GB2178387A

GB2178387A - Hand-operable boat propelling unit

Info

Publication number: GB2178387A
Application number: GB08616140A
Authority: GB
Inventors: William Mcmullan Hawthorne; Terence Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-07-02
Filing date: 1986-07-02
Publication date: 1987-02-11
Also published as: GB8616140D0; GB2178387B; GB8516741D0

Abstract

Hand-operable means, for propelling e.g. a small cabin cruiser, comprising a handle portion 11 connected to a blade portion 14 by a hinge 15 or hinge-action flexible connection in such a way that the blade portion folds backwards in relation to the handle portion on the power stroke whilst being free to fold in the opposite sense on the idle stroke when each said stroke is executed as a substantially axial thrust of the handle. A flexible cord 16 restricts the amount by which the blade folds towards the handle during the power stroke; and holds the blade rigidly in its attitude relative to the handle during the power stroke. <IMAGE>

Description

SPECIFICATION Hand-operable boat propelling means Field of the invention The invention relates to hand-operable means for propelling a boat such as a small cruiser, but which is novel, non-obvious and advantageous over traditional means such as the oar, the paddle and the punt pole.

Review of art known to the applicants By way of example, UK Patent Specification No 872 772 (Thomson) discloses a paddle comprising a handle component connected to a paddle component by a hinge or flexible connection whereby the two components are rigid with one another during the power stroke, and the paddle component folds backwards in relation to the handle component on the idle stroke. The idea of this is to make it unnecessary for the paddle to be raised from the water during the idle stroke, because the folding-back of the paddle component reduces the drag which would make a conventional paddle impractical to operate in this manner.

The paddles of this kind disclosed in UK Patent Specification No 872772 all have handles which in relation to the length of the blades are proportioned in much the same way as that of the conventional hand-operable paddle. Paddles with handles of this sort of length in relation to the length of the blade are conventionally suited to and intended for use over one or the other side of the boat, but do not lend themselves readily to use over the stern of the boat.

The paddles of Specification 872772 also rely, for their continued operation, on an exceptionally strong hinge or flexible connection at the folding juncture of the blade portions. During the power stroke, this hinge experiences a bending moment which tends to prise it from the components to which it is fixed.

There are thus drawbacks with paddles of the kind proposed in Specifiction 872772, whatever their possible theoretical advantages over conventional oars and paddles.

Summary of the invention The invention is embodied in hand-operable means, for propelling e.g. a small cabin cruiser, comprising a handle portion connected to a blade portion by a hinge or hinge-action flexible connection in such a way that the blade portion folds backwards in relation to the handle portion on the power stroke whilst being free to fold in the opposite sense on the idle stroke when each said stroke is executed as a substantially axial thrust of the handle so that a series of such strokes causes reciprocal movement of the handle; with means restricting the amount by which the blade folds towards the handle during the power stroke; and with means holding the blade rigidly in its attitude relative to the handle during the power stroke.

Such a product has many advantages over arrangements such as those of Specification No 872772. Its handle can be made long in relation to the length of the blade portion, and so it can be used over the stern of the boat, like a punt pole, as weil as or instead of over either side of the boat. Unlike the conventional punt pole, its use is not restricted to shallow waters.

The means restricting the amount by which the blade folds towards the handle on the power stroke may be, and indeed preferably are, means in addition to the hinge or flexible connection so that the hinge or connection is lighly stressed during the power stroke.

In addition, during the power stroke and the idle stroke a product embodying the invention tends to find its own level just below the surface of the water, whereas conventional oars may plough under the water if inexpertly used.

Preferably the means restricting the amount by which the blade folds towards the handle on the power stroke is such as to allow the intended rigidly-held power applying attitude of the blade to the handle to be adjusted to suit differing circumstances.

This increases the versatility of the product.

Preferably also, respective fin portions extend in opposite directions from the handle axis in the region of the join between the handle and the blade, in a configuration which in use will tend to restrict rotational movement through the water.

In the case just outlined, the fins may with advantage merge into the blade in the region of the hinge or flexible connection. This looks attractive, and it is well known that boating accessories are bought very often for aesthetic appeal if the choice is between two potentially equally useful competitive products. It is also dynamically efficient.

The blade portion may with advantage be backed by an extension of the handle portion and with the extension being sufficiently long that, when blade and handle are folded into substantially the same plane, the extension projects beyond the tip of the blade. In such an embodiment the extension protects the blade tip when the product is being stored or transported, and it also backs the blade if the blade folds flat into the plane of the handle during the idle stroke when in use.

The means restricting the amount by which the blade folds towards the handle during the power stroke may comprise a flexible but substantially inextensible cord running between the blade and the hinge region of the handle, or - in the case where an extension of the handle is provided as just outlined between the blade and the extension. In such an embodiment, the cord could also comprise the means holding the blade rigidly in that attitude during the power stroke.

The underside of the blade (i.e. that face of the blade which during the power stroke displaces the water) may with advantage be ribbed in order to increase its water-displacing efficiency.

Brief description of the drawings The accompanying drawings show at least one product embodying the invention. This product, although described and illustrated by way of example only, includes the best way currently known to the applicants of putting the invention into practice. In these drawings: Figures 1, 2 and 4 show in perspective a first, second and a third product each embodying the invention; and Figure 3 shows diagramatically the product of Figure 1, 2 or 4 in use over the stern of a boat.

Description of the preferred embodiments In Figures 1 and 2, an elongate and substantially straight handle 11 carries a flat generally triangular portion 12 towards one end region of the handle. The triangular portion 12 can be considered as comprising individual and respective fins 12a, 12b which extend in opposite directions from the axis of the handle 11 to define the single flat triangular portion 12. The handle 11 continues into an extension 13 which is co-extensive with the handle.

The handle 11 is circular-cylindrical and is of substantially constant cross section throughout the majority of its length up to the region where it merges into the flat portion 12 in Figure 1. It then assumes a substantially square cross section and this is the cross section of the extension 13.

In Figure 2, again the greater part of the length of the handle 11 is circular-cylindrical and is of constant cross section. This time, however, the flat portion 12 is carried by the handle 11, rather than the handle merging into the flat portion 12. The extension 13 of the Figure 2 embodiment is again square in cross section as illustrated.

In each embodiment, the extension 13 is cut off at an angle.

In each embodiment also, the extension 13 underlies the projects beyond the tip of the blade 14. In each embodiment the blade 14 is hinged to the flat portion 12 by a pin hinge 15.

A cord 16 is flexible but inherently inextensible and runs between extension 13 and blade 14 in each embodiment. The opposite ends of the cord 16 are knotted after the cord has passed through holes drilled in the extension 13 and the blade 14 respectively.

As shown, the cord 16 effectively restricts the amount by which the blade 14 can swing towards the handle 11 about the hinge axis 15. By untying and retying the knot at either end of the cord, this amount can be altered to suit circumstances of use.

The cord 16 also constitutes, in each embodiment, a means maintaining the blade 14 rigid in its attitude with respect to the handle 11 when the product is in use; whilst at the same time allowing the blade 14 to swing away from the handle 11 (i.e. towards the extension 13) when the product is moved appropriately.

Referring now to Figure 3, the product is shown in use over the stern 17 of a boat such as a small dinghy.

The blade 14 is held just below the surface 18 of the water on which the boat floats.

Pulling the handle 11 along its axis in the direction of arrow A in Figure 3 (i.e. towards the boat) will move the blade 14 through the water and will cause the blade automatically to fold towards - but not necessarily against - the extension 13 as the cord 16 flexes.

Subsequently pushing the handle 11 along its axis in the direction of arrow B in Figure 3 (i.e. away from the boat) will swing the blade up into the attitude illustrated in Figure 3 in which the cord 16 is taut.

Continued movement in the direction of arrow B will displace water from the underside of the blade and will propel the boat forward.

A succession of such movements, causing the handle 11 to reciprocate generally along its axis, can be used to manoeuvre the boat in a generally forwardly propelled sense.

The relative positioning and size of the blade 14, makes the product tend to find its own level just below the surface of the water. Portion 12 also acts as a stabiliser which helps to maintain blade 14 upright.

In the Figure 2 embodiment, ribs 19 are elongate and substantially straight and run down the underside of the blade 14. As illustrated, there are four such ribs, each equally spaced from the adjacent rib across the blade.

The leading edges of the portion 12, and the periphery of the blade 14, could with advantage be streamlined. So could the ribs 19. As illustrated specifically in Figure 2, screws 21 hold the portion 12 and the blade 14 in position on the handle 11; and allow these components to be removed as one and to be replaced with corresponding components having different proportions. Thus a single handle 11 and extension 13 can be used with a range of fins 12 and blades 14 to suit differing circumstances of use.

A product embodying the invention will most probably be used as an emergency aid in a boat deriving its primary propulsive power from motor and/or sails. It could be made in suitably high quality wood or in any other material judged suitable for marine use in this context. It is ligher than a pair of oars, just as easily stowed, and unlike a paddle it can be used effectively over the side or over the stern of a boat. The user can stand or sit, face forward or face aft, and can exercise close control over the manoeuvring of his boat through other boats in a crowded harbour or can free one hand to control a fishing rod whilst the other hand uses the product. It does not need a rowlock in which to operate, unlike a conventional oar.

In Figure 4, reference numerals which correspond to the numerals used in Figures 1 and 2 have been used for corresponding parts. Here, however, the fin portions 12a, 12b lie beneath the underside of the blade 14 and define, with the blade and with each of two opposite-side ribs 19, an open box configuration during the power stroke as shown.

The ribs 19 are triangular and their triangles each have a shortest side 1 9a which extends from the hinge axis 15. Both ribs are geometrically identical and project from the underside of the blade 14 at right angles to the plane of the blade. They are sufficiently large to form, with the underside of the blade, a scoop-like configuration; and, with the underside of the blade and the fins 12a, 12b, an open box configuration as just outlined.

The Figure 4 embodiment ends in a shaped preformed plastics handle 22, and its shaft 11 comprises a foamed plastics filled marine aluminium tube in two portions splined removably and coaxially together at 23.

In each of the embodiments described and illustrated, the blade 14 during its power stroke is held at approximately 90 to the axis of the shaft 11 by the taut cord 1 6. But this is not essential. As has already been indicated, the length of cord 16 can be adjusted to give differing blade-shaft angles to suit circumstances.

Claims

1. Hand-operable means, for propelling e.g. a small cabin cruiser, comprising a handle portion connected to a blade portion by a hinge or hinge-action flexible connection in such a way that the blade portion folds backwards in relation to the handle portion on the power stroke whilst being free to fold in the opposite sense on the idle stroke when each said stroke is executed as a substantially axial thrust of the handle so that a series of such strokes causes reciprocal movement of the handle; with means restricting the amount by which the blade folds towards the handle during the power stroke; and with means holding the blade rigidly in its attitude relative to the handle during the power stroke.

2. The invention of Claim 1 and in which the means restricting the amount by which the blade folds towards the handle on the power stroke is such as to allow the intended rigidly-held power applying attitude of the blade to the handle to be adjusted to suit differing circumstances.

3. The invention of Claim 1 or Claim 2 and in which respective fin portions extend in opposite directions from the handle axis in the region of the join between the handle and the blade, in a configuration which in use will tend to restrict rotational movement through the water.

The invention of Claim 3 and in which the fins merge into the blade in the region of the hinge or flexible connection.

5. The invention according to any of the preceding Claims and in which the blade portion is backed by an extension of the handle portion and with the extension being sufficiently long that, when blade and handle are folded into substantially the same plane, the extension projects beyond the tip of the blade.

6. The invention of any of the preceding Claims and in which the means restricting the amount by which the blade folds towards the handle during the power stroke comprises a flexible but substantially inextensible cord running between the blade and the hinge region of the handle, or - in the case where an extension of the handle is provided as just outlined between the blade and the extension.

7. The invention of Claim 6 and in which the cord also comprises the means holding the blade rigidly in the said attitude during the power stroke.

8. The invention of any of the preceding Claims and in which the underside of the blade is ribbed.

9. The invention of Claim 8 and in which the ribs project from opposite side regions of the blade and are sufficiently large to form, with the underside of the blade, a scoop-like configuration.

10. The invention of Claim 9 and in which the ribs are triangular and their triangles each have a shortest side which extends from the hinge axis.

11. The invention of Claim 9 or Claim 10 when appendant directly or indirectly to Claim 3 and in which the fin portions lie beneath the underside of the blade and define, with the blade and the opposite side ribs, an open box configuration during the power stroke.

12. Hand-operable boat propelling means substantially as described herein with reference to and as illustrated in Figure 1 of the accompanying drawings.

13. Hand-operable boat propelling means substantially as described herein with reference to and as illustrated in Figure 2 of the accompanying drawings.

14. Hand-operable boat propelling means substantially as described herein with reference to and as illustrated in Figure 4 of the accompanying drawings.