Understanding the effect of finger–ball friction on the handling performance of rugby balls

Handling errors are often seen in professional rugby games and even more so in amateur rugby. This paper analyses the problem of ball mishandling using high-speed video footage of passes and a bespoke finger friction rig. The high-speed video analysis showed that when the ball is caught, often there is a fluctuating movement of the fingers over the surface of the ball. It also showed that the fingers move over the surface of the ball when the ball is thrown, confirming that the dynamic friction is a good measure of how easily a ball can be handled. Rugby ball surface samples were used, on a finger friction rig, to assess the coefficient of friction between the finger and the balls. The currently manufactured balls displaying the highest coefficients of friction in clean, dry conditions were the design with square, ‘sharp’ pimples and also the design with a mixture of small and large pimples. The most consistent ball across wet and dry conditions was the ball with round, large, densely populated pimples. It was also shown that when water is added to the surface of the ball or finger, there was little variation in performance between the ball varieties.