Curling Rocks - United States Curling Association (USCA)

Curling is a team game, where all four team members’ efforts contribute directly to each shot. Teams can be composed of both sexes and all ages, and like golf, curling is a lifetime sport. A curler at any skill level, like a golfer, finds that his or her skills decline only gradually from about age 45 onward. A national class curler, like the pro golfer, realizes that once the physical aspects are mastered, the mental aspect of the game separates the good player from the champion.

To continue with the golf analogy, it can be said that the curler who is at the height of his or her game has the same edge as the golfer who is sinking the key putts: great nerves, will to win, and mental toughness.

Historical and Descriptive Notes
It is generally agreed that curling was developed in Scotland in the 16th century. The climate in Scotland was colder then, and curling took place on the many marshes (since drained).
Scottish farmers curled on the frozen marshes using “channel stones,”  which were naturally smoothed by the water’s action. The principles of the game were similar to the modern game, although there were many differences in rules and equipment.

Scottish immigrants brought the game with them to North America, first to Canada around 1759, then to the United States around 1832. By 1855, curling clubs flourished in New York City, Detroit, Milwaukee and Portage, Wis. Curling in the rest of Europe developed in the 20th century.
Two developments ensured that the modern game would be marked by a high degree of physical skill and mental toughness:
    1. the standardization of the stone, and
    2. indoor, refrigerated ice.
The modern stone is round, and about 42 pounds. Curling is played, for the most part, on indoor, refrigerated ice, which helps ensure a fast, consistent and predictable playing surface.

The Game
A game is made up of 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.

A 12-foot circle (the “house”) is the scoring area. For each stone closer to the center of the circles (the tee) 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' 5" 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.

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. 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 broom)
   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 twist 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 guards.
Sweeping—with either a straw broom, hog hair or horse hair 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.