Patent Publication Number: US-2013239860-A1

Title: Sailing Vessel

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a sailing vessel in accordance with the claims. 
     2. Description of the Related Art 
     A sailing vessel of such type is known, for instance, from GB 2 335 165 A. In this document a capsule-shaped boat is described comprising a float approximately round from the top view at which a keel is pivot-mounted. The rotation of the keel with respect to the float is carried out in the known solution by a person, wherein the latter fixes the keel in position with respect to the float through a holding means upon adjusting the desired angle of rotation. The forward thrust of the sailing vessel is performed by means of a stiff sail which in the known solution is supported at a pivot mechanism and is designed such that it closes the float in the form of a lid in a “position of non-use”. For sailing this sail can be rigged via an appropriate mechanism. The center of effort of this sail is (laterally) spaced in longitudinal direction vis-à-vis the pivot axis of the keel. It is the peculiarity of this sailing vessel that a change of direction is brought about by twisting the keel with respect to the sail, wherein the sail basically maintains its once adjusted position relative to the float. Such solution is different from conventional sailing vessels in which a keel is always arranged in the longitudinal direction of a hull and steering movements are initiated via a rudder, wherein the sail position then has to be trimmed by hauling tight or easing the sheets. 
     The solution demonstrated in GB 2 335 165 A has the drawback, however, that by adjusting the keel with respect to the sail a change of direction cannot be brought about with the required accuracy. 
     The authors of this document obviously also recognized this drawback and generally point out that a rudder can be formed at the hull. However, the steering behavior cannot be improved by designing such rudder at the hull. 
     A similar sailing vessel is disclosed in GB 2 082 127 A. For this sailing vessel also a hull that is approximately round from the top view is used in which the keel is arranged coaxially with respect to a pivot-mounted mast. 
     This solution basically shows the same drawbacks as the sailing vessel described in the beginning. 
     DE 35 31 994 A describes a sailing vessel in which an airfoil-type rig is equally rotatable coaxially with respect to a keel. The keel is rotated via an auxiliary rudder disposed at the trailing edge thereof. When setting this auxiliary rudder relative to the pivot-mounted keel, a steering pulse is transmitted to the keel so that the latter rotates in accordance with the setting of the rudder. As soon as the predetermined rotating position of the keel is reached, the rudder is neutralized again so that the sailing vessel moves in the direction predetermined by the keel with an appropriate relative trim of the sail. It is a drawback of this solution that little steering movements are sufficient already to twist the keel so that the steering behavior is relatively “nervous”. 
     WO 2005/120945 A1 shows a sailing vessel in which both a sailing rig and a keel are supported to be freely rotatable. The vessel is then steered by coordinating the angle of rotation of the sail and the keel. The disclosure of this document is rather theoretical—a solution adapted to be realized in practice is not described. 
     DE 20 2006 014 875 U1 discloses a sailing vessel having a conventional hull at which a rotatable keel is supported. The latter is operatively connected to a rotatable and pivoting mast so that a twisting of the mast is always accompanied also by a twisting of the keel. 
     While in the solutions described in the beginning the hull shape is designed such that the sailing vessel can move in any direction related to the hull, in the latter solution a direction of movement is possible always in the longitudinal direction of the conventional hull so that the keel and the sail are appropriately adjusted to each other. Such system shows the same drawbacks as a conventional sailing vessel in which the boat is steered via a rudder. In addition, this solution has the drawback that the mechanism for transmitting the pivoting/rotating movement of the mast to the keel requires considerable efforts so that such vessel is probably difficult to launch on the market as regards the costs and the weight. 
     SUMMARY OF THE INVENTION 
     Compared to this, the object underlying the invention is to provide a sailing vessel designed to comprise a pivoting keel which permits an efficient steering with a minimum effort. 
     This object is achieved by a sailing vessel comprising the features of the claims. 
     Advantageous further developments of the invention are the subject matter of the subclaims. 
     In accordance with the invention, the sailing vessel has a hull or buoyancy body which supports a sailing rig and to which a keel is pivot-mounted. The latter is operatively connected with a rudder for adjusting a change of sailing direction, the operative connection being designed such that substantially only when a predetermined critical rudder angle is exceeded a rotation of the keel with respect to the buoyancy bodies can be initiated through the rudder. 
     The sailing vessel according to the invention thus can be steered like a conventional sailing boat in the case of rudder angles which are smaller than the critical rudder angle, wherein the keel then maintains its position relative to the buoyancy body and the change of sailing direction is brought about solely by the rudder angle. The helmsman then is able to react very quickly to incident squalls or changes in the wind direction and—with an approximately constant intended sailing direction—to react to such changes of the wind pressure by luffing or bearing away. 
     As soon as the helmsman exceeds the critical rudder angle, a rotation of the keel and thus a corresponding change of the sailing direction is initiated, wherein a torque is transmitted to the keel by setting the rudder—as soon as the keel has reached its predetermined position relative to the buoyancy body, the rudder angle is neutralized again and accordingly the keel is fixed in position when falling below the critical rudder angle. 
     By the solution according to the invention the drawbacks of the state of the art are eliminated, wherein the maneuverability of the sailing vessel by the conventional steering via a rudder and the subsequent rotation of the keel is by far superior to the known solutions. 
     In a preferred embodiment of the invention the center of lateral resistance of the keel is offset vis-à-vis the center of effort of the sailing rig. 
     In an embodiment a coupling means of the sailing vessel is provided with a holding means which substantially maintains the position of the keel relative to the buoyancy body up to the critical rudder angle and releases the keel when the critical rudder angle is exceeded so that the latter is rotated based on the rudder angle. 
     Such holding means can connect the keel to the hull by force-fit and/or form-fit. 
     In a variant of the sailing vessel the rudder has a rudder shaft which is pivoted with the keel about a keel axis. That is to say, the rudder rotates along with the keel, wherein a relative angle of the rudder with respect to the keel always remains possible. 
     A further development of the sailing vessel consists in designing the rudder and the keel as a functional unit, the rudder being hinged at the keel or being formed integrally with the same. In the latter case the pivoting of the rudder can be effectuated by a flexible design of the keel and the rudder. Alternatively, the rudder and the keel can also be designed as substantially separate components, wherein it should be ensured by an appropriate transmission mechanism that the rudder shaft also rotates upon twisting the keel. On principle, the keel and the rudder can be operated as separate components and via servo motors, a synchronizing being performed through a central CPU. 
     The buoyancy body of the sailing vessel preferably has, viewed in the axis of rotation of the keel (top view), a rotation-symmetric or somewhat elliptic shape so that the sailing direction is not dependent on the hull shape or on a positional orientation of the hull with respect to the sailing direction. 
     It is provided in an embodiment of the invention to provide a critical rudder angle of between 10° and 45°, preferably at approx. 15°, so that the keel is twisted with respect to the buoyancy body when said angle is exceeded. 
     The steering of the sailing vessel is facilitated when the latter is designed to have an indicator for indicating the keel position with respect to the position of the buoyancy body. 
     The sailing rig can be made of flexible material or can be a wing sail. 
     It is provided in an embodiment of the invention to arrange the sailing rig to be tiltable at the buoyancy body. 
     In a variant of the invention the buoyancy body supports at least a cabin which can be part of the sailing rig. 
     On principle the sailing rig can be in the form of a support structure for functional elements such as e.g. solar cells, cabins, receipts for actors etc. 
     The sail area is preferably designed to be reducible. The rudder need not necessarily be in a conventional form having a rudder blade but can also be formed by trim tabs which are offset with respect to the keel and by adjustment of which the keel is rotated with respect to the buoyancy body. In this case the trim tabs should be supported to be rotatable with the keel, however. Then again the keel is rotated when a predetermined trim tab position is exceeded. 
     It is provided in an embodiment to design a rudder blade of the rudder to be pivotal at least in the underwater portion so that also the longitudinal trim of the sailing vessel is adjustable and uphauling is possible in shallow water. 
     In the above configurations a rotation of the keel is initiated when a critical rudder angle is exceeded. Said critical rudder angle need not necessarily be characterized by an angular position, but also the pulse forces which transmit a torque to the keel upon setting the rudder can be used as a measure so that the keel is rotated when a limit torque is exceeded. 
     In an embodiment of the invention a ballast element is provided by which the floating position of the buoyancy body can be influenced in response to the wind pressure so as to bring about faster gliding, for instance. Said ballast can be a counter-weight adjustable at or in the buoyancy body, several water tanks or the like. Such variable ballast elements for trimming the position of the float are known per se from the state of the art. 
     In an embodiment of the invention, the sail is designed so that it has a pushing effect (pushing sail)—it turned out in a surprising manner that the efficiency of the propulsion can be improved by such pushing sail compared to conventional solutions. 
     The concept according to the invention basically can be used with an approximately rotation-symmetrical buoyancy body, a rotatable keel and a rudder for rotating the keel and for bringing about a conventional change of direction even in motor-driven vessels. The applicants reserve themselves the right to direct an independent claim to this aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE EMBODIMENTS 
       Preferred embodiments of the invention are illustrated in detail by way of schematic drawings, in which: 
         FIG. 1  shows a strongly schematized side view of a sailing vessel according to the invention; 
         FIG. 2  is a top view onto the sailing vessel according to  FIG. 1 ; 
         FIG. 3  shows the sailing vessel of  FIG. 1  when following a circle from a close-hauled course; 
         FIGS. 4 ,  5  are views of the sailing vessel with different rudder angles; 
         FIGS. 6 and 7  are views of a holding means of a sailing vessel according to  FIG. 1 ; 
         FIG. 8  shows a keel having predetermined breaking points; 
         FIG. 9  shows a further embodiment of a keel in composite construction; 
         FIG. 10  shows different keel variants of the sailing vessel; 
         FIG. 11  shows options of fastening the keel to a buoyancy body; 
         FIG. 12  is an embodiment of a sailing vessel having a tiltable sailing rig; 
         FIGS. 13 ,  14  and  15  are variants of the embodiment according to  FIG. 12 ; 
         FIG. 16  is a sailing vessel with a cabin; 
         FIG. 17  is another embodiment of a sailing vessel with a cabin; 
         FIG. 18  shows a sailing vessel having a bipod mast; 
         FIGS. 19 ,  20 ,  21  and  22  are embodiments of a sailing rig for a sailing vessel according to the invention; 
         FIG. 23  shows a multi-part buoyancy body of a sailing vessel; 
         FIG. 24  shows a foldable buoyancy body of a sailing vessel; 
         FIG. 25  shows a sailing vessel with cabin and foldable mast; 
         FIGS. 26 to 29  illustrate further embodiments of a sailing vessel according to the invention including different keel designs and superstructures; and 
         FIGS. 30 to 34  are embodiments of a sailing vessel having a pushing sail. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The  FIGS. 1 and 2  show views of a sailing vessel  1  according to the invention, the latter being represented in  FIG. 1  in a side view and in  FIG. 2  in a top view (view according to  FIG. 2 ). Accordingly, the sailing vessel  1  has a hull or buoyancy body  2  on which a sailing rig  4  is supported. The latter substantially comprises a mast  6  at which a sail  12  is held by means of a boom  8  and battens  10  disposed approximately in parallel thereto. The mast  6  is supported on the buoyancy body  2  (hull) by a mast foot  14 . In the shown embodiment the mast  6  is designed to be non-stayed—basically, however, a stayed mast can be used as well. According to the representation in  FIG. 2 , the sail  12  is shaped approximately symmetrically with respect to the longitudinal axis of the mast  6 , wherein this shape is predetermined by a corresponding curvature of the boom  8  and the battens  10 . In the shown embodiment this curvature is approximately in the form of a segment of a circle. 
     With this solution the angle of attack of the sail  2  can be adjusted with respect to the wind or the buoyancy body  2  via trimming lines  16 ,  18  ( FIG. 2 ) which are guided and can be cleated on a deck  20  of the buoyancy body  2 . By easing or hauling said trimming lines  16 ,  18  the sail  12  can be rotated around the mast  6  in order to bring about the afore-mentioned angle of attack with respect to the sailing direction Y. In the representation according to  FIG. 1  the sail  12  is approximately symmetrical with respect to the longitudinal axis of the mast, the boom  8  being rotatably supported on the mast  6  by a support means not shown. 
     In accordance with the  FIGS. 1 and 2 , the sailing vessel  1  has a keel  22  held rotatably about an axis of rotation  24  at the buoyancy body  2  (hull). In the shown embodiment the keel  22  is a long keel extending approximately diametrally along an underwater hull  26  of the buoyancy body  2 . According to the representation of  FIG. 2 , this buoyancy body  2  or hull is circular from the top view, the axis of symmetry being located in the axis of rotation  24  of the keel. 
     According to the  FIGS. 1 and 2 , in this embodiment an outer end portion of the keel  22  is in the form of a rudder fixture  28  drawn along the circumferential edge of the buoyancy body  2  at which a rudder fitting  30  is arranged by which a rudder  32  is held to be rotatable about a rudder shaft  34 . Since in this embodiment the rudder fixture  28  is formed integrally at the keel  22 , the rudder  32  also turns when the keel  22  rotates about the axis of rotation  24 . The rudder can be rotated relative to the keel  22  by means of a tiller  36  about the rudder shaft  34  in order to bring about a change of the sailing direction. 
     In the shown embodiment the adjusted position of the keel  22  relative to the buoyancy body  2  is fixed in position via a coupling means  38 , wherein the latter is operatively connected to the rudder  32  such that up to a critical rudder angle of 15° (related to the longitudinal axis of the keel  22  visible in  FIG. 2 ) the coupling means  38  fixes the keel  22  in position with respect to the buoyancy body and the coupling means  38  releases the keel  22  only when said critical rudder angle is exceeded so that the keel is rotated corresponding to the rudder angle by the torque induced via the rudder angle which occurs when the sailing vessel  1  sails through the water in the sailing direction Y—the sailing direction Y varies accordingly, because the sailing vessel  1  moves approximately in the longitudinal direction of the keel  22 . The hull or buoyancy body  2  thus has no bow in the conventional sense, as the sailing direction Y depends on the position of the keel and not on the position of the hull. Upon reaching the predetermined sailing direction Y the rudder  22  is then set back again so that it is aligned with the keel  22 —the sailing vessel  1  then continues moving in the direction of movement Y, wherein the position of the sailing rig  4  relative to the buoyancy body  2  is substantially unchanged but varies with respect to the keel  22 . With an angle of attack of the rudder  32  lying below the critical rudder angle, similarly to a conventional sailing boat, a change of sailing direction is brought about dependent on the rudder setting, wherein these comparatively small rudder settings are substantially only used for trimming in order to compensate changes of the wind direction, squalls etc. In the embodiment shown in  FIG. 2  the coupling means  38  is a rope system  40  which is operatively connected to the rudder  32  and can be fixed by a holding means  42 , for instance belaying cleats on the deck  20  of the buoyancy body  2  in order to fix the relative position of the keel  22 . In the shown embodiment the rudder  32  is adjusted in that the helmsman  44  adjusts the tiller  36  as in a comparatively small sailing vessel. Instead of a tiller steering of this type, as a matter of course also a wheel steering, a joystick steering or the like can be used. 
     The theoretical center of pressure of the sail S is inserted in  FIG. 1 . It is obvious that this center of pressure of the sail S is spaced apart from the axis of rotation  24  of the keel  22 . The sailing behavior of such sailing vessel  1  referred to as “round boat” by the inventors is illustrated by way of  FIG. 3 . It is assumed that the wind blows from the direction marked with x. According to position “1” the sailing vessel (round boat)  1  is on close-hauled course Y on which the keel  22  is aligned in this sailing direction. The approximately symmetric sailing rig  4  is automatically set at a position relative to the keel  22  which is optimum for this close-hauled course. 
     For initiating a bearing away to a course with the wind abeam (y h ) the helmsman  44  operates the rudder  32  according to position “2”, wherein the angle of attack is to be larger than the critical rudder angle. That is to say, in the shown embodiment this critical angle is to be approx. 15° so that the rudder angle is selected to be correspondingly larger. According to the foregoing remarks, the holding means  42  releases the locking of the keel  22  with respect to the buoyancy body  2  when this critical rudder angle is exceeded so that a torque is exerted on the keel  22  by the water resistance acting upon the underwater hull such that the keel rotates with respect to the buoyancy body  2  and the vessel bears away into the new sailing direction y h  corresponding to the position marked with “3”. The position of the sailing rig  44  relative to the hull  2  remains substantially unchanged. 
     If the helmsman  44  intends to continue sailing on this course with the wind abeam y h , he/she resets the rudder angle to “0” so that the rudder  32  is aligned with the keel  22 . 
     In case that the helmsman  44  intends to bear off to a downwind course y v , the rudder  32  continues to be set such that the keel  22  rotates with respect to the buoyancy body  2  in the direction of the downwind course y v . When reaching such downwind course y v  (cf. positions “4”, “5”) the rudder is then set straight in alignment with the keel  22  so that the wind blows exactly from behind into the sail of the rig  4 . For jibing the rudder  32  is further turned according to position “ 6 ” from the downwind course y v  so that, in accordance with position “7”, the keel  22  is adjusted in the direction of the opposed course with the wind abeam y h′ —i.e. the sailing vessel moves opposed to the sailing direction y h  afore-marked with position “3”. 
     For luffing out of this course with the wind abeam y h   ,  the rudder  32  is set according to the afore-described remarks such that in position “9” the keel  22  is adjusted to the new close-hauled course y′ (wind from starboard). When reaching this new close-hauled course y′ the rudder angle  32  is neutralized so that the rudder is aligned with the keel  22 . By way of the representation in  FIG. 3  one recognizes that during jibing and the accompanying change of course from wind from port to wind from starboard first an area  46  of the sailing rig  4  is disposed at the flow side, while after jibing the area  48  initially disposed at the trailing side becomes the leading edge—these areas are inserted in the positions “1” and “9” according to  FIG. 3 . During all these changes of direction the trimming position of the sailing rig  4 , or more exactly speaking of the sail  12 , with respect to the buoyancy body  2  remains substantially unchanged. It can even be assumed that the sailing rig  4  automatically adopts an optimum position upon rotation of the keel  22 . A fine trimming or a change of the sail profiling dependent on the direction of wind incidence can be carried out by the trimming lines  16 ,  18 . 
     Further details of the buoyancy body  2  are explained by way of the representation of the  FIGS. 4 and 5 , the upper views showing a top view onto the buoyancy body  2  and the lower views showing a side view of the buoyancy body  2  with the keel  22 . 
     At the top of  FIG. 4  a top view of the round buoyancy body  2  is shown with the deck  20  on which the helmsman  44  is seated/standing. The keel  22  is indicated by broken lines. According to the foregoing remarks, when the critical rudder angle of 15° is exceeded, the operative engagement of the holding means  42  is disengaged so that the keel  22  can be rotated vis-à-vis the buoyancy body  2 . The respective keel position with respect to the buoyancy body  2  is indicated in the shown embodiment via an indicator  50  which rotates along with the keel  22  on the deck  20 . According to the remarks concerning  FIG. 3 , the keel  22  can be rotated with respect to the buoyancy body  2  about 360° so that the indicator  50  on the deck  20  of the buoyancy body  2  then passes a corresponding orbit. As a matter of course, instead of a mechanical indicator  50  also an electronic indicator can be provided in which the keel position is displayed on a screen or the like. By way of this indicator  50  the helmsman  44  receives a feedback about the current position of the keel  22  so that the steering is considerably facilitated. 
     In accordance with the side views of the buoyancy body  2  shown at the bottom of  FIGS. 4 and 5 , in the shown embodiment the indicator  50  is configured as an object emphasized in color as well as in geometry which is guided along an orbit on the deck  20 . This indicator  50  can also be directly connected to the keel  22 , of course, and can enclose a circumferential wall of the buoyancy body  2  via appropriate rods so that the path of movement of the indicator  50  is located outside the outer circumference of the buoyancy body  2 . 
     For adjusting a change of sailing direction downwards in  FIG. 5  the helmsman  44  sets the rudder  32  by more than 15° (critical rudder angle) so that the holding means  42  releases the keel  22  such that the latter swivels about the axis of rotation  24  corresponding to the rudder angle in arrow direction in  FIG. 5 . The indicator  50  also performs such swivel movement so that the helmsman  44  is constantly informed about the newly set course. As soon as the course corresponds to the input of the helmsman  44 , the rudder  32  is neutralized again so that the sailing vessel  1  then sails into the newly set direction. In the representation according to  FIGS. 4 and 5  the sailing rig  4  is omitted to simplify matters. 
     As explained in more detail hereinafter, the holding means  42  can be designed to have a rope system  40  including pulley blocks, cable brakes etc. Alternatively also other solutions such as a positive or frictionally engaged clutch, a motor drive with brakes or similar coupling/uncoupling means are possible, as a matter of course. 
     By way of the  FIGS. 6 and 7  a variant including a force-fit holding means  42  is explained. In the representation according to  FIG. 6  a partial area of the buoyancy body  2  with the deck  20  and the axis of rotation  24  is recognized which is supported in the hull-shaped buoyancy body  2  and bears the keel  22 . The latter is a long keel as in the afore-described embodiments and includes at its rear-side (view according to  FIG. 6  on the right) end portion the rudder fixture  28  guided around the outer circumference of the buoyancy body  2  on which the rudder fitting  30  with the rudder shaft  34  is supported. The rudder  32  is pivoted around the rudder shaft  34 . The holding means  42  is frictionally engaged in the embodiment shown in  FIGS. 6 and 7 , wherein a pivot arm  54  rotatable about a pivot hinge  52  (normal to the plane of projection in  FIG. 6 ) is supported on the rudder fixture  28 , the pivot arm being pressed onto a friction surface  60  of the deck  20  by a braking member  58  via a biasing element  56 . The friction pairing and the force of the biasing element  56  are chosen such that the position of the keel  22  relative to the buoyancy body  2  can be safely maintained up to an angle of attack of the rudder of 15°. When this critical rudder angle is exceeded, the frictional force can be overcome. This can take place, for instance, by the fact that when this critical rudder angle is exceeded the biasing element  56  is actuated via a guide link such that, according to the representation, it swivels the pivot arm  54  upwards and thus disengages the frictional engagement. In the concrete solution illustrated in  FIGS. 6 and 7 , instead of such guide link according to  FIG. 7  the tiller  36  is swiveled upwards out of the horizontal position in  FIG. 6 . This swivel movement is transmitted via a coupling means  38 , for instance a dragline, to the pivot arm  54  so that the latter is equally swiveled upwards about the pivot hinge  52  and thus releases the frictional engagement. It is a drawback of this solution that the helmsman  44  has to determine when the keel  22  is to be released with respect to the buoyancy body  2 . The afore-described variant, in which the engagement between the buoyancy body  2  and the keel  22  is disengaged via a guide link, any other guide or via electric, hydraulic, pneumatic actors, has the advantage that the critical rudder angle can be exactly observed even without a helmsman  44  so that an operating error is almost excluded. 
     By way of the  FIGS. 8 and 9  variants of the keel/rudder construction are explained.  FIG. 8  shows a variant of a keel  22  or fin in which the axis of rotation  24  is anchored in a support structure  64  of the keel  22  via reinforcing and load distributing elements  62 . This support structure  64  exhibits comparatively high strength and also supports the rudder fixture  28  for the rudder  32 . The shown keel is to be designed for a type of beach sailer which can be pulled from the beach into the water without a slip car and in the same way can be beached. In order to prevent excessive load of the support structure  64  and the axis of rotation  24  by the buoyancy body  2  and the rudder  32 , predetermined breaking points  66 ,  68 ,  70  are provided at the keel  22  and at the rudder  32  which specifically break in the case of a strong impact on the beach and thus avoid damage of the structure. The predetermined breaking points  66 ,  68 ,  70  are designed so that the exchange elements  72 ,  74 ,  76  marked by hatched lines can be exchanged so to speak as wear parts. 
       FIG. 9  shows a variant in which the axis of rotation  24  with its axial bearing  78  holding the keel  22  in the axial direction in the buoyancy body  2  is mounted to a support pipe  80  or a support plate extending along the convex underside of the buoyancy body  2  not shown and having a corresponding concave shape. In this embodiment, the keel  22  made of composite material with the rudder fixture  28  is attached to this very stiff support pipe  80 . In the embodiments described in the foregoing the rudder  32  is in the form of a continuous rudder blade hinged to the rudder fixture  28  by the rudder fitting  30 . In the embodiment according to  FIG. 9  a rudder  32  is used which has a rudder head  82  connected to the rudder fixture  28  through the rudder fitting  30  at which rudder head a rudder blade  86  rotatable about an axis  84  is held which can fold when beaching or encountering an underwater obstacle. The composite material of the keel  22  is chosen such that it withstands beaching by high wear resistance and can also be easily repaired or exchanged, if damage or excessive wear occurs. 
     As a matter of course, the rudder design according to  FIG. 9  can also be employed in the afore-described embodiments. 
       FIG. 10  illustrates some basic principles of construction of the keel design. In  FIG. 10   a  the afore-described basic concept including a keel  22  in the form of a long keel is shown which at the trailing side supports the rudder  32  and is pivot-mounted at the buoyancy body  2  via the axis of rotation, wherein in the contact area the keel has a concave shape corresponding to the underwater shape of the buoyancy body  2 . 
       FIG. 10   b  shows a concept having a comparatively short keel  22  which has by far more draught and is therefore not suited for beaching. In this variant, too, the rudder is formed at the flow side of the keel  22 . 
       FIG. 10   c  illustrates an embodiment with a long keel, wherein the weight distribution chosen differs from that of the embodiment according to  FIG. 10   a . In the latter embodiment the weight of the keel is distributed approximately evenly over the entire respective effective vessel length. In the embodiment according to  FIG. 10   c  the major percentage of the keel weight is provided in the front portion viewed in sailing direction so that an asymmetric keel having a keel bulb  88  is resulting. In the latter at least 55% by weight of the keel weight are concentrated which are offset to the front in the sailing direction. The rudder fixture  28  is then connected to the keel bulb  88  via a support structure or a comparatively light-weight keel portion  90 . 
     In  FIG. 10   d  a variant is shown in which instead of a rudder  32  one or more trim tabs  92 ,  94  are used that are disposed laterally offset with respect to the keel  22  in this embodiment and which can be extended or retracted for varying the sailing direction. These trim tabs  92 ,  94  are connected to the keel  22  via a structure not represented here so that they join the rotation thereof relative to the buoyancy body  2 . In the representation according to  FIG. 10   d  the sail  12  is in a downwind position with respect to the keel  22 . 
       FIG. 11  illustrates various possibilities of fixing the keel  22  in a comparatively light-weight sailing vessel  2  suited for the beach. In the embodiment according to  FIG. 11   a  the keel  22  has a weight concentration according to  FIG. 10   c —of course also other keel shapes can be chosen. The axis of rotation  24  is anchored at the keel  22 , the axial bearing  78  being detachably mounted to the axis of rotation  24 . For connecting the keel  22  to the buoyancy body  2  the axis of rotation  24  is inserted from the bottom ( FIG. 11 ) into a bearing shaft  95  and subsequently the axial bearing  78  is screwed thereto so that the keel with the axis of rotation  24  is held in the radial direction in the bearing shaft  95  and in the axial direction by the axial bearing  78 . 
       FIG. 11   b  shows a strongly simplified variant in which a tensioning element, for instance a very strong high-tensile rubber strap  96 , is fastened to the axis of rotation  24  immersing into the bearing shaft  95  of the buoyancy body  2  which rubber cord extends in the axial direction through the buoyancy body  2  and is belayed in a cleat  97  or the like when fixing the keel  22 . This design is only suited for very small sailing vessels, however. On principle, also other connecting means, such as high-tensile Dyneema ropes or the like, can be used, of course. 
     The rigging is illustrated in detail by way of the following figures. 
       FIG. 12  shows a top view (on the left) and a side view of an embodiment of a sailing vessel  1  having a long keel  22 . As explained before, the sailing rig  4  is supported on or at the buoyancy body  2 . As can be inferred especially from  FIG. 12   a , the sailing rig  4  has a central mast  6  including a curved boom  8  and several battens  10  predetermining the sail shape. The boom  8  is arranged at an axis of symmetry of the symmetrically shaped sail  12 . In the embodiment according to  FIG. 1  the sail  12  could be rotated around the mast  6  via the trimming lines  16 ,  18  in order to optimize the flow. In the embodiment according to  FIG. 12  the mast  6  and the sail  12  substantially exhibit a rigid design with their angle of attack being adapted to be varied with respect to the buoyancy body  2  via a downhaul  98  and/or an uphaul  100 , the mast foot  14  of the mast  6  according to  FIG. 12   b  being articulated and the pivot axis extending normal to the plane of projection in  FIG. 12 . The mast  6  thus can be easily put down in the case of heavy air. 
     In the embodiment shown in  FIG. 12  the helmsman  44  is seated on a bench  102  curved to form a segment of a circle which extends along an outer circumferential portion of the buoyancy body  2  over an angular range of about  120 ° . This curved bench  102  enables the helmsman  44  to align his/her seating position corresponding to the position of the keel  22  (in broken lines in  FIG. 12   a ) relative to the buoyancy body  2 . In the embodiment according to  FIG. 12   a  the sailing rig  4  is shown at a downwind position and thus transversely to the lateral area of the keel  22 . 
     According to  FIG. 12   b  the bench  102  is held at the buoyancy body  2  via an adequate support structure  105 . The tiller  36  shows an angular design so that an operating end portion is guided below the bench  102  into the access area of the helmsman  44 . The rudder  32  can be designed in accordance with any one of the afore-described concepts. 
       FIG. 13  shows a variant of the embodiment represented in  FIG. 12  in which the buoyancy body  2  has a planar deck  20 . In the embodiment according to  FIG. 13  the deck  20  is dished in the central portion to form a cockpit  104  which is self-bailing, wherein drain valves  106  are formed in the cockpit bottom  108  for draining. 
     The structure of the sailing rig  4  corresponds to that of the afore-described embodiment.  FIG. 7  shows a variant of the embodiment according to  FIG. 13 , the buoyancy body  2  being again designed to have a cockpit  104  being confined downwards by the cockpit bottom  108 . The circumferential walls of the buoyancy body  2  in this variant are in the form of an inflatable annular bead  110  preferably having plural chambers to which the cockpit bottom  108  is mounted. In other words, the buoyancy body  2  has a design similar to a life raft, with the cockpit bottom  108  being a rigid support structure for the keel. Also the cockpit  104  according to  FIG. 14  is self-bailing including drain valves  106 . 
     In  FIG. 15   a ,  15   b  a variant of the embodiment according to  FIG. 14  is shown. With this concept, too, the buoyancy body  2  is formed to have an annular bead  110  consisting of plural chambers to which the cockpit bottom  108  is mounted. The keel  22  is supported centrically at the cockpit bottom  108 . In the shown embodiment the mast  6  of the sailing rig  4  is arranged at a relatively small distance b from the axis of rotation  24  so that the symmetric sailing rig  4  is not supported, as in the afore-described embodiments, in the circumferential area of the buoyancy body  2  but in the central area. It is another special feature of the design shown in  FIG. 15  that the mast  6  does not consist of one piece but of three telescopic elements  6   a,    6   b,    6   c  so that, when not in use or for reducing the sail area, the mast can be telescoped. The telescopic mast is extended, for instance, by pulley blocks, by a hydraulic or pneumatic system or an electric motor drive. As illustrated already before, the angle of rotation of the keel  22  with respect to the rotation-symmetric buoyancy body  2  is adjusted by setting the rudder  32 . Depending on the sailing direction and thus depending on the position of the keel  22  relative to the buoyancy body  2  and to the sailing rig  4 , the helmsman  44  can vary his/her seating position on the ring-like circumferential annular bead  110  so as to always look into the sailing direction. 
     In the afore-described embodiments the sailing vessel  1  is rather designed for use by one or two persons and as a sailing boat capable of beaching. The  FIGS. 16 and 17  show concepts in which the sailing vessel  1  is designed as a sea-going yacht for a plurality of persons. In the embodiment according to  FIG. 16 , on the buoyancy body  2 , which again is rotation-symmetric, cabins  112   a,    112   b  serving for receiving passengers are provided. By way of the comparison of size to the helmsman  44  inserted in  FIG. 16  it is obvious that the sailing vessel  1  has considerable dimensions which may be within the range of from  40  to  50  feet, for instance. In the shown variant the two cabins  112   a,    112   b  are diametrally arranged, the mast  6  of the sailing rig in this variant being disposed coaxially with respect to the axis of rotation  24  of the keel  22 . 
     The keel  22  is again rotated by operating the rudder  32  which in this embodiment has a pivoting rudder blade  86  similarly to the variant of  FIG. 9 . It is provided in this embodiment to adjust the angle of attack of the sail  12  with respect to the apparent wind direction by trimming lines  16 ,  18  which are operated via self-tailing winches  111 . The latter can be driven electrically or hydraulically. 
       FIG. 17  illustrates a variant of the embodiment according to  FIG. 16  in which a central cabin  112  is provided which is not placed onto the deck  20  of the buoyancy body  2 , as in the embodiment according to  FIG. 16 , but extends into the buoyancy body  2 . In this cabin  112  a steering stand  114  is arranged which enables the helmsman  44  to steer the sailing vessel  1  in foul weather from the interior of the cabin  112 . The steering is performed via a steering wheel  116  which is operatively connected to the rudder  32  through the coupling means  38  including a transmission gearing  118  such that an adjustment of the steering wheel  116  entails a setting of the rudder  32  and correspondingly the keel  22  is rotated with respect to the buoyancy body  2  when the critical rudder angle is exceeded. It is furthermore a special feature of the embodiment shown in  FIG. 17  that the steering stand  114  rotates along with the keel  22  so that the helmsman always looks into the sailing direction. Accordingly, the cabin  112  is also rotation-symmetric or is at least designed such that the helmsman can always look into the sailing direction. 
     In the case of sailing vessels  1  of such size the keel  22  can be fixed in position with respect to the buoyancy body  2  by appropriate force-fit and form-fit braking means which engage electrically, hydraulically or pneumatically. 
     By way of  FIG. 18  an embodiment is illustrated in which the mast  6  is a bipod having two mast spars  120   a,    120   b  which are disposed at angles with respect to each other such that they converge in the mast top and at the mast foot side are supported on the buoyancy body  2  spaced apart from each other. The sail  12  is then held symmetrically at said bipod and can be further trimmed via trimming lines  16 ,  18 . In accordance with the representation in  FIG. 18  the buoyancy body  2  need not necessarily be rotation-symmetric (cf broken contour), but also a slightly asymmetric design (continuous line of the buoyancy body  2  in  FIG. 18 ) can be employed. 
       FIG. 19  shows another embodiment of a sailing rig  4  having a central mast  6  which forms a unit with the boom  8 . The sail  12  includes plural battens  10  extending approximately in parallel to the boom  8  which are supported at the mast  6 . The latter is arranged on the deck  20  of the buoyancy body via the mast foot  14  and a load distributing plate  122 . The angle of attack of the mast  6  with respect to the deck  20  can be adjusted by a downhaul  98  which is in the form of a pulley block in the represented embodiment. 
       FIG. 20  illustrates a variant in which the sail  12  is shaped similarly to a jib and is hauled by a halyard  124  at the mast  6  not shown here. This sail  12  can be used in addition to the afore-described sail designs, for instance on downwind course. Basically it is also possible to use the jib-like sail  12  alone, however. For the purpose of profiling the sail shown in  FIG. 20  has two reef rows  126 ,  128  by which the sail area can be adapted to the wind force. A window  130  can be provided in the sail  12  to improve the visibility. 
     The  FIGS. 21 and 22  show variants of the rig represented in  FIG. 20 . In the embodiment according to  FIG. 21 , the mast  6  again is in the form of a bipod, the two mast spars  120   a,    120   b  being arranged one behind the other in the plane of projection. They stretch the jib-like sail  12  which is stretched bi-directionally by means of a wishbone  132 . The latter is held at the two mast spars  120   a,    120   b.  This sail  12 , too, has a window  130 . 
     In  FIG. 22  a variant comprising a mast  6  in the form of a bipod is shown, wherein the jib-like sail  12  is stretched via two sprits  134   a  and  134   b  laterally projecting from the buoyancy body  2  transversely to the sail  12  and being telescopic for the purpose of improved maneuverability in the harbor or the like so that they can be retracted into the buoyancy body  2  when no sail is set or for reducing the sail area. In the representation according to  FIG. 22  the sail  12  is in downwind position so that the two spars  134   a,    134   b  and thus the sail  12  are arranged transversely to the lateral area of the keel  22 . The same also applies to the embodiment according to  FIG. 21 . 
       FIG. 23  shows the basic concept of a sailing vessel according to the invention in which the buoyancy body  2  is designed in several parts, for instance a central part  2   a  and two side parts  2   b,    2   c  in the form of segments of a circle which can be interconnected by a high-strength plug-in connection  136 , wherein appropriate fixing means, for instance a catch mechanism, a screwing, clamping or the like, are provided to hold the component parts together. This design is rather suited for small beach sailers. 
       FIG. 24  shows a concept suited for larger sailing vessels in which the two side parts  2   b ,  2   c  are held at the central part  2   a  through high-strength pivot bearings  136   a,    136   b  such that they are adapted to be set from the sailing position shown in broken lines into a harbor position shown by continuous lines in which the width of the sailing vessel  1  corresponds to that of the central part  2   a  so that little space is required in the harbor. Pivoting constructions of this type are known from trimaran construction, for instance from the Dragonfly®, so that further remarks are dispensable. The cabin  112  is formed at the central part  2   a  in this embodiment. The keel  22  then has to be aligned with the longitudinal axis of the central part  2   a.    
     Finally  FIG. 25  shows a highly technological concept in which the cabin  112  forms part of the sailing rig  4 . The latter is a rigid airfoil profile and supports solar panels  138  at its part connected to the cabin  112  for the energy supply of the electric consumers of the sailing vessel  1 . The wing rig can be telescopic so that it can be adapted to the wind force, wherein the telescopic portion of the sail area  140  located at the top in  FIG. 25 , for instance, can be retracted and/or extended so as to adapt the sail to the wind force. In the case that the wind force can no longer be handled with the minimum sail area, the part of the sailing rig  4  connected to the cabin  112  can be swiveled such that the effective sail area is reduced and only the cabin  112  optimized in terms of flow acts as a sail. For this purpose, the pivoting portion of the wing sail is designed to be pivotal about a pivot axis  142 . 
       FIG. 26  illustrates a side view and a top view of another embodiment in which a seat construction  144  is formed on the buoyancy body  2  with a bench  102  curved in the form of a segment of a circle. The keel is formed similarly to the afore-described embodiments and at one end portion supports the rudder shaft  34  including the rudder  32  and the tiller  36 . 
     As one can infer especially from the top view (at the bottom of  FIG. 26 ), in this variant of the invention the holding means for fixing the keel  22  at the set relative position is formed by a tackle  146  functionally connecting the tiller  36  to the axis of rotation  24  of the keel  22 . At the axis of rotation  24  a double pulley  148  is disposed along which the tackle  146  is deflected. Free end portions of the cable pull are fixed in cam cleats or other belaying means  150 . 
     The tackle  146  is designed such that it permits swiveling of the tiller  36  to the afore-described extent, for instance ±15°. A tiller deflection beyond this is then transmitted to the axis of rotation  24  via the tackle  146  and the pulleys  148 . 
     The sail  12  is supported along a horizontally extending pivot axis  142  with respect to the buoyancy body  2 . The sail  12  is pivoted about the pivot axis  142  via uphauls (not represented) and downhauls  98 . Moreover, the sail is supported by appropriate back braces  152 . In the shown embodiment the sail is in the form of a rigid wing profile, for instance, which can be designed to be approximately symmetrical with respect to the axis of the keel  22  (horizontal in  FIG. 26 ). 
     The keel shape approximately corresponds to that of the embodiment of  FIG. 10   c , wherein the actual keel bulb  88  is arranged laterally offset with respect to the axis of rotation  24 . 
     The keel part  90  making up merely for a part of the keel weight extends beyond the axis of rotation and supports the rudder shaft  34 . 
       FIG. 27  shows a variant of the embodiment from  FIG. 26 , wherein instead of a seat construction  144  a trampoline  154  is used as seating or lying area which substantially covers the entire surface of the buoyancy body  2 . 
     The trampoline is supported on a frame construction  156 . A further difference consists in the fact that in the variant according to  FIG. 27  no tiller  36  is used, but the rudder  32  is adjusted with respect to the keel  22  via a crossbar  158  which is mounted to the rudder head and which is adjusted by control cables  160 ,  162  which can be guided by multiple deflection via the pulleys  148 , on the one hand, and via deflection pulleys  164 , on the other hand, and can be belayed by means of cleats  166  so as to adjust the rudder angle. The control cable can also be circumferential in one piece. 
     The relative position of the keel with respect to the buoyancy body  2  can be adjusted via a tackle  146  and a pulley  148  as well as cam cleats or the like.  FIG. 28  shows an embodiment according to  FIG. 27  having a modified support structure for the sail  12 , wherein three back braces  152   a,    152   b,    152   c  are supported on a support profile  168  which is approximately anchor-shaped in the top view. 
       FIG. 29  represents a top view and a side view of a sailing vessel  1  having a split keel  22   a,    22   b,  wherein one of the two keel parts  22   a,    22   b  is pivotal. Basically also both keel parts  22   a,    22   b  can be synchronized, however, so that they go through an approximately equal pivotal movement. 
     The pivot axis  24  of the keel part  22   b  accordingly is arranged eccentrically. Thus, this keel part  22   b  simultaneously acts as rudder, wherein the adjustment is performed via a steering wheel  170 . What is not represented is an axis of rotation about which the two rudder parts  22   a ,  22   b  are pivotal in the afore-described manner. 
     Another special feature of the embodiment shown in  FIG. 29  consists in the fact that the sail  12  is movably guided along a traveler track  172 , wherein the angle of attack of the sail  12  can in turn be adjustable by pivoting about its pivot axis  142 . This pivoting then can be performed again via uphauls and downhauls or the like. A traveler slide  174 , upon which the back braces  152  of the sail  12  act, is guided in ball bearings on the traveler track  172 . 
     The sail  12  and the traveler slide  174  are adjusted along the traveler track  172  via an appropriate actuating means so as to permit exact adjustment with respect to the wind. 
     In a variant having a two-part keel  22   a,    22   b  it is preferred when, according to the schematic representation at the top right of  FIG. 29 , the distances a, b of the respective centers of lateral resistance of the two keel parts  22   a,    22   b  from the central or rotational axis  24  are equal to or smaller than the distance c of the center of pressure from the central axis of the buoyancy body  2 . In the embodiment according to  FIG. 29  the distance c of the center of pressure consequently is larger than the distances a, b of the keel parts  22   a,    22   b  from the central axis of the buoyancy body  2 . 
       FIG. 30  shows a variant of the embodiment according to  FIG. 29 , wherein one of the two keel parts  22   b  is in turn designed to have its own pivot or rudder shaft  34  and the entire keel arrangement with the two keel parts  22   a,    22   b  is rotatable about the central axis of rotation  24 . The keel part  22   b  in turn acts as a rudder, the rudder turn being admitted at a predetermined angle relative to the entire keel arrangement. The rudder/keel combination is in turn actuated by a tiller  36  acting upon the central axis of rotation  24 . 
     The sail is designed similarly to the embodiment according to  FIG. 28 , a substantial difference, however, being the fact that this sail is designed as “pushing sail” and thus is located, viewed in the wind direction, (pushing sail according to  FIG. 30 ) ahead of the axis of rotation  24  and the center of lateral resistance of the sailing vessel  1 . It turned out in a surprising manner that by a sail  12  pushing in such way the gliding state can be reached by far more rapidly so that the sailing speed is improved vis-à-vis a conventional “pulling” sail. 
     Pushing sails of this type can also be employed in all afore-described design variants. 
     Another difference consists in the fact that in this sail arrangement the seating, i.e. for instance the seat construction  144  is arranged in the area between the pushing sail  12  and the axis of rotation  24 , wherein the bench again has the shape of a circle segment. In this manner, the respective effective “bow” of the sailing vessel  1  is relieved so that the latter starts gliding more quickly. 
     Accordingly, in this pushing sail arrangement also the keel part  22   b  pivotal per se is arranged toward the sail  12 . 
       FIG. 31  shows an embodiment in which the sail  12  is a pushing sail and is movable via a traveler slide  174  along a traveler track  178  curved in the form of a circle segment. This variant, too, is designed to have, as the embodiment according to  FIG. 30 , tiller steering  36  acting upon the joint axis of rotation  24  of both keel parts. The keel part  22   b  facing the sail  12  as such is designed to have a rudder shaft  34  for relative swiveling with respect to the keel part  22   a.    
     The seating for the helmsman again is constituted by a bench in the form of a circle segment  102  extending at a parallel distance inside the traveler track  172 . Accordingly, the tiller  36  is enclosed in sections by this bench  102 . 
     In the embodiment according to  FIG. 32  a steering wheel  170  is provided instead of a tiller steering. 
       FIG. 33  illustrates a variant of a comparatively large sailing vessel  1  having a superstructure, for instance a cabin  176 , in which the steering stand and passengers&#39; cabins can be accommodated. The keel again is designed in two parts having keel parts  22   a,    22   b,  wherein the latter are jointly pivotal about the central axis of rotation  24 . The keel part  22   b  close to the sail is in turn pivotal about a rudder shaft  34  so as to permit a slight independent rudder turn. The sail  12  in turn is a pushing sail and is guided to be adjustable along a traveler track  172 . 
       FIG. 34  finally shows an embodiment of a sailing vessel including a pushing sail  12  in which again two keel parts  22   a,    22   b  are provided which are arranged transversely offset with respect to each other in the manner of a bilge keel and are pivotal synchronously to each other via a differential  180  or the like so that a steering movement at the steering wheel  170  is converted to a corresponding swiveling of the keel parts  22   a,    22   b.    
     As a matter of course, also such design can be used in a conventional “pulling” sail. 
     As explained already, all afore-described design variants can practically be combined with each other in any way without leaving the scope of the invention. 
     By way of  FIG. 34  a further development of the invention is explained which is equally applicable to the afore-described embodiments, of course. As indicated in dot-dash lines in  FIG. 34 , at the buoyancy body  2  a ballast element  182  indicated in broken lines can be provided whose position relative to the sail  12  is adjustable so as to bring about weight compensation—similarly to a sailor&#39;s hiking in a dinghy. This ballast element  182  can be guided along appropriate guides to be adjustable in or at the buoyancy body  2 . On principle, it is also possible, as in the case of high-tech offshore yachts, to provide the buoyancy body  2  with a plurality of water tanks  182  which are then filled with water or are emptied via pumps depending on the desired weight trim. 
     There is disclosed a sailing vessel comprising a buoyancy body at which a rotatable keel is held which can be adjusted by setting a rudder. 
     Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the above invention is not limited thereto. It will be manifest that various additions, modifications and rearrangements of the features of the present invention may be made without deviating from the spirit and the scope of the underlying inventive concept.