| CLAIMS 1. A rowlock which includes a thole pin (1), a swivelling oar-retaining member (2), and a base mounting (30), the swivelling member comprising a transverse arm (20) and an upright arm (21) which is spaced from the thole pin with an in- turned portion (22) at its upper end so that the swivelling member and an upper part of the thole pin together define an open-topped aperture (10) for receiving an oar(50), characterised in that a lower end of the thole pin is stepped inwardly to form an integral spigot (12) of reduced diameter relative to the upper part of the thole pin, the base mounting has a socket (31) in which the spigot is secured, and the transverse arm is formed with a sleeve (23) which is swivellably mounted on the spigot. 2. A rowlock according to Claim 1 which includes one or more bushes (5) which can be placed on the spigot (12) between the sleeve (23) and the socket (31) to vary the working height of the rowlock. 3. A rowlock according to Claim 1 in which the spigot (12) is releasably secured in the socket (31). 4. A rowlock according to Claim 1 in which the base mounting (30) comprises a mounting plate (3), which incorporates the socket (31), and an attachment plate (4) which is fixed to the gunwale of a boat in use. 5. A rowlock according to Claim 4 in which the position of the mounting plate (3) is adjustable relative to the attachment plate (4). 6. A rowlock according to Claim 5 in which the attachment plate (4) is elongate transverse to the thole pin (1) and the mounting plate (3) can be secured in different positions along the attachment plate. 7. A rowlock according to Claim 6 in which the mounting plate (3) is secured to the attachment plate (4) by screws. 8. A rowlock according to Claim 1 which includes a flexible cord (40) extending between the in-turned portion (22) of the upright arm and the transverse arm (20) of the swivelling member. 9. A rowlock according to Claim 8 in which the cord (40) is resiliently extensible. |
TECHNICAL FIELD OF THE INVENTION
This invention relates to rowlocks which are used for connecting oars to a rowing boat.
BACKGROUND
Much of the pleasure which people derive from leisure rowing is due to the ability to achieve relatively silent progress through the water. GB 2 141 984 A describes a rowlock in which a U- shaped oar-retaining hook swivels around a stud or bolt at the top of a thole pin. Such an arrangement has the advantage of not transmitting power though a turning joint that is otherwise liable to wear, get loose and rattle, especially when made of a relatively soft metal like bronze, and the rowlock therefore remains virtually silent throughout its life. Rowing against a fixed thole pin also avoids the rowlock re-aligning itself as soon as the pressure is applied at the beginning of the stroke, which delays, for a fraction of a second, the motive power of the "catch" connecting with the boat and driving it forward. This delay is seldom noticed by most oarsmen until they experience the positive action of an old-fashioned thole pin, the disadvantage of which is that the oar slides away from the pin at the end of the stroke, along the sill the oar is resting on, until it is stopped by another pin which transfers to the boat the remaining momentum in the weight of the oar and so tends to prevent the boat reaching its maximum speed which has to carry it through to the beginning of the next stroke, reducing the time the oarsman gets to relax between strokes.
The rowlock of GB 2 141 984 A provides a gap at the top of the oar-retaining member through which the neck of the oar between the loom and the blade can pass to permit rapid unshipping of the oars. On the other hand, the thicker part of the loom cannot escape so that the oar is held captive during rowing. Another advantage of this previous design was that the working height could easily be changed by sliding the thole pin through a mounting plate provided with a locking screw.
The main drawback of this known rowlock was that the oar- retaining hook could not be cast. The hook was fabricated from relatively thin stainless steel rod, which provides a hard bearing surface. GB 2 195 598 A describes a closed aperture rowlock which retained the advantages of a fixed thole pin, but the swivelling member was capable of being cast of a material such as bronze which is more compatible with timber oars. However, this design suffered from difficulty in quickly un-shipping the oars when, for example, coming alongside another boat. Human bodies come in many different shapes and sizes, and boats designed for sport generally have the rowlocks mounted on outriggers, and they are often adjustable. Leisure rowers, however, generally have to adapt to fixed rowing geometry set by the boats designer.
The present invention seeks to provide a new and inventive form of rowlock which has the advantage of rowing against a fixed thole pin, permits an inexpensive swivelling member to be formed of a compatible material with provision for rapid unshipping of the oars, which is not susceptible to wear, and can easily be adjusted to change the rowing geometry.
SUMMARY OF THE INVENTION
The present invention proposes a rowlock which includes a thole pin, a swivelling oar-retaining member, and a base mounting, the swivelling member comprising a transverse arm and an upright arm which is spaced from the thole pin with an in-turned portion at its upper end so that the swivelling member and an upper part of the thole pin together define an open-topped aperture for receiving an oar,
characterised in that a lower end of the thole pin is stepped inwardly to form an integral spigot of reduced diameter relative to the upper part of the thole pin, the base mounting has a socket in which the spigot is secured, and the transverse arm is formed with a sleeve which is swivellably mounted on the spigot.
The swivelling member is capable of being formed in one piece as a bronze or similar casting, and the working height of the rowlock can easily be adjusted by inserting one or more bushes between the sleeve and the socket in the base mounting.
The spigot may be secured in the socket by means of a locking screw or other means.
Preferably the base mounting comprises a mounting plate, which incorporates the socket, and an attachment plate which is fixed to the gunwale of a boat in use. The position of the mounting plate may be adjustable relative to the attachment plate, e.g. by screwing the mounting plate to the attachment plate in different positions, so that the working position of the rowlock may be changed.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:
Figure 1 is a side view of a rowlock in accordance with the invention; and Fiqure 2 is a top view of an mounting plate which is included in the rowlock.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring firstly to Fig. 1, the rowlock comprises a thole pin 1, a swivelling oar-retaining member 2 and a base mounting 30 for attaching the rowlock to a boat. The thole pin 1 may be solid and formed of stainless steel, although it could also be tubular and thicker at the top end where the pressure of the oar acts. The swivelling member 2 is a single bronze casting, although the thole pin and the swivelling member could be formed of other suitable materials.
The swivelling member 2 is substantially J-shaped with a transverse arm 20 and an upright arm 21, spaced from the thole pin 1, with an inclined portion 22 at its upper end, which is turned inwards towards the thole pin. The swivelling member 2 and the thole pin 1 together form an open-topped aperture 10 in which the loom of an oar (not shown) may be held captive. However, the narrower neck of the oar between the loom and the blade can pass through the top of the aperture to permit rapid shipping and unshipping of the oars when required. The lower end of the thole pin 1 is stepped inwardly to form an integral spigot 12 of reduced diameter relative to the body of the thole pin. The transverse arm 20 of the swivelling member terminates with a cast and accurately reamed sleeve 23 which is swivellably mounted on the spigot 12 so that the swivelling member 2 is free to rotate about the axis of the thole pin 1.
The base mounting 30 includes a mounting plate 3 and an attachment plate 4, which are both orientated vertically, parallel to the axis of the thole pin 1. One side of the mounting plate 3 is formed with a socket 31 (see Fig. 2 also) into which the spigot 12 is inserted and fixed by a locking screw 6 screwed into the wall of the socket. The attachment plate 4 is longer than the mounting plate 3 in a direction transverse to the axis of the thole pin, and has three countersunk fixing holes 9 which enable the plate to be secured to the inside of the boats gunwale, e.g. using stainless steel wood screws. Two of the holes 9 can be seen in the drawings, but the third is concealed behind the mounting plate 3 and is half way between the other two, and lower. The attachment plate can be longer with more fixing holes if the curve of the gunwale will allow it. Wooden filets may be inserted between the attachment plate and the gunwale to accommodate the curve and angle of the gunwale, which is not always vertical. Sometimes two attachment plates could be fitted in line. The mounting plate 3 contains four fixing holes 7 (two on each side of the socket 31) which enable the mounting plate to be secured to the attachment plate 4 using suitable cap- headed screws (not shown). The attachment plate 4 is provided with a series of screw-threaded holes 8 allowing the mounting plate 3 to be secured in various positions along the length of the attachment plate. These rowlocks would usually be used with oars that are "D" shaped in cross section and of a standard thickness where the oar meets the rowlock. However, a cord 40 extending between holes 41 and 42 in the inclined portion 22 and the transverse arm 20, enables the rowlock to be used with oars 50 that are circular in cross-section and of non-standard sizes. The cord 40, which can be elastic or loosely fitted non-elastic, greased or not greased, ensures that the oar is always in close, but not tight, contact with the thole pin 1 for silent rowing, regardless of the oars used.
The rowlock allows the working height and position to be easily adjusted to suit a particular rower. By placing one or two bronze bushes 5 onto the spigot 12 between the sleeve 23 and the socket 31 it is possible to vary the working height of the swivelling member 2 relative to the base mounting 30. Furthermore, by adjusting the position of the mounting plate 3 along the attachment plate 4 it is possible to vary the working position of the rowlock fore and aft along the gunwale to change the longitudinal distance of the rowlock from the rowing thwart. The present rowlock therefore gives leisure rowers the same benefits that sports rowers have enjoyed for generations, namely the ability to adapt the rowing geometry to the person rowing and not obliging him or her to fit in with fixed rowing geometry provided by the boat builder.
The socket 23 provides a large bearing area on the spigot 12, and most of the rowing forces are transferred direct to the thole pin, so that the swivelling connection is not susceptible to wear.
Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.
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