...that appears to be random could in fact be influenced by certain events.

Friday, December 11, 2009

Friday, December 4, 2009

Rules and regulations

The regulations listed here are generally based around regulations set by the United States Bowling Congress and the British Tenpin Bowling Association. These rules are followed by all sanctioned leagues and events, such as tournaments.

This information is clarified by the World Tenpin Bowling Association in its “Statutes & Playing Rules”.

Playing area

The sport of ten-pin bowling is performed on a straight, narrow surface known as a lane. This bowling lane is 60 feet (18.29 m) from the foul line to the head pin (1-pin). About 15 feet (4.57 m) from the foul line are a set of guide arrows. The lane is 41.5 inches (1.05 m) wide and normally consists of 39 wooden boards or a synthetic material. The bowling lane has two sets of approach dots; from the foul line back to the first set of approach dots is about 12 feet (3.66 m) and to the second set of approach dots is about 15 feet (4.57 m) (an additional 3 feet (0.91 m)). Although this figure varies, the lane is protected by about 18 ml of oil. The PBA events use about 30 ml of oil, and the PWBA events use 25 ml. The oil starts from about 4 inches from the foul line and is applied for about 38 feet (11.58 m) down the lane from that point.


Position of the ten pins from above.

USBC rules specify that a pin must be 15 inches (38 cm) tall and about 4.7 inches (12 cm) wide at its widest point, where a rolling ball would make contact. There are additional measurements which delineate the shape. The weight of a single pin must be at least 3 pounds, 6 ounces (1.47 kg) and no more than 3 pounds, 10 ounces (1.64 kg). Within a set of ten pins, the individual weights may vary by no more than 4 ounces (113.4 g), if made from wood or plastic coated, or just 2 ounces (56.7 g) if synthetic. The top of the pin shall have a uniform arc with a radius of 1.273 inches (32.3 mm), ± 1/32 inch (31.5 – 33 mm).

The USBC also has regulations governing the weight distribution of the pin from top-to-bottom. Pins are allowed one or two “voids” (holes) in the belly area (which can be viewed if the pin is cut in half from top-to-bottom). The voids are needed to balance the narrower top half of the pin with the wider bottom half. Without them, the pins would be too bottom-heavy to fall properly when struck.

The pins must show the name and mark of the maker, either “USBC Approved” or “BTBA Approved” and appear uniform.

The head pin or 1 pin stands on board 20 of the lane.

Bowling ball

The circumference of the ball must not be more than 2.25 feet (0.69 m), and the ball cannot weigh more than 16 pounds (7.26 kg). The ball must have a smooth surface over its entire circumference except for holes or indentations used for gripping the ball, holes or indentations made to bring the ball back into compliance with weight-distribution regulations, identification letters and numbers, and general wear from normal use.

For much of the history of bowling, bowling balls were made using a three piece construction method. Starting in the mid 1990s, however, most manufacturers switched to a two-piece method. In response to these innovative ball designs, the American Bowling Congress placed further restrictions on the technical characteristics of the ball such as the radius of gyrationand hooking potential.

Rules of play

A game of bowling consists of ten frames. In each frame, the bowler will have two chances to knock down as many pins as possible with his bowling ball. In games with more than one bowler, as is common, every bowler will take his frame in a predetermined order before the next frame begins. If a bowler is able to knock down all ten pins with the first ball, he is awarded a strike. If the bowler is able to knock down all 10 pins with the two balls of a frame, it is known as a spare. Bonus points are awarded for both of these, depending on what is scored in the next 2 balls (for a strike) or 1 ball (for a spare). If the bowler knocks down all 10 pins in the tenth frame, the bowler is allowed to throw 3 balls for that frame. This allows for a potential of 12 strikes in a single game, and a maximum score of 300 points, a perfect game.


In general, one point is scored for each pin that is knocked over. So if a player bowls over three pins with the first shot, then six with the second, the player would receive a total of nine points for that frame. If a player knocks down 9 pins with the first shot, but misses with the second, the player would also score nine. When a player fails to knock down all ten pins after their second ball it is known as an open frame.

In the event that all ten pins are knocked over by a player in a single frame, bonuses are awarded.

A ten-pin bowling scoresheet showing how a strike is scored.
  • strike: When all ten pins are knocked down with the first ball (called a strike and typically rendered as an “X” on a scoresheet), a player is awarded ten points, plus a bonus of whatever is scored with the next two balls. In this way, the points scored for the two balls after the strike are counted twice.
Frame 1, ball 1: 10 pins (strike)
Frame 2, ball 1: 3 pins
Frame 2, ball 2: 6 pins
The total score from these throws is:
  • Frame one: 10 + (3 + 6) = 19
  • Frame two: 3 + 6 = 9
TOTAL = 28

Two consecutive strikes are referred to as a “double.” (image unavailable)

A double's pinfall is:

Frame 1, ball 1: 10 pins (Strike)
Frame 2, ball 1: 10 pins (Strike)
Frame 3, ball 1: 9 pins
Frame 3, ball 2: 0 pins (recorded as a dash '-' on the scoresheet)
The total score from these throws is:
Frame one: 10 + (10 + 9) = 29
Frame two: 10 + (9 + 0) = 19
Frame three: 9 + 0 = 9
TOTAL = 57

Three strikes bowled consecutively are known as a “turkey” or “triple.” (image unavailable)

A triple's pinfall is:

Frame 1, ball 1: 10 pins (Strike)
Frame 2, ball 1: 10 pins (Strike)
Frame 3, ball 1: 10 pins (Strike)
Frame 4, ball 1: 0 pins (Gutterball)
Frame 4, ball 2: 9 pins
The total score from these throws is:
Frame one: 10 + (10 + 10) = 30
Frame two: 10 + (10 + 0) = 20
Frame three: 10 + (0 + 9) = 19
Frame four: 0 + 9 = 9
TOTAL = 78

Any longer string of strikes is referred to by a number attached to the word “bagger,” as in “four-bagger” or “five-bagger” for four or five consecutive strikes. Recently, the event of bowling four consecutive strikes has also been called a “sombrero” or “ham bone.” This terminology is used most often when a bowler is “off the strikes.” (i.e. has previously bowled a string of several strikes but failed to strike on his most recent ball.) When a player is “on the strikes,” a string is often referenced by affixing “in a row” to the number of strikes bowled consecutively. Six strikes in a row are sometimes referred to as a “six pack.” Six strikes and nine strikes in a row can also be referred to “Wild Turkeys” and “Golden Turkeys” respectively. Any string of strikes starting in the first frame or ending “off the sheet” (where all of a bowler’s shots from a certain frame to the end of the game strike) are often referred to as the “front” or “back” strikes, respectively (e.g. the “front nine” for strikes in frames 1-9, or the “back six” for strikes in frames 7, 8, and 9 with a turkey in the tenth). A “Perfect Game” or 12 strikes in a row is also colloquially referred to as the “Thanksgiving Turkey.”

A player who scores multiple strikes in succession would score like so:
Frame 1, ball 1: 10 pins (strike)
Frame 2, ball 1: 10 pins (strike)
Frame 3, ball 1: 4 pins
Frame 3, ball 2: 2 pins
The score from these throws are:
  • Frame one: 10 + (10 + 4) = 24
  • Frame two: 10 + (4 + 2) = 16
  • Frame three: 4 + 2 = 6
TOTAL = 46
The most points that can be scored in a single frame is 30 points (10 for the original strike, plus strikes in the two subsequent frames).
A player who bowls a strike in the tenth (final) frame is awarded two extra balls so as to allow the awarding of bonus points. If both these balls also result in strikes, a total of 30 points (10 + 10 + 10) is awarded for the frame. These bonus points do not count on their own, however. They only count as the bonus for the strike.
A ten-pin bowling scoresheet showing how a spare is scored.
  • spare: A “spare” is awarded when no pins are left standing after the second ball of a frame; i.e., a player uses both balls of a frame to clear all ten pins. A player achieving a spare is awarded ten points, plus a bonus of whatever is scored with the next ball (only the first ball is counted). It is typically rendered as a slash on scoresheets in place of the second pin count for a frame.
Frame 1, ball 1: 7 pins
Frame 1, ball 2: 3 pins (spare)
Frame 2, ball 1: 4 pins
Frame 2, ball 2: 2 pins
The total score from these throws is:
  • Frame one: 7 + 3 + 4 (bonus) = 14
  • Frame two: 4 + 2 = 6
TOTAL = 20

A player who bowls a spare in the tenth (final) frame is awarded one extra ball to allow for the bonus points.

Correctly calculating bonus points can be difficult, especially when combinations of strikes and spares come in successive frames. In modern times, however, this has been overcome with automated scoring systems, linked to the machines that set and clear the pins between frames. A computer automatically counts pins that remain standing, and fills in a virtual score sheet (usually displayed on monitors above each lane). However, even the automated system is not fool-proof, as the computer can miscount the number of pins that remain standing.

The maximum score in a game of ten-pin is 300. On Feb. 2, 1997, University of Nebraska sophomore Jeremy Sonnenfeld became the first person ever to roll three perfect games of 300 in a three-game series (as approved by the American Bowling Congress). This has only been achieved a handful of times since.

In Britain, the youngest bowler ever to achieve a perfect single game score of 300 (12 consecutive strikes), in a sanctioned competition was 12 years, 71 days old Elliot John Crosby, at AMF Purley in South London, England in the Surrey County trials on January 7 2006. Crosby beat the previous British 300 shooter record holder Rhys Parfitt by more than a year. Parfitt was 13 years, 4 months when he achieved a 300 point game at the London international tenpin bowling tournament in 1994. In the United States, the youngest ever bowler to achieve this in a sanctioned competition is two-handed bowler Chaz Dennis of Columbus, Ohio. He achieved this competing in the Hillcrest Preps-Juniors league at Hillcrest Lanes in Columbus, Ohio on December 16, 2006 at 10 years, 88 days old. Dennis was 20 days younger than the previous record-holder, Michael Tang of San Francisco, California, who set his record when he was 10 years, 108 days old competing in the Daly City All Stars Scratch Trios League at the Sea Bowl in Pacifica, California.

Scoring: Alternative method

There does exist an alternative method for keeping score. It is used by scoreboards at some tournaments, and by some bowling software programs. It is exactly the same as the conventional scoring described above, except that the score is always current (i.e. what the player would have if s/he never knocks down another pin).

The basic rules are as follows:

  • Spare = Points scored for the next ball are doubled (2 points per pin knocked down);
  • Strike = Points scored for the next two balls are doubled (2 points per pin);
  • Two or more strikes in a row = Points scored for the next ball are tripled (3 points per pin). If this roll is not a strike then the next ball is counted with doubled points.
  • If all ten pins are not knocked down, no bonuses are scored on subsequent throws - only actual pinfall.

Let's go through a sample game:

Frame 1 = Let's say our bowler leaves a 10-pin and picks up the spare. Score 10.

Frame 2 = Strike. Score 20 (10x2). Total = 30.

Frame 3 = Bowler leaves a 7-10 split and picks up one of the remaining pins. Score 16 on the first ball (8x2) and 2 on the second. Total = 48.

Frame 4 = Bowler throws an errant shot and the ball lands in the gutter, but knocks down all ten pins on the next ball. However, because it is the second ball of the frame only a spare is earned - and because the previous frame was open, all pins count face value. Score 10. Total = 58.

Frame 5 = Bowler leaves a solid 7-pin and picks it up. Score 18 for the first ball (9x2) and 1 for the second. Total = 77.

Frame 6 = Strike. Score 20 (10x2). Total = 97.

Frame 7 = Strike. Score 20 (10x2). Total = 117.

Frame 8 = Strike. Score 30 (10x3) because our bowler was working on a double. Total = 147.

Frame 9 = Strike. Score 30 (10x3). Even though three strikes in a row had been thrown previously, our bowler is still considered to have a double working because the bonuses for the strike in the sixth have expired. Total = 177.

The scoring for the tenth frame goes as follows:

  • If a spare was earned in the ninth frame, score double on the first ball in the tenth frame and face value (single) for the second and third balls, if there is a third ball.
  • If a strike was earned in the ninth frame, score double on the first two balls in the tenth frame and single on the third ball.
  • If strikes were earned in the 8th and 9th frames (as in our sample), score triple on the first ball in the tenth, double on the second ball, and single on the third.
  • If the ninth frame was open (all 10 pins not down on 2 balls), then all three balls in the tenth count single.

Back to our game—Frame 10 = Strike. Score 30 (10x3). Total = 207. As for the two bonus balls, let's say our bowler leaves a 6-10 and picks it up for the spare. Score 16 for the first fill ball (8x2) and 2 for the second.

Final score = 225. This game is an illustration of how dramatically a player's score can skyrocket as a result of stringing together several strikes.


A hook in ten-pin bowling is a ball that rolls in a curving pattern (versus straight.) The purpose of the hook is to give the ball a better angle at the 1-3 pocket (right-handers) or 1-2 pocket (left-handers.) When a ball is rolled straight, hitting the pocket must be precise. By hooking the ball, the ball will hit the pins with more force, producing better carry - especially on the 5-pin during a strike ball. Straight roll - even when it hits the pocket, will tend to leave a tap, such as the 5-pin on a light hit, or the 10-pin if the ball was just slightly right of the head pin. A hook ball can create strikes with less precise hits at the pocket.

A hook ball can also help the bowler shape the shot on challenging oil patterns.

In other games of bowling, such as duckpin bowling or candlepin bowling, a hook is virtually non-existent for experienced bowlers since the ball is much smaller than in ten-pin bowling, and rolls too fast to the pins to allow a hook to even develop.


There are two ways to produce a hook. The first method involved bowling technique. At the moment of throwing the bowling ball, the hand should be behind the ball and where the thumb (for a right-hander) is anywhere between 10-o'clock and 12-o'clock, and the two fingers are between 4-o'clock and 6-o'clock. Just before releasing the ball, the entire hand starts rotating in a counter-clockwise motion. The thumb must fall out of the ball first. And then, the middle and ring finger release almost simultaneously, again in a counter-clockwise direction. The two fingers releasing while rotating is called "lift," where this type of a release gives the roll more torque and therefore more power. This release technique gives the bowling ball its spin needed for the hook. When the two fingers lift the ball correctly, it will cause the thumb to naturally fall out of the ball first, so one does not have to make a conscious effort to remove the thumb before the fingers.

Of course there are innumerable variations in style and technique and the position of the thumb can vary from person to person. Some bowlers, including professionals, will actually roll the bowling ball with just the two fingers, allowing the hand to give the ball even more torque without having to worry about the thumb restricting the spin.

The second way to produce a hook is by modifying the bowling ball. Legally, one can play with the weighting of the bowling ball, such as drilling the ball so that there is more side weight on the right side of the ball (for a right-hander,) which would cause the ball to pull from right to left, causing a hook. Bowling balls ship with the weighting specifications on the container. A bowling shop professional can drill a bowling ball by first knowing the type of roll the bowler wants, and then can pick out the bowling ball with the weighting specifications in mind that match the bowler's needs. For a beginning bowler, the professional will usually drill the ball with the label directly in the middle, and between the fingers and thumb holes, causing the weighting to be balanced on both sides, causing the ball to roll straight.

Under USBC regulations, one can drill up to five holes on the bowling ball. Since most bowlers use three holes (thumb and two fingers,) one could drill additional holes on other parts of the bowling ball, to take additional weight off of a portion of the bowling ball, such as an axis hole that allows the bowling ball's hook to stabilize during its roll to the pins. Doctoring the bowling ball by adding additional holes is not recommended unless the bowler is experienced enough to know where to place these holes, such as studying the track area of the ball and knowing where to place the axis hole.


A backup ball produces the opposite result of a hook. When a ball is rolled by a right-hander, the ball will hook from left to right. The exact same principles of hooking a ball are applied on a backup ball, except the hand rotates clockwise. A backup ball comes natural for some women, as the construction of the female wrist allows for it to rotate clockwise more naturally. Some women have stuck with the backup ball and had successful bowling careers.

The history of bowling ball

Bowling can be traced back to approximately 5200 B.C., when ancient Egyptians used stones for their balls. Pre-Columbian Indians also practiced bowling variants.


The first bowling balls used in the United States were made of wood, especially oak, and lignum vitae wood. In about 1906 the first hard rubber balls were produced, such as the Brunswick"Mineralite" ball, and these remained the standard until the 1960s and 70s. These decades saw the emergence of plastic (polyester) balls.

In the early 1970s, people began experimenting with the hardness of the plastic balls, notably PBA member Don McCune. McCune at the time worked for Chuck Hamilton who invented the "soaker"—a plastic (usually polyester) ball he softened "in the garage" with chemical solvents such as MEK, sometimes to the point that the balls might even end up lopsided. These and balls subsequently manufactured with the resulting softer cover came under ABC scrutiny because of the increased scoring, particularly by McCune, who with his "soaker" won six PBA tournaments in 1973 and PBA Player of the Year honors. A ball hardness rule of 72 was established, based on durometer readings, which barred some of the softer balls.

At some point in ball making and drilling, the ABC introduced ball balance regulations to prevent people from taking advantage. It was possible to drill the grip at a location relative to the weight block so that it would achieve some effect, such as to help the bowler make it roll earlier or hook more.

In 1981 Ebonite began manufacturing the very first polyurethane cover stock bowling balls and sold the rights to AMF. Ebonite produced AMF balls at that time. Ebonite did not believe that bowlers would pay the $80.00 price this new technology would demand. That ball became the AMF Angle and this one coverstock change allowed the ball to get a better grip on the polyurethane finishes used on natural wood lane surfaces, which changed the nature of the bowling game significantly. Then in the late 1980s or early 1990s, Nu-Line (Columbia) produced the X-Caliber a reactive resin cover.

Prior to about 1990, the ABC "static" ball balance regulations were adequate. The core was usually a uniform sphere centered inside the ball. Then competition among ball manufacturers motivated the production of balls designed to offer more than the "static balance" tricks. Materials and fabrication changes have since allowed the assembly of balls whose interior components have a much greater range of density, thereby offering a new ball choice that, in physics terms, involves the moment of inertia of a solid sphere. Eventually, "dynamic balance" regulations had to be adopted.


Weight Block Basics

In order to continue this discussion, a systematic description of ball rotation must be introduced. For various formulaic purposes, physicists divide rotation into three components, assigning portions to x, y and z axes that are mutually perpendicular. For bowling, the x-axis can be assigned to a line that is parallel to the foul line, the y-axis to the line parallel to the boards, and the z-axis to the vertical. Forward-roll is rotation about the x-axis, side-roll is rotation about the y-axis and mid-roll (or spin) is rotation about the z-axis. The pure full-roller delivery is a combination of forward- and side-roll only. Semi-rollers include spin. Spinners may have very little side roll. In a very strict physics sense, a ball may be delivered with rotation, but usually not in a roll, because that would imply complete traction. The technique of the great majority of bowlers involves a delivery that starts the ball in a skid that evolves into a roll that hooks into the pins.

It has been known since before the 1960s that a "full-roller" type of delivery does not hook as well as "3/4 rollers" on oily lanes. On successive rotations, the "full roller" repeatedly contacts the lane on the same full circumferential circle, on which the oil accumulates, making it harder for the side-roll to find traction and create hooking action. The "full-roller" had been the dominant choice before the changes in lane coatings and oil. The "semi-roller" is now preferred (it may also be called "3/4 roller" or by other slang terms). With a 3/4-roller a bowler puts the ball into a rotation whose contact ring is smaller, and on successive rotations enlarges (subsequent examination of the ball often shows a flaring of the circles of oil). This is because at every spot along the circle, friction reduces the rotation, and that includes the spin component, causing rotation on a continually larger circle. This has the effect of bringing relatively dry ball surface in contact with the lane, increasing traction for both forward-roll and side-roll. It probably goes without saying why bowlers often wipe oil off the ball.


Another effect of ball imbalance (either static or dynamic) is the ability to introduce gyroscopic effects on the rotation. The component of imbalance along the rotation axis provides a leverage that can change the orientation of the axis on its horizontal plane, an action physicists call precession. It is basically the same thing as a spinning toy top "going around in a circle." In the case of a rotating bowling ball, as it moves along the lane, there is only time for its total rotation axis to move along a short arc, but this is enough to reorient the total rotation so that some of the forward-roll becomes side-roll, increasing the side-roll provided in the bowler's delivery, thereby achieving more hook. It is possible to use dynamic ball balancing to achieve a stronger gyroscopic effect than static balancing alone.

The advent of dynamic ball balancing meant that bowlers could achieve "ball flare" without the need for a 3/4 roller delivery, and more hook. Additionally, balls with covers that create higher friction, such as "particle" balls, provide for more traction and hook. Bowlers are embracing these choices, buying balls whose characteristics complement or enhance their deliveries.

It is the opinion of many people in the bowling community that these advances in bowling ball technology have undermined bowling skill and have made it more difficult for lane maintenance personnel to lay out fair and credible conditions for participants. This is because advanced players using hi-tech balls "need" more oil to score high and might complain about the radical behavior of their balls on "dry" lanes. At the same time, less aggressive players might complain when they can not get their balls to hook. These complaints have been part of the game throughout USBC history. It has been a matter of which group prevails within the USBC—or what new technology comes along next.

Manufacturers of ten-pin bowling balls

  • Ebonite International, which includes
    • Columbia 300 Industries
    • Hammer Bowling
    • Track International
    • Dyno-Thane (Overseas brand only)
  • Brunswick Corporation
    • Viz-A-Ball
    • Quantum (contract made by Brunswick overseas)
    • MoRich Enterprises (contract made by Brunswick)
  • Visionary Bowling Products
  • Storm Bowling
    • Roto Grip
    • AZO (contract made by Storm)
  • 900 Global,
    • AMF
    • Lane #1 (contract made by 900 Global)
    • Elite (contract made by 900 Global)
    • Motiv (contract made by 900 Global)
    • Seismic (contract made by 900 Global)
  • Lane Masters

Bowling ball

A bowling ball is a round ball made from urethane, plastic, reactive resin or a combination of these materials which is used in the sport of bowling. Ten-pin bowling balls generally have a set of three holes drilled in them, one each for the ring and middle finger, and one for the thumb; however, rules allow for up to five finger holes. A five-pin bowling ball has no finger holes and is smaller so that the bowler can hold the ball in the palm of his or her hand. Candlepin bowling balls also fit in the hand, but are lighter than five-pin balls.

Most bowling alleys provide free balls for patrons to use, called house balls, although avid bowlers may purchase their own. These are often customized, and can feature specially sized finger holes (in the case of ten-pin balls) or monograms. Because purchased balls are usually drilled to match the owner's fingers, most can throw a customized bowling ball that is one to two pounds heavier than the house ball they previously used.

Bowling balls come in many varieties of colors, and are often either a single flat color, a swirl-like design of multiple colors, or a single color with an iridescent look. It is even possible to obtain transparent bowling balls, painted in such a way as to make it appear as though an object is inside. Some objects have included skulls, footballs, and baseballs.

Inside the ball is a core which makes each ball do something different. These cores are dynamically imbalanced to cause the ball to try to stabilize as it is rolling down the lane.[1] This makes the ball roll over a different point on the surface every time it revolves and "flares" or causes multiple oil rings.

Bowling ball cores are constructed with different densities as well. Some are center heavy (low rg) and some cores are made with the weight distributed more towards the cover of the ball (high rg). Low rg balls will spin more easily than the high rg balls.