WO2007042977A2

WO2007042977A2 - Guiding appendage for sailboats and similar floating vessels

Info

Publication number: WO2007042977A2
Application number: PCT/IB2006/053660
Authority: WO
Inventors: László DÁVID
Original assignee: David Laszlo
Priority date: 2005-10-10
Filing date: 2006-10-06
Publication date: 2007-04-19
Also published as: HU0500930D0; HU226796B1; HUP0500930A2; EP1981754A2; WO2007042977A3

Abstract

A guiding appendage positioned under the ship body, parallel with its longitudinal axis (LA), of sailboats and similar floating vessels, whereas said guiding element comprises a core element (5), fastened to the ship body, parallel with its longitudinal axis (LA), and a flexibly deformable shroud element (6) enveloping the core element. On both sides of the core element (5), between the core element (5) and the shroud element (6), a chamber is being formed, which is filled with a pressure medium capable of streaming. The chambers filled with pressure medium on the two sides are independent of one another, and each is connected via a conduit (22, 23) to a pressure controlling device (24). The shroud element (6) is a flexible plate and, at least upon increase of the pressure of the pressure medium, the external shroud profile is a streamlined form in the horizontal cross-section of the guiding element (4). The chambers act as deforming elements (18, 19), with sealing means allowing the parallel and perpendicular motion of the shroud element (6) relative to the core element (5), or arranged in between them. The shroud element (6) is of changing flexibility in the direction of the longitudinal axis (LA) of the ship body, its flexibility being the biggest in the vicinity of the biggest width (wmax) of the streamlined form and decreasing gradually towards the leading and trailing edges (LE, TE), respectively, of the guiding element (4). The invention relates further to a guiding appendage for sailboats and similar floating vessels including at least one guiding element positioned under the ship body parallel with its longitudinal axis, wherein the guiding element (4) is coated with a thin elastomer layer (17) .

Description

Description GUIDING APPENDAGE FOR SAILBOATS AND SIMILAR

FLOATING VESSELS

Technical Field

[1] The present invention relates to improvements in or relating to a guiding appendage positioned under the ship body, parallel with its longitudinal axis, of sailboats and similar floating vessels, whereas said guiding element comprises a core element, fastened to the ship body, parallel with its longitudinal axis, and a flexibly deformable shroud element enveloping the core element. On both sides of the core element, between the core element and the shroud element, a chamber is being formed, which is filled with a pressure medium capable of streaming. The chambers filled with pressure medium on the two sides are independent of one another, and each is connected via a conduit to a pressure controlling device. The shroud element is a flexible plate and, at least upon increase of the pressure of the pressure medium, the external shroud profile is a streamline form in the horizontal cross-section of the guiding element.

Background Art

[2] A known, albeit unimplemented, solution known from the patent literature consists of designing the guiding element of the sailboat so as to make its profile changeable. This means that the shroud of the guiding element characterized by a streamlined cross-section is bulged on one side and its bulge is reduced on the other. Hence a 'lifting force' is created, which will ensure that the boat keep to its course in crosswind, too.

[3] Many solutions have been devised for altering the said profile. These usually agree in that pressure is being exerted at one or several points on the shroud of the guiding element for the purpose of its deformation, on the side required for stabilization, whereby the shroud is bulged outward, while on the other side, the shroud is either pulled inward mechanically, or the pressure acting on the shroud constructed in a pre- stressed way is reduced, and hence the latter strives to straighten out.

[4] Initially, mechanical elements have been used to deform the shroud. These mechanical solutions, however, required a complicated design and a complicated operating structure and, therefore, in order to replace them, purely hydraulic solutions have been devised.

[5] US 4,538,539, for example, describes a solution whereas the inner vertical core element of the guiding element has, itself, a streamlined profile. The shroud element is fixed exclusively at the trailing edge of the vertical core element, while at the leading edge, it is free to displace laterally. There are inflatable bags inserted in between the core element and the shroud element, in the section behind the leading edge, which are connected with conduits to a fixture on board, so that the pressure of the operating medium inside the said bags can be increased or decreased through the said conduits. Upon the deformation of the shroud element, the axis of symmetry of the streamlined profile loses its parallel position to the axis of symmetry of the boat, and hence excess resistance is generated.

[6] From a functional point of view, a similar solution is described in FR 2.473.005, in which the inner vertical core element of the guiding element is a plane sheet, and the two lateral shroud elements are fixed to its front and rear edges. The shroud elements are connected at three places in longitudinal direction by spacers, led through holes formed in the vertical core element. In between two spacers, there are bags inserted between the shroud elements and the vertical core element, which can be filled or discharged to alter the bulge of the adjacent shroud element. At those surfaces which are not supported by the bags, however, laminar flow is not ensured, therefore, turbulence is generated at the places of direction change so that the streaming medium (water) generates excess drag due to burbling instead of laminar flow.

[7] The solution described in JP 57-55.284 differs from the above exclusively in that there are bags inserted under the entire inner surface of the shroud elements. However, the stretching of the shroud element is not resolved, and hence neither is the operation of this design ensured.

[8] A theoretically similar solution is presented in the FR 2.587.675, but there the inner vertical core element of the guiding element is of a shape the profile of which corresponds on both sides to the concave guiding element profile. Only the rear one- third of the guiding element, the section behind the widest point of the profile, is covered with deformable shroud elements and they are sealed at their edges to the core element. The spaces between the core element and the shroud elements are filled with a liquid, and they are connected through a pipe system to the fixtures on board.

[9] Said prior art describes a variant whereas the two spaces are connected exclusively by a hole through the core element. The profile of the guiding element is altered automatically under the effect of the difference in pressure generated on its two sides, under which the liquid in the area on one side of the core element flows over to the area on its other side. An essentially similar solution is presented in the GB 2.387.144 but there the simultaneous deformation of the two shroud elements can also be ensured by the interconnecting spacers. Both solutions have the drawback that they do not allow to modify the streamlined profile in line with speed. Disclosure of Invention Technical Problem

[10] As can be seen from the above overview, the hydraulically deformable guiding elements are easy to design and manage, and hence, from this point of view, they are more advantageous than the corresponding mechanical solutions. However, they still have one of the general defects of deforming structures.

[11] In both the mechanical solutions and the hydraulic ones presented above, the deforming force acts on the shroud element at certain points of the guiding element only. It is easily understood that the shroud element - behaving, essentially, as a two- support beam - will not be deformed so as to match the ideal streamline curve. The situation is similar in the case of those hydraulic solutions where the bag is put under the entire surface of the shroud element, as this exerts an even pressure throughout the length of the guiding element, which, again, cannot be expected to produce the uneven deformation matching the streamline curve. Although there exist some mechanical solutions whereas several deforming elements are positioned one behind the other in the guiding element, these, too, only approximate the ideal streamline curvature, even if the shroud elements on the two sides are interlinked with spacers.

[12] Furthermore, if the shroud element is not supported under its entire surface, but only under part or certain points of it (by bags smaller than the entire surface of the shroud element and/or spacers), in the part without proper support (in between the spacers as well) the shroud may be subject to oscillatory motion, which, in turn, will result in turbulence, then the burbling of the streaming medium (water) and hence in excess resistance. Resistance is equally increased if the axis of symmetry of the streamline profile is at an angle with the longitudinal axis of the boat, as this will increase the traveling (longitudinal) cross-section.

Technical Solution

[13] Therefore, the objective of the present invention is to design the elements involved in the deformation so as to ensure that the deformation of the shroud elements should produce in every case the ideal streamline form.

[14] The invention is based on the recognition that, by choosing shroud elements of different rigidity values in the longitudinal direction of the guiding element, it is possible to create a shroud element which will be deformed, despite being subject to other than ideal power effects, in a way matching the ideal streamline curve. This task is solved by altering the rigidity, so that the rigidity value be bigger at the leading edge of the guiding element and decrease continuously towards the rear end of it, to increase again continuously from around the widest point of the guiding element on, towards the trailing edge of the guiding element. By changing the bulge of the shroud element, the leading and trailing edges, too, are given such control as will ensure that the axis of the entire streamline profile should remain parallel to the longitudinal axis of the boat.

[15] It is part of the recognition, moreover, that in guiding elements having a shroud consisting of several parts, inevitably, such depressions will be formed on the surface of the guiding element at the junctures of the shroud elements as will increase its resistance. This can be avoided by giving the external surface of the guiding element a thin elastomer coating.

[16] Our proposed solution to the objective set above is based on a guiding element positioned under the ship body, parallel with the longitudinal axis, of sailboats and similar floating vessels, whereas the said guiding element comprises a core element fastened to the ship body, parallel with its longitudinal axis, and a shroud element enveloping that, made of a flexibly deformable sheet. In the horizontal cross-section of the guiding element, the external profile of the shroud element is a streamlined form. In the space between the core element and the shroud element, on each side of the core element, a deforming element is created. The deforming element is a pressure medium capable of streaming, filled into chambers created by pressure-resistant, flat liquid- holding vessels with flexible walls, arranged circularly between the core element and the shroud element, with sealing means allowing the parallel and perpendicular motion of the shroud element relative to the core element, or arranged in between the core element and the shroud element. The closed spaces created on the two sides of the core element are either connected by conduits to one another or they are connected individually to a pressure controlling device. The shroud element according to the present invention is of changing flexibility in the direction of the longitudinal axis of the floating vessel, its flexibility being the biggest in the vicinity of the biggest width of the streamlined form and decreasing gradually towards the leading and trailing edges, respectively, of the guiding element.

[17] According to one preferred embodiment of the guiding element according to the present invention, the flexibility of the shroud element is biggest at the biggest width of the streamlined form.

[18] According to an other preferred embodiment of the guiding element according to the present invention, the flexibility of the shroud element changes in longitudinal direction in inverse proportion to the width of the streamlined form.

[19] According to an other preferred embodiment of the guiding element according to the present invention, the thickness of the shroud element is uniform, but the coefficient of elasticity of its material is smallest at the biggest width of the streamlined form and it increases towards the leading and trailing edges, respectively, of the guiding element.

[20] According to an other preferred embodiment of the guiding element according to the present invention, the coefficient of elasticity of the material of the shroud element is uniform, but its thickness is smallest at the biggest width of the streamlined form and it increases towards the leading and trailing edges, respectively, of the guiding element.

[21] According to an other preferred embodiment of the guiding element according to the present invention, both the coefficient of elasticity and the width of the material of the shroud element is smallest at the biggest width of the streamlined form, and increases towards the leading and trailing edges, respectively, of the guiding element.

[22] According to an other preferred embodiment of the guiding element according to the present invention, the entire shroud element is made of a single piece, which is axially symmetrical to the plane of symmetry of the guiding element.

[23] According to an other preferred embodiment of the guiding element according to the present invention, the shroud element is divided into three sections along the longitudinal axis of the ship body, so that the leading shroud element section in the vicinity of the leading edge and the trailing shroud element section in the vicinity of the trailing edge are rigid units, while the two middle lateral shroud element sections are made of flexibly deformable sheets; the leading and trailing shroud element sections are connected to the core element; the lateral shroud element sections are longer in the same cross-section of the guiding element than the biggest distance between the neighboring edges of the leading and the trailing shroud element sections, respectively, and there is a connection allowing longitudinal linear movement between the adjoining edges of the lateral shroud element sections and the leading and trailing shroud element sections, respectively.

[24] According to an other preferred embodiment of the guiding element according to the present invention, the shroud element is divided into three sections along the longitudinal axis of the ship body, so that the leading shroud element section in the vicinity of the leading edge and the trailing shroud element section in the vicinity of the trailing edge are rigid units, while the two middle lateral shroud element sections are made of flexibly bendable and stretchable sheets; the leading and trailing shroud element sections are connected to the core element, and there is a connection allowing longitudinal linear movement between the adjoining edges of the lateral shroud element sections and the leading and trailing shroud element sections, respectively.

[25] According to yet another preferred embodiment of the design according to the present invention, the leading shroud element section and the trailing shroud element section is attached in a revolving manner, with hinges, to the core element, whereas the axis of the hinges is arranged in the plane of symmetry of the guiding element, towards the inside of the guiding element from the leading and the trailing edges, respectively.

[26] Finally, in another preferred embodiment of the guiding element according to the present invention, the leading shroud element section and the trailing shroud element section are in operating connection with one another allowing the chord connecting the leading and the trailing edges to move essentially in parallel to the longitudinal axis of the ship body.

[27] The invention relates, moreover, to such embodiments of one or several guiding elements of sailboats or similar floating instruments positioned below their ship body, parallel with the longitudinal axis of the latter, whereas the guiding element according to the invention is coated with a thin elastomer layer.

Description of Drawings

[28] Features and advantages of the invention will be apparent from the following description of preferred embodiment, given for the purpose of disclosure and taken in conjunction with the accompanying drawings wherein

[29] Figure 1 shows the hull equipped with a guiding element according to the present invention, in side view,

[30] Figure 2 shows the cross section of the guiding element according to the invention along the line I-I in Fig. 1,

[31] Figure 3 shows a detail of the vertical section of the guiding element according to the invention along the line II-II in Fig. 2,

[32] Figure 4 shows the cross section of one of the lateral shroud element sections unassembled,

[33] Figure 5 shows the guiding element without coating layer, in a part side view as indicated by HI in Fig. 2,

[34] Figure 6 shows the shroud element in the partial cross section IV-VI indicated in

Fig. 5,

[35] Figure 7 shows the guiding element positioned asymmetrically in section along the line I-I in Fig. 1 and, finally,

[36] Figure 8 shows another embodiment of one of the lateral shroud element sections, unassembled, in cross section.

Best Mode

[37] Figure 1 shows a sailboat very schematically. A ship body 1 is equipped with a mast 2 and rig 3. At the bottom of ship body 1, an appendage in form of a guiding element 4 is formed.

[38] The guiding element 4 is arranged as usual in a longitudinal axis LA of the ship body 1, perpendicularly downwards. (Such guiding elements are usually referred to as centreboard or keel.) The structure of the guiding element 4 is revealed in more detail in Figure 2, showing the cross-section I-I defined perpendicularly to the vertical plane of symmetry on the longitudinal axis LA of the ship body 1. As can be seen in this cross-section, in a neutral position, the guiding element 4 has a symmetric form, the plane of symmetry SP of which coincides with the vertical axis of symmetry on longitudinal axis LA of the ship body 1.

[39] (It shall be emphasized that, although the following exemplary embodiment shows an arrangement whereas a vertical guiding element is built onto the bottom of the ship body 1, the solution according to the present invention can be used for other arrangements as well. Hence it is applicable to such guiding elements as well which are equipped with a balance weight at the bottom, or which can be tilted relative to the ship body. It can also be applied to such cases when the ship body is equipped with two guiding elements, which may even diverge from the perpendicular direction.)

[40] The frame of the guiding element 4 is provided by a core element 5, fastened to the bottom of the ship body 1. The core element 5 is a plane sheet, positioned in the axis of symmetry SP of the guiding element 4. The solidity of the core element 5 is of such degree as will allow it to assume the entire lateral load bearing on the guiding element 4 (and to carry, in the given case, the balance weight suspended onto it).

[41] The external profile of the guiding element 4 is defined by a shroud element 6, consisting of several parts.

[42] In the vicinity of a leading edge LE of the guiding element 4, a leading shroud element section 6a is being formed. The leading shroud element section 6a is a rigid, convex form, made up, essentially, of the short, arched sections of the shroud element 6 behind the leading edge LE. The leading shroud element section 6a comprises on the inside brace elements 7 extending backwards. The brace elements 7 are fastened in a revolving manner, with hinges 8, in the manner shown in Figure 3, to the front edge of the core element 5.

[43] Similarly, in the vicinity of a trailing edge TE of guiding element 4, a trailing shroud element section 6b is being formed. The trailing shroud element section 6b is a V-shaped form, the stems of which are the short sections in front of trailing edge TE. The trailing shroud element section 6b, too, is a rigid unit, provided with brace elements 9 on the inside. The brace elements 9 are fastened in a revolving manner with hinges 10 to the rear edge of the core element 5.

[44] As can be seen in Figures 2 and 3, hinges 8 and 10 are formed by the holes made along one and the same axis in the brace elements 7 and 9, respectively, and in core element 5, and the axes led through them. In a aqueous environment, it may be more advantageous to use solutions not including elements revolving in one another. Such a hinge design may connect the brace elements 7 and 9, respectively, and the core element 5 with flexible elements, e.g. rubber sheets, which can only bend outward around the theoretical axis of the hinges 8 and 10, respectively, but not in the direction of the axis.

[45] The middle part of the shroud element 6, between the leading shroud element section 6a and the trailing shroud element section 6b, is made up by lateral shroud element sections 6c and 6d located on the two sides of the core element 5.

[46] Figure 4 shows the cross section of a removed lateral shroud element section 6c.

(For the sake of better representation, the thickness of lateral shroud element section 6c is increased disproportionately relative to its length.)

[47] The lateral shroud element section 6c is, essentially, a flexibly deformable plate, the material of which includes load-bearing and bonding agents. However, as can be seen in Figure 4, the individual load-bearing material layers 11 are not identical. The first load-bearing material layer 11 from the external side of the lateral shroud element section 6c is a continuous not-broken layer, while the second load-bearing material layer 11 is interrupted in a short section in the middle, the third load-bearing material layer 11 is interrupted in a longer section and the further load-bearing material layers in sections of increasing length.

[48] It is easily understood that, as a result of the load-bearing material layers 11 being of different lengths, the flexibility of the lateral shroud element section 6c changes in longitudinal direction, so that it is least flexible in the areas comprising most load- bearing material layers 11, that is, its edges towards the leading edge LE and the trailing edge TE, respectively, while being more flexible on the inside, where there are less load-bearing material layers 11. As shown in Figure 4, the inner ends of load- bearing material layers 11 define such a curve cu as is similar to the external contour of guiding element 4. That is, this curve cu defines the longitudinal change in flexibility of lateral shroud element section 6c as well. As can be seen, lateral shroud element section 6c is most flexible in the surroundings of the biggest width w of the max streamlined form, and its flexibility is inversely proportional with the width of the streamlined form.

[49] The lateral shroud element section 6d is designed, as a matter of course, in the same way, except for being the mirror image of the lateral shroud element section 6c.

[50] The neighboring edges of the lateral shroud element sections 6c and 6d and the leading shroud element section 6a and the trailing shroud element section 6b, respectively, are connected to one another. As shown in Figure 2 in a symbolic manner and in Figures 5 and 6 in more detail, at the edges concerned, combs 12 are being formed, their teeth protruding into one another. The combs 12 are covered on the inside by a sheet 13, fastened to the lateral shroud element sections 6c and 6d, respectively, with rivet 14, while at the leading shroud element section 6a and the trailing shroud element section 6b, respectively, they are equipped with slots 15, guided by bolts 16 fastened in the leading shroud element section 6a and the trailing shroud element section 6b, respectively. This design ensures the aperture-free connection of the edges of the leading shroud element section 6a and the trailing shroud element section 6b and the lateral shroud element sections 6c and 6d, respectively, while also providing for longitudinal linear motion in between the lateral shroud element sections 6c and 6d and the leading shroud element section 6a and the trailing shroud element section 6b, respectively.

[51] Although the junctures of the lateral shroud element sections 6c and 6d and the leading shroud element section 6a and the trailing shroud element section 6b, respectively, are formed in an aperture-free way, in order to reduce the resistance, the entire surface of the guiding element 4 is coated with a thin coating layer 17. The material of the coating layer 17 is an elastomer of some sort, e.g. rubber, because it has to be flexible and flexibly stretchable. In between the core element 5 and the shroud element 6, on the two sides of the core element 5, deforming elements 18 and 19, respectively, are formed in the following manner.

[52] There is a liquid holding vessel 20 inserted between the core element 5 and the lateral shroud element section 6c. The liquid holding vessel 20 is, essentially, a flat, pressure-resistant bag with flexible walls, equivalent in size to the inner surface of the lateral shroud element section 6c. Given the fact that practically the entire external surface of the liquid holding vessel 20 is supported, its material may have features similar to the inner tubes of tires used in motorcars. A similar liquid holding vessel 21 is positioned between the core element 5 and the lateral shroud element section 6d.

[53] Liquid holding vessels 20 and 21 are connected by conduits 22 and 23, respectively, to a pressure controlling device 24. The pressure controlling device 24 comprises a pump 25, a liquid container 26, manually operated valves 27 and pressure gauges 28. The liquid holding vessels 20, 21, conduits 22, 23 and pressure controlling device 24 are filled with a pressure medium capable of streaming, such as hydraulic fluid. As a matter of fact, in this embodiment, deforming elements 18 and 19, respectively, are formed by this hydraulic fluid.

[54] The guiding element 4 presented above is applied as follows.

[55] In the assembly phase of the guiding element 4, the lateral shroud element sections

6c and 6d are nearly flat, with only plates 13 providing a little pre-stressing. Once the assembly is accomplished, the liquid holding vessels 20 and 21 are filled with hydraulic fluid from liquid container 26 with the help of a pump 25, so that the increasing pressure inside them shall bulge the lateral shroud element sections 6c and 6d, and hence guiding element 4 shall take on the desired streamlined shape. The realization of the desired bulge can be checked with pressure gauges 28, calibrated not to the pressure values but directly to the extent of the bulge instead.

[56] Obviously, the liquid holding vessels 20 and 21 exert even pressure on the inner surface of the lateral shroud element sections 6c and 6d, respectively, and hence - in case of applying simple, smooth plates - the shape of the latter would be a curve symmetric to the bisector of their two perpendicular edges. Since the flexibility of lateral shroud element sections 6c and 6d changes longitudinally in accordance with curve cu shown in Figure 4, despite the even pressure, they will longitudinally be deformed to different degrees in accordance with their different flexibility values, that is, they will adopt a streamlined shape.

[57] In case of headwind, when lifting force shall be generated on the guiding element 4 to increase the stability and course-consistency of the sailboat, the cross-section of the guiding element 4 shall be made asymmetrical, that is, the bulge shall be increased on the luff side and it shall be reduced on the lee side. In this case, an amount of the hydraulic fluid shall be poured with the help of the pump 25 from the liquid holding vessel 20 or 21 on the side where the bulge shall be reduced to the liquid holding vessel 21 or 20 on the side where it shall be increased. As a result of this operation, the guiding element 4 will adopt the cross-section shown in Figure 7 (Figure 7 shows the contours of the guiding element 4 only for the sake of providing a more transparent depiction). As can be seen quite clearly, this is the shape know as 'wing profile', on which lifting force F is generated. Obviously, as a result of the change in flexibility in longitudinal direction, the more bulging one of the lateral shroud element sections 6c or 6d will remain streamlined, while the other will become more and more straight.

[58] Figure 7 shows, moreover, that not only the shape of the lateral shroud element sections 6c and 6d is changed, but the leading shroud element section 6a and the trailing shroud element section 6b, too, turn a little around the hinges 8 and 10, respectively. This not only promotes the change of the shape of the lateral shroud element sections 6c and 6d, but it is also necessary for the emergence of the regular 'wing profile'.

[59] It is also revealed in Figure 7 that the leading shroud element section 6a and the trailing shroud element section 6b turn in such way that the chord c connecting the leading edge LE and the trailing edge TE will remain parallel at all times with the longitudinal axis LA of the ship body 1. This has the advantage that the alteration of the shape of the guiding element 4 will only generate lifting force F, but the force- component provoking a change in the course of the boat will not be created.

[60] The pressure controlling device 24 is designed so that the extent of the change in the shape of the lateral shroud element sections 6c and 6d can be controlled independently and in an infinitely variable way. That is, the guiding element 4 cannot only be made asymmetrical, but its thickness, too, can be altered. (The extra hydraulic fluid required for increasing thickness can be supplemented from the liquid container 26, and the excess hydraulic fluid can be flown back to the same.)

[61] Thanks to the above option, lifting force F, too, can be altered. Hence the shape of the guiding element 4 can always be set in accordance with the boat speed and wind pressure ever. (As is well-known, an increase in the cross section perpendicular to the streaming direction of the guiding element 4 or the bigger boat speed will increase the resistance of guiding element 4, hence in case of bigger boat speed, it is advisable to choose a smaller cross-section.)

[62] As can be seen clearly from the exemplary embodiment described above, as a result of the changing flexibility of the lateral shroud element sections 6c and 6d in longitudinal direction, the guiding element 4 can be altered in such way as will allow it to retain the ideal streamlined shape.

[63] The interconnection of the lateral shroud element sections 6c, 6d and the leading and trailing shroud element sections 6a and 6b, respectively, with the combs 12 and the plates 13, provides a quasi-continuous surface under the coating layer 17, the external surface of which is consequently completely even and perfectly smooth. By applying the coating layer 17, the friction of the guiding element 4 is reduced to the smallest possible value. Ideally, thanks to its soft and slightly uneven surface, the coating layer 17 is also suitable for damping the micro-oscillations of the streaming medium (water).

[64] The embodiment according to the present invention can be realized in numerous other variants as well. In what follows, we shall describe, by way of example only, some of these variants.

[65] The most important point is the design of the lateral shroud element sections 6c and

6d themselves. In addition to using load-bearing layers of different lengths to ensure longitudinally changing flexibility, other solutions are conceivable as well.

[66] Hence, for example, in the manner shown in Figure 8, the load-bearing layers 11 are not interrupted, but their density changes according to the curve cu. Both variants can be realized also by adjusting the thickness of the lateral shroud element sections 6c and 6d to the curve cu.

[67] Thickness-adjustment to the curve cu can also be realized for plates that are not reinforced by load-bearing layers. For such plates, another proper solution may be to form vertical grooves or holes of a depth or density corresponding to the curve cu.

[68] Another solution for the design of the shroud elements is to prepare them of elastomer material with adequately chosen and arranged reinforcement (e.g. textile) so as to make them capable, in addition to flexible bending, of longitudinal flexible stretching as well. Hence the lateral shroud element sections 6c and 6d can be permanently fixed to the leading and trailing shroud element sections 6a and 6b, respectively.

[69] As already mentioned, in unassembled state, the lateral shroud element sections 6c and 6d shown in Figures 4 and 8 are plane sheets. Therefore, the bulge of the guiding element 4 can only be reduced to the extent until which the lateral shroud element section 6c or 6d becomes completely flat. In part of the current solutions known in the art, the lateral shroud element sections 6c, 6d can be deformed more than that, to the extent of being concave. This is feasible with the embodiment according to the present invention. That would make it necessary to make the lateral shroud element sections 6c, 6d at least as concave prior to assembly as we want them to be upon the alteration of the shape of the guiding element 4.

[70] Although connecting the lateral shroud element sections 6c, 6d and the leading and trailing shroud element sections 6a and 6b, respectively, with combs 12 provides the best surface for the coating layer 17, the creation of the combs 12 is rather labor- intensive, and, therefore, a simpler solution might be needed.

[71] The simples solution is to arrange the vertical edges of the lateral shroud element sections 6c, 6d in a stepped way, so that these step- wise parts arranged inward should simply reach under the leading shroud element section 6a and the trailing shroud element section 6b, respectively. The vertical edges of the lateral shroud element sections 6c, 6d shall be, obviously, at such distance from one another that they should not hinder the turning of the leading shroud element section 6a and the trailing shroud element section 6b, respectively. This step-wise solution also prevents that the lateral shroud element sections 6c, 6d should slip from under the leading shroud element section 6a and the trailing shroud element section 6b.

[72] Although in the step- wise linking described above grooves are being formed, the lateral shroud element sections 6c, 6d and the leading and trailing shroud element sections 6a and 6b, respectively, create an essentially uninterrupted surface, and hence the coating layer 17 can be omitted. Of course, the friction of the guiding element 4 will in this case be a little bigger.

[73] The design of the shroud element 6 described above is the most advantageous not only in terms of the operation of the guiding element 4, but also in terms of manufacturing technology. Nevertheless, the principle of the design according to the present invention of the shroud element 6 can be applied also, for example, in those prior-art solutions where the shroud element 6 is made of one piece, in a band-like manner. It is a different issue altogether that, in such cases, the ideal movement of the leading edge BAE and the trailing edge TE as shown in Figure 7 will not be realized.

[74] Theoretically, in both the exemplary embodiment and the solutions presented above, it may be feasible for the lateral shroud element sections 6c, 6d to move in longitudinal direction, damaging thereby, occasionally, the liquid holding vessels 20, 21 or the coating layer 17. This risk can be eliminated by connecting one of the vertical edges of the lateral shroud element sections 6c, 6d with a hinge to the appropriate vertical edge of the leading shroud element section 6a or the trailing shroud element section 6b, with a step- wise arrangement at their other vertical edge, reaching under the leading shroud element section 6a and the trailing shroud element section 6b, re- spectively.

[75] The lateral shroud element sections 6c, 6d could also be attached to the core element 5 with hinged arms. These arms could be positioned at the lower and upper edge of the guiding element 4, below and above the liquid holding vessels 20, 21. One hinge point of the arms could be located in the vicinity of the front hinges 8 on the core element 5, while the other hinge point on the lateral shroud element sections 6c, 6d on the lateral shroud element sections, in the vicinity of the rear vertical edges.

[76] If stronger liquid holding vessels 20, 21 are used, the longitudinal propping of the lateral shroud element sections 6c, 6d can also be solved by creating, on both the inner surface of the lateral shroud element sections 6c, 6d and on the core element 5, such nests into which the liquid holding vessels 20, 21 will fit exactly. Under pressure, the liquid holding vessels 20, 21 will be flexed in the nest, and prevent perfectly the longitudinal movement of the lateral shroud element sections 6c, 6d.

[77] As mentioned already in connection with Figure 7, upon turning of the leading and trailing shroud element sections 6a and 6b, respectively, the chord c linking the leading edge LE and the trailing edge TE will remain parallel with the longitudinal axis LA of the ship body 1. It is most advantageous if this can be ensured through the dimensioning of the different parts, because then no efforts are needed to position further parts. At the same time, dimensioning means that so many parameters are to be taken into account that sometimes a mechanical connection of some sort between the leading shroud element section 6a and the trailing shroud element section 6b might be more expedient. Figure 7 shows such a solution as well, in dotted lines.

[78] The leading shroud element section 6a is fixed to the axis of the hinge 8, the upper end of which extends into the ship body 1, with an arm 26 being fixed onto it. Similarly, the trailing shroud element section 6b, too, is fixed to the axis of hinge 10, with an arm 30 being fixed on its upper end extending into the ship body 1. Arms 29 and 30 are connected with a tie rod 31.

[79] The operation of the said mechanism requires no further explanation, but the dimensioning of the individual parts does. It will be understood easily that if, for example, the ratios of the distance da between the leading edge LE and the axis of the hinge 8 and of the length Ia of the arm 29 on the one hand, and of the distance db between the trailing edge TE and the axis of hinge 10 db and of the length Ib of the arm 30 on the other are identical, and the arm 29 is perpendicular to the straight line crossing leading edge LE and the axis of the hinge 8, and the arm 30 is perpendicular to the straight line crossing trailing edge TE and the axis of the hinge 10, the turning of the leading shroud element section 6a and the trailing shroud element section 6b is synchronized in such way as will allow that chord c linking the leading edge LE and the trailing edge TE remain parallel at all times with longitudinal axis LA of ship body 1. [80] Finally, although of no direct relevance for the solution according to the present invention, mention shall be made of the fact that this design can be used also in such cases when the deforming elements 18, 19 are designed in another way than the one presented above.

[81] This is the case, for example, in the version when, instead of the liquid holding vessels 20, 21, the closed space for the hydraulic fluid is created with sealing means inserted between the core element 5 and the lateral shroud element sections 6c, 6d. The sealing means is a relatively wide rubber band, the edges of which are glued to the core element 5 and to the inner surfaces of the lateral shroud element sections 6c, 6d, respectively. It is necessary to use a relatively wide rubber band, because the distance between the core element 5 and the lateral shroud element sections 6c, 6d changes, anyway, in longitudinal direction, and upon the deformation of the lateral shroud element sections 6c, 6d, in addition to this distance, the individual points of the core element 5 and of the lateral shroud element sections 6c, 6d also migrate a little relative to one another. The closed area created this way can be filled with hydraulic fluid the same as the liquid holding vessels 20, 21.

[82] Thanks exactly to the design of the lateral shroud element sections 6c, 6d, as a matter of fact, such prior-art solutions can also be used in which the deforming element does not affect the entire surface of the lateral shroud element sections 6c, 6d. Thus, for example, the liquid holding vessels 20, 21 can also be smaller than the lateral shroud element sections 6c, 6d. Let us emphasize that this is noted, mainly, as a theoretical option, as these designs have a major drawback, namely that the lateral shroud element sections 6c, 6d are not supported adequately, they will start to oscillate easily, which will generate turbulence, raising considerably the resistance of the guiding element 4.

[83] Let us note, again as theoretical option, that for example compressed air, too, can be used as pressure medium capable of streaming. On a sailboat having no power generating means of its own, however, it would be difficult to solve the problem of producing compressed air, while the pump of the hydraulic fluid can be operated easily manually, too. Hence the probability of applying the compressed air variant is rather small.

[84] List of the used reference signs

[85] cu - curve

[86] c - chord

[87] Ia - length

[88] Ib - length

[89] w max - biggest width

[90] da - distance [91] db - distance

[92] LE - leading edge

[93] F - lifting force

[94] LA - longitudinal axis

[95] TE - trailing edge

[96] SP - plane of symmetry

[97] 1 - ship body

[98] 2 - mast

[99] 3 - rig

[100] 4 - guiding element

[101] 5 - core element

[102] 6 - shroud element

[103] 6a - leading shroud element section

[104] 6b - trailing shroud element section

[105] 6c - lateral shroud element section

[106] 6d - lateral shroud element section

[107] 7 - brace element

[108] 8 - hinge

[109] 9 - brace element

[HO] 10 - hinge

[111] 11 - load-bearing material layer

[112] 12 - comb

[113] 13 - sheet

[114] 14 - rivet

[115] 15 - slot

[116] 16 - bolt

[117] 17 - coating layer

[118] 18 - deforming element

[119] 19 - deforming element

[120] 20 - liquid holding vessel

[121] 21 - liquid holding vessel

[122] 22 - conduit

[123] 23 - conduit

[124] 24 - pressure controlling device

[125] 25 - pump

[126] 26 - liquid container

[127] 27 - valve

[128] 28 - pressure gauge [129] 29 - arm

[130] 30 -arm

[131] 31 -tie rod

Claims

[1] 1. A guiding appendage for sailboats and similar floating vessels including at least one guiding element positioned under the ship body parallel with its longitudinal axis, comprising a core element fastened to the ship body parallel with its longitudinal axis and a shroud element enveloping said core element and made of a flexibly deformable sheet where the external profile of the shroud element is a streamlined form in the horizontal cross-section of the guiding element, and in the space between the core element and the shroud element, on each side of the core element, a deforming element is provided where the deforming element is a pressure medium capable of streaming, filled into chambers created by pressure-resistant, flat liquid-holding vessels with flexible walls, arranged circularly between the core element and the shroud element, with sealing means allowing the parallel and perpendicular motion of the shroud element relative to the core element, or arranged in between the core element and the shroud element; the closed spaces created on the two sides of the core element are either connected by conduits to one another or they are connected individually to a pressure controlling device, characterized in that the shroud element (6) is of changing flexibility in the direction of the longitudinal axis (LA) of the ship body (1), its flexibility being the biggest in the vicinity of the biggest width of the streamlined form and decreasing gradually towards the leading and trailing edges (LE, TE), respectively, of the guiding element (4).

2. The guiding appendage according to claim 1 characterized in that the flexibility of the shroud element (6) is biggest at the biggest width (w_ max ) of the streamlined form.

3. The guiding appendage according to claim 1 characterized in that the flexibility of the shroud element (6) changes in longitudinal direction in inverse proportion to the width of the streamlined form.

4. The guiding appendage according to any of claims 1 to 3, characterized in that the thickness of the shroud element (6) is uniform, but the coefficient of elasticity of its material is smallest at the biggest width (w_ ) of the streamlined max form and it increases towards the leading and trailing edges (LE, TE), respectively, of the guiding element (4).

5. The guiding appendage according to any of claims 1 to 3, characterized in that the coefficient of elasticity of the material of the shroud element (6) is uniform, but its thickness is smallest at the biggest width (w_ max ) of the streamlined form and it increases towards the leading and trailing edges (LE, TE), respectively, of the guiding element (4) .

6. The guiding appendage according to any of claims 1 to 3, characterized in that both the coefficient of elasticity and the width of the material of the shroud element is smallest at the biggest width (w_ max ) of the streamlined form, and increases towards the leading and trailing edges (LE, TE), respectively, of the guiding element (4) .

7. The guiding appendage according to any of claims 1 to 6, characterized in that the entire shroud element (6) is made of a single piece, which is axially symmetrical to the plane of symmetry (SP) of the guiding element (4) .

8. The guiding appendage according to any of claims 1 to 6, characterized in that the shroud element (6) is divided into three sections along the longitudinal axis of the ship body (1) , so that the leading shroud element section (6a) in the vicinity of the leading edge (LE) and the trailing shroud element section (6b) in the vicinity of the trailing edge (TE) are rigid units, while the two middle lateral shroud element sections (6c, 6d) are made of flexibly deformable sheets; the leading and trailing shroud element sections (6a, 6b) are connected to the core element (5) ; the lateral shroud element sections (6c, 6d) are longer in the same cross-section of the guiding element (4) than the biggest distance between the neighboring edges of the leading and the trailing shroud element sections (6a, 6b) , respectively, and there is a connection allowing longitudinal linear movement between the adjoining edges of the lateral shroud element sections (6c, 6d) and the leading and trailing shroud element sections (6a, 6b) , respectively.

9. The guiding appendage according to any of claims 1 to 6, characterized in that the shroud element (6) is divided into three sections along the longitudinal axis (LA) of the ship body (1) , so that the leading shroud element section (6a) in the vicinity of the leading edge (LE) and the trailing shroud element section (6b) in the vicinity of the trailing edge (TE) are rigid units, while the two middle lateral shroud element sections (6c, 6d) are made of flexibly bendable and stretchable sheets; the leading and trailing shroud element sections (6a, 6b) are connected to the core element (5) , and there is a connection allowing longitudinal linear movement between the adjoining edges of the lateral shroud element sections (6c, 6d) and the leading and trailing shroud element sections (6a, 6b) , respectively.

10. The guiding appendage according to any of claims 1 to 6, 8 or 9, characterized in that the leading shroud element section (6a) and the trailing shroud element section (6b) is attached in a revolving manner, with hinges (8, 10) , to the core element (5) , whereas the axis of the hinges (8, 10) is arranged in the plane of symmetry (SP) of the guiding element (4) , towards the inside of the guiding element (4) from the leading and the trailing edges (LE, TE), re- spectively.

11. The guiding appendage according to any of claims 1 to 6, 8 or 9, characterized in that the leading shroud element section (6a) and the trailing shroud element section (6b) are in operating connection with one another, allowing the chord (c) connecting the leading and the trailing edges (LE, TE) to move essentially in parallel to the longitudinal axis (LA) of the ship body (1) .

12. A guiding appendage for sailboats and similar floating vessels including at least one guiding element positioned under the ship body parallel with its longitudinal axis, characterized in that the guiding element (4) is coated with a thin elastomer layer (17) .