Originally Posted by vangator
Every article I've read on the internet so far indicates that grain does influence the break. Plus, I've putted on grainy grains for 35 years in Florida and I'm not dreaming when I see how the grain affects putts. I'm an engineer and I know computer model can be flawed. I just fixed one as a matter of fact. So I take some of the "science" with a grain of salt, just like global warming.
Mark Sweeney developed a computer program that, given a map of a green, determines how much a ball will break. It won an Emmy, and was the software they used to plot the AimPoint on Golf Channel for a number of years.
The software assumes there is no grain - just a uniform surface of a given stimp (the slopes are laser mapped to a millimeter or so). On the grainiest greens on the PGA Tour (in Hawaii), the software was off an inch or two over twenty feet. That could be accounted for by adjusting the speed of the green in the software by about 1 foot on the stimp - down when you're into the grain and up when you're down-grain. Also, if you could grow grainy grass on a little platform or something, then make it dead level and hit a 20 foot putt perpendicular to the grain, the ball would move less than an inch.
Your experience doesn't really mean a lot. Grain almost always grows downhill, so almost every time you're putting WITH the grain it's a downhill putt.
If the stimp is 10, and so uphill putts are like 9 and downhill putts are like 11… A twenty-foot putt at 45° on 3% slopes breaks:
- 16 inches from 45° uphill (18")
- 42 inches from 45° downhill (35")
The numbers in parentheses are what the greens would break at 10 on the stimp (i.e. no grain effect at all). Downhill putts break more. People often don't give this credit, so grain can, in their minds, get a lot more weight than its due.
I'm cynical about EVERYTHING. The first thing I do with new stuff is try to disprove it. But… I don't give a lot of weight to my "experiences" because they're a lot more likely to be wrong than some good science.
Grain affecting the break of a putt is a bit of a myth, or at the very least, a bit of mistaken identity or something: it affects the SPEED of a putt, which affects the read slightly. Not a lot, though. Two inches on that uphill putt. And 3% slope is pretty steep across a twenty foot section of green. 2% is far more common.