All this talk about work in past columns—and the end of summer looming—makes me think about golf. You may not discuss golf and measurement in the same breath, but there are a lot of critical measurements involved in golf. There are also a lot of variables in angle, force, and direction to be considered and adjusted for when using that equipment, no matter how well—or poorly—you play.

Some basics
In case you aren’t a golfer, let’s start with some basics to put the measurements into context. The United States Golf Association sets specific guidelines for golf equipment. First, there is the ball. Although they can’t weigh more than 1.62 ounces and must be spherical with a diameter of at least 1.68 inches, golf balls aren’t all alike (not to mention that British specs are slightly different). How much the ball compresses when struck at the typical velocity of ~70 meters/sec., the number of layers and their composition, and the size and shape of the dimples—which affect the aerodynamics of a ball in flight, causing turbulence that increases lift—are characteristics users don’t need to measure, but that affect how a ball feels and behaves when struck. (For this discussion, we will avoid the emotional and psychological aspects of the ball’s brand and cost.)

Then there are the clubs—the irons, the woods, and the putter. Golf club shafts vary in length and stiffness. Club heads are now being made with exotic metal alloys—it’s hard to find a wooden wood these days. Most clubs have grooved faces to put a spin on the ball when struck properly, and the shape of the grooves has been controversial in professional golf in recent months. There are even choices of grips for each club. Finally, there’s the choice of which tee to use: the length (within defined limits), the material (wood or plastic), and even whether to use a tee at all.

OK, so you select from a wide range of golf equipment. You go to a golf course, where the wind and weather can be different every day, or even during a round, where the ground conditions change with the season and the amount of rain, where the hole location is changed daily on each green. Then you introduce all the variables of your own skill: Selecting the right club, swinging it properly, and hitting the ball. You repeat this process using as few strokes as possible until it goes into the 4.25” diameter hole 9 or 18 times. Fun, right? Tiger Woods seems to have figured it out.

Technology
As with many things in our lives, technology is a big factor in golf. A skeptic would say that innovations in golf exist simply to sell more balls and clubs. An avid player will consider what every new advancement might do to help his or her game. The USGA keeps tabs on these advancements so none of them gives an unfair advantage. It’s a very dynamic sport in equipment alone (and I didn’t even mention golf shoes).

There are other technology tools that aren’t necessary to play the game, but can give a golfer an advantage. One is the laser rangefinder, which provides measurements to the flag in the hole from any location on the course. These devices claim accuracy to ±1 yard, which isn’t bad when you’re 200 yards away and trying to decide which club to use.

More about golf clubs
Golf is played with a set of clubs that vary in shaft length and the angle of their “faces,” the part that strikes the ball. These angles range from ~10° for a driver to ~56° for a sand wedge. The smaller the angle, the longer the distance the ball will fly. Thus, the putter face is at 0°, because the ball never leaves the ground when putted. A golfer can legally carry 14 clubs. All clubs but the putter have grooves in their faces that impart a spin on the ball when struck. It’s estimated that a ball spins at 3,600 rpm when struck by a driver and 6,000 rpm when struck by a sand wedge. This backwards spin affects the flight path and what the ball does when it strikes the ground after flight.

Then there’s the golfer
Golfers don’t need to measure (or even know) these angles or club lengths, but they should be fitted for and use clubs that best fit their swing.

No matter how good the golfer, changing equipment may have minimal effect on performance: if you stink, you can buy $3,000 clubs and still stink. This is why estimated measurements influence every shot.

So, now you think there are a lot of parameters involved in golf equipment, eh? Here are some measurements to consider when you stand at the first tee:

• Estimate the distance to the hole, factoring in the height of the hole relative to the tee.
• Consider the influence of the wind on the ball once it is hit.
• If you can reach the green, estimate how hard or soft the green is so you can decide where to land the ball and consider whether it will stop where it hits, roll forward, or spin backward.

From this information, select the appropriate club to use.

Now you have to decide whether to put the ball on a tee or hit it off the ground. If you choose to tee it, you have to decide how far to push the tee into the ground. How high the ball is teed can be significant when driving the ball, especially if your swing is not always exactly the same. You want to hit the sweet spot on the driver face. Tee too high and you can swing under the ball, too low and you can “top it.”

Next, take your stance relative to the ball and the tee. Quite a range of angles and distances here! Imagine looking down from above. First there is the line of your feet relative to the line from the ball to the hole (which the swing hopefully follows). Then there’s the distance from your feet to the ball, which influences whether the selected club will strike the ball at the proper point in the swing arc (remember, the shaft lengths vary by club). Then there is the distance your feet are apart, typically farther apart when using clubs that hit greater distances. Then there is the position of the ball within the space between your feet. For long clubs, like a driver, the ball is in line with the instep of your forward foot. For steeper-angled, shorter-shaft clubs the ball can be near the middle of your stance. Now you swing the club.

If all your estimates are correct, as well as the arc of your swing, and the speed and angle of the club at impact are as planned, the ball will land somewhere close to where you intended. It’s easy to understand why a hole-in-one is such a rare occurrence.

Those “special” circumstances
There are more factors to consider and estimate when playing a round of golf. Take the grass, for example. The length of the grass affects club and shot selection. Fairways have short grass, which makes it possible to strike the ball cleanly and impart the desired spin. The rough, the grass on either side of the fairway, is longer and usually longer still as you move out from the fairway (where I usually end up). Hitting a ball in deep grass is a challenge. It slows the clubhead speed, and grass between the clubface and ball can kill any spin. The result? A game of chance.

Let’s not forget the wind. How far a ball flies when there is no wind is different than when there’s a prevailing breeze. The strength and direction of that breeze affect the calculation of which club to use and what to do with your swing to hit the ball the proper distance. You don’t measure the wind speed or direction directly, but tossing some grass in the air will give a coarse measure of wind speed and direction. There’s a major shortcoming with the grass toss method, however—it only tells you about the wind where you are. The wind can be doing something very different at the hole, or anywhere on the way to it. Throw in wind gusts, especially those across the line of flight to the hole, and the best estimates are futile.

Then there are sand traps, the notorious bunkers. Hitting a ball into a sand trap introduces another set of variables that must be judged properly to minimize the number of strokes required to play the hole. First, there is the sand wedge, a club with a very shallow angle designed for lifting the ball out of the sand and giving it spin that will slow it down when it lands on the green. All kinds of adjustments are made for sand shots, which violate many of the aspects of shots off the tee or grass. Instead of aligning yourself to the hole, you “open” your stance by facing somewhat left of the hole if you’re right handed. You also “open” the club face so the edge of the blade isn’t perpendicular to the line of flight. Then there is the swing itself, which may require “blasting” the ball from the sand to get the required distance. Perfecting your swing isn’t a one-size-fits-all proposition.

Ah, golf
With so many variables, it’s easy to see why golfers can play the same course every day of the year with different results.

You think measurements matter in golf? They sure do. And yet we do far more estimating than measuring when we play. May you estimate well.