GB2370024A

GB2370024A - Man-powered marine craft

Info

Publication number: GB2370024A
Application number: GB0030441A
Authority: GB
Inventors: Ferid Hickmet
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-12-13
Filing date: 2000-12-13
Publication date: 2002-06-19
Anticipated expiration: 2020-12-13
Also published as: GB2370024B; GB0105663D0; GB0030441D0

Abstract

A marine craft comprises a pair of man-powered piston pump arrangements 15b mounted on a ski-shaped unitary plastic moulding 11. Each pump arrangement comprises a duct open at both ends with a tube (21, Fig 4) slidably engaged within the duct, a flap valve (39, Fig 4) hingedly connected to the rear of the tube and man-operable means 35b arranged to allow the tube to be displaced back and forth along the duct. During use, as the tube is moved forwards the flap valve opens to allow free movement of the tube and as the tube is moved backwards the flap valve closes so that the tube acts as a piston to force fluid in the duct out of the rear end to drive the craft along. The man-operable means may be levers or pedals (47a and 47b, Fig 8).

Description

MARINE CRAFT This invention relates to marine craft, and is concerned particularly, though by no means exclusively, with marine craft for sporting, exercise, or amusement uses.

According to the invention, a marine craft is constituted as specified in the claims, or any of them, set out in the claims schedule of this Application and, accordingly, the substance of said clauses and the inter-dependencies therebetween are to be regarded, notionally, as being set out here, also.

Embodiments of a marine craft in accordance with the invention are hereinafter described with reference to the accompanying drawings in which: Fig. l is a schematic diagram showing, in plan, a first embodiment of the marine craft; Fig. 2 shows schematically, in side elevation, the craft of Fig. l ; Fig. 3 shows schematically, in rear end elevation, the craft of Figs. l and 2; Fig. 4 shows, schematically, a longitudinal axial section of one of two constructionally identical man-operable hydraulic pumps incorporated in the vehicle depicted in the preceding Figures, the pump being in one of two operating states; Fig. 5 shows, schematically, an end elevation of the pump, when in the operating state shown in Fig. 4; Fig. 6 is a schematic diagram corresponding to Fig. 4, the pump being now in the other of its operating states; Fig. 7 shows, schematically, an end elevation of the pump when in the operating state of Fig. 6; Fig. 8 is a schematic diagram showing, in plan, a second embodiment of the marine craft; Fig. 9 shows schematically, in side elevation, the craft of Fig. 8; and, Fig. 10 shows schematically, in rear end elevation, the craft of Figs. 8 and 9; The body of the craft, in either of the embodiments depicted in the drawings, is formed as a unitary moulding 11 in a plastic material, suitably polypropylene, being moulded, to a an external shape, such as that shown in the Figs. 1 to 3, calculated to offer substantially minimal drag, this, clearly, in the interests of propulsion efficiency.

More particularly, the body 11 of the craft has a generally ski-form deck portion 13, and dependant from said deck portion, at the sides thereof, first and second duct housings 15a, 15b, respectively, the longitudinal axes of said duct housings 15a, 15b, extending parallel to the fore and aft direction of the deck portion 13. In the example, the duct housings 15a, 15b, are constructionally identical duct housings having a generally oval internal cross-section.

A seat 17, contoured to the human form and constituting part of the unitary moulding 11, is situate towards the stern of the deck portion 13. Midships of the craft body, the deck portion 13 thereof has first and second fore and aft extending laterally disposed slots 19a, 19b, respectively.

Within the duct housings 15a, 15b, there are first and second constructionally identical pistons, such, for example, as piston 21 (Figs. 4 to 7}. The pistons 19 each have a tubular piston wall, as 23, of cross-section conforming substantially in size and shape to that of the internal size and shape of the duct housings 15a, 15b, within which they respectively sit. The pistons 21 are each composed of a plastic material, as polypropylene, and are formed at their forward ends each with a structure 25 of crossed reinforcement strut portions 27, integral with one another and with the piston walls 23.

Junctures, as 29, of portions 27 of the respective structures 25, respectively intercept the longitudinal axes of the duct housings 15a or 15b, as the case may be, and support integral rearwardly projecting lug portions, as 31, each having a transverse passage, as 33, therethrough.

First and second manually operable levers 35a, 35b, are rockable independently of one another, within certain angular limits, respectively about first and second transversely aligned hinge axes Y---Y, fixed in the deck portion 13, respectively at locations within the slots 19a, 19b. The levers 35a, 35b, have, at their free upper ends, handle portions 37a, 37b, respectively, these being within comfortable range of the user's right and left hands, respectively, whilst seated.

Returning to the matter of the construction of the pistons 21, the rear ends thereof are constituted as first and second closure members, as 39, these serving as water flow obturator elements, rockable, with respect to the generally oval cross section piston wall 23, about individual hinge axes H---H which are offset with respect to the major axes of the oval crosssections of the tubular piston walls 23.

The walls 23 are formed, in their moulding, with portions, as 41, appropriately contoured for the purpose of avoiding fouling between the closure members 39, and the tubular piston walls 23, in the course of angular displacement of the closure members 39 about their hinge axes H---H.

The levers 35a, 35b, are hingedly connected at their lower ends to the forward ends of first and second connecting rods, as 43, respectively, the rear ends of the connecting rods being respectively hingedly connected to the lug portions 31, of the pistons 21.

For the purpose of giving enhanced directivity to water discharged at the rear ends of the ducts 15a, 15b, these are respectively fitted with nozzles, 49a, 49b. The reduction in orifice size effected by the use of nozzles gives rise to an increase in friction between the water and the duct walls. The design of the nozzles employed therefore involves an assessment of the trade-off between loss of efficiency in propulsion due to the additional friction introduced and the gain in efficiency arising from the directivity achieved in water expelled.

In operation, with the user seated on the seat 17, with his hands gripping the handle portions 37a, 37b, of the levers 35a, 35b, respectively, rocking movement of said levers and consequent, generally fore and aft, movement of their connecting rods 43 causes the pistons 21 to slide back and forth along their respective ducts 15a, 15b. At each rearwards movement of a lever, the closure member 39 of the piston 21, the lug portion 31 of which is coupled to the lever, is caused to swing counter-clockwise (as viewed in Fig. 4} under the initial forwards motion of the piston 23, the opening of the piston at its rear end giving to the piston substantially unimpeded freedom of movement for the remainder of its forward stroke, and substantially no water being, in consequence, expelled from the duct in the direction of the piston forward movement.

At each rearward stroke of the piston, however, its closure member 39 is rocked to the position at which the piston closure member serves, under the thrust of water thereon, as water flow obturation means, continued movement of the piston thereby causing the expulsion of water from the duct, 15a or 15b, as the case may be, at its rear end, such expulsion producing a forward impulse acting to impel the craft forwardly.

The levers 35a, 35b, being independently movable, may be moved with any desired phase relationship between their respective movements, and with any desired rate of change of displacement that might be called for in the execution of desired manoeuvres of the craft. In particular the levers 35a, 35b, may be moved differentially such as to impart steering movement to the craft, as determined by the magnitude of the differential movement.

In the embodiment of Figs. 8 to 10, the man-operable propulsion means includes a bar 45 which spans the craft, which is connected at its centre to the deck portion 13, and which carries first and second pedal members 47a, 47b, respectively.

The ends of the bar 45 are, hingedly connected, as with the levers of the first described embodiment, to first and second connecting rods 43.

In the embodiment depicted in Fig. 8 to 10, the connecting rods 43 are not independently movable, the pistons always moving such that with one piston executing a stroke in one sense along the duct within which it lies, the other piston is constrained by the bar 45 to execute a stroke in the opposite sense.

The craft of Figs. 8 to 10 is, perhaps, less versatile in its ability to manoeuvre than is the case with the first described embodiment. The reason for this stems from the fact that whereas the use of hand and arm in the propulsion of the craft enables force to be exerted on the levers independently in both forward and rearward motion of the levers, where, as with the craft of the second embodiment, the craft is propelled under pedal action, force may be exerted on the pedals only by forward thrusts of the feet. No significant force is capable of being exerted on the pedal during its return. In the embodiment of Figs. 8 to 10 other means must, therefore, for the purposes of steerage, be provided in the craft. Whilst means for steerage of the craft has not been shown in Figs. 8 to 10, it is contemplated that not only may the craft be provided with conventional rudder means, it may, as an alternative, be provided with steerage means in the form of first and second concavely curved deflector means (not shown) respectively associated with the ducts 15a, 15b, at the rear ends thereof, and being angularly displaceable in azimuth. Such deflector means are commonly used in jet skis and boats and may be used to provide not only steerage for the craft but even to cause water expelled from the rear ends of the ducts to be reversed in direction thereby to exert a reverse thrust on the craft.

It is thought, notwithstanding the complication introduced by the lack of steerage in the basic craft of Figs. 1 to 3 for the simple reason that the magnitude and speed of delivery of the thrust capable of being exerted using the power of the human leg is significantly greater than is achievable using the human arm. Higher performance is to be expected in the craft of Figs 8 to 10.

Forces applied to the man-operable means, whether levers or pedals, must, of course, be reacted in the body of the craft.

In the embodiment of Figs 8 to 10, one or the other of the legs of the operator is exerting a force, in the forward direction, at one or the other of the pedals, and the reactions to the forces so applied are reacted directly by the seat, especially the seat back, and finally absorbed by the platform body of the craft. With either embodiment it might be desirable to provide the seat cushion with a contour which has a substantial depression, even a bucket form, calculated to assist in reacting the forces developed in the operation of the pump means.

Claims

CLAIMS 1. A marine craft which has, for the propulsion thereof, hydraulic positive displacement pump means, being pump means comprising: at least one duct extending with its longitudinal axis in the general fore and aft direction of the marine craft ; slideable lengthwise of said duct, a tube the outer surface of which conforms in size and shape substantially to that of the internal surface of said duct; a flap valve hingedly connected to said tube at the rear end of said tube; and, coupled to said tube, man-operable means movement of which under manual force exerted thereon to cause said tube to be displaced back and forth along said duct; and in which, the several aforesaid said parts of the pump means are constructed arranged and adapted such that, in use, during each pump operating cycle, at forwards motion within said duct of said tube, said flap valve, under the action thereagainst of water present within said tube, is caused to rock about its hinge axis to a position such that said tube is substantially open throughout its length, the tube and said flap valve being thereby substantially unimpeded in motion in the forward direction of the duct, notwithstanding the presence of water occupying said duct, and upon rearwards motion of said tube within said duct, said flap valve is caused to rock about its hinge axis, under the action of water present in said duct, to a second position, being a position at which said tube is substantially closed against the flow of water therethrough, the tube and said flap valve then constituting a piston, movement of which, in the rearwards direction of the duct is effective to expel a charge of water at the rear end of said duct, and, concurrently to draw a fresh charge of water into said duct at the forward end thereof.

2. A marine craft as claimed in claim 1 which comprises: first and second pump means, each as stated, one at the port, the other at the starboard side of the craft.

3. A marine craft as claimed in claim 2 which has a craft operator's seat; and said man-operable means includes, in respect of each pump means, as the case may be, an individual linkage including, within comfortable physical reach of an operator seated at said seat, means at which force is to be exerted for the movement, to and fro within its duct, of the tube to which the relevant linkage is coupled.

4. A marine craft as claimed in claims 3 which comprises: an elongate member, extending athwartships of the craft, said member being pivotally coupled at its centre to the craft hull and at its ends to input members of first and second linkages respectively coupled to the tubes of said port and starboard pump means; and first and second pedal parts carried by said elongate member at spaced apart positions therealong.

5. A marine craft as claimed in claim 3 in which said force input means comprises first and second levers spaced apart transversely of the craft hull and being coupled respectively to individual ones of the tubes of said port and starboard pump means.

6. A marine craft substantially as herein described with reference to Figs. 1 to 3 of the accompanying drawings.

7. A marine craft substantially as herein described with reference to Figs. 8 to 10 of the accompanying drawings.

CLAIMS 1. A marine craft which has, for the propulsion thereof, hydraulic positive displacement pump means, being pump means comprising: at least one duct extending with its longitudinal axis in the general fore and aft direction of the marine craft; slideable lengthwise of said duct, a tube the outer surface of which conforms in size and shape substantially to that of the internal surface of said duct; a flap valve hingedly connected to said tube at the rear end of said tube; and, coupled to said tube, man-operable means movement of which under manual force exerted thereon to cause said tube to be displaced back and forth along said duct; and in which, the several aforesaid said parts of the pump means are constructed arranged and adapted such that, in use, during each pump operating cycle, at forwards motion within said duct of said tube, said flap valve, under the action thereagainst of water present within said tube, is caused to rock about its hinge axis to a position such that said tube is substantially open throughout its length, the tube and said flap valve being thereby substantially unimpeded in motion in the forward direction of the duct, notwithstanding the presence of water occupying said duct, and upon rearwards motion of said tube within said duct, said flap valve is caused to rock about its hinge axis, under the action of water present in said duct, to a second position, being a position at which said tube is substantially closed against the flow of water therethrough, the tube and said flap valve then constituting a piston, movement of which, in the rearwards direction of the duct is effective to expel a charge of water at the rear end of said duct, and, concurrently to draw a fresh charge of water into said duct at the forward end thereof.
2. A marine craft as claimed in claim 1 in which the rear end of said at least one duct comprises a nozzle or like tapering duct portion.
3. A marine craft as claimed in claim 1 or 2 which comprises: first and second pump means, each as stated, one at the port, the other at the starboard side of the craft.
4. A marine craft as claimed in claim 3 which has a craft operator's seat; and said man-operable means includes, in respect of each pump means, as the case may be, an individual linkage including, within comfortable physical reach of an operator seated at said seat, means at which force is to be exerted for the movement, to and fro within its duct, of the tube to which the relevant linkage is coupled.
5. A marine craft as claimed in claims 4 which comprises: an elongate member, extending athwartships of the craft, said member being pivotally coupled at its centre to the craft hull and at its ends to input members of first and second linkages respectively coupled to the tubes of said port and starboard pump means; and first and second pedal parts carried by said elongate member at spaced apart positions therealong.
6. A marine craft as claimed in claim 4 in which said force input means comprises first and second levers spaced apart transversely of the craft hull and being coupled respectively to individual ones of the tubes of said port and starboard pump means.
7. A marine craft substantially as herein described with reference to Figs. 1 to 3 of the accompanying drawings.
8. A marine craft substantially as herein described with reference to Figs. 8 to 10 of the accompanying drawings.