Curling

Curling is one of the sports games in Sochi Winter Olympics which attracts my attention for a while. There are tournaments among teams of different countries of the world. In this Olympics, the champions in Men’s and Women’s Curling all go to the strong teams of Canada.

In a Curling game, players slide stones on a sheet of ice towards a target area which is segmented into four concentric rings. Two teams, each of four players, take turns sliding heavy, polished granite stones, called rocks, across the ice curling sheet towards the "house", a circular target marked on the ice. Each team has eight stones. The purpose is to accumulate the highest score for a game; points are scored for the stones resting closest to the centre of the house at the conclusion of each end, which is completed when both teams have thrown all of their stones. A game may consist of ten or eight ends.

The curler can induce a curved path by causing the stone to slowly turn as it slides, and the path of the rock may be further influenced by two sweepers with brooms who go with it as it slides down the sheet. On the way, the sweepers use their brooms to rub on and melt the ice in front of the stone. A great deal of strategy and teamwork go into choosing the ideal path and placement of a stone for each situation, and the skills of the curlers determine how close to the desired result the stone will achieve. This gives curling its nickname, "chess on ice".

It is interesting that sometimes a team send some stones out to guard the area around the “house” so as to protect their own stone(s)  near the centre of the house from being hit away.

The process of sliding a stone down the sheet is known as the delivery.

The skip, or the captain of the team, will usually determine the required weight, turn, and line of the stone. These will be influenced by the tactics at this point in the game, which may involve taking-out, blocking or tapping another stone.

Please note the following points:
•    The weight of the stone is its velocity, which depends on the leg drive of the delivery rather than the arm.
•    The turn, handle, or curl is the rotation of the stone, which gives it a curved trajectory.
•    The line is the direction of the throw ignoring the effect of the turn.

The skip may communicate the weight, turn, line, and other tactics by calling or tapping a broom on the ice. In the case of a takeout, guard, or a tap, the skip will indicate the stones involved.

Before delivery, the running surface of the stone is wiped clean and the path across the ice swept with the broom if necessary, because any dirt on the bottom of a stone or in its path can alter the trajectory and ruin the shot. Intrusion by a foreign object is called a pick up or pick.

After the stone is delivered, its trajectory is still influenced by the two sweepers under instruction from the skip. Sweeping is done for two reasons: to reduce friction underneath the stone, and to decrease the amount of curl. The stones curl more as they slow down, so sweeping early in travel tends to increase distance as well as straighten the path, and sweeping after sideways motion is established can increase the sideways distance. When sweeping, pressure and speed of the brush head are key in slightly increasing the layer of moisture that builds up under the stone.

One of the basic strategy aspects of curling is knowing when to sweep. When the ice in front of the stone is swept, a stone will usually travel both farther and straighter. In some situations, one of the two alterations in path is not desirable. For example, a stone may have too much weight, but require sweeping to prevent curling into a guard. The team must decide which is better: getting by the guard but traveling too far, or hitting the guard.

Much of the yelling that goes on during a curling game is the skip calling the line of the shot and the sweepers calling the weight. The skip evaluates the path of the stone and calls to the sweepers to sweep as necessary to maintain the intended track. The sweepers themselves are responsible for judging the weight of the stone, ensuring the length of travel is correct and communicating the weight of the stone back to the skip. Some teams use stopwatch timing, from back line to the nearest hog line as a sweeping aid. Many teams use the Number System to communicate in which of 10 playable zones it is estimated the stone will stop.

Sweeping is allowed anywhere on the ice up to the tee line, as long as it is only for one's own team stones. Once the leading edge of a team stone crosses the tee line only one player may sweep it. Additionally, when a stone crosses the tee line, one player from the other team is allowed to sweep it. This is the only case that a stone may be swept by an opposing team member. In international rules, this player must be the skip; or if the skip is throwing, then the sweeping player must be the third.