ELONGATED PROPELLING MEANS FOR MANUALLY MOVING A SAILING CRAFT OVER THE WATER SURFACE

Abstract: An elongated propelling member (9) for manually advancing a sailing craft over the water surface, said propelling member (9) comprising a stick-like grip and thrust means through which a thrust can be exerted on the water, said grip forming part of a stick (4) carrying the thrust means, while said thrust means are made of a flexible, substantially circular foil (1) which along the circumference thereof, at substantially equal interspaces, is provided with radial stiffening members having a length smaller than the radius of the circle and which foil (1) furthermore is provided in the centre of the circle with a concentric tube stub-like opening (3) and being connected via said stub whether or not detachably around and with said stick, (4) while the foil (1) furthermore is provided, in the direction of the stick end to be inserted in the water, with members (10) defining thee angle between the foil face and the stick (4).

Description: - I Title: Elongated propelling means for manually moving a sailing craft over the water surface. The invention relates to an elongated propelling means for manually moving a sailing craft over the water surface, said propelling means being provided with a stick¬ like grip and with thrust means with which a thrust can be exerted on the water. Such a propelling means is known from Dutch application 8004444 and can be defined as a stick provided with opposable thrust faces. It is an object of the invention to provide a propelling means of an improved construction in the sense that at a given span width and and enclosed angle between the thrust face and the stick, the thrust surface is much larger, while the resistance encountered during withdrawal is precisely reduced. To this effect according to the invention there is provided an elongated propelling means of the above- described type, characterized by a stick carrying the propelling means, which propelling means consist of a flexible, substantially circular foil which along the circumference thereof and at substantially equal interspaces, is provided with radial stiffening members having a length smaller than the radius of the circle, which foil furthermore in the centre of the circle is fitted with a concentric tube stub-like opening and being connected via said stub, whether or not detachably around and to the stick, while the foil furthermore in the direction of the end of the stick to be inserted in the water is provided with means defining the angle between the foil face and the stick. The foil ofthe thrust means of a propelling member according to the invention is preferably made of soft polyvinylchloride material, while the radial stiffening members serve to increase the stiffness, to facilitate the collapsing during the retraction of the member in the water and to realize a substantial pre-tension in the released condition. According to a further elaboration of the invention, the angle defining members are formed of strings, cords, thin strips or lamellae, which are attached with their one end to the circumference of the foil and with the other end to the lower part of the stick. The angle defining members such as strings may be connected to the end not attached to the foil, e.g. with an eye screw in the head of the stick. In this manner there is produced an umbrella-like construction. During the folding of the foil, only little water need be displaced, so that the retraction of the member from the water takes place practically without resistance. The foil associated with the thrust means has the tendency to assume in the released condition the form of an equilateral triangle. During the pushing off in the water, however, the foil circumference more or less assumes the circular form, while during retraction from the water, the foil assumes a star shape. Both the triangular and the star-shape are caused by the three radial stiffening members/ which e.g. may have the form of folds applied inthe foil. The tube stub through which the foil is connected to the stick may be a separate member which is inserted in an opening concentrically applied around the centre of the circle in the foil and fixedly connected along the circumference thereof to the foil, while the stick is fittingly inserted through the tube stub, said stub being clamped around the stick. Another possibility is one in which the tube stub is a member integral with the foil, formed by upsetting during insertion of the stick via an opening with smaller diameter than the outer diameter of the stick applied concentrically around the centre of the circle. The foil associated with the thrust means may be designed as an assembly of two foil layers on each other, radially provided with stiffening members. The foils may be jointed onto each other, thereby locally leaving clear non- jointed interspaces between the foils according to a given pattern, which interspaces can be pumped up with a gas for obtaining the stiffening members. An advantageous method of attachment of the angle defining members, e.g. the strings, to the head of the stick is the one in which on the one end the stick has a tubular end to be inserted in the water wherein on the other end there is provided a chamber formed against further penetration of water via a sealing cap fittingly admitted in the tubular end all around and a cover fittingly pushed over the tubular end all around, the wall of said cover containing a central opening through which the angle defining members connected -8- with the one end to the foil circumference are conducted and are secured in the chamber by mutual tieingj preferably the angle defining members are strings made of a thermoplastic synthetic material, which strings are fused together to a ball for mutual tieing in the chamber. The above advantage of the attachment method of angle defining members results in that thus the strings cannot get entangled, while the common junction can be made in a simple manner. By manufacturing the foil from a plastics material, it is possible for the foil, in a period when the propelling means is not used, to assume an asymmetric form due to the properties of the plastics material, so that the propelling effect is reduced in many cases. To avoid this, a band is pushed about the thrust means in such a way that the legs of the triangle are enclosed helically. When the propelling member is used again, it no longer has the pure triangular shape in the released condition, but a more or less helical model, while during the retraction through the water a star shape with curved points is produced. The opening of the thrust member at the beginning of the thrust stroke, after application of the band, takes place in a.more uniform and quicker manner. The band may be designed both endless and with a knot or clasp connection. Although the starting material is not essential, a substance having a large coefficient of friction relative to the substance from which the foil is made is preferred, since in that case the band remains in the proper position even at a slight clamping stress. The invention is particularly suitable for being applied for propelling self-substaining water skis, offering as substantial advantages the large thrust, accompanied by the substantially resistance-less retraction of the pusher sticks. One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a top view of a propelling member in the released condition designed according to the invention. Fig. 2 is a top view of the propelling member in loaded condition; Fig. 3 is a top view of the propelling member during the retraction in the water; Fig. 4 is a cross-section of the propelling member on the line IV-IV of Fig. 2; Fig. 5 is a cross-section on the line. V-V of Fig. 1; Fig. 6 is an axial cross-section of the end or lower end of an embodiment of the propelling member according to the invention to be inserted in the water; Fig. 7 is a view of the lower end of the embodiment of the propelling member according to Fig. 6; Fig. 8 is abottom view of the end • or lower end ■ of a different embodiment of the propelling member according to the-invention to be inserted in the water; and Fig. 9 is a side view of the embodiment of the propelling member according to Fig. 8. The propelling member 9 (Figs. 1-5) consists of thrust means comprising a thin circular foil 1 provided with three folds 2. The foil 1 is provided in the centre with a tubular opening 3 by means of which the foil 1 is clamped or screwed onto the stick 4. An eye screw 5 is attached to the lower end of the stick 4. Strings 10 are stretched between said eye screw 5 and the attachment points 6 and 7 disposed along the circumference of the foil, said strings defining the enclosed angle of the thrust member in loaded condition. The attachment points 6 also serve to apply the folds 2. The attachment point at the lower end of the stick 11 of the embodiment of the propelling member according to the invention, as shown in Figs. 6 and 7, comprises the cover 12 wherein a hole 13 is drilled through which the bundled strings 14 are inserted. At the inner side of the cover 12 there is applied a knot 15 in the string bundle 14 by means of which the disentanglement of the bundle is avoided. The sealing cap 6 prevents the penetration of water in the stick 11. The cover 12 in conjunction with the sealing cap 16 constitutes the chamber 17. The folded band 21 (Figs. 8 and 9) is mounted at the bottom end of the foil 22 after the angles 23 of the triangle (compare Fig. 1) have been helically wound about the stick 24. Naturally, modifications may be applied in the propelling member according to the invention, as discussed in the above and as shown in the drawings, without departing from the scope of the invention.

Claims: C L A I S 1. An elongated propelling member for manually advancing a sailing craft over the water surface, said propelling member being provided with a stick-like grip and with thrust means with which a thrust can be exerted on the water, characterized by a stick carrying the thrust means, said thrust means being made of a flexible, substantially circular foil which along the circumference thereof, at substantially equal interspaces, is provided with radial stiffening members having a length smaller than the radius of the circle and which foil furthermore is provided in the centre of the circle with a concentric tube stub-like opening and is connected via said stub whether or not detachably around and. with the stick, while the foil furthermore, in the direction of the stick end to be inserted in the water, is provided with members defining the angle between the foil face and the stick. 2. A member according to claim 1, characterized in that the angle defining members are formed by strings, cords, thin strips or lamellae, which at their one end are attached to the circumference of the foil and at the other end to the lower part of the stick. 3. A member according to claim 1, characterized in that the tube stub is a separate member which is inserted in an opening applied concentrically around the centre of the circle in the foil and along the circumference thereof is fixedly connected to the foil, while the stick is fittingly inserted through the tube stub and the stub is clamped around the stick. 4. A member according to claim 1 , characterized in that the tube stub is a member integral with the foil, formed by upsetting during insertion of the stick via an opening applied in the foil concentrically around the centre of the 5 circle, said opening having a diameter smallerthan the outer diameter of the stick. 5. A member according to claim 1 , characterized in that the foil is composed of two foil layers on each other, radially provided with stiffening members. 106. A member according to claim 1, characterized in that the stick is composed of two axially connectible parts. 7. A member according to claim 5, characterized in that the foils are fused onto each other, while locally leaving non-fused interspaces between the foils unoccupied according 15 to a given pattern, which interspaces can be pumped up with a gas for obtaining the stiffening members. 8. A member according to claims 1-7, characterized in that the stick has a tubular end to be inserted in the water wherein there is applied a chamber formed against 20 further penetration of water via a sealing cap admitted into the tubular end and fitting all around, and a cover pushed over the tubular end and fitting all around, the wall of which having a central opening through which are conducted the angle defining members connected with their one end to 5 t e foil circumference and being secured in-tfe chamber by mutual tieing. 9. A member according to claim 8, characterized in that the angle defining members are strings made of a thermoplastic synthetic material, which strings are fused to a ball for 0 mutual tieing in the chamber. OMP∑ 10. A member according to claims 1-9, characterized in that it is an assembly of the stick carrying the thrust means and an endless band or a band to be detachably interconnected with the ends and to be attached in the rest position about the foil folded around the stick. O PI ? AT10

Inventors: LENTEN HENDRIK, LENTEN, HENDRIK
Applicants: LENTEN HENDRIK, LENTEN, HENDRIK
Application year: 1983
Main classification: A63C15
IPC codes: B63B35, B63H16