## Monday, August 24, 2009

### Science and Motion (SAM) Analyzes Skid-Roll

Fantastic link from Science and Motion into what factors into the skid-roll (http://scienceandmotion.com/minicms/zeigseite.php?filename=sam_highspeed_video&navid=109&lang=en&node=11:109)

Here's some observations:

The above pic shows a putt with moderate skid and moderate roll. The golfer has O* of shaft lean. The loft on the golfer should be 3.5* because the effective loft is 3.5* and there is 0* of shaft lean.

Effective loft = Loft of Putter Face + Shaft Lean (negative for forward shaft lean, positive for backward shaft lean)

Since the degrees of upward hit is less than the effective loft, that creates more skid and backspin.

This is probably the thing I disagree with Stan Utley the most, who suggests that he average golfer does not play with enough loft on the putter. If the golfer plays with say a 5* loft on their putter and they have neutral shaft lean, then they will have to hit way up on the ball in order to reduce the skid. But what Utley actually does is he has quite a bit of shaft lean on his higher lofted putter and plays the ball further up in his stance. This makes his effective loft LESS than the loft on the putter face, so he doesn't need to hit way up on the ball...but moving the ball forward in his stance allows him to hit further up. One of the issues with moving the ball up forward in your stance is you're likely to miss putts left. It not only causes the golfer to tend to have a left aim bias, but the golfer is likely to start closing the putter face by the time they reach impact as well.

The pic above says the putter has 'added loft.' I would assume that means a backward shaft lean. Here the effective loft is at 5* and the rise angle is very low at 1*. That causes significant skid and backspin. Zach Johnson adds loft to his putter at address and he uses the SeeMore putter which has 3* of loft. My guess is that he probably finds a way to de-loft the putter come impact. Either that or he has a ton of upward hit because Zach is a very good putter and you can't putt well with a ton of skid.

The pic above shows how to do it (in optimal situations). The golfer has an effective loft of 1*, but a rise angle of 4*, that reduces the skid and gets the ball rolling right away. This can become an issue if the greens are slow and you're better off finding a putter with added loft to help get the ball in the air a bit.

I carry two putters, a Yes! putter and a Mizuno Bettinardi. I use the Yes! putter most of the time since the greens I usually play on have decent speed to them (10-12 on the stimpmeter). But on slower greens I use the Bettinardi because it gets the ball up in the air a bit more, but with 'topspin.' If you're on slow greens, you don't just want to add loft to the putter if it creates backspin. You would want a putter with higher loft that can still create some topspin as it skids.

3JACK