Distance Report Closer Look: "The performance of golf balls has changed significantly over the last 25 years, with many of those changes contributing directly to hitting distance increases."

What I have read so far adds up to one impressive piece of documentation and yes, at times, subtle maneuvering. Before finishing the entire Distance Insights Report compiled by some smart and very talented folks at the governing bodies, I can’t help but highlight parts that get at prevailing debates.

The USGA and R&A have come at this issue from many angles, with the early portion of the report laying the groundwork to get at key questions related to primary causes of sudden jumps in distance, the increases at different levels and around page 22, the role of equipment in distance gains.

For those keeping an open mind, the report’s detailing of aerodynamics related to the golf ball and driver heads builds a case before concluding that a disproportionate advantage is enjoyed by elite players as the golf balls have grown, gulp, stiffer.

From page 34 of the report:

The performance of golf balls has changed significantly over the last 25 years, with many of those changes contributing directly to hitting distance increases. The most significant change in golf balls in this period has been the replacement of the wound-core golf balls used since the early 1900s with the multi-layer, solid-core balls that are ubiquitous today. Multi-layer solid construction golf balls is not a new innovation, but many golfers continued to use wound golf balls until as late as the beginning of the 2000s. Typically, multi-layer, solid-core balls spin considerably less than wound-core balls at typical driver impact angles (R20 - Effect of Equipment on Distance - Golf Balls). This is an important factor for driver shot distance because decreases in spin can directly contribute to increases in distance. For example, referring to Figure 27, a decrease of spin of around 250 rpm can lead to an increase in distance of as much as five yards at a swing speed of 120 miles per hour.

A comparison of a popular, older, wound-core golf ball and a popular, modern, solid-core golf ball suggests that the latter has both improved aerodynamics and is optimized for a lower spin rate. It can be seen in Figure 27 that for the impact speed typical of elite male golfers, at a spin rate of 3000 rpm, the aerodynamic improvement of a modern solid-core ball was calculated to be worth approximately ten yards over a traditional wound-core ball.

Couple that with what happens at impact and you have, well elite players getting a bigger boost from recent advances than the rest of us:

The coefficient of restitution of the impact between the club and the ball, previously discussed in Section 3.2.1.1, is also dependent on ball material and construction. As impact speed increases, more energy is lost in the collision between the clubhead and the golf ball resulting in a lower coefficient of restitution. However, the stiffness of a golf ball can significantly reduce this decrease in coefficient of restitution, especially for the impact between the ball and a clubhead having significant spring-like effect. A golf ball with a lower stiffness will have a lower coefficient of restitution reduction at higher clubhead speeds (R19 - Effect of Equipment on Distance - Driver, Figure 28).

It can be seen in Figure 28 that the difference in the coefficient of restitution (and thus the resulting launch speed and distance) between a soft ball and the stiff balls (A-C) is much greater at high impact speeds than at low ones.

While certainly not warm and fuzzy language, this case is an important part of the debate over possibly tightening up certain equipment rules. Many average golfers believe possible elite player equipment rule changes will cause them to lose all of their hard-bought distance gains. The science says otherwise.