When watching someone play field hockey, you may wonder why there are dimples on the ball much like the texture of golf balls. For years, the dimples have been the norm on the field, and you may be surprised to learn the big effect they have on a field hockey ball.
Field hockey balls have dimples to help the ball travel further. The air that gets trapped in the dimples pushes the ball farther and faster while decreasing drag. This helps the ball to go over 100 mph when hit properly.
Though there are many unanswered questions about sports, you can have one answered today. There are logical reasons behind why there are dimples on hockey balls, so let’s dive in.
The Purpose of Hockey Ball Dimples
When using a dimpled ball, you may wonder what really is the difference between dimpled balls and smooth balls. Some people may think there is no difference at all besides feeling in your hand. However, the dimples are actually quite useful.
When a smooth ball travels in the air, the air pushes against the ball, causing resistance. This slows it down.
However, a ball with dimples gives the air small pockets to enter right on the ball’s surface. So, instead of pushing against the ball as resistance, some air moves with the ball, tucked into its dimples.
The air that would be putting resistance and friction on your ball is now in contact with the air pockets in the dimples. This results in less friction, allowing for higher speeds. This is called turbulent flow.
Turbulent flow allows for less drag behind the ball, which is why it is able to go faster than the smooth balls.
Furthermore, dimpled balls move more smoothly over wet pitches and surfaces. That is why hockey fields are kept wet. The water helps reduce the friction against the dimpled hockey ball, and it causes the ball to bounce less, minimizing any injuries to the players. The water is also helpful in minimizing injuries when the players fall on the ground.
If you want to learn more about dimpled hockey balls and the effect the dimples have, click HERE to watch a video explaining the physics of dimpled hockey balls.
A Hockey Ball Without Dimples
Like mentioned before, a smooth hockey ball goes a bit slower when traveling in the air. The friction caused by the air rubbing against the smooth surface of the ball causes it to be slowed down more than a dimpled ball. This is called laminar flow.
This resistance and fraction on anything, such as a field hockey ball, is drag. Drag is commonly described as a vacuum. It pulls the ball back which causes it to slow down. A dimpled ball doesn’t have as much drag because the air surrounds the ball by using turbulence. Small pockets of air turbulence in the dimples surround the ball and moves with it leaves less space for drag.
Below is a table comparing both types of balls:
|Year Invented||Type of Flow||Drag||When Is It Suitable?||When Is It Unsuitable?|
|Smooth Ball||Field hockey can be traced back 4,000 years in Egypt. Although the type of ball they used is unknown, it is safe to assume they used a version of the smooth ball. The type of field hockey we are more familiar with can be traced back to the mid-1800s in England.||Laminar Flow||There is a larger amount due to the space made available by the type of flow||They are usually used on sand-based turf or for indoor games. They are also used sometimes for practicing||The friction against smooth balls and artificial grass makes it unsuitable which is why the dimpled ball was made.|
|Dimpled Ball||Like mentioned before, Kookaburra created the dimpled ball for Hockey Australia in 1982. Since then, there have been improvements made.||Turbulent Flow||There is less drag due to the flow||Dimpled balls are usually preferred for high-level games and particularly for outside games on artificial grass.||Dimpled balls aren’t preferred on smooth surfaces like sand or inside.|
The Physics of Hockey Balls
Like mentioned before, the flow of dimpled balls is turbulent while the flow of smooth balls is laminar. The flow is very important to the flight of the ball, and it can make all the difference in how fast and far the ball goes.
Laminar flow is the flow of the smooth ball which has more drag keeping the ball from going as far. It is a much smoother flow than the turbulent flow. Since there are no dimples for the air to occupy, the air moves in a straight line until it moves along the surface of the ball.
Behind the ball is the section called the wake which is where the drag is. With laminar flow, the wake comes from the front of the ball rather than the back because the air doesn’t stick to the ball like with the dimpled ball. Since there is more space for the drag to occupy, it slows down the ball more.
Turbulent flow is the airflow over the dimpled ball which actually doesn’t have as much drag – allowing it to go faster and farther. The air moves in a very turbulent fashion against the ball due to the dimples, hence the name. While the layers move parallel to each other with laminar flow, they tend to overlap and move chaotically with turbulent flow.
With turbulent flow though, there is much less drag. The air goes along the surface of the ball farther back because it tends to stick to the ball a bit better. Therefore, there is less room for drag to pull the ball back.
Turbulent and laminar flow are indeed very interesting, and there is still plenty to learn about them! Click HERE to be directed to a link providing you with more info including a couple of diagrams that will help explain the difference between the two.
The History of Dimpled Balls
Kookaburra, one of the most popular hockey ball manufacturers, was asked by Hockey Australia to make a hockey ball that was suitable for wet, artificial grass in 1982. Up until then, they used a leather ball that would soak up the water and swell up making it unusable.
Since Kookaburra has been a loyal company to the world of hockey ever since 1956 when their balls started being used at the Olympics, they, of course, took on this challenge. They were successful in tackling this challenge, and their plastic dimpled hockey ball called the Kookaburra Dimple Elite has been used in all international tournaments since 1984.
Since then, they have had other accomplishments and inventions including the Dimple Elite yellow ball which was specifically made to be used in the 2012 London Olympic Games.
Before dimpled balls were invented, hockey became more known in the 1800s in England. Hockey started being funded in most schools in London like Eton and Harrow. The first set of rules is believed to have been created in 1852.
It became a common activity that eventually made its way out of London, and more people started learning about the sport. Though it was occasionally played on ice, London was more about field hockey.
From there, the sport continued to spread, and the sport became a worldwide known sport leading up to the creation of the dimpled hockey ball in 1982.
If you are ever playing hockey on artificial grass, it is important to use a hockey ball with dimples. The dimples allow less friction on the grass and in the air. Your game will go much smoother, and your ball could even go over 100 mph in the air!