Curling 101

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A game is composed of 8 – 10 ends (like innings). An end consists of each team member shooting (delivering) two rocks, or stones, alternately with the opponent’s player at the same position. When all 16 rocks have been delivered, the score for that end is determined.

Where To Play

A 12-foot circle (the “house”) is the scoring area. For each stone closer to the center of the circles (“tee” or “button”) than any of the opponent’s, one point is scored. The team scoring shoots first in the next end, giving the opponent the “hammer” or last shot of that end.

Teams will sometimes ignore taking a point to retain the next end’s hammer. The sheet of ice (playing surface) is 16 feet, 5 inches wide and 150 feet long, set up to accommodate play in both directions. Most curling takes place in curling clubs, which commonly have two to six sheets of ice. Hockey arenas are also used as temporary curling rinks; they accommodate up to six sheets.

Who Plays

All four players shoot two rocks per end, beginning with the player referred to as the “lead.” The “second” shoots next, and then the “third,” or “vice skip.” The skip usually shoots the last rocks and calls the strategy for the game.

How to Play

The skip decides on shot selection and “reads” the curl in the ice for the shooter. The shooter must be accurate in three functions:

  1. Aim (at the bottom)
  2. “Weight” (velocity imparted to the stone)
  3. Imparting the correct handle (curl) to each shot

Shots are called either to stop at a certain point on the sheet (“draws” or “guards”) or to have enough weight to strike another rock out of play (“takeouts” or “hit and rolls”). Each running stone curls, or curves, as it proceeds down the ice based on the turn given the handle during the delivery. The amount of curl varies based on the ice surface and the speed of the rock. The curl allows for better control of the stone and also provides a means to shoot around the guards.

Sweeping, with either a straw broom, hog hair or horsehair brush, or synthetic brush, adds the element of fitness to curling because, to be effective, sweeping must be very vigorous. Sweeping slightly melts the ice, which reduces the friction between the running stone and the ice. The result is that the stone will curl less and slide farther.

Sweeping is called for when the stone has not been delivered firmly enough and/or when the shot is aimed “narrow,” or inside the broom target. Sweeping can help a rock slide up to an additional 15 feet. Top teams control most shots by using aim and weight “within the sweeping zone.” Strategy is a major part of curling. Shots are played with an eye to the last rocks of each end, not simply placed at the center of the circles. The strategy can be rather complex. Innovations are constantly being made and adopted when the innovators win, similar to other sports where strategy and the game plan plays a major role. It is common for games between national-class teams to be very close, with both skips jockeying for the last shot in the last end.

Curling Stone (Rock)

The curling stone or rock is made of granite and, as defined by the World Curling Federation, is circular in shape and weighs between 44 and 38 pounds (20 and 17kg) with a handle and bolt attached. The stone has a maximum allowable circumference of 36 inches (910 mm). A stone must be a minimum of 4.5 inches (110 mm) in height. The handle is attached to the stone by means of a bolt that runs vertically through the hole in the center of the stone.

The handle allows the rock to be gripped and rotated upon release. When the rock is thrown with the right hand, the clockwise rotation is referred to as an in-turn; counterclockwise rotation is referred to as an out-turn. The opposites are true if the rock is thrown with the left hand. The handles are colored to differentiate the rocks belonging to each team. Two popular colors are red and yellow. The handle may be an “eye on the hog” variety for detecting hog line violations.

The top and bottom of a curling stone are concave. The surface in contact with the ice, known as the running surface, is a circle 0.25 to 0.50 inches (6.3 to 13mm) thick. This narrow running surface is where the ice and the stone interact. On properly prepared ice, the rock’s path will bend (curl) in the direction the front edge of the rock is turning, especially toward the end of its motion. The degree of curl depends on several factors, including the preparation of the ice and the flattening of common paths to the house during the game. Ice on which the rocks curl well is said to be “swingy.”

The Scots, in particular, believe that the best-quality curling stones are made from a specific type of granite called “ailsite,” found on the Ailsa Craig, an island off the Ayshire coast. According to the Scottish Curling Stone Company, ailsite has very low water absorption, which prevents the action of freezing and melting water from eroding the stone. In the past, most curling stones were made from this granite. However, the island is now a wildlife reserve and is no longer used for quarrying. Because of the particular rarity of ailsite, costs for curling stones can reach as much as $1,500 for the best stones. Many curling clubs use a lower grade of stone that can cost upwards of $500. There are also stones that use a disc with a running surface of ailsite attached below another type of granite. Very informal neighborhood curling clubs with limited resources may make cylindrical “curling stones” out of concrete-filled cans. Kays of Scotland has been making curling stone since 1851 and has the exclusive rights to Ailsa Craig granite as granted by the Marquess of Ailsa, whose family has owned the island since 1560. The last “harvest” of Ailsa Craig granite by Kays took place in 2002, yielding 200 tons. Kays of Scotland has been the exclusive manufacturer of curling stones for all three Olympics where curling has been a medal sport.


After both teams have delivered eight rocks, the team with the rock closest to the button is awarded one point for each of its own rocks that is closer than the opponent’s closest rock. Rocks that are not in the house (further from the center than the outer edge of the 12 foot ring) do not score even if no opponent’s rock is closer. A rock is considered in the house if any portion of its edge is over any portion of the 12-foot (3.7 M) ring. Since the bottom of the rock is rounded, a rock just barely in the house will not have any actual contact with the ring, which will pass under the rounded edge of the stone, but it still counts. This type of rock is known as a “biter.”

Last Rock (“The Hammer”)

Last rock advantage in an end is called the hammer. Before the game, teams typically decide who gets the hammer in the first end by coin toss or similar method. (In tournaments, this is typically assigned, giving every team the first-end hammer in half their games.) In all subsequent ends, the hammer belongs to the team that did not score in the preceding end. In the event that neither team scores, the hammer remains with the same team. Naturally, it is easier to score points with the hammer than without. In tournament play, the team with the hammer generally tries to score two or more points. If only one point is possible, the skip will often try to avoid scoring at all in order to retain the hammer until the next end, when two or more points may be possible. This is called a blank end. Scoring without the hammer is commonly referred to as stealing, or a steal, and is much more difficult.