How Many Dimples Are On A Golf Ball? What do they do?

imageHow many dimples are on a golf ball?

While it varies from model to model, golf balls typically have between 300 and 500 dimples. On average, it seems that balls have around 330 dimples; 336 has been cited as typical.

Dimples typically have a depth of 0.010 inches.

Some models have extraordinary numbers. The Dimplet has 1070 dimples: 656 small ones, and 414 large. By contrast, the new Caesar ball has none—it’s as smooth as a billiard ball.

Dimples however, are necessary for a golf ball’s flight. They have two effects.

First, a bit of physics: Any moving object leaves a wake in the air behind it; wakes in turn create drag, slowing the object. Reducing drag is a key to going faster. That’s why “drafting” works in NASCAR. Having a second car immediately behind the first reduces the wake of the first car, allowing it to go faster. The second car also goes faster because it doesn’t have to push as much air out of the way.

Dimples work to reduce drag by creating microscopic eddies on the surface of the ball. This has the effect of reducing the following wake of air. A smaller wake means less drag.  Although it’s counterintuitive, because of the wake, a smooth ball actually has higher drag.

The dimples also work with spin to create lift. The spinning ball creates higher air pressure on the bottom of the ball than on the top. Like an airplane wing, this forces the ball upward.

Golf balls actually “fly”—they aren’t just shoved through the air.

This principle was discovered by early ball makers, who, when molding gutta percha balls by hand would press random marks into the surface. Later, molds were created that had the impressions built in. Early models, such as the one shown at left had a cross-hatch pattern rather than dimples. The effect, however, was the same.

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