A hack is what a player pushes off from whilst delivering a curling stone. The hacks are frozen into the ice so that they do not move when being used during the game. The base of the hack is made of metal and the two footholds on the hack are made of rubber.
Curling hacks are slightly elevated, angled rubber blocks that are secured to the ice. They provide athletes with a fixed object, ideal for pushing off of with the foot when delivering the stone. Competitors use their gripper shoe when doing so.
Generally, there is one hack on both sides of the centerline, for a total of two at either end of the curling sheet. They are fastened to a piece of wood, or another material, and are immersed in the ice. Conversely, there may be a single hack that can be moved about, allowing it to be repositioned from one side of the center line to the other.
In terms of official rules, the hacks must not be longer than eight inches and are placed six inches away from each other, three inches from the center line. The points fasted to the ice should also not be further than two inches below the ice’s surface.
If you are playing on arena ice, you need to heat the bottom of your hacks with hot water before they are placed into the ice.
On the metal bottom of a hack, there are holes along its edges. This allows the hot water that the hacks are heated with to freeze the hack into place, making it safe to use.
Typically, someone will stand on the hack for five to ten minutes after the hack is placed so that there is enough time for the water to freeze around it. If you didn't stand on the hack, it would not be firmly frozen to the ice.
If you are playing on dedicated ice, you may never see the bottom of the hack, as it is frozen in between the layers of the ice.
The Rubber Footholds
As mentioned earlier in Curling Sheet Parts, there are two rubber footholds, one on each side of the hack. If a curler is delivering the stone by pushing off with their left foot, they will place that foot in the right foothold. If a curler is delivering the stone by pushing off with their right foot, they will place that foot in the left foothold. We will see why this is the case later in Curling Stone Delivery Prep.