If you want to be a good fast bowler in cricket, you may have heard your coach or other players tell you to work on your swing bowling. But what exactly does swinging a cricket ball mean, and how can you get better at it?
In cricket, the ball swing happens when a bowler makes the ball move to one side or the other in the air instead of bowling straight on the pitch. Swing bowling can be enhanced by increasing the speed of the bowl, increasing the ball’s roughness, or changing the position of the seam.
Today we are going to discuss the basics of the technique. We will review the science behind swing bowling. And we will give you some tips and drills that you can practice to improve your skills. If you want to play cricket, or more importantly, if you want to be good at cricket, then you need to learn how to master the art of swing bowling.
What Does Swing Bowling Mean in Cricket?
Swing bowling is when the ball curves or “swings” in different directions after it is released. When you swing the ball, you bowl it in a way that causes it to deviate sideways as it travels toward the batsman.
The cricket ball swings primarily based on the way the seam of the cricket ball is positioned in the wrist. Holding the ball in a particular seam position affects how the air flows around the ball while it is traveling toward the batsman. This causes the ball to swing either in one direction or the other.
Research done at the CSIR National Chemical Laboratory at Pune shows that six different factors determine the swing of the ball.
- The ball’s raised seam
- The direction that the seam is faced
- The wear and tear of the ball’s surface
- Any polishing liquid used on the ball
- The delivery speed
- The action of the bowler
To get a good swing with a cricket ball, the two sides of the cricket ball must be inconsistent with respect to each other. This means that one side will be smooth, and the other side will be rough.
Before we get further into the bowling swing, let’s discuss the ball itself. Cricket balls have a core made of cork. That cork is covered by a leather casing that is divided in half with a raised sewn seam down the middle.
As the game progresses, the surface on the sides of the ball begins to degrade. Wear and tear will start to show on one or both sides of the ball. This affects the symmetry of it, which then can allow the ball to swing. Players will often try to smooth one side of the ball so that it has one shiny side and one rough side.
This imbalance makes it easier to swing the ball in mid-air.
What Makes the Ball Swing?
Okay, let’s discuss some physics and aerodynamics for a minute.
After a bowler releases the ball, a thin layer of air forms on the ball’s surface, this is called the boundary layer. The boundary layer doesn’t wrap all the way around the ball. Instead, it separates from the ball’s surface at a certain point. This is called the boundary separation point.
Where the boundary layer separates determines the pressure. When you have a late separation on one side, you will get lower pressure on that side. That is where the swing comes from. The swing is generated when there is a difference in pressure or force between the two sides of the ball.
After the ball is bowled, the boundary layer of air exists in two different states: the laminar state and the turbulent state. The laminar state is smooth and steady. The turbulent state is just as the name suggests, chaotic and turbulent.
The state of the boundary layer is determined by either the smooth side of the ball or the rough side. How the boundary air transitions from a laminar state to a turbulent state depends on the surface’s roughness. The smooth side of the ball will create a laminar state, while the rough side will generate a turbulent state.
A laminar boundary layer can turn into a turbulent boundary layer when it is tripped with a disturbance. That disturbance can be caused by surface roughness or a local protuberance. When this occurs, the laminar layer is forced to become turbulent.
The turbulent layer contains more energy and activity. That means that it can stay attached to the surface of the ball for a longer distance than a laminar layer. And that causes the ball to swing.
What Is the Reynolds Number?
The Reynolds Number is how we determine whether the airflow around the ball will be laminar or turbulent.
To find the Reynolds Number, we use the equation R=Ud/v. In this equation, the U represents the speed of the ball. The d is the diameter of the ball, and the v represents the viscosity of the fluid.
A typical cricket ball has a diameter of 7.2 centimeters. If the ball is moving at a speed of 30 m/s, the Reynolds Number will be approximately 140,000. A Reynolds Number of more than 200,000 will cause turbulent airflow around the sphere. This is the point where the laminar flow turns turbulent.
As we have discussed, a rough surface on the ball encourages turbulence at lower speeds. This results in a reduction of the Reynolds Number.
The Rough and Shiny Sides to Swinging a Cricket Ball
Cricket balls are not smooth. Even when the ball is new and shiny, it will have printing and trademarks stamped on it. This small detail makes the ball slightly rough even before you start playing with it.
As you play the game, the ball gets rougher and rougher, and it loses its shine.
Fast bowlers will try to preserve the smoothness or shine on one side of the ball. They do this by polishing and rubbing the ball on their hands or pants. It’s important to note that they only shine one side of the ball. The other side will remain rough.
They do this because of the difference in the separation points with the boundary layer of air. Remember that this is what causes the ball to swing.
If you bowl with the seam pointing in the direction in which the ball is traveling or upright, this will cause the boundary layers to separate symmetrically around the sphere. The result of that will be no swing in the ball.
The above video further explains the scientific reasons behind both conventional swings and reverse swings.
How to Know the Direction of the Swing
Now, if you bowl the ball fast enough to exceed the Reynolds Number for the rough side of the ball, and if you have the shiny side faced forward with the seam upright, but at an angle, the ball will swing toward the direction where the seam is pointing.
Let’s say that the laminar boundary layer on the polished side of the ball separates at the 80-degree position. The rougher side of the ball will trip the boundary layer so that it becomes turbulent. This means that the airflow will separate more to the back of the ball.
When this happens, it causes the air pressure on one side of the ball to be lower than the other. You will have a higher air pressure on the shiny side of the ball, and that will create a force that pushes the ball sideways. All that means that the ball will swing in the direction that the seam is facing.
If the seam does not stay upright, the ball will not swing. This can happen when the ball spins during flight.
To prevent that from happening, fast bowlers will use some backspin as the ball leaves their hands. The backspin will keep the seam upright. The thing that makes swing bowling so challenging is that you have to find a way to control that backspin.
Role of Ball Speed for Swinging a Cricket Ball
The speed plays a big role in swinging the ball. One thing that we should know at the outset is that the best swing happens when the ball is not too fast or not too slow.
If you bowl too fast, then you will not be able to swing the ball. The reason for this is that the ball’s super-fast pace exceeds the critical value of the Reynolds Number. This can happen even when the ball is new.
When you bowl too fast, the boundary layer becomes turbulent on both sides of the ball. That means that there is no pressure difference between the two sides of the ball.
You will also have trouble swinging the ball if you bowl too slow. When the ball is moving too slow, the Reynolds Number will be less than the critical value. That means that the boundary layer will not become turbulent.
The problem with the ball traveling too fast or too slow is that you could end up with a consistent airflow (either laminar or turbulent) all the way around the ball. When this happens, there is no sideways net force acting on the ball.
If you want to swing the ball in cricket, then you must bowl at the optimal speed. Swing bowling is most effective between 112 and 135km/h. For reverse swing bowling, the optimal speed is 140-150km/h. We will talk more about the reverse swing in a minute.
Other Factors That Affect the Ball’s Swing
A cricket ball can swing in distances from 47 centimeters to 65 centimeters. It has been a long-held belief of cricketers that the ball will swing more if the weather is humid.
Another important factor in swing bowling is the seam position. The position of the seam determines the point at which the airflow around the ball turns turbulent. It not only controls where the separation point is but also directly affects the sideways force on the ball.
Ideally, you want the seam angle to be around 45 degrees from the ball’s motion.
Inswinger vs. Outswinger
The inswinger and outswinger are two different ways that you can swing the ball. An inswinger will swing the ball inward towards the batsman. The outswinger is the opposite. It swings the ball out and away from the batsman.
To bowl an inswinger, you will hold the ball with the seam vertical and your first two fingers just a little across the seam. You will want it to be angled to the leg side. You will also place the rough side of the ball on the leg side.
For an inswinger, you will hold the ball with the seam angled slightly to the right. You want the shiny side of the ball on the left-hand side as you hold it.
The video above will show you how to bowl an inswinger.
To bowl an outswinger, you will hold the ball with the seam at an angle. Your first two fingers should run along either side of the seam. You can also place one finger on the seam, depending on whether you are bowling to a right-handed batsman or a left-handed batsman.
To bowl a great outswinger, you must release the ball at a 12 o’clock position. And your follow-through will feature your hands moving a little toward the left and then pushing down to get a good backspin.
The above video will give you some tips on how to throw a proper outswinger.
How to Bowl an Inswinger to a Right-Handed Batsman
- First, grip the ball correctly.
- The seam should be upright and pointed toward the leg.
- Keep the shiny side of the ball facing the off-side.
- As the ball travels through the air, the seam should remain vertical and angled.
- The swing will move from the off-side to the leg-side, causing the ball to travel in toward a right-handed batter.
How to Bowl an Outswinger to a Right-Handed Batsman
- Grip the ball correctly.
- The seam should stay upright and pointed toward the third man.
- Keep the shiny side of the ball facing the leg-side.
- As the ball travels through the air, the seam should remain vertical and angled.
- The swing will move from the leg-side to off-side, causing the ball to travel away from a right-handed batter.
The Reverse Swing
Another type of swing bowling is the reverse swing. Once the ball has aged, you can bowl the reverse swing. To do this effectively, you must be able to bowl above 85mph.
A reverse swing is when the ball reverses direction in flight. This is a way to fool the batter. Instead of an expected outswinger, he will instead get an inswinger, and vice versa.
To bowl a reverse swing, you will angle the seam as if you were going to bowl a conventional swing. The difference is that you will face the rough side of the ball toward the batter.
If you bowl the ball at least 85mph, the laminar layer will go into a turbulent state before it gets to the seam. The seam will affect the turbulent layer so that it separates earlier than the bottom surface.
A lateral force is created just like with a conventional swing because of the difference in pressure on the two sides of the ball. But with a reverse swing, the lateral force works in the opposite direction.
I mentioned the critical speed that you need to reach to bowl a reverse swing. But it is still possible to generate a reverse swing even if you cannot reach that speed. In this case, the roughness of the ball helps to reduce the speed needed.
As the ball gets older and shows more wear and tear, the surface gets rougher. This makes it easier to reverse swing.
Sometimes players can get into trouble for trying to increase the roughness illegally. They take this risk because a rougher ball makes it easier to reverse swing at lower speeds.
How to Bowl a Reverse Swing
- First, you need one side of the cricket ball to be very scuffed and dry.
- The other side of the ball should be smooth, shiny, and damp from polishing.
- As the cricket ball travels through the air, the seam should remain vertical and angled.
- When you bowl at extremely high speeds, the ball will move toward the shiny side.
For some more great tips on how to bowl a reverse swing, watch the above video where Pakistani Great Swing Bowler Waqar Younis shares his expert tips.
How to Hold the Ball for Swing Bowling
You will hold the ball with your first and middle fingers and your thumb for a conventional swing. Your ring finger and pinkie will fold in toward your palm under the ball.
You will place your first and middle fingers on either side of the seam with your thumb on the seam on the underside of the ball. There should be about a finger’s width of space between the back of the ball and your palm.
Do not grip the ball too tightly. You also don’t want to grip too loosely so that you sacrifice control.
The Wrist Position
As the ball leaves your hand, you want your wrist to be cocked back and locked. This will allow the ball to roll off your fingers while keeping the seam straight.
You will want to hold your wrist upright and behind the ball as it is released.
The above video will show you how to hold your hand and wrist when you are swing bowling.
Some Common Problems with Swing Bowling
Some common problems come up for bowlers when they try to swing the ball. Knowing about these issues and how to fix them will allow you to take more wickets and be a more effective fast bowler in your matches.
The seam Doesn’t Come Out Upright
If the seam doesn’t come out of your hand upright, it is unlikely that the ball will swing.
If you don’t swing the ball, you are making it easier for the batter to read the length and line of the delivery. That means that you are giving them more chances to score runs. And it makes it less likely that the batsman will make a critical mistake and get out.
Moral of the story? Keep the seam upright as it leaves your hand.
You Only Swing the Ball in One Direction
I suppose that being able to swing the ball in one direction is better than not swinging at all. But it’s not ideal. The problem with swinging only to one side is that it can become predictable, making it easier for batters to score runs.
If you do not want the batsman to know which side you are going to swing the ball, then you must be able to do it on both sides.
To give yourself more opportunities to take wickets, you should take the time to practice bowling, both inswingers and outswingers.
7 Fast Bowling Tips
Here are seven drills that you can practice to work on your fast bowling.
1. Controlling the Spin
As we have already gone over, it is especially important that you set the ball correctly in your hand before you bowl. Place your first finger and your middle finger on top of the seam. And hold your thumb on the seam on the underside.
You can practice spinning the ball backward by flicking it up into the air. As you spin the ball, be sure to keep the seam straight up. This motion is the reverse action of the wrist that you usually use for swing bowling.
This drill will give you a good feel for wrist control. Practicing the motion will help you to determine how tightly or loosely you need to position the ball to control the seam.
Your goal is to make the ball spin without any wobbling of the seam.
2. Practice Keeping the Seam Straight
To work on keeping the seam straight when you bowl, you can work on this simple drill. You will need a teammate for this one.
Standing about five yards away from your partner, hold your elbow with the opposite hand of your bowling hand. Then flick the ball using your wrist to your partner.
Your goal is to put backspin on the ball while you keep the seam up straight.
3. Control the Seam
For this drill, you will also need a partner.
Stand about 10 yards away from your partner. Then, in a standing position, bowl the cricket ball to your partner without letting it bounce.
Practice bowling the ball with no wobbling, keeping the seam up. This drill will help you to control the “feel.” And it will teach you the right wrist position.
4. Practice Your Outswing
Start by gripping the ball with your first and middle fingers on the top of the ball on the seam and your thumb on the seam underneath. Then cock your wrist up and slightly angle your hand to first slip. You do not want your hand to be straight here.
Gently bowl to your partner. If you are a right-handed bowler, you will see the ball start to swing from right to left.
As you practice this drill, make sure that you let your bowling hand sweep across your body and past your left hip.
5. Practice Your Inswing
For this drill, you will practice turning the seam slightly toward the fine leg. Place your thumb outside of the seam. This will allow your wrist to soften.
You should release the cricket ball with a flick. You want your bowling hand to sweep down and through, going past your right hip.
The more that you practice this drill, the more feel you will get for the deliveries.
6. Cross the Seam
If you are having trouble controlling the ball as it swings wildly, you can do this drill. Instead of your regular grip, hold the cricket ball across the seam. This grip position will stop the swing altogether, and it will let you bowl straight.
Do this drill to help settle yourself. Get a length and line going.
You should be able to master this drill before returning to your regular grip for inswingers and outswingers.
This drill will also help you to roughen up the ball for your reverse swings.
7. Tape up a Ball
To work on your swing, try taping one half of a tennis ball. Then practice bowling the swing into the nets. Many of the greatest fast bowlers mastered their arts by practicing this way.
Experiment with it. Try turning the ball around before you bowl.
Swing bowling is an art form. Be patient with yourself. Play around with the ball and experiment so that you can find what works best for you.
Final Thoughts
Swing bowling is an essential part of cricket, and it takes a lot of practice and skill to master. Cricketers with a basic understanding of aerodynamics will be able to develop new swinging methods, even beyond the conventional and reverse swings.
This unique art can be explained with physics and aerodynamics. Ultimately the swing is caused by the asymmetrical airflow around the ball, which creates different pressure on one side of the ball. This produces a sideways force that makes the ball swing.
You can enhance the asymmetrical force on the ball by increasing the speed of the bowl, increasing the roughness of the ball, or changing the position of the seam.
