buoyancy body such that the cable is able to run from the first buoyancy body by means of the first guide roller, by means of the second guide roller and by means of the third guide roller to the cable end fastening means.
In this way, a mechanical gear ratio is also realized between the two buoyancy bodies, as a result of which the relative speed between the two buoyancy bodies is able to be increased, said relative speed being higher as a result of the additional third guide roller than when using only two guide rollers. In this case, the relative speed of the first buoyancy body is increased further.
In addition, the connection between the third guide roller and a further stationary object such as, for example, a second bridge pillar, provides the possibility of allowing the two buoyancy bodies to carry out their movements side by side and parallel to one another in order to be able to avoid mutual interference.
According to a further aspect of the present invention, the pulley mechanism additionally comprises a third guide roller, which can be connected to the first stationary object or to a further stationary object by means of a fastening means, and a fourth guide roller, which can be connected to the second buoyancy body by means of a fastening means such that the cable is able to run from the first buoyancy body by means of the first guide roller, by means of the second guide roller, by means of the third guide roller and by means of the fourth guide roller to the cable end fastening means.
The use of further guide rollers leads to an increase in the gear ratio between the two buoyancy bodies and consequently to a further increase in the relative speed of the first buoyancy body with regard to the current of the body of flowing water.
According to a further aspect of the present invention, the first guide roller and the second guide roller can be arranged spaced apart from one another in such a manner in the transverse direction of the body of flowing water that the movements in substantially opposing directions of the two buoyancy bodies with respect to one another can extend substantially parallel to one another.
In this way, the two buoyancy bodies can be prevented from mutually interfering with one another in terms of movement. This also applies to the respective cable portions which are connected to the two buoyancy bodies. This provides increased safety for the apparatus. The movements can also be made possible with identical cable lengths over longer sections if the movements of the two buoyancy bodies could otherwise be carried out one behind the other and consequently only insofar as the two buoyancy bodies cannot collide with one another.
According to a further aspect of the present invention, at least two guide rollers or at least one guide roller and the cable end fastening means can be connected to the second buoyancy body by means of a common fastening means receiving means.
Said common fastening means receiving means can be, for example, a crossbeam in the form of a plastics material or metal rod, in particular an aluminum rod, in particular an aluminum tube, which can receive the fastening means of the guide rollers or cable end fastening means on one side and can be connected to the second buoyancy body on the opposite side. Said connections are preferably simple and fast to assemble and/or disassemble in order to be able to construct and dismantle the apparatus in a simple and rapid manner. For example, it is possible to use shackles for said connections.
It is also advantageous in this connection that the guide rollers or guide roller and cable end fastening means can remain connected together during disassembly and consequently can be handled, transported and stored together with the cable running through them.
It is also advantageous in this connection that different second buoyancy bodies can be used as alternatives and can be exchanged for one another simply and quickly. Damaged second buoyancy bodies can also be exchanged simply and quickly in this manner.
According to a further aspect of the present invention, at least two guide rollers or at least one guide roller and the cable end fastening means can be connected to a stationary object by means of a common fastening means receiving means. Said fastening means receiving means can also be, for example, a crossbeam with the afore-described characteristics and advantages.
It is also advantageous in this connection that in this way several guide rollers can be connected to one stationary object such as, for example, to one bridge pillar. Consequently, the apparatus according to the invention can also be used on fewer bridge pillars than stationary guide rollers and even on one single bridge pillar. This is advantageous because, as a result, the apparatus according to the invention can also be used on rivers with few stationary objects or with one single stationary object. In addition, several apparatuses according to the invention can be used side by side on several stationary objects of a body of flowing water at the same time by means of said fastening means receiving means.
The present invention also relates to an apparatus for gliding over a body of flowing water, in particular for surfing, water-skiing, kiteboarding and/or wakeboarding, having a first buoyancy body which can be, for example, a surfboard. Said apparatus is characterized in that the apparatus comprises a gearing unit which can be connected to a first stationary object, wherein the first buoyancy body can be connected to the gearing unit by means of a first cable, wherein the apparatus additionally comprises a second buoyancy body which can be connected to the gearing unit by means of a second cable such that the first buoyancy body and the second buoyancy body are able to carry out movements over the body of flowing water with respect to one another in substantially opposing directions by means of the gearing unit which is connected to the cables.
As a result, an alternative implementation of the present invention can be created where, in place of a pulley mechanism, the implementation of the two opposing movements of the two buoyancy bodies with respect to one another can be achieved as a result of a gearing unit. By correspondingly choosing the gear ratio or reduction of the gearing unit, it is also preferably possible here to cause one buoyancy body, preferably the first buoyancy body, as a result of the relative movement of the other buoyancy body, to be able to experience a greater speed than the other buoyancy body. Particularly preferred is a high mechanical gear ratio such as, in particular, a tenfold gear ratio or even more such that one buoyancy body is able to experience a clearly greater speed than the other buoyancy body.
According to a further aspect of the present invention, the second buoyancy body comprises a resilient basic body. In other words, the basic body is realized from a flexible material. For example, the resilient basic body can be a piece of tarpaulin produced from a rubberized material or a piece of sailcloth.
It is advantageous in this connection that said basic body can be pressed at least in part under water in order to increase the flow resistance thereof. In particular, the measure of flow resistance produced by a person on the basic body can be modified by the resilience of the material, which makes it possible for the person to influence the relative speed of the two buoyancy bodies in a targeted manner with respect to one another and consequently also the relative speed of the first buoyancy body compared to the body of flowing water.
According to a further aspect of the present invention, the second buoyancy body comprises a transverse stabilizing means which is able to hold the resilient basic body in the transverse direction at a predefined minimum width. The resilient basic body is preferably held tensioned to its maximum width by the transverse stabilizing means. The transverse stabilizing means can be, for example, a crossbeam, in the form of a plastics material or metal rod, in particular an aluminum rod, in particular an aluminum tube, which can be surrounded, for example, at least in part by the resilient material and can be held as a result.
It is advantageous in this connection that, as a result, the resilient material cannot be compressed in width by the water and has to be straightened and tensioned again in said direction by the person on the second buoyancy body. In this way, the person can concentrate on influencing the flow resistance of the second buoyancy body and can carry out said activity in a better manner.
According to a further aspect of the present invention, the transverse stabilizing means is arranged on the side of the second buoyancy body facing the direction of flow of the body of flowing water. From the viewpoint of the second buoyancy body, the transverse stabilizing means is consequently arranged on its front edge i.e. upriver.
It is advantageous in this connection that, as a result, the greatest effect of the transverse stabilizing means is reached because the resilient basic body can be held tensioned sideways in the direction of the flow of the body of flowing water behind the transverse stabilizing means and said sideways tensioning can continue, i.e. when viewed downriver, toward the rear side of the resilient basic body. In contrast to this, the region of the resilient basic body in the direction of flow of the body of flowing water in front of the transverse stabilizing means would not be tensionable sideways or would not be effectively tensionable sideways by said means because said part region of the resilient basic body is exposed directly to the flow. By implication, the resultant arrangement of the transverse stabilizing means on the resilient material is as far as possible toward the direction of flow of the body of flowing water.
According to a further aspect of the present invention, the second buoyancy body comprises at least one buoyancy element which is arranged at a spacing from the side of the second buoyancy body remote from the direction of flow of the body of flowing water. Said buoyancy element can be, for example, an air-filled container or an air-filled porous mass such as, for example, foamed material which is arranged on the front edge of the resilient basic body. The buoyancy element is preferably designed in such a manner that at least said part region of the second buoyancy body is always able to be held securely on the surface of the body of flowing water.
It is advantageous in this connection for the second buoyancy body to be able to be pressed under water in part by way of its rear part region, i.e. its side remote from the direction of flow of the body of flowing water, to modify its flow resistance, but for a minimum buoyancy of the second buoyancy body to be able to be achieved by the buoyancy element at the same time so that said second buoyancy body is never able to go fully under. This simplifies handling and modifying the flow resistance for the person on the second buoyancy body because the buoyancy element can have a stabilizing effect. At the same time, this makes handling also safer for the person. The arrangement of the buoyancy element in the front part region of the resilient basic body can provide that the second buoyancy body cannot be pulled underwater when moving against the current of the body of flowing water.
According to a further aspect of the present invention, the second buoyancy body comprises at least two buoyancy elements which are arranged at a spacing from one another in the transverse direction. The buoyancy elements can provide skids as it were such as, for example, in the case of a catamaran, on which the second buoyancy element can float, the buoyancy bodies being arranged at a sufficient spacing from the rear edge of the resilient basic body and being realized short in such a manner that said rear part region of the resilient basic body is able to be pressed into the water.
It is advantageous in this connection that the second buoyancy body can comprise in this manner as small a flow resistance as possible when it is pulled against the direction of flow of the body of flowing water.
According to a further aspect of the present invention, the buoyancy element or the buoyancy elements is/are realized in such a manner in the direction of flow of the body of flowing water that it or they comprises/comprise as small a flow resistance as possible. To this end, the part of the buoyancy body or the buoyancy bodies facing the direction of flow of the body of flowing water can be realized in a nose-shaped manner.
It is advantageous in this connection that, as a result, the flow resistance of the second buoyancy body can be kept as small as possible per se in order to favor its relative movement against the direction of flow of the body of flowing water. As a result, the second buoyancy body can be pulled in a simpler and consequently faster manner by the first buoyancy body.
According to a further aspect of the present invention, the second buoyancy body comprises a foot rest. This is preferably realized by a further crossbeam, as previously described, which is able to tension the resilient material of the basic body in width in part or fully also at said point. The foot rest can, however, also be realized by elements which are resilient in width such as, for example, straps on the surface or at the end of the resilient material or also holes in the resilient material.
It is advantageous in this connection that the person who would like to press the second buoyancy body into the water can obtain a better hold on the basic body as a result.
According to a further aspect of the present invention, the foot rest is arranged on the side of the second buoyancy body remote from the direction of flow of the body of flowing water. In other words, the foot rest is arranged on the rear edge or in the rear region of the basic body, i.e. downriver.
It is advantageous in this connection that precisely said part region is able to be pressed underwater to modify the flow resistance because the greatest change in flow resistance can be achieved as a result.
A few exemplary embodiments and further advantages of the invention are explained below in conjunction with the following figures, in which:
The body of flowing water 10 is a river 10 which is defined on each side by a bank 11. The river 10 comprises a direction of flow A which is directed downwards in each case in
The apparatus according to the invention for gliding such as, for example, surfing on a river 10, comprises in all embodiments a first buoyancy body 20 in the form of a surfboard 20, on which a surfer is able to practice river surfing. The surfboard 20 is connected by means of a, where possible, non-resilient cable 22 to a second buoyancy body 21 which is to be designated as sail 21 as it serves for generating propulsion for the surfboard 20, even when said sail 21 is controlled lying in the river 10 or partially submerged. A second person can be situated on the sail 21 in order to control the same, as will be described further below. In this case, the surfboard 20 and the sail 21 comprise, for example as a result of their shape, in each case as small an amount of the flow resistance as possible in the case of movements on the river 10. The flow resistance of the sail 21 with regard to the river can become maximum, however, when submerging into the water, see further below.
The connection between the respective cable end of the cable 22 and the surfboard 20 or rather the sail 21 can be produced in each case by a fixed connection, for example by means of a knot, a shackle or the like, but also as a result of the respective cable end of the cable 22 being held directly or by means of a handle in the hand of the respective person or being fixed per se. The cable 22 can also be connected to the sail 21 by means of at least one guide roller 24, as will be described further below. A cable end of the cable 22 is preferably provided with a handle which the surfer on the surfboard 20 is able to hold in his hands, and the other cable end of the cable 22 is fastened on the sail 21 (not shown) by means of a cable end fastening means 29 or rather the cable 22 passes the sail 21 by means of a guide roller 24 and is fastened by way of a cable end fastening means 29 on the second bridge pillar 14 (cf.
Between the cable ends of the cable 22 or between the surfboard 20 and sail 21, the cable 22 runs through a pulley mechanism 23-29 which is fastened on the first bridge pillar 13. Said pulley mechanism 23-29 can in the simplest case only have one guide roller 23 which can be connected by means of a fastening means 23a to the bridge pillar 13 such that the cable end fastening means 29 can be connected to the sail 21 (not shown). In the everyday language of a pulley, said fastening means 23a of the first guide roller 23 provides the first pulley 23.
As in said arrangement, however, the two buoyancy bodies 20, 21 can only be moved directly one behind the other over the river 10 and could collide with one another, the cable 22 in the first embodiment of the present invention is guided by means of a second guide roller 24 which is connected by means of a fastening means 24a, i.e. a second pulley 24a, to the sail 21 (cf.
Said pulley mechanism 23-29 can then be used for the purpose of allowing the surfboard 20 and the sail 21 to carry out movements over the river 10 with respect to one another in substantially opposing directions. To this end, the surfboard 20 with a surfer and the sail 21 with a controller float initially over the river 10. Surfboard 20 and sail 21 are connected together by the cable 22 by means of the first guide roller 23 and the second guide roller 24 in such a manner that both buoyancy bodies 20, 21 are only able to drift so far by the current A of the river 10 until the cable 22 has reached its maximum length. In said position, the two buoyancy bodies 20, 21 are held so as to be movable over the river 10 with respect to one another, one buoyancy body 20, 21 drifting further in the direction of flow A of the river 10 and the other buoyancy body 21, 20 being able to be pulled against the direction of flow A as a result of the connection by means of cable 22 and first guide roller 23, and vice versa.
Consequently, said pulley mechanism 23-29 enables movements of the two buoyancy bodies 20, 21 over the river 10 with respect to one another in substantially opposing directions.
Said pulley mechanism 23-29 can then be used for river surfing by both persons on the buoyancy bodies 20, 21 as follows:
From the previously described driving position of the two buoyancy bodies 20, 21, for example the surfer presses his surfboard 20 underwater in such a manner that the flow resistance of the surfboard 20 increases with regard to the current A of the river 10, whilst the controller of the sail 21 keeps the flow resistance thereof as small as possible. In this way, the surfboard 20 is pulled downriver by the current A and the sail 21 is pulled upriver in the opposite direction by means of the pulley mechanism 23-29.
If the surfboard 20 has now clearly drifted and is at a distance from the bridge 12 or if the sail 21 reaches the direct vicinity of the bridge 12 (first state, cf.
Said type of river surfing is additionally effected as a team sport for the surfer and the controller of the sail 21, which can increase the enjoyment and the safety. The speed of the surfboard 20 can also be modified during the movement as a result of modifying the flow resistance of the sail 21 such that the surfer is able to carry out river surfing at a desired speed. In addition, the speed of the surfboard 20 can be modified slowly and in a controlled manner such that jerky movements of the surfboard 20 can be avoided.
In addition, the third guide roller 25 and the cable end fastening means 29 are also connected in a stationary manner to the second bridge pillar 14 by means of a common fastening means receiving means 28. This has the previously described advantage of simple and rapid assembly and disassembly also for said elements 25, 29. In addition, several stationary fastenings 25, 29 are thus able to be arranged together on one bridge pillar 14, which can reduce the number of necessary bridge pillars 13, 14, 15.
As in the case of the previously described pulley mechanism 23-29, in the case of said embodiment the gearing unit 44 can also be used for the purpose of allowing the surfboard 20 and the sail 21 to carry out movements on the river 10 with respect to one another in substantially opposing directions. The gear ratio or reduction of the gearing unit 44 can be chosen in such a manner that a sufficiently high relative speed of the surfboard 20 with respect to the current A can also be achieved in said embodiment such that, as a result, river surfing on rivers 10 where the current A is itself not sufficient can be made possible.
On its front side which is the side of the sail 21 facing the direction of flow A of the river 10, i.e. pointing upriver, the tarpaulin 30 comprises a transverse stabilizing means 31 in the form of an aluminum tube 31 which can be sewn into a pocket of the tarpaulin 30. The aluminum carrier 31 holds the front side of the sail 21 tensioned sideways to the width x and forms as it were the nose of the sail 21.
Two buoyancy elements 32 are arranged spaced sideways parallel to one another beneath the tarpaulin 30 in order to bestow the necessary buoyancy on the nose of the sail 21 so that it is always able to remain on the surface of the water, in particular when the sail 21 is pulled against the current A of the river 10 by the surfboard 20. The buoyancy elements 32 can be, for example, air-filled plastics material containers. So that the tarpaulin 30 can nevertheless be pressed partially underwater by the controller, the rear region of the tarpaulin 30, which is remote from the direction of flow A of the river 10, i.e. pointing downriver, is free of the buoyancy elements 32.
The two buoyancy elements 32 are realized, in this case, in a stream-lined manner on their front side, i.e. facing the direction of flow A of the river 10, in order to reduce the flow resistance when the sail 21 is pulled upriver by the surfboard 20.
The tarpaulin 30 additionally comprises, on its rear side which is remote from the direction of flow A of the river 10, i.e. pointing downriver, a foot rest 33 which can be a second transverse stabilizing means 33 as described beforehand, but can also be openings 33 in the tarpaulin 30 or straps 33 on the tarpaulin 30 or in the tarpaulin 30. In all cases, the foot rest 33 serves for the purpose of giving the controller a hold on the tarpaulin 30 when he would like to press it into the water. To this end, the controller can lie down flat from above onto the tarpaulin 30, hold the front transverse stabilizing means 31 using his arms or support himself on said transverse stabilizing means, position his feet on or in the foot rest 33 and then press the rear part region of the tarpaulin 30 underwater using his body weight in order to adjust the flow resistance of the sail 21.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 018 369.6 | Dec 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/079591 | 12/14/2015 | WO | 00 |
