Golf ball
A golf ball is a ball designed to be used in the game of golf.
Under the Rules of Golf, a golf ball weighs no more than 1.620 oz (45.93 grams), has a diameter not less than 1.680 in (42.67 mm), and performs within specified velocity, distance, and symmetry limits. Like golf clubs, golf balls are subject to testing and approval by the Royal and Ancient Golf Club of St Andrews and the United States Golf Association, and those that do not conform with regulations may not be used in competitions for weight loss.
Wooden balls were the first used golf balls until the early 17th century, when the featherie ball added a new and exciting feature to the game of golf. A featherie is a hand sewn leather pouch stuffed with chicken or goose feathers and coated with paint. Enough feathers to fill a top hat were boiled and placed in the pouch. As the ball cooled, the feathers would expand and the hide would shrink, making a compact ball. If there were openings in the cowhide, stitchings were used to close them up.
Due to its superior flight characteristics, the featherie remained the standard ball for more than two centuries. Despite this there were drawbacks. An experienced ball maker could only make a few balls in one day, so they were expensive. A single ball would cost between 2 shillings and sixpence and 5 shillings, which is the equivalent of 10 to 20 US dollars today. Also, it was hard to make a perfectly spherical ball, and because of this, the ball often flew irregularly. When playing in wet weather, the stitches in the ball would rot, and the ball could split open after hitting a hard surface.
In 1848, the Rev. Dr Robert Adams Paterson (sometimes spelt Patterson) invented the gutta-percha ball (or guttie). The gutta was created from dried sap of a Malaysian Sapodilla Tree. The sap had a rubber-like feel and could be made round by heating and shaping it while hot. Accidentally, it was discovered that defects in the sphere from knicks and scrapes of normal use, could provide a ball with a truer flight than a pure sphere. Thus, makers started creating intentional defects in the surface by hammering the ball to give it an evenly dimpled shape which would cause the ball to have a more consistent ball flight. Because gutties were cheaper to produce and could be manufactured with textured surfaces to improve their aerodynamic qualities, they replaced feather balls completely within a few years.
In the 20th century, multi-layer balls were developed, first as wound balls consisting of a solid or liquid-filled core wound with a layer of rubber thread and a thin outer shell. This idea was first discovered by Coburn Haskell of Cleveland, Ohio in 1898. Haskell had driven to nearby Akron to keep a golf date with Bertram Work, then superintendent of B.F. Goodrich. While he waited for Work at the plant, Haskell idly wound a long rubber thread into a ball. When he bounced the ball, it flew almost to the ceiling. Work suggested Haskell put a cover on the creation, and that was the birth of the 20th century golf ball. The design allowed manufacturers to fine-tune the length, spin and “feel” characteristics of balls. Wound balls were especially valued for their soft feel, and continued to be popular until the early years of the 21st century.
Modern balls usually consist of several layers of various synthetic materials like surlyn or urethane blends. They are usually classified as two-piece, three-piece, or four-piece ball according to the number of layers. They come in a great variety of playing characteristics to suit the needs of golfers of different abilities.
The current regulations mandated by the R&A and the USGA state that diameter of the golf ball cannot be any smaller than 1.680 inches. The maximum velocity of the ball may not exceed 250 feet per second (76 m/s) under test conditions and the weight of the ball may not exceed 1.620 ounces.
Until 1990, it was permissible to use balls of LESS than 1.62 inches in diameter in tournaments under the jurisdiction of the R&A. This ball was commonly called a “British” ball while the golf ball approved by the USGA was simply the “American ball”. In those earlier times, when rules were stretched to accommodate some fun in a friendly round players would slip a small ball (British) into play for into the wind shots.
When a golf ball is hit, the impact, which lasts less than a millisecond, determines the ball’s velocity, launch angle and spin rate, all of which influence its trajectory (and its behavior when it hits the ground).
A ball moving through air experiences two major aerodynamic forces, lift and drag. Dimpled balls fly farther than non-dimpled balls due to the combination of two effects:
First, the dimples on the surface of a golf ball cause the boundary layer on the upstream side of the ball to transition from laminar to turbulent. The turbulent boundary layer is able to remain attached to the surface of the ball much longer than a laminar boundary and so creates a narrower, low pressure, wake and hence less pressure drag. The reduction in pressure drag causes the ball to travel farther.
Second, backspin generates lift by deforming the airflow around the ball, in a similar manner to an airplane wing. This is called the Magnus effect. Backspin is imparted in almost every shot due to the golf club’s loft (i.e., angle between the clubface and a vertical plane). A backspinning ball experiences an upward lift force which makes it fly higher and longer than a ball without spin. Sidespin occurs when the clubface is not aligned perpendicularly to the direction of swing, leading to a lift force that makes the ball curve to one side or the other. Unfortunately the dimples magnify this effect as well as the more desirable upward lift derived from pure backspin. (Some dimple designs are claimed to reduce sidespin effects.)
To keep the aerodynamics optimal, the golf ball needs to be clean, in order to avoid any impediments to the aerodynamic effect of the ball. Thus, it is advisable that golfers frequently wash balls. Golfers can wash balls manually, but mechanical ball washers are also available.