Appendix III - The Ball

Introduction

Appendix III is divided into the following six categories:

  1. General
  2. Weight
  3. Size
  4. Spherical Symmetry
  5. Initial Velocity
  6. Overall Distance Standard

1. General

The ball must not be substantially different from the traditional and customary form and make. The material and construction of the ball must not be contrary to the purpose and intent of the Rules.

Prior to 2008, the Rules on the golf ball were precise and numerical in comparison to the more descriptive rules relating to clubs. In 2008, the USGA added general language to the Rules on golf balls to ensure that any new technology which may be developed in the future which might circumvent the intent of the Rules, while generally covered in the preamble to Appendices II and III, was also directly addressed in Appendix III.

Golf Ball Construction

Only golf balls constructed entirely from elastomeric materials (i.e., viscoelastic materials having a low elastic modulus) will be considered to be of traditional and customary form and make; allowance may be made for the presence of some traces of non-elastomeric materials. The elastomeric materials may be thermoset or thermoplastic polymers, but must not be designed or manufactured to facilitate intentional modification of the ball’s playing characteristics. In addition, the design of the golf ball may not include parts or components that move with respect to each other or the ball, or that are not concentric with the golf ball.

Exceptions to the requirement that the ball must not be substantially different from the traditional and customary form and make are noted below.

Exceptions:

Golf balls may have a single, concentric core with a diameter of < 0.9-in (22.9mm), provided that the core:

  • Contains fluid constrained within a single chamber; OR
  • If non-elastomeric, is effectively rigid (such as solid or hollow, thick shell metallic spheres)

Other than this general provision, all of the specifications listed below are tested and checked under laboratory conditions. These specifications are discussed briefly below. However, the official test protocols are available on the USGA's website. Along with these specifications, the USGA conducts additional testing and inspections to identify golf balls with unusual material, construction and/or performance characteristics which may be considered substantially different from the traditional and customary form and make and/or contrary to the purpose and intent of the Rules.

2. Weight

Appendix III, 2 states that a ball must not weigh more than 1.620 ounces avoirdupois (45.93 gm). This is one of the simpler tests because all that is required is an accurate scale. There is no minimum weight, thus a ball can be as light as the manufacturer desires.

3. Size

The ball must have a diameter of not less than 1.680 inches (42.67 mm). The instrument used to measure size is a metal ring gauge. It is important to note that there is no maximum size, the ball can be as large as desired provided it conforms to all other standards.

4. Spherical Symmetry

The intent of this rule is simply to ensure that a ball is designed and manufactured to behave symmetrically.

5. Initial Velocity

There is a formal test procedure carried out on equipment approved by the USGA to check that golf balls meet the Initial Velocity specification. The intent of this Rule is to limit the speed of the ball off the clubface.

6. Overall Distance Standard

This Rule was introduced in 1976 in order to restrict the overall distance (carry and roll) that a ball can travel under specific conditions. This test protocol is continuously reviewed to ensure that it reflects the game as played with modern equipment.