Curling 101: Rules

Curling 101: Rules

Erika Brown curling at the 2014 Sochi Olympics

The Playing Surface    

The playing surface in curling is 150 feet (45.7 meters) long and 16 feet, 5 inches (5 meters) wide. The ice is set up to accommodate play in both directions, meaning the surface is symmetrical with four concentric circles, known as the house, at each end. 

The center circle, or the tee, of the house is 1 foot in diameter, the next circle is 4 feet, the next 8 feet and the outside circle 12 feet. This outside circle marks the edge of the house.

Players start a stone moving from a rubber block called the hack. The hack is 126 feet from the tee line, which is at the center of the house. Players swing the stone back and then forward before pushing off from the hack and sliding along the ice. Players must release the stone before the front edge touches the hog line, a line running width-wise through the center of the tee at the other end. The hog line is located is 33 feet from the hack and 93 feet from the tee line.

At the rear edge of each house is the back line.  It is located 6 feet from the tee line.

Free Guard Zone

The area in front of the house, between the hog line and the tee line (not including the concentric circles of the actual house) is known as the Free Guard Zone. No stone in this area may be removed from play by the opposition until the first four stones in an end have come to rest. Players are allowed to bump other stones with shots, but are not allowed to knock a stone out of play. 

Any shot played when the Free Guard Zone rule is in effect that results in an opposition stone being knocked out of play is an infraction. In this case, the played stone is removed from play and any other stone that was moved is replaced. For any stone lying within the house, normal rules apply at all times.
    
This rule was enacted in 1991 to hinder defense-oriented play. In the past, teams would knock out one another’s rocks repeatedly resulting in low scoring games that were considered boring.

Sweeping    

After a stone is thrown, players are allowed to sweep the ice in front of the stone. Sweeping clears the ice of any debris that might slow the stone down or send it off course. Sweeping also melts a thin layer of ice that reduces friction and thus increases the distance the rock travels. 
    
Sweeping is allowed by any player on the throwing team between the two tee lines. Players are not allowed to sweep opponents’ stones in that area. 

Behind the tee line at the playing end (where the stones stop moving), only one player from each team may sweep at any one time. This may be any player of the delivering team, but only the skip or vice-skip (third) of the non-delivering team.

Only stones in motion – termed “running stones” – may be swept. Players may not touch any stones while sweeping. Also, they may only sweep in front of the stone, in a direction perpendicular to the direction of motion.

Players are allowed to sweep stones that are set in motion by other stones.

Player substitution

If a player is injured and cannot continue to play, or cannot start the game, the team has two choices. One is to continue the game with only three players, with the first and second player in the lineup each throwing three stones. The second is to insert the alternate into the missing players spot at the start of the next end. The playing rotation can be changed when a substitute enters the game.

Violations

Hogline violation 

If a player releases a stone after it has touched the hogline, a violation is called and the stone is removed from play. If the stone has hit another stone, all affected stones are put back to their original location.

Touching a moving stone

1) If a moving stone is touched by anyone on the playing team or their equipment, the touched stone shall be removed from play immediately. The opposing skip may return any stones the touched stone has affected back to their original position. If, however the opposing skip believes the removal of the stone would be beneficial to the offending team, then the skip may place the stone as nearly as possible to the position he or she believes it would have come to rest. That skip may also reposition any stones that would have been displaced had the moving stone not be touched. He also has the choice to leave the stones where they are. 

2) If a moving stone is touched by the opposing team, the stone shall be placed where the skip of the team to which it belongs believes to would have come to rest had it not been touched.

Touching a stationary stone

1) If a stone that would have altered the course of a moving stone is displaced by the playing team, the moving stone shall be allowed to come to rest and may either be left there or removed from play at the discretion of the opposing skip. If the stone is removed from play, then all displaced stones shall be placed where they were originally. If the moving stone is left in play, the other stones shall be left as well. 

2) A stationary stone that is displaced but has no effect on the outcome of the shot shall be replaced where it was originally by the opposing skip.

Playing out of order

If a player delivers a stone out of order, the stone is removed from play immediately, provided the mistake is discovered before the stone has come to rest or struck another stone. The stone is returned and then delivered in the proper order. If the mistake is not discovered until after such an event occurs, the end shall continue in the normal fashion. The player whose turn was missed shall deliver the last rock for the team in the end.

Incorrect sweeping

If a stone is swept improperly by a team, the non-offending team has the option of allowing the play to stand, or of placing the stone, and all stones it would have affected, where they would have come to rest had the violation not occurred.

Shooting Percentage

The primary stat used to judge a player’s performance is shooting percentage, which essentially measures the player’s rate of success during a game. To determine shooting percentage, each shot is evaluated by a scorer on a four-point scale. Four points would be awarded for a perfectly executed shot, three points for a good shot, two points for a poorer shot, and so on. For very difficult shots, bonus points can be awarded, so a player could conceivably score five or six points (out of a possible four) on a particular shot.

A player’s shooting percentage is determined by dividing the number of points awarded by four times the number of shots taken. In a normal, 10-end game, the player’s total points would be divided by 80 (4 points per shot X 2 shots per end X 10 ends) to determine shooting percentage.
    
Since shots get more difficult as the end goes on, the skip, who shoots last, will generally shoot the lowest percentage and the lead, who shoots first, the highest percentage.

Awards

One gold, one silver and one bronze medal will be awarded to each member of the top three teams, respectively. Diplomas will be awarded to the members of the first through 10th-place teams.

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