Propulsive device for watercraft

Abstract

A propulsive device for watercraft, for example an oar or a paddle, includes a handle 2 for pulling and pushing at least one blade, through water adjacent to the watercraft to create propulsive force. The device further comprises a blade 1 and an attachment means for attaching the blade to an end of the handle such that the blade is held at a predetermined angle of between 60 and 120 degrees relative to a reference line running through the long axis of the handle when measured in a vertical plane coincident with said reference line. The blade is additionally held orthogonal to the reference line when measured in a second plane coincident with said reference line and set at 90 degrees to said vertical plane. The device may comprise additional blades, vertical fins 3. The device may be disassembled, folded , have an adjustable length to enable storage. The device may have a cranked, or offset handle or incorporate additional buoyancy means.

Description

This invention relates to a device for the propulsion of watercraft through water by the use of muscle power. Paddles are commonly used as a main or secondary means of propulsion for watercraft, but the effectiveness of a paddle for certain tasks is limited by the need to use both hands to efficiently generate a propulsive force. It is also the case when using a paddle to manoeuvre watercraft that generating a propulsive force other than one acting parallel to the long axis of the vessel requires greater skill to accomplish and is a less efficient process. Previous design alternatives to the conventional paddle have employed hinged flaps and folding scoop arrangements, but these devices are inherently inefficient because the operator’s arm needs to move a considerable distance before the flap or scoop is fully deployed and therefore able to engage with water to produce thrust. To efficiently overcome the limitations encountered when using a paddle for certain operations, the present invention proposes a muscle powered propulsive device for watercraft comprising a blade, a fin, and a handle. These components are assembled in a configuration such that the blade may be pushed or pulled through water adjacent to the watercraft in a substantially face-on orientation by operator applied force acting along, and in the direction of, the long axis of the hand gripping portion or portions of the handle. The fin is present to counteract lateral wavering when force is applied to the device while it is submerged. The pushing or pulling motions described above, henceforth termed power strokes, move the vessel in the opposite direction to the blade motion by reactive force. Each power stroke starts by lowering the propulsive device into water, and at the end of each power stroke the propulsive device is lifted free of water in preparation for another power stroke, or set aside until it is needed again. To improve the versatility and efficiency of the propulsive device for certain applications, embodiments of the present invention may include any or all of the following: • Additional blades to increase the blade surface area while retaining a compact form. • A plurality of fins. • An extendable or elongate handle to increase the operator’s reach. • A cranked or offset handle to improve the operator’s reach. • Additional buoyancy. • Detachable and / or folding components allowing the device to be stored in a compact form. 15 1024 As the present invention requires the use of simple pull, push, and lifting motions rather than the varied, often complex and difficult to perform strokes required when employing a paddle to propel a vessel in directions other than the long axis of the vessel, many of the limitations encountered when using a paddle for propulsion and manoeuvring are overcome. A further advantageous feature of the present invention is that it can be quickly picked up and used with one hand. This leaves one hand free for other tasks on the vessel, or to operate ancillary equipment. Earlier attempts to overcome the difficulties encountered when trying to use a paddle with one hand led to the design of various devices incorporating braces and / or straps to transfer torsional forces to the wrist and / or arm, but these arrangements disproportionally increase operator fatigue, delay deployment, snag on clothing, and make the device difficult to fit without using both hands. The invention will now be described solely by way of example using non-limitative, illustrative examples and with reference to the accompanying drawings in which: Figure 1 is a non-restrictive, perspective view showing the general arrangement of the major components of one embodiment of the present invention. Figure 2 is a non-restrictive, perspective view showing an alternative embodiment of the present invention incorporating two blades in parallel alignment. Figure 3 is a non-restrictive, perspective view showing an alternative embodiment of the present invention incorporating two fins. Figure 4 is a non-restrictive, perspective view showing an alternative embodiment of the present invention incorporating a forward mounted fin. Figure 5 is a non-restrictive, diagrammatic representation showing one embodiment the present invention being moved though various stages of a push cycle (as seen from one side). Figure 6 is a non-restrictive, diagrammatic representation showing one embodiment of the present invention being moved though various stages of a pull cycle (as seen from one side). Figure 7 is a non-restrictive outline drawing showing how the present invention may be used to create propulsive force in various directions (as seen from above). Figure 8 is a non-restrictive outline drawing showing an embodiment of the invention which has an offset handle. Figure 9 is a non-restrictive outline drawing showing an embodiment of the invention which incorporates additional buoyancy. 15 1024 Embodiments of the present invention shown in Figures 1 to 4 illustrate, by way of example, the general layout of components of the propulsive device. Generally rectangular blades 1 and fins 3 together with handles of circular section 2 are used here for illustrative purposes only; the shape and size of these components may vary according to specific needs and aesthetic requirements. The handle may, for example, vary in length and / or include shaped areas and / or specialised handgrips. The present invention may be constructed from materials commonly used in the manufacture of oars and paddles: for example wood, metal, and plastics. The blade(s) 1, the handle 2, and the fin(s) 3 of certain embodiments of the present invention may be permanently joined by, for example, glue or mechanical fixings, or moulded as a single item from, for example, plastic or a reinforced polymer composite material. In an alternative arrangement, blade(s), handle, and fin(s), may be held together using detachable means to allow the propulsive device to be dismantled for easier transport and storage. In other embodiments allowing the propulsive device to be wholly or partially folded for transport or storage, the blade(s), handle, and fins(s) are held together by locking hinges. Use of hinges in combination with the aforementioned detachable means is also possible. Figure 1 shows the major components of one embodiment of the present invention. One face of a blade lis attached to a handle 2, with a vertical fin 3 attached to both handle and blade. In such a configuration, the blade may be pushed or pulled through water adjacent to the watercraft in a substantially face-on orientation by operator applied force generally acting along a reference line running through the long axis of the hand gripping portion of the handle. The presence of a fin 3, fixed in alignment with a vertical reference plane running through the long axis of the hand gripping portion of the handle 2, reduces lateral wavering when the propulsive device is pushed or pulled through water during a power stroke. Reducing lateral wavering increases stability and efficiency, and reduces operator fatigue. In alternative embodiments, a fin 3 may be solely attached to the blade 1, or solely attached to the handle 2. Figure 2 shows an embodiment of the present invention incorporating an additional blade 1 to increase blade area. Embodiments of the present invention may incorporate a plurality of blades. Figures 3 and 4 are non-limitative examples illustrating how fins 3 may be attached to the propulsive device in a variety of locations. Embodiments of the present invention may incorporate a plurality of fins. Figure 5 is a diagrammatic representation of the present invention being moved though stages of a push cycle (as seen from one side). During the power stroke of the cycle, reactive force 15 1024 created by resistance to the device being pushed through water is transmitted through the operator’s body to the operator’s watercraft to propel the watercraft in the opposite direction to the direction of operator applied force. In use, the operator holds the handle with one or both hands through the cycle to lower the propulsive device into water, apply force along the handle, and to lift the propulsive device from water at the end of each power stroke. At position a, the propulsive device is shown being lowered into water. The propulsive device is then pushed through water to position b by operator applied force acting along the handle. The propulsive device is then lifted from water to position c before being returned above the waterline to a point above position a. The propulsive device is now ready for re-immersion and commencement of a subsequent power stoke. Figure 6 is a diagrammatic representation of the present invention being moved though stages of a pull cycle (as seen from one side). During the power stroke of the cycle, reactive force created by resistance to the device being pulled through water is transmitted through the operator’s body to the operator’s watercraft to propel the watercraft in the opposite direction to the operator applied force. In use, the operator holds the handle with one or both hands throughout the cycle in order to lower the propulsive device into water, apply force along the long axis of the handle, and to lift the propulsive device from water at the end of each power stroke. At position d, the propulsive device is about to be lowered into water. At position e, the propulsive device is being pulled through water by the operator applying force along the handle. At position f, the propulsive device is being withdrawn from water prior to being returned to position d in readiness for another power stroke. As the present invention is a hand-held human operated device, execution of push and pull cycles may vary between users and also be affected by prevailing conditions. In figure 7, four diagrammatic examples (g,h,i, and j) illustrate how the present invention may be employed to generate a propulsive force at various locations on a watercraft. The four locations shown are shown here are by way of example only; suitable embodiments of the present invention may be used to generate a propulsive force from any accessible location on the watercraft. The simple motions shown in figures 5 and 6 and described above may therefore be used to move a watercraft in any desired direction. In certain circumstances (for example use from a high-sided watercraft) it may be advantageous to use an embodiment of the present invention which employs a cranked or offset handle as shown diagrammatically in figure 8. Embodiments of the present invention possessing positive buoyancy are better able to resist excessive immersion resulting from operator applied force and are generally easier to use, but some otherwise desirable construction materials may not impart sufficient buoyancy for optimal use of the propulsive device. Additional buoyancy may be provided by incorporating a buoyant material such as plastic foam, or sealed, air-filled compartments during manufacture. This additional buoyancy may be fitted on or within the blade(s) 1 and / or handle (2), and / or the fin(s) 3. A non-limiting example of one such arrangement is shown in figure 9 where additional buoyancy 4 is shown attached to the blade 1, 15 1024

Claims

1. A muscle-powered propulsive device for watercraft, comprising: a blade with two faces; a handle with two ends, said handle incorporating a hand gripping portion or portions; an attachment means for attaching said blade to said handle; a fin; an attachment means for attaching said fin to said handle and / or said blade; wherein said components are assembled in a configuration such that when the propulsive device is in use:(i) said blade faces are held by said blade attachment means at a fixed angle of between 70 and 110 degrees relative to a reference line running through the long axis of said handle when measured in a vertical plane coincident with said reference line;(ii) said blade attachment means additionally holds said blade faces at a substantially orthogonal orientation to said reference line when measured in a second plane which intersects said reference line and is set at 90 degrees to said vertical plane;(iii) said fin attachment means holds said fin in parallel or direct alignment with said vertical plane;(iv) said embodiments of the present invention enable the operator to push or pull a blade through water in a substantially face-first orientation by using one or both hands to apply muscular force substantially acting along said reference line.

2. A muscle-powered propulsive device according to claim 1, wherein one or more additional blades are consecutively attached by an attachment means along said handle, with each additional blade fixed in parallel alignment to the first blade.

3. A muscle-powered propulsive device according to claim 1 or 2, which incorporates multiple fins, each set in parallel or direct alignment with said vertical plane and fixedly attached to said handle and / or said blade or said blades.

4. A muscle-powered propulsive device according to any preceding claim in which the blade or blades, and / or the fin or fins, are attached by a detachable means to allow the propulsive device to be wholly or partially disassembled for storage in a more compact form.

5. A muscle-powered propulsive device according to claims 1, 2, or 3, in which the blade or blades and / or the fin or fins are attached by a lockable hinged means to allow the propulsive device to be folded into a more compact form for storage.

6. A muscle-powered propulsive device according to claims 1, 2, or 3, in which the blade or blades and / or the fin or fins are attached by a combination of detachable means and hinged means to allow the propulsive device to be disassembled and folded for storage.

7. A muscle-powered propulsive device according to any preceding claim, in which the handle is adjustable in length.

8. A muscle-powered propulsive device according to any preceding claim in which the handle incorporates one or more cranked or offset sections.

9. A muscle-powered propulsive device according to any preceding claim which incorporates additional buoyancy means.

10. A method of operation for a propulsive device according to any preceding claim by which the operator executes a propulsive stroke, said method comprising the steps of:(i) using one or both hands to lower the propulsive device into water;(ii) using one or both hands to apply muscular force substantially acting along said reference line to push or pull the propulsive device through water with the blade or blades in a substantially face-first orientation;(iii) using one or both hands to lift the propulsive device above the water surface at the end point of said propulsive stroke;(iv) using one or both hands to move the propulsive device to a position above the selected commencement point of the next propulsive stroke for re-immersion and execution of a subsequent propulsive stroke.

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