Effect of Seam Height on Baseball Flight

Abstract

The National Collegiate Athletic Association (NCAA) Division I baseball committee voted to reduce the seam height for baseballs from 0.048 inches to 0.031 inches beginning in the 2015 baseball season. The NCAA claimed that the ball would travel further while maintaining player safety. To test these claims, two balls were donated from the 2014 baseball season and two balls from the 2015 baseball season from Texas Christian University's Division I baseball team. A ball from each season was tested in the two-seam configuration and the four-seam configuration. Using wind tunnel analysis, the forces that act on the baseballs were calculated to model flight path. Different initial conditions were simulated by the model to verify these claims. First, the model simulated a home run returning from the bat at 95 miles per hour, 1400 revolutions per minute at 25 degrees from the horizontal. On average, the new ball traveled 18 feet farther than the old one did. Next, the model simulated a well-hit line drive at 115 miles per hour at 1 degree above the horizontal. On average, the new ball travels half of a millisecond faster. Thus, the model proved the NCAA claims hold: the new ball travels further while maintaining pitcher safety.Furthermore, the new ball travels half of a millisecond faster for a well-hit line drive. Since half a millisecond is considered negligible for reaction time, the model proved the NCAA claims hold: the new ball travels further while maintaining pitcher safety.