The Curling School
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This section will cover a wide variety of sweeping topics. Specifically, the areas covered are:
In the early days of curling, when games were played outdoors on the lochs, snow and other debris had to be cleared from the path of the moving rocks. Bunches of sticks were used as debris clearing devices. However, as the sport evolved, it became clear that, in addition to clearing debris, vigorous sweeping affected the moving rocks.
The purpose of sweeping is twofold:
1. Sweeping makes the rock travel farther.
2. Sweeping makes the rock travel straighter.
Before discussing the mechanics of sweeping, it is important to understand what is happening underneath the rock as it travels down the ice. Curling rocks are approximately 12 inches in diameter; however, there is a smaller, ringed portion that the rock rides on. This narrow ring is about 5 inches in diameter and is called the running surface.
Rocks are intentionally rotated either clockwise or counter-clockwise when thrown. Most rocks, if thrown without a rotation, will assume a rotation at some unpredictable point. Intentional rotation provides the necessary degree of predictability as the rock travels down the ice. As the rock is rotating, one side of the running surface will always be moving faster than the other as it travels over the ice surface.Example: When a rock traveling down the ice has a clockwise rotation, the left side of the rock is traveling faster over the ice than the right side.
There are several explanations of why rocks curl. Most of them are very technical and hard to follow. The following explanation is very straightforward and easy to understand. Some people may disagree with the exact details of why rocks curl.
The running edge of the rock that is moving faster is known as the "outside edge" and the slower side as the "inside edge". Objects moving faster create more friction. The faster edge has more friction than the slower edge. Because the fast side (the outside edge) has more friction, it causes more "frictional melting" of the ice. Since ice with a small layer of water on it is more slippery than dry ice, the slippery side (fast side or outside edge) bites the ice less. The slow side bites more causing it to "pivot" to the right. Therefore, a rock with a clockwise rotation will curl from left to right.
How Sweeping Works
The sweeping motion briefly polishes the ice just before the rock travels over it. Warming the ice slightly increases the overall frictional melting and allows the rock to continue moving. This results in the rock traveling farther. This is technically defined as decreasing the rate of deceleration. The overall reduction in friction has another effect: Since the rock is biting less on both sides, the rock will travel straighter.
Sweeping cannot make a rock move faster, only farther!
The Weight Window
The amount of force necessary to propel a rock forward is known as "weight". Good sweepers can add an additional 8 - 12 feet to a rock's distance. This is important to know because, as you are throwing the rock, your throwing weight needs only to fall inside this 8-12 foot "weight window". This provides a fairly comfortable margin of error for the thrower.Example: A rock thrown 8 feet short of the house without sweeping can easily be swept into the house by good sweepers. As a thrower, your responsibility was to hit the window and not the actual finished shot. This is what makes sweeping such a critical part of the game.
There are a variety of sweeping devices being used today. Synthetic-type as well as the traditional horsehair or hog's hair. The more popular synthetic brooms have a fabric, such as Cordura, stretched over a padded surface. Although introduced many years ago, these synthetic brooms became popular in the early 1990's and are the standard sweeping device today. They are very effective and keep the ice very clean. Some people argue that the synthetic brooms are so effective in polishing the ice that they erode the valuable pebble that the rocks ride on. This creates an undesirable "flat" surface with more friction.
CurlTech Choice for individual (league type) sweeping:
#1 Hammer XL adjustable
#2 Any "swivel" type
The above brooms have the flexibility to sweep on both sides.
Let's talk about what makes a good sweeper. The best sweepers today are effective and efficient. Sweeping effectiveness has been the focus of much debate over the last thirty years or so. While many people argue that the most effective sweeping comes from rapid movement of the brush, others argue that effective sweeping is caused by increased pressure of the brush on the ice. CurlTech believes that a strong balance of both will achieve optimum results. Rapid movement with as much pressure as possible is what great sweepers strive for.
Sweeping efficiency refers to a sweeper's ability to be the most effective while using the least amount of energy. The sweeping style discussed in this section is the preferred method of most top teams. The method, known as "sweeping high" is the best combination of effectiveness and efficiency.
The Sweeping Stroke
To start sweeping properly, take a standing position that is 45-90 degrees to the rock's path, trying to face the rock and the skip at the same time. With the brush head on the ice, place the inside hand (the hand closest to the rock) on top of the brush handle about half way down. This is the bottom hand and it will be supporting much of your body weight during the sweeping stroke. The outside hand (top hand) should be placed underneath the handle about one foot from the top. The end of the handle will be tucked into the arm.
The rules state that you must move the brush from side to side. It is not clearly stated as to what side to side really means only that it should "roughly perpendicular" to the rock's path. The most effective sweeping motion is approximately 90 degrees to the rock's path and covers an area just wider than the running surface, (remember, it's only five inches). A sweeping motion that is shorter than this is subject to scrutiny by the officials and a motion greater than this is waste of energy. The stroke should be away from your body, and then back towards your body. Keep your top arm tight to your body. By staying tight, you will begin to put more and more pressure on the head as you begin to move your weight over the top of the brush.
The power of the sweeping stroke comes from the top shoulder. The shoulder "drives" the brush head out and pulls it back. Because of this, most right-handed curlers (strong right side) will feel more comfortable sweeping on the right side of the rock.
For best results, place the strongest sweeper about 4 to 5 inches in front of the traveling rock. This is called "taking the rock". Move the brush head across the path approximately 3 inches (the brush width is approximately two inches so the movement plus brush width will cover the five inch running surface). The "angle" brush is slightly different and is discussed later. The second sweeper should be as close as possible to the inside sweeper without risking contact with the brushes. As a beginner, you may want to stay well clear of the rock to avoid hitting it with the brush. The most effective team sweeping is with the sweepers on opposite sides because the brushes can easily stay close together. Eighty percent of team sweeping effectiveness comes from the inside sweeper. The outside sweeper representing the other twenty percent. However, the only way the inside sweeper can achieve this eighty percent is with the second sweeper present. The lead sweeper (farthest away) prepares the ice for the inside sweeper. They work together to create great sweeping. Sweeping with only one person will reduce the effectiveness by fifty percent.Note: Adding a third sweeper accomplishes almost nothing. As a skip or a thrower, avoid "jumping in" to help. This is a waste of time and only increases the chances of you or a teammate burning a rock.
The Adjustable or "Angle" Brush. The angle brush is a standard brush with the head turned at a 45-degree angle. It was created to cover the entire running surface while using a shorter stroke. This was done to keep the path as clean as possible without the need to move the brush quickly (Figure 2). Another strong benefit of the angle brush is the decreased distance between the inside and outside sweepers since the angle brush head is perpendicular to the path instead of parallel.
The Foot Motion
In the delivery section, the use of a slider was discussed. Proper sweeping must be done without a slider. If you throw with a slider, remove it for sweeping. If your slider is built into your shoe, cover it with a gripper. Sweeping effectiveness requires a solid platform to sweep from. The proper sweeping motion, when moving with the rock, looks like a skating motion. Walking fast or jogging next to the rock is not very effective or efficient. As you move with the rock, your inside foot should be skating forward. Your outside foot should also be skating forward but it will lead the body. The outside foot will extend much farther than the inside. The inside foot should also never cross the outside foot during the motion. The most pressure is created when the body weight is over the top of the brush. This can only happen using the tripod method (Figure 2) with two feet and a brush head. In the beginning, you will have to support your weight on your feet. When you become more comfortable, begin to shift more and more weight onto the brush head.
To have the greatest degree of flexibility with your teammates, learn to sweep effectively on both sides of the rock. This will allow you to sweep with anyone at any time.
Preparing to Sweep As the shooter prepares to throw the rock, the sweepers must take a position near the tee line and the side lines. This allows the shooter to view the skip. As the shooter begins to come out of the hack, the sweepers slowly meet the delivery at or near the hog line. When finished, move immediately to the sides and walk back.
Read more about advanced sweeping techniques and team sweeping in the Advanced Sweeping section.
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