Why does sweeping help in curling

This also causes the stone to spin, or curl, which is where curling gets its name. The added slidey-ness technical term , also makes the stone go farther, which allows the thrower to play a little more fast and loose with how hard the stone is thrown. According to The Curling School, the distance window for the thrower is actually pretty wide, and the sweepers are mostly responsible for where the stone ends up:. This provides a fairly comfortable margin of error for the thrower.

But the opposite happens in curling due to another phenomenon. Shegelski believes that the high pressure warms the ice more in the front, which creates a very thin, liquid film. The melted ice acts as a lubricant to reduce the force of friction at the front of the rock. The friction at the front of the stone, which is exerted to the right, is now less than the friction at the back, which is to left, so the rock curls left.

Curling is not played on smooth ice used for sports like bobsledding or skating. Instead the surface has little bumps, called "pebbled" ice, made by spraying tiny droplets of water on the ice that freeze.

The curl is too much on smooth ice, making it hard to herd the stone toward the target. Pebbled ice is used because it makes the spin controllable, according to Shegelski.

In addition, the curling rock is made from a rare granite that repels water well. This "waterproof" property keeps the rock, which is slightly hallowed out on the underside, from suctioning to the surface of ice and getting stuck. In the game of curling, sweeping is critical.

It's what changes the path of stone after it's thrown down the ice. Sweeping works by warming up the ice and reducing friction, which makes the rock curl less and therefore move straighter, says Shegelski. Because of this the rock runs straighter. Sweeping the outside edge of a draw could make it curl more but seems to be much less effective.

Corner sweeping results in more manipulative sweeping. This could result in less predictable shots. CurlTech suggests you leave corner sweeping for emergencies only. Our staff members have seen corner sweeping in action and work very well. We've also seen disastrous results from corner sweeping every shot. If you really need to get around that guard, use it.

Even though corner sweeping may be more effective, most good teams prefer to concentrate on good overall sweeping skills. Fixed Head Differential Pressure The most effective way to corner sweep is to use differential pressure. This can only be achieved using a fixed-head broom. Swivel types don't work as well and are covered in the next paragraph.

Start by covering the five-inch running surface with the head of the broom. This will give you good coverage to begin with and is a good overall technique. Once you hear a panic call from your skip, "twist" the handle to apply pressure only on the desired side.

We suggest you use good, solid sweeping most of the time and twist in the extreme cases. Working the edge is nearly impossible with a swivel type broom. Forward Stroke Corner Sweeping Most curlers today use some type of swivel head broom. Swivel head brooms offer maximum head contact with the ice at almost any angle. The downside to the swivel is that you cannot use differential pressure.

Since differential pressure is not an option, the inside edge of the rock can be swept by using a stronger forward stroke than return stroke. This happens naturally since it's easier to drive the broom away from the body rather than back toward the body. Sweepers must identify the inside edge on each shot and the person "taking the rock" changes. Note:To straighten a rock, corner sweeping and directional sweeping use roughly the same stroke.

So far, no studies have been done on which mechanism is dominant. In , a new fabric type was introduced to broom technology. Instead of the standard weave that had been used for decades, a "bi-directional" weave was created.

Immediately, curlers protested the design as being inconsistent with the principles of the sport. Apparently, the new fabric scratched the ice surface and allowed much more control of the curl.

Similar to the corner sweeping principle, sweepers could target the area to scratch one side to keep straight, the other to curl more with greater, almost unnatural results. It did not take long for the new fabric to be outlawed. The WCF, citing too much control over the rock and possible ice surface damage, instituted a moratorium on the use of this fabric. The idea of directional sweeping, the millennial version of corner sweeping, evolved from the new fabric controversy.

Sweepers argue that the brush stroke, which is more powerful on the forward stroke than the return stroke, could effectively reduce friction on the inside edge. This is slightly different than the old corner sweeping because it focuses on the direction of the outward stroke instead of the result of the pressure. Since there is no way to change the pressure on a swivel head broom as opposed to the fixed head , the direction of the stroke causes scratches in the ice that the rock tracks on.

In addition, sweepers argue that a second sweeper on the opposite side would "counter" the work of the inside sweeper. As a result, you will see only one sweeper working the inside edge of a rock that needs to be straightened. Mechanics of Directional Sweeping Straightening To keep a rock straight, take a position on the inside of the curl right side on an in-turn for example with your body at a degree angle to the line of delivery.

Drive the broom away from your body at a starting at a point on the inside of the running surface. This will create scratch grooves in the ice up to 45 degrees to the line or path. Since rocks, in part, curl see the Why Rocks Curl Section by channeling the natural rock scratching, the rock will stay straighter trying to move over the grooves and not with them.

Be sure to cover the entire running surface area of approx. This will create scratch grooves in the ice near 45 degrees to the line. In theory, the rock will curl as it moves with the grooves and not over them. Be sure to cover the entire running surface area of approximately five inches.

Parallel scratching on draws Consider this… In theory, our brooms create scratches and grooves that effect the rock. On draws that do not need straightening or more curl, try sweeping more "with" the rock, near parallel to the natural scratches created by the rock.

This could create grooves that rock can move with and not against. You Decide: Creating parallel grooves requires one sweeper to sweep parallel to the natural scratch, the brush stroke prevents the second sweeper from staying close. Is it better for two sweepers to sweep at opposite degree angles?

This would create a "neutral" scratch condition allowing the rock to travel farther. In the Delivery Section, rotating the rock at release is discussed in depth.

Many curlers at all levels target rotations. In the "Why Rocks Curl" Section, the natural scratching of the running surface over the ice is explained.

It is suggested that the ice is scratched by the leading edge of the running surface as it decelerates. This creates a scratch 90 degrees to the path of the rock. Since the rock is also moving forward, the natural scratch will get shallower as the rock travels faster see the hart below. To summarize, the scratches created by the rock itself are dependent on how hard the rock is thrown and how fast it is rotating.

Because the variability of the natural scratches, the speed and rotation change the angles needed for directional sweeping. For carving, the broom scratch angle should be just outside the natural scratch angle degree natural scratches would require a broom scratch angle of 50 degrees. This not only compliments the natural scratch action, but it also helps the rock curl beyond its natural non-swept ability. Consider the following chart for directional sweeping.

Not for distance. Draw Time To complicate matters further, the rock will decelerate in speed faster than it will in rotation. This means the sweeping scratch angle will sharpen as the rock approaches the house. It's important for teams to agree on a rotation standard for the sweeping angles to match each player. A team member who throws 2 draw rotations will need a shallow angle 20 while the team member throwing 5 rotations will need a deeper angle Most curlers associate sweeping with rocks traveling farther and straighter.

This is true for most shots. There is a case though when sweeping will cause a rock to appear to curl more. As a draw is coming to rest, many newer curlers continue to sweep the rock in an attempt to keep it straight. Sweeping will keep the rock moving, which means it continues on its path. Imagine the arc of a rock that is curling. It begins straight then starts to curl see The Curl Profile.

If the rock could move forever, it would eventually leave the sheet of ice across the sideline. Sweeping rocks after the curl begins does two things: It reduces the amount of additional curl.

It keeps the rock moving on its current path. Finishing the rock refers to keeping it moving on its arc. This pulls the rock even deeper behind a guard because the rock is still moving on its curl path. This is important to know since many come-around shots can be "finished", meaning the rocks can be swept under the guard.

The mistake many new skips and vices make is to stop sweeping. This only makes the rock stop short and not continue to curl under. On the other hand, if a rock is curling too much at the end, stop sweeping.

Additional sweeping here will only continue the rock's path. Directional sweeping can help here. Not only will it keep the rock moving, but it may also help the rock curl more. Directional sweeping can offer something never seen before when it comes to finishing the draw. Directional sweeping on the inside of a finishing draw may keep it from curling. Be careful and test this theory yourself. The sweepers are responsible for split-timing shots.

Split timing short times is an excellent sweeping tool to help manage weight judgement and distance. As mentioned earlier in this section, sweeping can dramatically affect any given shot. Whether it's a takeout thrown narrow or a draw that needs help, effective sweeping is essential. Like many systems, sweeping effectiveness is measurable. Brush head pressure and head speed are the two quantifiably measured components. Head speed is measured by the number of brush strokes per second.

Out and back equals one stroke. Head pressure is measured by pressure sensors in the head of a special test broom. Since curlers are different sizes, the standard is measured in percent of body weight applied to the head.

Coverage is measured by sustained coverage of the running surface, approximately five inches. Of course, these standards must be maintained for the entire sweeping session, sometimes the entire length of the shot. Do not expect to achieve the high-performance standard without being in top physical shape.

Strength, particularly in the arms, shoulders and core is required to maintain the high-performance standard. The shoulder drives the brush out and the core pulls it back. A sweeping system is an interrelated group of sweeping activities. Teams should design their own system by compiling known and proven components. The best team brooms are the ones that create the most friction with the least effort and allow the two sweepers to sweep in close proximity.

Lighter, carbon fiber handles dramatically reduce the weight of any broom reducing fatigue, particularly over longer competitions. The carbon fiber handle brooms are slightly harder to control due to the lack of weight. Head "float", meaning the head of the broom drifts off the line, may result during the transition to these brooms.

As the head grabs the ice, the friction pulls the head toward the rock causing an oval pattern to the sweeping stroke. Many teams, however, will agree that the advantages outweigh the disadvantages of these brooms. For team sweeping, where the players are in fixed positions for each shot, swivel-head brooms provide the best coverage. If using fixed angles, it will be necessary to switch brooms for different players. A team switching system is simple if the players are in proper position after each shot.

A team can own four broom types for efficiency. A straight broom for sliding and skipping and angles for sweeping. CurlTech Choice for team sweeping equipment: 8" or 10" light weight swivel. Sweeping Style The same sweeping style described earlier in this section should be used by the advanced players.

The sweeping stroke must be short, vigorous and with as much pressure as possible. Why are they sweeping the ice? Curling is named after the unique turning that occurs at the end of the stone's path on the ice. The curling stone, or rock, is made of dense polished granite from Ailsa Craig, Scotland, and in the Olympics, each rock weighs The bottom of the stone is concave so that only the outside ring, called the running band, is in contact with the ice.

This minimizes the friction and allows the stone to slide farther. So what causes this curling motion? Each ice sheet is different. The reason the ice has bumps and the reason the teams sweep the ice in front of the stone are both to control friction and control the curl of the stone.

Adding bumps to the ice is known as pebbling. Ice technicians sprinkle two layers of water droplets on top of the ice that freeze to form two heights of bumps. The pebbles, just like the concavity in the bottom of the stone, minimize the surface area of the rock and therefore minimize the friction.

If the ice were flat, the friction on the stone would be too high and the rock would not travel half as far.