By Nicki Mours
USBC Equipment Specifications Team

In the past, bowling ball motion was examined using visual analysis. That analysis led to the conclusion that bowling balls go through three distinct phases of motion, skid, roll, and hook, in that order; however, that conclusion was proven inaccurate when USBC Equipment Specifications and Certification department researchers examined the results of the Bowling Ball Motion Study, which, through the use of equations and graphical data analysis, definitively proved that the actual progression is skid, hook and roll.

The Bowling Ball Motion Study, which was a joint venture undertaken by USBC researchers and bowling ball manufacturers, arrived at these new conclusions by examining bowling ball path data generated by C.A.T.S. (Computer Aided Tracking System). This system tracked the paths of bowling balls as they rolled down a lane, taking precise measurements that allowed researchers to closely monitor and analyze every aspect of the three phases of ball motion.

As the graph above clearly illustrates, the first phase of a bowling ball's path is mathematically linear, meaning it travels along a straight line moving away from the head pin. This phase is known as skid.

As the ball continues down the lane, its path transitions into a curved shape. This non-linear, parabolic portion of the ball path is the hook phase.

Finally, in the third phase, the ball migrates back to a linear path and begins rolling in a direct line toward the pins. This final segment is defined as the roll phase.

In real-time, the true phase transition points can be very hard to see. For that reason, this video has been slowed down and notated to illustrate the instant in which the ball transitions from the end of one phase into the beginning of the next.

So what's the take-home message for league or tournament bowlers who are not tracking and analyzing their ball paths via computer?

First off, communication is crucial. Being able to talk to your teammates during league or tournaments, especially about what the bowling ball is doing, can be a huge advantage. Doing so will allow the bowler and his or her teammates to line up and play the lanes successfully.

This information also comes in handy when communicating with a USBC-certified coach. A bowler's ability to accurately explain what his or her bowling ball is doing on the lane will allow the coach to suggest appropriate physical-game modifications that will help the bowler alter the way his or her ball moves throughout the various phases of ball motion.

Lastly, this knowledge will aid in the communication between pro-shop professionals and bowlers. If a bowler can verbalize his or her desire to see a longer skid phase or a more-defined hook phase in their ball motion, the pro-shop professional will be able to adjust a drilling layout and surface preparation to meet what the bowler needs or wants to see on the lane.

The USBC Equipment Specifications and Certification department has diligently examined every nuance of bowling ball motion in the hope that the understanding it has attained can be passed on to bowlers, who will use that knowledge to take their own games to new heights.

Bowling ball:
Circumference: 26.704 to 27.002 inches
Diameter: 8.5 to 8.595 inches
Weight: May not exceed 16 pounds; there is no minimum weight.