The Science

The amount and angle of roll can be calculated from the ball's velocity, the angle of slope, and the friction of the putting surface. The force the angle of the plane will exert on the ball varies greatly. It turns out that the correct angle of offset or "aim" remains the same regardless of distance from the hole. For example, if the resulting angle of offset is 10 degrees at a distance of 5 ft, it will also be 10 degrees at a distance of 50ft.

Methodology

In a controlled environment, we carefully observed the roll of the ball on greens of different speeds. Specifically, data was recorded on greens with a stimpmeter rating between 7.5 and 11.5. From the data, we observed a relationship for ball trajectory and reversed engineered a formula which accounts for the forces on the ball resulting from friction and the angle of slope of the green. From this data, we are able to predict the roll of the ball for a putt with "perfect distance." Perfect distance is assumed to be the velocity that results in the ball coming to rest 2 ft past the hole. The application will draw two arcs, one showing the roll of the ball if it were hit directly at the hole and another arc displaying the angle of offset to aim. The application correctly accounts for differences in ball trajectory resulting from the speed of the green, break near the hole, and uphill and downhill slopes.

How does it work?