The first impact skill required to get the ball to roll as described is to strike the middle of the ball with the sweet spot of the putter. This is a projection on the face of the centre of gravity of the putter. It is so-called because centred strikes feel relatively softer and more stable (as there is no twisting of the face) compared to off-centre hits. They also produce more appetising results. Off-centre hits (unless perhaps they are consistently in the same spot) compromise distance control AND direction.They can:
Lose over 10% of roll out even if the clubhead speed was perfect
Cause the putter face to open or close by over 3 deg. For context, more than 1 deg error misses a putt from 10 feet that otherwise would have dropped
Unwanted side spin/backspin - if the centre of gravity of putter and ball don’t match up at impact, the ball will not spin as you wish and cause putts to miss short or left/right even of all other impact factors were good.
The effective sweet spot on a putter is similar to the 1 cm diameter of a snooker cue. Whilst varying spin is a valuable skill in snooker, it is an unwanted variable in putting. Knowing where the sweet spot is on your putter is key.
Finding the sweet spot on your putter
Hitting the ball out of the sweet spot (centre of gravity) is important for distance control and accuracy. Unfortunately the sight lines on putters are not necessarily indicative of the sweet spot and need to be established and marked.
Hold the putter by your non-dominant hand by the thumb and forefinger at a point on the putter handle where your lower hand would be.
With your dominant hand, hold a tee peg in your thumb and forefinger and tap the putter face on various spots between heel and toe to find the place where the putter moves back and forth and no twisting occurs. Mark this with pencil on the top edge of the putter so you can see it at address.
Test it out with some putts to verify by feel. Use some impact spray or lipstick to reveal actual impact location. Once certain we have the correct sweet spot, if it doesn’t correspond exactly with the sight line, make a new mark on the putter’s top edge.
Remember, the ball goal is to launch the ball up 1-2 degrees, with topspin. It is the marriage of two impact features, effective loft and rise angle, that determine whether this happens or not - the combination is called Spin Loft. Effective loft is the amount of loft presented by the putter at impact. If a putter’s static loft is 3 degrees, and the golfer had the shaft leaning forward a degree at impact, the effective loft would be 2 degrees.
This alone would ensure the ball launched up, but the rise angle (the amount the whole putter was hitting up the ball at impact) would need to be slightly greater to get topspin. The video on the right shows the effect of this upward hit. Set-up features that can influence rise angle and effective loft include ball position and hand position respectively. The static loft of the putter can often be adjusted by a clubfitter to solve Spin Loft problems.