Cue sports techniques
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Cue sports techniques (usually more specific, e.g., billiards techniques, snooker techniques) are an immensely important aspect of game play in the various cue sports such as carom billiards, pool, snooker and other games. Such techniques are used on each shot in an attempt to achieve an immediate aim such as scoring or playing a safety, while at the same time exercising control over the positioning of the cue ball and often the object balls for the next shot or inning.
In carom games, an advanced player's aim on most shots is to leave the cue ball and the object balls in position such that the next shot is of a less difficult variety to make the requisite carom, and so that the next shot is in position to be manipulated in turn for yet another shot; ad infinitum.
Similarly, in many pocket billiards games, an advanced player's aim is to manipulate the cue ball so that it is in position to pocket (pot) a chosen next object ball and so that that next shot can also be manipulated for the next shot, and so on. Whereas in the carom games, manipulation of the object ball's position is crucial as well on every shot, in some pool games this is not as large a factor because on a successful shot the object ball is pocketed. However, many shots in one-pocket, for example, have this same added object ball control factor for most shots.
If a player is not attempting to score or pocket, depending on the game, then the goal is usually to exercise control over the cue ball to leave some type of safety to make it more difficult for the opponent to score or pocket.
In order to control the cue ball on a shot, a player must master a wide variety of techniques, and have a well-founded conceptual grasp of the mechanics involved. As stated by George Fels, "pool's poet laureate":[1]
The mere pocketing of a ball isn't that hard; in fact, it's relatively simple. What drives many, many players to distraction is the unpredictability of the cueball's path of travel...the game of billiards requires you to drive a ball someplace; pool, in any form, mostly asks you to stop a ball someplace. In either case, you'll fare much better when you understand the how and why of a ball's getting from one place to another.[1]
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[edit] Sidespin (english)
The term english (called "side" in the UK, and sometimes simply called "left" or "right", and sometimes "check side" for left-hand side, and "running side" for right-hand side) normally refers to sidespin put on a cue ball by hitting it to the left or right of center. Generally, english is used to change the angle of reflection of the cue ball after it contacts a rail. English also affects the direction an object ball takes on impact (the "throw" effect), as well as the path of travel of the cue ball after impact with a cue ("deflection" or "squirt").
Sometimes english is conflated to refer as well to spin imparted on the vertical axis of the cue ball. However, an above center hit is more precisely referred to as 'follow,' ('top' in the UK) and a below center hit, as 'draw' ('screw' or 'back spin' in the UK). Any time the cue ball is not struck directly in the center, some spin will be imparted, whether left or right english, follow or draw. Unintentional sidespin is a common source of missed shots. Spin is not always placed on the cue ball by the shooter; spin is naturally imparted to the cue ball from contact with pool cloth on the bed of the table and on the table's cushions.
[edit] Follow
Follow, sometimes called top spin or simply "top," is spin in the direction of travel of the cue ball, such that it is spinning faster than it would from its natural roll. If the cue ball has top spin on it, it will resume rolling forward after making contact dead-on with the object ball and "follow" the object ball rather than stopping abruptly.
Top spin is imparted to a ball by hitting it above the midpoint of its vertical plane as it faces the shooter. Top spin is spin in the direction a ball naturally "wants" to take in reaction to friction from contact with the pool cloth. Because of this, a ball sliding on the cloth will rapidly pick up follow. Likewise, a ball struck so that it is spinning backwards (with draw — see below) immediately starts losing that spin, and if it travels far enough, will reach a sliding point (no spin), soon graduating to natural follow.
Follow applied to a non-dead-on shot will cause the angle of departure of the cue ball from the object ball to widen shortly after impact; the thicker the hit on the object ball, the more this effect will be noticeable (on very thin cut shots it practically does not exist). Similarly, top spin will cause a widening of the cue ball's rebound angle after impact with a rail cushion.
Follow also increases the rate of cue ball travel, both before and after object-ball impact, and actually imparts a small amount of draw to the object ball.
[edit] Force-follow
Force-Follow is an extreme variation of follow. On a straight-on shot, the cue ball will hesitate for a split-second, then charge forward through anything in its path. It may also refuse a normal rebound from the rail by striking the same rail a second time. This shot is useful both in trick-shots, and positional play.
[edit] Draw
Draw, sometimes called back spin or "bottom," is backward spin applied to the cue ball by hitting it below the midpoint of its vertical plane as it faces the shooter. If the cue ball is hit with draw, and if that spin remains on the cue ball at the moment of impact with an object ball, the cue ball will reverse direction on a dead-on or center-to-center hit, and "draw" backwards. Draw is referred to in the United Kingdom as "screw" or "back spin".
Draw applied to a non-dead-on shot will cause the angle of departure of the cue ball from the object ball to narrow shortly after impact. Similarly, it will cause a narrowing of the cue ball's rebound angle after impact with a rail cushion.
Draw also slows the rate of cue ball travel, both before and after object-ball impact, and actually imparts a small amount of follow to the object ball.
[edit] Slide
"Slide" refers to a cue ball that is sliding across the cloth with no follow or draw spin. To illustrate this principle, if a ball was marked with a single red dot on it which faced the ceiling at the time the cue ball was struck, an observer would see the cue ball traveling with that red dot remaining fixed at the top of the ball, because the bottom of the ball is sliding over the cloth.
In order to initially achieve a sliding cue ball, a middle-ball hit is employed. The more speed with which the cue ball is hit in this manner, the longer the cue ball will slide before picking up natural forward roll from cloth friction. However, because of this tendency of the cue ball to acquire follow from friction, in order to deliver a sliding cueball to an object ball at a distance, the cue ball must be precisely hit with the necessary degree of draw so that by the time it reaches the object ball, the draw has dissipated and the cue ball is sliding at the moment of impact.
[edit] The stop and stun shots
When a sliding cue ball contacts an object ball dead-on (a center-to-center hit), the cue ball and object ball are of the same mass, and neither follow nor draw is on the cue ball at the moment of impact, the cue ball will transfer all of its momentum to the object ball and come to a complete stop; this is a stop shot. If the sliding cue ball in the preceding scenario has sidespin on it when it contacts an object ball dead on, it will come to a complete stop but spin in place at that position until the sidespin dissipates. If the cue ball and object ball contact is not dead-on but still very full, the result will often be a "stun" shot, where the cue ball departs the object ball in the expected direction but travels only a short distance. The stun effect can often be enhanced with a minimal amount of draw, to reduce cue ball speed before impact with the object ball.
[edit] The tangent line
If a cue ball is sliding at the time it contacts an object ball at an angle (i.e. on a cut shot — not a center-to-center impact), the cue ball will travel in a line tangential to the point of impact between both balls — the tangent line. Because Billiard balls are somewhat elastic, the resulting tangent line is slightly less than 90 degrees from perpendicular to a line formed by the contact point between the balls.
If the cue ball hits an object ball at an angle and has follow on it, the cue ball will first travel on the tangent line and then parabolically arc forward from the tangent line in the direction of cue ball travel. By the same token, when such impact is made and the cue ball has draw on it, the cue ball will first travel on the tangent line and then parabolically arc backward from the tangent line in the opposite direction of cue ball travel. Whether follow or draw is on the cue ball, the faster the cue ball is traveling at the moment of impact, the farther it will travel on the tangent line before arcing forward or backward.
[edit] Throw
"Throw" refers to an object ball's motion away from the impact line due to relative sideways sliding motion between the cue ball and object ball caused by sidespin or a cut angle.
When a ball with english (sidespin) on it hits an object ball with a degree of fullness, the object ball will be "thrown" in the opposite direction of the side of the cue ball the english was applied. Thus, a cue ball with left hand english on it will "throw" a hit object ball to the right.
This effect is sometimes overarchingly referred to as "the gear system;" so-called because the interaction of the cogwork gears of a clock — each circular gear is interlocked with an abutting circular gear and each spins in the opposite direction of its neighbor in a series. English on the cue ball can cause a very similar effect. If the cue ball with left hand english in the preceding scenario contacts an object ball relatively full and that object ball is frozen to another, the first object ball is thrown to the right and the second to the left, exactly as the name implies.
Throw is also imparted to a ball by collision from a cue ball with no english on it through friction. This is sometimes called "collision-induced throw". The direction of the throw depends entirely on the direction the cue ball hits the object ball from. Unlike throw caused by spin, friction from a collision induced throw "pushes" the cue ball in the same direction as the cue ball was traveling before impact. Thus, a cue ball traveling from the left will cause an impacted object ball to be thrown slightly to the left of the natural angle it would otherwise be sent.
Both varieties of throw are highly influenced by speed. Generally, the less momentum the cue ball possesses at the time of impact, the more that throw will affect the object ball's resultant path of travel.
[edit] The semi-massé ("curve" or "swerve") shot
A cue ball can be made to curve in its path of travel with a semi-massé shot. This is usually employed for the purpose of avoiding an interfering ball or balls. In order to achieve a curve, a player's cue stick must be elevated and the cue ball struck with english. A curve to the left is accomplished by hitting the cue ball with an elevated cue and left-hand english. A curve to the right is accomplished by hitting the cue ball with an elevated cue and right-hand english. The higher the elevation of the cue, the more steep the degree of curve. The more speed a cue ball is hit with the farther it will travel in the direction it was hit before beginning to curve.
Such shots are typically referred to as "curve shots" by North Americans and "swerve shots" by the British (not be confused with the swerve effect, below).
Much steeper curves and even reversal of cue ball direction can be achieved with a massé (below).
[edit] The massé shot
"Massé" refers to imparting a high degree of spin along the vertical axis and often on the horizontal axis as well, such that the cue ball reverses direction, sharply curves, or both a few moments after being struck without the necessity of ever contacting another ball or rail.
A massé is performed by hitting the cue ball with a highly elevated cue stick. In general, the degree of a curve depends upon the distance from the center of the ball that the contact is made (the further from the center that the tip contacts the cue ball, the sooner the ball will begin to curve). The delay between the time that the ball is hit and the time that it starts curving is determined by the elevation of the cue but (the more elevated it is, the more the ball curves). Massés are quite difficult for non-experts, and are not allowed in some venues, as the table's cloth can be easily damaged by unskilled players.
[edit] Swerve effect
Whenever a pool ball is struck with any degree of english, and with a cue that is not perfectly level, a curve results. In the two immediately-preceding sections, intentional curves of lesser and greater degrees were described. However, because in most billiards shots, the cue is slightly elevated, if english is employed, an unintentional (and imperceptible to the naked eye) curve results. This is known as "swerve" or "the swerve effect". The farther away an intended target is from the cue ball's original shooting position, the more swerve of the cue ball will affect where the cue ball arrives. For this reason, use of english (and unintentional english) are complicating factors in billiards and swerve must be compensated for. The swerve effect should not be confused with a "swerve shot," previously defined as commonwealth terminology for a curve shot.
[edit] Deflection (squirt)
"Deflection" can be described as displacement of the cue ball from the aimed direction in the opposite direction of the side english was applied. Like the swerve effect, deflection is an unwanted complicating factor in pool, present whenever english is employed.
The physics of deflection has been studied extensively. Basically, when english is used, the cue ball will always begin its travel in a direction not exactly as aimed; it will "squirt" off of the line parallel with the cue's direction. Deflection increases the faster the cue stick is traveling at impact and the more english has been applied.
Deflection can be decreased by the type of cue used, and at the high levels, players will often select a personal playing cue based on the amount of squirt the cue imparts (the less the better).
Because swerve and deflection (for very different reasons) each cause the cue ball to take a different path than aimed, but each does so in the opposite direction of the other, under the right conditions swerve and deflection can cancel each other out.
[edit] The jump shot
A "jump shot" describes any shot where the cue ball is intentionally driven into the air in a legal manner. It is not permissible in some games (e.g. Snooker) and may be frowned upon or even forbidden in some venues as attempts at it by unskilled players may cause damage to a table's cloth. A legal jump shot requires that the cue ball be hit above center, driving it down into the table, such that the ball will leave the table surface on a rebound. All authoritative rule sources deem it illegal to "scoop" under the cue ball with the tip of the cue to fling it into the air (technically because it is illegal to contact the cue ball with the ferrule of the cue, and because the cue ball is struck twice, both of which are classic fouls).
Unintentional small jumps are ubiquitous to billiards. In most billiards shots, a player's cue is slightly elevated. Whenever a ball is struck with an elevated cue, a jump, no matter how slight, occurs. An oft-used way to illustrate this principle is to lay a coin on the table approximately an inch in front of the cue ball. When shot very softly, the player will audibly hear the coin being struck and see the cue ball's reaction to that collision. When the same shot is performed with any degree of speed no sound or collision is evident, and it is clear that the coin is being jumped.
[edit] References
- ^ a b Harris, Walt (December, 1991). The Billiard Atlas on Systems & Techniques [Vol. 1]. Cocoa Beach, Florida: Billiard Atlas, "Introduction" at p. xvii.. ISBN 0-9631204-0-9.
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