WO1999006123A1 - Hard court bowling game and bowl therefor - Google Patents

Abstract

The present invention relates to the sport of bowling and bowls therefor, and in particular relates firstly to an improved bowl and secondly to an improved playing surface and bowls combination. Broadly according to a first aspect of the invention a biased bowl for use in playing bowls comprises a hard and dense central core (11) and a pliant outer cover (12). The bowl is constructed such that when it is used on a hard surface its rolling and retardation characteristics approximate that of a conventional hard lawn bowl used on a conventional lawn bowling surface. Broadly, according to a second aspect of the invention, a bowling court and bowls combination comprises a bowl as described above and a hard substantially horizontal surface wherein the combination provides an approximation to the conventional lawn bowling combination in terms of bowl rolling and retardation characteristics.

Description

HARD COURT BOWLING GAME AND BOWL THEREFOR

The present invention relates to the sport of bowling and bowls therefor, and in particular relates firstly to an improved bowl and secondly to an improved playing surface and bowls combination.

BACKGROUND

Lawn bowls or bowling is generally played on a playing surface consisting of grass or grass-like material using balls with a hard surface known as bowls. As the bowls roll along the playing surface they are retarded primarily by the distortion of the playing surface.

There are many proprietary brands of lawn bowls manufactured throughout the world, however each bowl is produced by very similar generic production methods. These methods typically involve a die moulding process of thermosetting powders which after cooling go through several finishing operations including computer turning to produce a standard bias lawn bowl. The bowl is then tested for bias and balance. Finally the bowl is engraved and polished and must be tested to the exacting standards of the World Bowls Board. The production methods and finish thus described produce a biased lawn bowl of homogenous solid construction with a highly polished hard external surface.

The aforementioned proprietary brands of lawn bowls have been specifically designed to be used in the game of lawn bowls. The hard finished exterior of these bowls make them suitable for use on a bowling green the surface of which is constructed either of a suitable living turf or a manufactured pliant material often referred to as artificial turf or synthetic greens.

Playing surfaces, known as greens, comprising natural or hybrid grasses are labour intensive and require expensive care and maintenance. Costs include wages, machinery depreciation, chemicals, fertilisers, pesticides, electricity and water. The pesticides used can be toxic and detrimental to the environment. Similarly playing surfaces comprising artificial turf or synthetic greens also have their problems. They are extremely costly to install, have a limited life (approximately 10 years) and are still labour intensive and are not maintenance free as they are often subjected to surface deterioration owing to wind, rain, algae and mould growth.

There is a considerable variation between the characteristics of greens. The result of this variation is a variation in the rolling characteristics displayed by bowls on different greens.

The speed of a conventional green is referred to as "green speed" and is measured by recording the time taken for a conventional hard bowl (conforming to the World Bowls Board (WBB) specification) to travel a straight-line distance of 90 feet where the bowl is bowled at a speed such that it comes to rest after travelling the aforementioned 90 foot straight-line distance. Because of the bowl's bias, the actual path taken by the bowl during the green speed test will be curved.

Soft greens, such as those found in parts of Scotland can have green speeds as low as 10-12 seconds. For these slow greens, it is necessary to deliver the bowl at a high speed (with very little allowance for curving of the bowl), to compensate for the rapid deceleration of the bowl caused by the momentum absorbing properties of the soft green.

In contrast, hard greens, such as those found in parts of New Zealand, have green speeds as high as 22 seconds.

This variation between greens can produce difficulties in competitions played on "away" greens and has inhibited the growth of international lawn bowls competitions. Further problems associated with conventional bowling surfaces and bowls include: the difficulty of obtaining consistency over the entire playing surface, and the condition of the playing surface in different weather conditions.

It is therefore an object of the present invention to provide a bowling game that overcomes the aforesaid problems.

It is a further object of the present invention to provide a bowl adapted to be used on a bowling court with a hard surface.

It is a still further object of the present invention to provide a hard court design which overcomes the aforesaid problems.

It is a still further object of the present invention to provide a combination of bowls and a bowling court with a hard surface which results in a bowl having a rolling characteristic approximating that of conventional lawn bowls.

SUMMARY OF THE INVENTION

Broadly according to a first aspect of the invention therefore, an improved biased bowl for use in playing bowls comprises: a hard, dense central core; and a pliant outer cover.

Preferably the bowl is constructed such that when it is used on a hard surface its rolling and retardation characteristics approximate that of a conventional hard lawn bowl used on a conventional lawn bowling surface. Preferably the bowl further comprises a core of thermosetting material and a pliant outer cover formed from a foamed thermoplastic material.

Broadly, according to a second aspect of the invention, a bowling court and bowls combination comprises: a bowl according to the first aspect of the invention, and a hard substantially horizontal surface wherein the combination provides an approximation to the conventional lawn bowling combination in terms of bowl rolling and retardation characteristics.

Specific embodiments of the invention will now be described in some further detail with reference to and as illustrated in the accompanying figures. These embodiments are illustrative, and are not meant to be restrictive of the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig 1 shows according to a first embodiment of the invention, a bowl in an upright position in plan view, with part sectional view cutaway also shown.

Fig 2 shows the bowl shown in Fig 1 in an upright position in side view.

Fig 3 shows, according to a second embodiment of the invention, a bowl in an upright position in sectional view through a horizontal plane.

Fig 4 shows a plan view of the hard court surface shown in Fig 1.

Fig 5 shows a sectional view "4-4" of the hard court surface shown in Fig 4.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The rolling friction between a bowl and its playing surface and hence the rate of retardation of the bowl's movement is influenced by the degree of distortion of the two contacting surfaces under pressure. During normal lawn bowls play this distortion is observed mainly in the playing surface of the natural turf or synthetic green material. The bowl in motion will also distort to a minute extent. Thus deformation under load plus rolling friction produces an elastic hysteresis which is the main source of rolling friction. The science which deals with interacting surfaces in relative motion is called tribology.

A pliant covered biased bowl according to the invention rolled on a hard surface exhibits tribological characteristics which emulate a normal lawn bowl rolled on a conventional green.

In hard court bowling, using bowls according to the present invention, the green is replaced by a hard playing surface and the momentum absorption comes from the bowl's pliant covers rather than the playing surface. The same "green speed" test applied in the conventional game of lawn bowls (and as described above under the heading "Background") can be used in hard court bowling however what is being measured is a characteristic of the bowl rather than of the playing surface. In hard court bowls the equivalent of the "green speed" of conventional bowls is called "line speed". The line speed of a bowl according to the invention depends largely upon the properties of the outer cover and can range from 10 to 25 seconds using the equivalent of the World Bowls Board green speed test. However a line speed of between 10 and 18 seconds has been found to be preferable.

An advantage of a bowl according to the invention is that it can be used on a hard playing surface or rink. This overcomes many of the problems associated with playing conventional lawn bowls and provides a game of bowls that is unencumbered by the vagaries and environmental conditions or by the high cost involved in maintaining natural or synthetic bowling surfaces or greens.

Preferred embodiments of a bowl according to the invention will now be described with reference to Figs 1 to 3. Figs 1 and 2 show a first embodiment of the invention comprising a central core 11 encased in a pliant outer cover 12. The central core 11 is a thermoset phenolic plastic resin impregnated with a high density material moulded or machined into the substantially spheroidal shape shown in Figs 1 and 2. High density materials for impregnation may include metals minerals silicas or any other suitable high density materials. The pliant outer cover 12 is formed from a polymeric material. The overall shape of the bowl, as shown in Figs 1 and 2 provides it with a bias substantially within the range of biases exhibited by conventional lawn bowls. The maximum diameter of the bowl is in the range of 100 mm to 140 mm and is preferably about 120 mm.

The central core 11 is hard and dense (Shore A Hardness of 80 and density of 1.86 grams per cubic centimetre) resulting in a bowl that has an appropriate mass of between 1.3 kg and 1.6 kg (and preferably between 1.4 kg and 1.45 kg) and is dimensionally stable.

The bowl shown in Figs 1 and 2 includes a pliant cover with radially outwardly extending projections 13. The shape and size of these projections and their material specifications all influence the tribological characteristics of the bowl.

The bowl shown in Fig 3 is a second embodiment of the invention in which the pliant outer cover 12 has a substantially continuous and smooth surface and is moulded from a plasticised or foamed polymeric plastics material. Other suitable rubbers or synthetic rubbers may be used. Foamed polyvinyl acetate or foamed polyvinyl chloride has proven particularly suitable. The Shore A Hardness of this bowl is in the range of 8 to 15 and is preferably about 10.

The pliant outer covers of both the first and second embodiments of the invention gives the bowls their tribological characteristics and enable them to absorb their momentum as they roll along a hard floor surface in a manner so as to provide substantially the same roll to that of conventional hard lawn bowls rolled on conventional lawn greens.

The pliant covered biased bowl of either form may also be modified by changing the surface projections in order to enhance its playing characteristics for different conditions or in order to provide the optimum feel for the bowler. This may be accomplished by incorporating different materials and embodiments in its design with respect to weight, size and surface. It may also be designed to encompass all reasonable degrees of the laws of motion depending on the surface conditions required and, or, the experience and skill of the bowler.

The pattern of surface projections may be varied around the bowl to assist the sight impaired.

The bowls described above not only come to rest with uniform retardation when played on a suitably designed hard playing surface but also exhibit excellent parameters of weight "and green" with the regulation dimensions of a standard bowling rink.

An embodiment according to the second aspect of the invention is a playing surface shown in Figs 2 and 3. The playing surface 20 is preferably constructed on a hard and solid sub-surface of material 21 supporting a relatively hard, thin top surface layer 22 of preferably green pigmented acrylic polymer or similar. The playing area (hard court) is preferably flat and level and is sub-divided into smaller areas called rinks. The hard court is either square or rectangular, and its boundary geometry is determined by the number of rinks contained therein. The hard court is preferably surrounded by an excavation called a ditch 23 preferably not less than 200mm wide. The hard court is arbitrarily divided into a number of rinks, each one preferably between 5.5 metres and 5.8 metres wide and forms the sub-playing area for a hard court bowling game between, preferably, two or more players (refer Fig 4). The hard court geometry is preferably extended so that the continuation of the outer wall of the ditch 23 above the surface 22 of the hard court forms a bank 24 which is the end boundary of each rink. The top of the bank 24 is preferably not less than 250mm above the surface 22 of the hard court. The face of the bank 24 is preferably constructed so that a bowl or jack striking it will not be damaged. Each rink is marked by boundary pegs located on the bank. These define the limits of the playing area of the rink. To determine the centre of each rink a numbered peg is preferably located on the bank 24 exactly half the distance between the left hand and right hand pegs marking the extremities of the rink. Each rink is preferably individually marked with a centre line painted on the playing surface for a distance of preferably 4 metres, beginning 2 metres from each ditch and so marked as to indicate the playing length of the rink and from which position a bowling mat is preferably placed at the commencement of a game.

The playing surface 20 of the hard court preferably consists of a suitable substructure 25 over which a solid surface such as concrete, bitumen, tiling or timber is laid and on which is coated a hard surface 22 of relatively thin, green pigmented acrylic polymer or similar. A playing surface of this construction will provide a high performance surface similar to that used in the construction of tennis courts etc and will require little or no maintenance as compared with the very high maintenance required for upkeep of natural turfs or synthetic and artificial turfs. Optionally the court can be located under cover or indoors. A particular advantage of such an acrylic surface is that it can be formulated to developed standards for a uniform and international court speed as compared to the variable, sometimes erratic, green speeds at present associated with the game of lawn bowls.

In another form, the hard court may comprise a facility for indoor and outdoor bowling, the playing surface of which is an already existing hard court surface such as a basketball, netball or tennis court. In order to utilise the geometry of an existing surface for the game of hard court bowls a barrier or fender is preferably erected at each end of the playing area. Such barrier or fender may be either fixed or free standing and is preferably constructed of suitable materials so that a bowl or jack striking it will be constrained within the playing area of the existing court.

The barrier or fender is designed to show the limits of each rink. To determine the centre of each rink a number is preferably indicated or marked on the barrier exactly half the distance between the left and right hand pegs marking the extremities of each rink division.

Each rink is preferably between 5.0 metres and 5.5 metres wide and forms the sub- playing area for a hard court bowls game. By erecting a suitable barrier/ fender system on an already existing playing surface an inexpensive form of hard court bowls is readily available within existing facilities worldwide.

In yet another form, the hard court comprises a facility for indoor and outdoor bowling, the playing surface of which is preferably constructed of removable sectional pieces of a suitable non-hard material coated with a green pigmented acrylic polymer. Each piece or tile is preferably laid on a suitable sub-surface to form an overall playing area in accordance with the geometrical requirements of a bowling hard court as described previously.

The rules for hard court bowls will be formulated to enhance the game of hard court bowls but will be compatible to those used for the game of lawn bowls, and in hard court bowls the game is preferably played by two or more players, each player having a requisite number of bowls depending on the game being played. In one form of a game of hard court bowls an "end " is declared and a coloured ball called the jack is rolled along the rink a distance of 21 metres or more. The players then deliver bowls in turn. The player whose bowls rest nearest to the jack, after all the other players' bowls have been delivered, scores "shots", or points, according to the number of his/her bowls nearer to the jack than any bowl of the other players. The winner is the player, or team of players, scoring the most "shots" after an agreed number of ends have been played.

Hard court bowls may be played without the restrictions and high costs associated with playing on, and maintaining, natural turf or synthetic greens. Furthermore, the present invention relates to a surface game which can be designed and formulated to provide more efficient performance criteria with respect to the speed a bowl traverses a playing surface (the green or court speed) as required by international standards and in accordance with Olympic and Commonwealth Games recommendations .

While the present invention has been described in terms of preferred embodiments in order to facilitate better understanding of the invention, it should be appreciated that various modifications can be made without departing from the principles of the invention. Therefore the invention should be understood to include all such modifications within its scope.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A biased bowl for use in playing bowls comprising: a hard, dense central core; and a pliant outer cover.

2. A biased bowl as claimed in claim 1 wherein said pliant outer cover is formed from a polymeric material.

3. A biased bowl as claimed in claim 2 wherein said hard, dense central core is formed from a phenolic thermoset plastic resin impregnated with a high density material and wherein said pliant outer cover is formed from a foamed thermoplastics material.

4. A biased bowl as claimed in claim 3 wherein said foamed thermoplastics material is a polyvinyl acetate or a polyvinyl chloride.

5. A biased bowl as claimed in claims 1 or 2 wherein said pliant outer cover has radially outwardly extending projections.

6. A biased bowl as claimed in claim 5 wherein said radially outwardly extending projections are distributed over the entire surface area of said pliant outer cover.

7. A biased bowl as claimed in any one of the preceding claims having a bias substantially within the range of biases of conventional lawn bowls.

8. A biased bowl as claimed in any one of the preceding claims having a shape substantially within the range of shapes of conventional lawn bowls.

9. A biased bowl which has: a mass in the range of 1.3 kg to 1.6 kg; a maximum diameter in the range of 100 mm to 140 mm; and a surface Shore A Hardness in the range of 8 to 15.

10. A biased bowl having: a central core with a density of approximately 1.85 grams per cubic centimetre; an outer cover with a surface Shore A Hardness in the range of 8 to 15; and a maximum diameter in the range of 100 mm to 140 mm.

11. A biased bowl having a pliant outer cover which is arranged to absorb the bowl's momentum as it rolls along a hard floor surface in a manner so as to provide substantially the same roll to that of a conventional hard lawn bowl rolled on a conventional lawn green.

12. A biased bowl as claimed in the preceding claim having a bias substantially within the range of the biases of conventional lawn bowls.

13. A biased bowl as claimed in either of claims 11 or 12 characterised in that it has a line speed when rolled on a hard surface of between 10 and 25 seconds using the equivalent of the World Bowls Board green speed test.

14. A biased bowl as claimed in the preceding claim characterised in that it has a line speed when rolled on a hard surface of between 10 and 18 seconds using the equivalent of the World Bowls Board green speed test.

15. A biased bowl as claimed in any of the preceding claims wherein said bias is equal to or greater than that of the equivalent of the World Bowls Board Reference Bowl.

16. A biased bowl as claimed in any of the preceding claims having a mass in the range of 1.4 kg to 1.45 kg.

17. A biased bowl substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.