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Curling Boundary Rules

What tells you when a stone is in play or out of play in curling? Get ready to learn about the boundaries of a curling sheet.

Boundary Rules

In curling, there are three main lines that determine whether a stone is either in-play or out-of-play. The boundary lines on a curling sheet are called:

  1. The Sidelines
  2. The Backlines
  3. The Hog Lines

Below, is an image of the boundary zones for a curling stone. The shaded area represents where a stone can be considered in-play. Additionally, these lines also serve as a basis for where curlers are allowed to stand when their team and their opponent is shooting, which we will learn about in Curling Etiquette.

Curling In-Play Area

The Sidelines

If any part of a stone crosses the sideline, it is considered to be out-of-play, and is removed immediately. Usually, this does not happen when a stone is being thrown, but could occur. This may happen if the stone is thrown and hits another stone at rest, causing it to reach one of the sidelines.

Curling Sideline

The Backlines

If a stone fully crosses the backline, it is considered to be out-of-play, and is removed immediately. The stone is in-play as long as any part of it remains in front of the backline, even if it is just a tiny sliver of the stone.

Curling Backline

The Hog Lines

After a stone is delivered, it must fully cross the farther hog line to be considered in-play. Even if a tiny sliver of it is in front of the hog line, the stone must be removed from play. There is one exception to this rule. If a stone runs into another stone and cannot fully cross the hog line, it is allowed to remain in-play. This is because if the other stone wasn't there, the thrown stone would have crossed the hog line, and would be in-play.

Curling Hog Line

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