The Short Game Explained: probably more than you need to know, but HERE’S why the ball does what it does.
To most golfers the short game is a mystery. Whenever we take a significant break from playing, it’s these little shots that usually acquire the most rust. Figuring them out again is tough, because there are so many ways to experiment with technique. Unlike with the full swing, our notion of textbook form around the greens is less specific.
That said, at the moment of truth (impact), well-struck short-game shots are not mysterious, at least when viewed through the realm of physics. Using a TrackMan launch monitor and my best students, I recorded data on three essential shots: a greenside bunker shot, a low-flying “skid-spinner” chip and a flop shot. I then shared this data with John McPhee, PhD, a member of the Golf Digest Technical Panel and professor of systems design engineering at the University of Waterloo in Canada. We examined the physics of successful shots and discovered some common elements, which we’ll share with you here.
As complicated as the science might seem, a basic understanding can really help. The next time you’re grinding at the practice area, you’ll at least know what you’re trying to do.
—with Max Adler & John McPhee, phd.
1. THE BUNKER SHOT
Match your speed to the moisture
McPhee says:
On a greenside bunker shot that spins and stops quickly, there’s less sand between the clubface and the ball. Think of the sand on the face as layers that slide over one another. The fewer the layers, the greater the transfer of shearing force to the ball, which creates more backspin. Moist sand has higher shear strength than dry sand (this is why wet sand castles can be built taller), so moist sand layers can withstand higher shear forces before they slide. When sand is dry and powdery, more of the club’s energy is spent on sliding the sand layers than on imparting backspin to the ball.
Mccormick says:
The takeaway here is how to plan. With moist sand (not wet, heavy sand), you can try for backspin. If the sand is dry, expect more rollout. We also see how critical clubhead speed or velocity is. In our tests, I had to swing the club 102 km/h to fly the ball 18 metres [below]. In dry sand, I had to swing 109 km/h, or near my physical limit with a wedge. To get faster through the sand, swing to a fuller finish. But if you’re a slow swinger, you’re better off adjusting your club’s entry point. The closer to the ball you enter the sand, the less you’ll be robbed of speed, and spin.
2. THE SKID SPINNER
When low on the face is actually good
McPhee says:
For this low chip that halts quickly after its second or third bounce, the ball must be hit low on the clubface. This rotates the clubhead clockwise during impact, which has two effects: First, the club is delofted by the impact force, so the ball’s trajectory is lowered. Second, because the ball compresses and rolls up the clubface, the clockwise club rotation creates anticlockwise ball rotation, known as vertical gear effect. This dynamic adds to the spin that results from the club’s loft. The glancing blow allows more of the club’s velocity to go towards spin than speed.
McCormick says:
This is such a fun shot. It comes off like a skull and bewilders your playing partners when it sizzles to a stop. What we know is, you have to hit the ball low on the face and a bit towards the toe helps. The key is to make a shallow pass through the ball. Widen your stance and feel that the club swings close to the ground, especially on the follow-through [below]. This allows the club to skid through impact right where the bottom of the ball meets the ground to create a tangential blow. You shouldn’t take a divot, so it’s easier to achieve this shot off of firm turf or when the ball is perched high on a bed of grass.
3. THE FLOP SHOT
The club’s bounce goes under the ball
McPhee says:
On this shot, the ball is hit higher on the clubface with more direct impact than the skid spinner. The ball stops quickly on the green because of its steep landing angle, not its backspin. For Cameron’s 27m flop shot, the backspin is only 4,100 revolutions per minute, but the launch angle is up to 51 degrees.
The ball speed is similar to that for the 27m skid spinner, even though the club’s velocity is much faster. The reason is simple: More energy is going into hitting the ground with the bounce of the club to create a slightly upward angle of attack on the ball.
McCormick says:
At address, lay the clubface so it points up to the sky. This open face, where you can see the leading edge, creates a high probability that you’ll deliver maximum loft. How, you ask, can you strike the ball high on the clubface when it’s open this much? At impact, the club’s sole is going to push down into the ground to create room for it to slide under the ball. The key is fast wrists and no tension.The wrists should hinge so that the clubhead rises higher than the shoulders on both sides of the swing [below]. Feel that the clubface passes under the ball very quickly, like a spatula sliding under a pancake.
Cameron McCormick is an Australian-born instructor who coaches American star Jordan Spieth.
