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Curling 101

 

See also:  Curling 101 - Review of Sport for 2014 Winter Olympics

In hopes of providing a simple explanation for how the great game of curling is played, the following explanation is provided. Watching a curling event is truly the best way to fully understand the game, particularly if having it explained by a curler as well!

THE ICE: A sheet of curling ice is dimensioned at 138 ft x 14 ft. Unlike hockey ice, the curling surface is carefully groomed by frequent shaving to keep it perfectly level. Before each game, a light spray of water droplets is applied to the surface and immediately freezes in place as a fine pebble. It is on this pebble that curling stones ride easily and react predictably to a player's delivery.

CURLING STONES: Curling stones are made from a shock-absorbing granite. Each piece of granite is carefully machined and balanced, and a goose-neck handle is added for the player's convenience. The result is a standard 42 to 44 pound rock, with a diameter of one foot, and a height of 4.5 inches, not including the handle.

SWEEPING: Sweeping in front of a running stone accomplishes several things. First, it cleans the path of any debris that may be on the ice that could otherwise alter the stones travel. Secondly, by applying pressure to the broom while sweeping in front of the stone, the ice is slightly warmed, creating less friction between the ice and the stone - this can help the stone travel further than it would have, and it can also affect the curl of the stone.

THE TEAM: A curling team consists of four players: the first player of the group is called the Lead, the second player is appropriately known as the Second, and the third is called (you guessed it) the Third, or the Vice-Skip. The Fourth, known as the Skip, is the captain of the team. He / she directs the strategy of the game and calls the shots. Though the order that stones are delivered typically follows this sequence, there are teams that play with the Skip throwing in a different position.

PLAY: A curling game is played according to the following procedures:

- The Skips of Teams A and B position themselves at the far end of the ice.
- At the near end, the Vices of Teams A and B flip a coin to determine which foursome will start first.

Let's say Team A loses the toss ...

- Team A's Skip moves into the house (circles, rings) at the far end, and calls for the first stone from Lead A.
- Lead A throws from the hack at the near end of the ice with the intent that the rock will come to rest at the far end position called by the Skip.
- The stone must be released by the Lead before it crosses the nearest hog line, and be allowed to run freely on its path.
- Team A's Second and Vice may help to control the path of the stone by sweeping, in front of it.

After Lead A's first rock comes to a halt ...

- Team B's Skip takes over in the house and calls Lead B's first shot.

When Lead B's stone comes to rest ...

- Skip A takes the house again to call Lead A's second rock.

Play continues in this alternating manner, until all members of both teams have delivered their two rocks.

At this point, the first "end" of play has been completed and the score is tallied (See OBJECT of the GAME, below). The team that posts a score in the end must then throw the first rock of the next end. The next and subsequent ends are played by simply delivering back to the opposite house.

An end of play normally takes about 15 minutes. The number of ends per game has varied greatly since the inception of the sport. Nowadays, a regular game, played for enjoyment and sociability, has eight ends. A competitive game, played for titles and prizes, normally has ten. Extra ends are added to break ties that may exist after regulation play.

OBJECT of the GAME: The object of the game is to complete each end with as many of your team's rocks closer to the button than the nearest of your opponent's stones. Scores are awarded as one point for each such rock.

It isn't as complicated as it may seem! To get a better idea of the game, talk with curlers at a club near you, or come to the club during a bonspiel or other event watch a game - curlers are always glad to explain the intricacies of the sport to newcomers.

 Different types of events and activities

Leagues - Regular, round-robin play between teams on a given league night. Each league offers a bit of something different.

Bonspiels - Bonspiels are scheduled events, separate and unrelated from leagues. They can be thought of as tournaments - though the style of the event varies from a relaxed 'fun spiel' to more serious 'cash spiels'.

Playdowns - Serious, competition level play. These teams are vying for the right to represent their club and state at the national and possibly the world curling championships.

Learn to Curl - Classes for teaching the sport of curling to newcomers, though sometimes the classes can help some of us old timers as well!

Other Events - Our club will occasionally hold other events that are unique unto themselves. These will be posted on the calendar as they arise.

TERMINOLOGY

Curling uses many terms unique to the game - we hope you find this list useful!

Back Board: Border at extreme ends of the sheet

Back Line: Crosswise line at back edge of the house - stone is out of play if it completely crosses this line

Back Ring: Diameter of 12-foot circle behind the tee line

Biter: Stone just touching the outside circle

Bite Stick: Equipment used to determine whether or not a stone is a biter

Bonspiel: A tournament in which a number of teams play in several events for prizes

Broomstacking: Socializing with other curlers after a game

Burned Stone: Contact is made with a moving stone by a person or equipment

Button: The 1-foot circle at the very center of the house

Cash Spiel: Tournament played by competitive teams, usually as a preparation for playdowns

Centerline: Line running lengthwise down the center of the sheet

Chip & Lie: When a played stone strikes the edge of another stone and moves to another position in play

Counter: Any stone lying closer to the center than any of the opponent's stones

Curl: Lateral swing on stone during its travel down the ice

Draw Weight: Enough weight (or momentum) for a stone to stop in the house

End: When all stones have been played from one end of the sheet to the other - there are usually 8-10 ends in a game

Free Guard Zone: Area in front of the house, between the hog line and tee line, where a rock cannot be removed from play by the opposing lead (Canadian rules vary slightly)

Freeze: When a stone has just enough momentum to stop just as it touches another stone

Front Ring: Diameter of 12-foot circle in front of the tee line

Fun Spiel: Bonspiel oriented to recreational/fun play, often shorter duration games, and may have unusual formats

Guard: A stone lying in front of another stone

Hack: An immovable brace for the foot in or on the ice at point of delivery

Hammer: Last rock to be delivered in an end

Hog: When a played stone fails to clear the far hog line - it is removed from play

Hog Line: Crosswise line 21 feet from the tee line

House: Scoring area, designated by rings - 12 feet in diameter

In-Turn: Stone rotating clockwise as it travels - it will curl towards the right

Keen Ice: When less effort is needed to deliver a rock a given distance

Lead: Player who delivers the first pair of stones for a team

Measure Stick: Equipment used to determine which of two or more stones is closest to the center when they are too similar to know with visual inspection

Narrow: Stone delivered "off the broom" - between the skips broom and objective

Northern Mixed: An event format where teams must have at least one person of the opposite sex on the team

Off-The-Broom: Stone not delivered on line to the skips broom

On-The Broom: Stone delivered directly at the skips broom

Out-Turn: Stone rotating counter-clockwise as it travels - it will curl towards the left

Pebble: Surface formed by sprinkling the ice with a mist-spray of water

Playdowns: Competitive play towards club, state, national, and world championships

Port: Opening between two stones sufficient to allow another stone to pass through

Raise: Hitting a stone, causing it to be advanced while remaining in play

Rink: (a) Group of players makeing up a team, or (b) a curling facility

Rock: Another term for 'stone'

Roll: Any movement of a stone after striking another

Second: Player delivering the second pair of stones for a team

Second Shot: Stone that is second nearest the center

Sheet: Ice area on which a curling game is played (146' long by 14'-15' wide)

Shot Rock: Stone that is lying closest to the center of the house

Skip: Captain of the team, often delivers the fourth pair of stones for a team

Slide: Forward movement of player during delivery of a stone

Spinner: Stone traveling with a rapid rotation

Steal: When the team without the last rock (hammer) scores in an end

Stone: A 42-pound, precisely shaped piece of granite with a handle attached (8 stones per team are used in a game)

Straight Handle: (also Dead Handle) Stone traveling without rotation

Sweep: To use a brush or broom in front of a moving stone to clean the path and/or to apply pressure to the ice in front of a moving stone to help it travel further and/or curl more or less

Swingy Ice: When curl or arc of traveing stone is greater than usual

Take-Out: Striking another stone hard enough to remove it from play

Tee Line: Crosswise line at center of house

Third: (also Vice-Skip) Player that delivers third pair of stones for a team and holds the broom and calls line while the Skip delivers his/her stones, the Third also determines the score in each end in conjunction with the opposing Third

True Mixed: An event format where the teams must have two men and two women, played in alternating positions

Weight: Speed of the traveling stone - determines how far the stone will travel before stopping, also affects how much a stone will curl in a given distance

Wick: (also Chip) When a stone strikes the edge of another stone

Wide: Stone delvered 'off the broom' - on the side away from objective

Wobbler: Stone that rocks from side to side as it travels because it is not resting on its running surface

 Many thanks to icing.org for parts of this thorough, but simple explanation of the game.

Just what ARE the forces that make a rock curl?

First, it is necessary to understand how a stone is able to move on ice.

The pressure of the 40-pound rock melts the ice surface which it comes in contact with, creating a thin layer of water, this water reduces the resistance or friction encountered between the rock and ice and enables the rock to move. The colder the temperature, the harder it will be to get and keep the rock in motion.

The same situation occurs in skating. Your weight exerted on the skate blade melts the ice under the blade - the skate actually rides on this thin film of water. If you have ever been skating in below-zero weather, you will readily appreciate how difficult it is to melt the ice - it then becomes very difficult to move at all, the frictional resistance is so great.

The type of ice surface played upon influences your game considerably. When the ice is pebbled, the stone comes in contact with less ice area than it would if the surface were unpebbled - only a portion of the running surface of the stone are in contact with the ice instead of the entire running surface area. Friction will naturally not be as great. However, as the pebble wears off and the stone gets closer to the ice surface, friction increases.

Scale is exaggerated for demonstration purposes

Possible forces which could cause a rock to curl:

1. Air Pressure

It has been suggested that the unequal flows of air on opposit sides of a moving rock will cause the rock to pull it to one side, according the application of a theory known as Bernoulli's Principal.

This, however, cannot explain why a curling stone curls. Because a curling stone is rotating so slowly, the friction with the air or pileup of the air on one side more than the other, must be negligible.

Dr. Harrington, late professor of physics and an ardent curler, conducted an experiment on an indoor ice rink in order to show the complete inadequacy of the air pressure theory as applied to curling. A number of stones were thrown down the ice and an electic vacuum cleaner was carried abreast of each stone thrown. The air blast from the nozzle was aimed at the stone in the opposite direction to the normal curling direction of the stone. The stone could not be made to depart appreciably from its path, even though the turn imparted was counter the direction of the air blast, the stone curled directly against it - and this blast of air was many times stronger than ever encountered by a stone in a curling game.

2. Ice Friction

The problem now involves studying the ice friction encountered by a moving rock, in order to deduce the causes underlying the motion of curling stones. A moving stone has two components of velocity: (a) a forward speed relative to the ice, which is called linear velocity; and (b) a rotational motion about the center of the stones own gravity, which is called angular velocity. This angular velocity is produced when you apply a torque or twist to your stone in order to give it an in- or an out-turn.

Suppose that a stone is thrown with an in-turn. The right hand side (viewed from the point of delivery) travels with resect to the ice surface at a slower speed than that of the left hand side. The left side of the moving stone has a combined speed of S+s (forward velocity + angular velocity (because the left side rotation is going with the forward motion)), whereas the right side has a combined speed of S-s (forward velocity - angular velocity (because the right side rotation is going away from the forward motion)).

In other words, there is greater friction on the right side of the stone.

Why does the stone sometimes 'hook' near the end of its run?

If the stone has an angular velocity that is relatively high, the velocity of the slow side may actually become zero as the speed of the stone decreases. What has happened is that the rotational speed has reached a point where it is equal to the forward speed. Because the rotational speed is going in a direction away from the direction of the forward speed, the forces cancel themselves out and the right hand side is actually inert, there is no movement at the point of contact between the stone and the ice on the on the right side. The right side 'sticks' to the ice and the stone will seem to whirl about the contact of the slow edge as a pivot. This is the 'hook' that you sometimes observe near the end of a rocks run.

Fast and slow rocks will actually curl the same amount, provided they are allowed to run their full course. A fast rock does not curl because the velocity is always above the critical speed - i.e. the speed at which friction becomes greater and has its effect on the slower moving side.

A fast-spinning rock doesn't grab the ice surface as hard as a slowly curling stone - hence less curl. Watch the rear wheel of a car on ice and you can see the same occurance. If the tire skids, it is spinning around at a high speed relative to the ice - but the tire doesn't grip the ice. When the tire does not skid, it is rvolving slowly at a low speed relative to the ice - and there is more traction. The tire grips the ice and moves in the direction desired.

 HOW TO READ THE SCOREBOARD

It's been said that, for the newcomer or non-participant of curling, the hardest thing about the game of curling is reading the scoreboard!

We're going to give you a (hopefully) simple explanation of a curling scoreboard.

Things to remember about scoring in curling:

- Only one team can score in each end
- The score can be from zero to eight points (maximum number of rocks per team) per end
- If a team scores in an end, that team delivers the first stone in the next end - they lose the hammer
- A scoreless end is called a 'blank end', the team that had the hammer in a blank end retains the hammer in the next end

How to read the scoreboard

This is a sample scoreboard and a description on how to read it - keep in mind the simple rules listed above!

- The colored blocks on the left end are the team colors, often represented as the handle color on the stones
- The numbers running to the right of each team color block represent the ends that that team scored, these are added to the scoreboard at the completion of each end
- The row of red numbers between the team rows is the running score, used by both teams - these numbers are permanent and do not change
- The bottom row, marked 'blank' represents ends with no score by either team

1st End: The BLUE team scores 2 (the '1' in the blue row represents the end, it is placed over the total points for the team at the completion of the 1st end). The score after the 1st end is BLUE=2, YELLOW=0

2nd End: The YELLOW team scores 1 (the '2' in the yellow row represents the end, it is placed beneath the total points for the team at the completion of the 2nd end). The score after the 2nd end is BLUE=2, YELLOW=1

3rd End: The BLUE team scores 1 (the '3' in the blue row represents the end, it is placed above the total points for the team at the completion of the 3rd end - 2 points in the 1st end plus 1 point in the 3rd end equals 3 total points for the blue team). The score after the 3rd end is BLUE=3, YELLOW=1

4th End: The YELLOW team scores 1 (the '4' in the yellow row represents the end, it is placed below the total points for the team at the completion of the 4th end - 1 point in the 2nd end plus 1 point in the 4th end equals 2 total points for the yellow team). The score after the 4th end is BLUE=3, YELLOW=2

5th End: The YELLOW team steals and scores 2 (the '5' in the yellow row represents the end, it is placed below the total points for the team at the completion of the 5th end - 2 points after the 4th end plus 2 points equals 4 total points for the yellow team). The score after the 5th end is BLUE=3, YELLOW=4

6th End: Neither team scored in this end (the '6' is placed on the row marked for blank ends). The score after the 6th end is BLUE=3, YELLOW-4

7th End: The BLUE team scores 2 (the '7' in the blue row represents the end, it is placed above the total points for the team at the completion of the 7th end - 3 points after the 3rd end plus 2 points equals 5 total points for the blue team). The score after the 7th end is BLUE=5, YELLOW=4

8th End: The YELLOW team scores 2 (the '8' in the yellow row represents the end, it is placed below the total points for the team at the completion of the 8th end - 4 points after the 5th end plus 2 equals 6 total points for the yellow team). The score after the 8th end is BLUE=5, YELLOW=6

This was an 8-end game, therefore the yellow team won 6-5.