Dimples mean more than you may think
The first time I became aware of the benefits of dimples on a golf ball was when I was a teenager in the 1970s. Standing on the first tee, I placed a brand-new ball on the peg, took a cut and watched in disbelief as the ball went out about 80 yards and took the nastiest left-hand turn I had ever seen, nose-diving to the ground. For once, however, it was the equipment and not me.
When I got to the ball I noticed one half of the ball was normal while the other half was perfectly smooth with no dimples at all. This manufacturing defect (and quality-control gaffe) has stayed with me for some 30 years. The lesson I learned that day was this: Dimples matter -- a lot.
So, what are they worth to you? If you swing like a PGA Tour player, about 160 yards. According to Frank Thomas, Golf Digest's chief technical advisor and former technical director of the USGA, a smooth golf ball with no dimples would travel about 130 yards when hit with a modern driver by a tour-caliber player. Conversely, a ball with well-designed dimples, struck the same way, will travel about 290 yards.
The reason is that a ball with no dimples is akin to a bullet -- it will fly but it lacks backspin and therefore has little or no lift. A dimpled ball creates more spin and, combined with lift, climbs into the air more easily as a result. But all dimples do not behave alike. According to Thomas, the size, shape, depth, number, pattern and overall surface coverage of a ball's dimples all influence its aerodynamic lift and drag properties.
And what do the equipment police at the USGA say about dimple design? Not much, actually. In fact, there are no formal rules covering dimples, and that has opened the door for some rather unusual dimple patterns over the years as golf-ball manufacturers worked to make better products and capture the consumers' eye at the same time. Remember the Royal Plus Six with its hexagon-shaped dimples? Or the Wilson ProStaff with its "truncated cone" indentations? More recent (and technologically advanced) examples include Callaway's HX pattern, Wilson's shallow, flat-bottomed dimples and Hogan's soon-to-be-released "Deep Six" pattern.
One exception to the "anything goes" mantra was the Polara. Hitting the market in 1977, the ball, which supposedly corrected hooks and slices during flight, had six rows of standard dimples around its equator and shallower dimples around the rest of the ball. Although it did not appear to violate any rules, the USGA did not approve it. In 1980 the association added a rule stating a ball must be aerodynamically symmetrical. A lengthy lawsuit ensued with the USGA finally settling out of court and paying Polara $1.375 million while the ball was removed from the marketplace.
In addition to shape, there also are no restrictions on the number of dimples a ball may have. And although there is no true standard, approximately 90 percent of all golf balls on the USGA Conforming Ball List fall in the 300- to 450-dimple range. More than that, says Tom Kennedy, Top-Flite's golf ball R&D chief, and you run the risk of too much drag. In addition, he said, small features on the surface of the ball, such as very tiny dimples, are difficult to keep consistent throughout the entire manufacturing process, not to mention they fill with dirt or grass easily. Even when it doesn't involve microscopic-sized dimples, the number still can impact a ball's playing characteristic. "We had 500 dimples on some of our balls a few years back," said Bob Thurman, principal engineer, aerodynamics for Wilson. "But that limited our freedom to make the ball fly differently. It essentially dictated that we produce a lower trajectory ball." And remember the "High Trajectory" and "Low Trajectory" Titleist balls? How did they know whether to get up in the air or stay closer to the ground? It was the size and depth of the dimples.
Today the trend is toward balls with larger (and therefore fewer) dimples to coincide with today's desire by better players for high launch and low spin. But more germane than the number of dimples, however, is the depth of them. It's not so much that large dimples help create a higher trajectory (some, in fact, argue that the opposite is true), but rather that bigger dimples tend to be shallower. This often will offset the effect of the bigger dimple and a higher trajectory is achieved. It also is the ultimate in splitting hairs. If golf is a game of inches, when it comes to dimples it's a game of thousandths of an inch. A standard dimple measures approximately 7/1000ths of an inch deep. What's the effect of adding or subtracting a mere 1/1000th? "About five yards in some cases," said Thurman.
With that in mind, it's no wonder that Titleist's website shows eight pages devoted to golf-ball aerodynamics (with a good portion focusing on dimples) while Callaway's website reveals a close-up schematic of the 38 separate facets that make up one dimple on its HX Tour ball. That's a bit more advanced than some early dimple designs. In fact, at Spalding some 50 years ago, dimple patterns often were hastily sketched out on ... bowling balls.
But I bet they at least had dimples on both sides.
The number of dimples on the Dimplit golf ball - the most of any ball on the USGA's conforming golf ball list. The ball features 414 larger dimples (in four different sizes) and 656 smaller (about pinhead-sized) dimples.