To the untrained eye, all golf balls look pretty much the same, and you may have wondered what all these advertisements are talking about when they claim their ball provides greater distance or spin. After all, they’re all circular, white, and covered in dimples. In reality though, each is uniquely constructed, and these dimples play a major role in making one golf ball different from another. How, you might ask? Unless you’re a physicist you probably won’t know, but these little holes can have a huge impact on where your ball ends up, so let’s delve into an important golfing question; why do golf balls have dimples?
Detailed explanations about the impact of dimples can get a little confusing, particularly if you’re not scientifically inclined, but bear with me. On a basic level, dimples help to reduce drag, and produce lift. This is because they create turbulence in the layer of air immediately surrounding the ball.
Lift is obviously the motion which occurs when an object moves upwards, and dimples in your golf ball help to produce this by creating more pressure at the top of your golf ball than at the bottom. The higher pressure atop your ball forces the air downwards to the lower pressure area, subsequently lifting your ball further into the air. This is not dissimilar to the way an aeroplane works, with the wings helping to force air downwards, and the plane into the sky.
As a concept, drag is relatively straightforward. It is basically a force going in the opposite direction to your ball, but how dimples affect this is a little more complicated, so I’ll try to keep it as simple as possible for you. There is inevitably going to be some ‘pressure drag’ created by a moving ball, as a low pressure ‘wake’ is always created behind your ball. This is in contrast to the high pressure at the front of your ball, and as a result pulls back on the ball as it moves forward.
So, the aim of dimples is to make this low pressure wake as small as possible, in order to reduce wake. On a smooth ball, the boundary layer around its outside is ‘laminar’. You probably haven’t heard of this term, but essentially with this type of of boundary layer there is less skin friction between the air and the ball, which is good. The negative, however, is that the air doesn’t stay attached the rear of the ball, which in turn creates a larger wake.
Dimples change the boundary surface from laminar to ‘turbulent’. A turbulent boundary layer actually has some drawbacks, in that there is greater skin friction on the surface of the ball. Where it benefits your shot, however, is that the air is able to hang on to the back of the ball for a little longer than when it has a laminar boundary layer. As a result, the low pressure wake created behind the ball is smaller, and there is less pressure drag on the ball.
Of course, I’m not an expert, but Mark Maughmer of Penn State University is, and in this article he explains a little more eloquently exactly why dimples are so useful. The aerospace engineering professor explains how the dimples create more skin friction, but less pressure drag, resulting in an overall net positive.
More lift + less drag = more distance
The end result of all of these complicated physics concepts is that you’ll get greater distance on your shot. If you’ve ever watched somebody hit a perfectly round golf ball, without any dimples, you’ll notice that they’re lucky to hit a driver 150 metres. Better yet, take a look at this video, created by Titleist, which shows what happens when you hit a ball with no dimples, or a ball with dimples on just one side.
The footage of dimples on just one side of the ball is a good way to demonstrate their influence. With no dimples on the left, the ball goes flying out to the right, the same side on which the ball’s surface is dimpled. As the video explains, this is because there is more lift on that side, which forces the ball to move in that direction.
As we’ve discovered, detailed scientific explanations about the origins of dimples in a golf ball can get a little tedious, but the end result of these tiny little holes speaks for itself. Your ball flies further, and it flies straighter. If you think golf is hard enough as it is, imagine playing with a ball without dimples. Your drives would look a lot like those in Titleist’s demonstration video, and your handicap would be a whole lot higher. If you have any more questions about why golf balls have dimples, feel free to put them in the comments section.