GB2233946A - Forward facing, adjustable rowing system - Google Patents

Abstract

A device for manually propelling small craft comprising an oar handle 1 and an oar blade 2 each pivotally mounted on a supporting member 5 and connected by at least one link 7 which is adjustable in such a way as to make the angular velocity of the blade equal to that of the handle or to accelerate relative to the handle. The device enables a rower to face forward. <IMAGE>

Description

DEVICE FOR MANUALLY PROPELLING SMALL CRAFT This invention relates to a device for manually propelling small craft, which utilises the handles and blades of traditional oars, but in addition incorporates certain elements of design which are aimed at improving the safety and convenience of rowing, as well as the pleasure where rowing is enjoyed as a sport, an exercise, or simply for relaxation.

Oars as most commonly used each consist of a single unit, usually made of wood, with one end fashioned into a blade and the other into a handle. The rower sits on a fixed or sliding seat and using a pivot on the edge of his craft as a fulcrum drives the blade through the water, the resulting thrust on the pivot propelling the craft. In this the most common system the rower faces the stern of his craft and cannot see in the forward direction except by looking over one shoulder from time to time, but the system does enable him or her to expend a near maximum effort using the muscles of legs, back and arms.

The present invention entails mounting the blade and handle of each oar separately, and connecting these by a link (or links) which can be so arranged that the oar blade will accelerate relative to the handle movement during the power stroke. Thus as his craft accelerates the rower maintains a steady pull with little or no acceleration of the oar handle.

Alternately the angular movement of the blade can be arranged to equate with that of the handle, as with a traditional oar. A second feature of the invention is that the rower faces forward while still retaining the potential to expend near-maximum effort, should he or she so wish, with negligible loss of efficiency.

In this invention the pivots on which both handle and blade are mounted are secured to a supporting member tiltable about a fore-and-aft axis and the pivots being perpendicular to the supporting member ensures that the handle and blade can move only in arcs which are in the same plane. The supporting member is secured to the craft by a hinge the pin of which is parellel to the centre line of the craft itself, and is located on or outboard of the gunwale. With handle and blade approximately athwartship raising the handle will submerge the blade and vice versa, while any forward or aft movement of the handle will effect a similar movement in the blade.

A device in accordance with the invention which may be called a link oar unit can be designed with the handle and blade forming a straight line in the mid-stroke position, or the design can incorporate an extended supporting member with the blade located forward of aft of the handle. A forward located blade is of considerable assistance to a rower operating in weed (such as along lake margins and in canals) enabling him or her to avoid or at least remedy blade entanglement more easily than with a traditional oar.

These and other features of the invention are dealt with in the following drawings and comments. As a general rule the port side oar only is illustrated, to avoid duplication.

Figure 1 shows in isometric projection an example of how a link and supporting member are used to connect the oar handle with an oar blade.

Figure 2 shows an oar attached to a dinghy in plan and stern views.

Figure 3 illustrates diagrammatically three systems for linking an oar handle to its blade.

Referring to the drawing all link oars comprise a handle 1 which is mounted on a pivot 2 on which the handle can rotate. Similarly the oar blade 3 is mounted on a pivot 4, and both pivots are secured to a supporting member 5 which incorporates a hinge 6 (or in an alternative design both handle and oar are mounted on the same pivot as described below). The hinge is fixed on or near the gunwale of the craft with its centre line parallel to the centre line of the craft itself. In figures 1 and 2 the handle 1 is fabricated with a crank la, and the blade 3 with a crank 3a. Each crank is is fabricated from two metal plates, with the handle or blade secured between them, to provide rigidity for the whole device. For clarity's sake the link 7 is shown in solid lines and the upper plate of each crank in broken lines, and a cover plate has been omitted.The link invariably connects handle to blade in such a way that a sternward movement of the handle results in a sternward movement of the blade, and vice versa. Also an upward movement of the handle will submerge the oar as the whole tilts on the supporting member 5, and this action too is reversible.

In Figure 1 two alternative links 7 may be provided, one being longer than the other. The shorter link 7 is mounted on crank pins 8 and 9, with the pin-hole 10 unused. With this linkage any angular movement of the handle fore and aft results in a near equal angular movement of the blade. If however a longer link mounted on crank pins in positions 9 and 10 is used a steady angular movement of the handle results in an accelerating movement of the blade. This is further illustrated in Figure 3A this being a diagrammatic plan illustrating precisely the crank angles and proportionate lengths employed, where the short link connects crank pins 8 and 9, while the long link is of a dimension 9a to 10 (shown in broken lines).When the long link is used and the handle is pulled through an arc from a forward position to a rearward position through six equal increments of 100, the corresponding increment of blade movement are approximately 70 7≈ 80 90 10≈ and 120 as illustrated in Figure 2.

Figure 3B illustrates a three link systems devised for very light craft such as racing shells. It has the following features: (a) The main pivot 2 is supported on a hinge with its pin fore and aft.

(b) Links 11 and 12 are about 50 cm. long, with all other dimensions of the system being in the proportions illustrated. During operation by an average rower links 11 and 12 are subjected to stresses around 70 kg. during a power stroke, while link 13 would be under about 45 kg. tension.

(c) To change from an action where the blade's angular movement is equal to the handles movement to an action where the blade is accelerated, link 12 is exchanged for the shorter link 16, and the inboard location of the end of link 13 is changed from location 15 to location 17.

These features ensure that the links themselves can be very lightly constructed, and little local stiffening is required for the hull.

Drawing 3C illustrates how the oar blade 3 can be mounted forward of the handle 1 on an elongated support member 5 thereby bringing the blade action well within the rower's arc of vision and facilitating manoeuvring particularly when passing through weed and such obstacles.

Claims (6)

1. A device for manually propelling small craft comprising an oar handle and an oar blade each pivotally mounted on a supporting member and connected by at least one link which is adjustable in such a way as to vary or equalise the angular velocity of the blade relative to the handle, said device enabling a rower to face forward when propelling his craft.

2. A device according to Claim 1 where the supporting member is tiltable athwartship but not fore-and-aft.

3. A device according to Claim 1 where the oar handle and oar blade are mounted on a common main pivot, and both handle and blade are equipped with their own links which all pivot in a same plane, such links being connected by a third link to the gunwale.

4. A device according to Claim 3 wherein the main pivot connecting the handle and the blade is tiltable athwartship but not fore-and-aft.

5. A device as claimed in Claims 1 and 2 wherein the oar blade is mounted well forward of the handle with the blade end within the normal field of view of a rower looking forward.

6. A device for manually propelling small craft substantially as described herein with reference to figures 1 - 3 of the accompanying drawing.