ABSTRACT
The golf shaft is a mediator between the golfer and clubhead during the swing. A primary role of the shaft in a golf club is to allow the golfer to deliver the clubhead to the ball with a specific amount of kinetic energy. For most full swings, greater kinetic energy is desired. A second purpose is to facilitate the delivery of the clubhead to the ball such that, at impact, the clubhead is travelling in a specific direction with a specific orientation and the intended spot on the face makes contact with the ball. Said another way, the shaft can influence the position, velocity, and orientation of the clubhead relative to the ball at impact (MacKenzie & Boucher, 2015). These clubhead kinematics have a near-causative relationship with the impact kinetics, which determines the initial velocity and spin of the ball. The initial velocity and spin of the ball are the primary determinants of its trajectory. This is important because the fundamental objective of any particular golf shot can be represented by its trajectory. A ball’s trajectory is simply the path the ball traces out during the shot and includes all features such as the curve, carry distance, bounces, and final resting location. Not only must a proficient golfer be able to generate specific trajectories, but the variability in reproducing a particular trajectory, on command, should also be as low as possible. While most advances of the golf ball towards the hole do not require a specific trajectory, it can be reasoned that certain trajectories offer a higher probability of success depending on the conditions. For example, curving around a tree instead of going through it, or sending a bunker shot on a high trajectory to avoid the lip of the trap. There is also a clear benefit to maximizing the trajectory length off the tee with a driver. In 2016, on the PGA Tour, the top eight in strokes gained off the tee all averaged >300 yards in driving distance, which was 10 yards more than the average driving distance in 2016 (PGA Tour, 2017).
