What's the deal with grain?

[natureboy]

5 hours ago, sjduffers said:

I beg to differ somewhat: I regularly play a course on the Big Island of Hawaii that has kikuyu grass on both the fairways and the greens, basically everywhere.  This is somewhat rare: kikuyu is usually used only on the fairways and rough, with something like a strain of bermuda for the greens. Besides interesting/positive agronomic properties, that kind of grass is very strong and grabs your club in the rough and even in the fairway if you don't use the bounce around the greens. Beware!

On the greens, it is like velcro when against the grain and pretty smooth when going with the grain: the difference in speed is huge going with vs against the grain, much more so than 9 vs 11 on the stump: more like 6-7 vs 10!  As for the amount of grain, it's enough to move a ball over 6 inches in the last 2-3 feet of a putt as the ball dies. Yes, clear across the hole! And you wouldn't believe how hard you have to strike a putt going uphill into the grain, against the wind. 

The grain general direction is towards the sunset, which is also the general slope of the surrounding terrain, but it does not quite follow each and every little slope or contour of the green. It can visibly be checked at the cup as the side towards the grain is very frayed, much more so than with bermuda grass.

The first time I played there, I couldn't believe it, but grain is definitely a big factor on this course, nearly as much as slope (not to mention the wind, which can easily gust to 30mph+). Of course, in many areas of this course, it's downhill with the grain and uphill against, but that is far from being the overwhelming rule. In particular, there is an elevated green sloped back to front (back much higher to help hold shots) but the grain is going front to back and despite the significant rise from front to back, it is extremely easy to land a ball at the front of the green and see it roll all the way through, off the back, even with a PW-8i, thanks to the grain!

Very interesting description of your out of the ordinary experience. I wonder if the shading from Mauna Kea relative to the more open western prospect accentuates the tendency toward grain on top of the regular Kikuya habit.

You pointed out that on the long putts you noticed the grain effect more nearer the hole as the ball slowed down. This makes sense with my expectations that the effects of grain may not be strictly proportional to distance unless you're mostly with or against the grain. So the apparent effects when putting across grain may actually be more noticeable as the deviation within say 3' of the hole would be a much larger percentage of the total break on shorter putts and a 2-6" deviation is less of an issue on a long putt that you're primarily lagging anyway.

What was your experience on long vs. shorter putts?

3 hours ago, Golfingdad said:

Yeah, I was fortunate enough to play Kapalua this summer and the difference seemed bigger there as well.  His point, of course, wasn't that it would always be 2 point difference or anything, just that that is really the only place you'll see it pop up.

Unless you have a weird green, which does happen. I understand it's very rare. Just want to  know more about the effect.

1 hour ago, iacas said:

It would be almost the same as if there was no grain, because the grain affects the putt and lets it break a little more in the first part, and then helps "hold it up" a little tiny bit during the latter half.

Note of course it's highly unlikely that you'll find a green with grain growing like that with an inflection point and yet constant slope.

I'm not really interested in the particular read for this scenario. I'm more curious about how the path of the ball would look. I'd expect when falling downhill with the grain, the ball would curve pretty significantly. I'd expect when it's falling against the grain that it would continue falling downhill per physics, but more slowly than with the grain due to the increased friction.

From the vantage point of the viewer and the putter the change in curve from what was expected might make a small 'flattening' of trajectory seem like a 'jog' uphill or a significant break absent a noticeable change in slope. Sort of the same visual/cognitive effect of the 'rising' fastball.

I'm aware it's rare. But it's still in the realm of possibility and interesting.

1 hour ago, iacas said:

I don't think you understood what I meant when I shared the Mark Sweeney stuff from above.

I understood Sweeney looked at 20' putts and saw a significant, but small effect at that distance.

He's very reputable and I would generally trust his approach. I would wonder if he specifically looked at grain changes across sections of constant slope (no noticeable inflection or change in fall line), but there may not have been any to test. Also did he also look at the grain effect on putts 5' or less? If so was there a relationship of deviation per foot of putt due to the grain? There's kind of an implication in the 2" over 20' metric that shorter putts will have a proportional change in break due to grain. But that might not be correct. It might be related to distance traveled across the grain at a certain speed. If he ran those tests too, I'd like to read it.

My expectation is that cross-grain deviation from expected path on a non-grainy green of equal slope would be close to equal on shortish putts as I'd expect the ball to be more susceptible to the cross-grain effects when it's moving slower when it's at the end of a long putt or having being struck softer from a closer initial distance.

1 hour ago, iacas said:

(And this is where your intuition about the speed affecting the second half of the putt is off base, because the trajectory of the "input" is changed, too.)

In the scenario I gave, I was not implying that the grain would only affect the second portion. I was saying the two sections of grain would result in a perceptible change in the curvature of the putt as it traveled to the hole. More curve as the ball is falling downhill with the grain and less curve as it falls against the grain.

From the perspective of the putter or an observer would the putt appear to move/break even though it is just falling downhill at a different speed, because it has deviated from where your gravity intuition expects it to end up based on the initial curve when it's falling downhill with the grain?

I wonder if an optical illusion like this (similar to the 'rising fastball' effect) may explain some of those stories where someone swears their putt 'broke uphill'. If you had a seriously imbalanced ball I suppose the torque might create a similar effect, but is that a more common / expected scenario than patches of opposing grain on areas of the same or very similar slope?

6 hours ago, Club Rat said:

Oh, really good videos, thanks for posting.

Sure thing.

Edited January 10, 2017 by natureboy

[sjduffers]

3 minutes ago, natureboy said:

So the apparent effects when putting across grain may actually be more noticeable as the deviation within say 3' of the hole would be a much larger percentage of the total putt length on shorter putts and a 2-6" deviation is less of an issue on a long putt that you're primarily lagging anyway. What was your experience on long vs. shorter putts?

Yes, when going cross-grain, the effect is much more perceptible on the shorter putts. But, to be fair, you integrate that in your "computer", aka brain, when you have a longer putt that will travel across grain and the average move over 20ft may not be as pronounced as it appears towards the end when the ball slows down.

So, say if the putt moves a foot overall, your start line accomodates that 1ft move, even though the actual move may only appear to take effect in the last few feet. But that is consistent with what a putt would do going across a slope (say at 30 degree to the fall line, as in Erik's post above) without any grain at all. A putt holds its line much better against both slope and grain when its speed it greater, including at the start of a longer putt.  The fact that the grain is usually with the slope just makes this phenomenon even more obvious.

[iacas]

43 minutes ago, natureboy said:

I'm not really interested in the particular read for this scenario. I'm more curious about how the path of the ball would look. I'd expect when falling downhill with the grain, the ball would curve pretty significantly. I'd expect when it's falling against the grain that it would continue falling downhill per physics, but more slowly than with the grain due to the increased friction.

Seeing as how we're talking about tiny changes and without an adjustment to speed, I don't think "curve pretty significantly" is accurate.

The curve would be a tiny bit steeper than "expected" and then shallow out a tiny bit. You probably wouldn't even be able to detect it, because the curve naturally sharpens as the ball slows down (that's more a function of time than speed, but people suck at understanding time in some contexts), right when the grain is doing a tiny bit to flatten that curve a tiny bit.

43 minutes ago, natureboy said:

From the vantage point of the viewer and the putter the change in curve from what was expected might make a small 'flattening' of trajectory seem like a 'jog' uphill or a significant break absent a noticeable change in slope. Sort of the same visual/cognitive effect of the 'rising' fastball.

I don't think it would look like it went uphill. And the effects of grain are still small and take place over time. I doubt it would appear to be a "sudden" movement at all. It's not like the path of the ball would have a "corner" or "kink" in it.

43 minutes ago, natureboy said:

I'm aware it's rare. But it's still in the realm of possibility and interesting.

I disagree.

43 minutes ago, natureboy said:

I understood Sweeney looked at 20' putts and saw a significant, but small effect at that distance.

Odd use of the word "significant." The significance was how small it was.

43 minutes ago, natureboy said:

He's very reputable and I would generally trust his approach. I would wonder if he specifically looked at grain changes across sections of constant slope (no noticeable inflection or change in fall line), but there may not have been any to test.

That's primarily what he tested: the many planar sections of greens at Kapalua (IIRC). And most other golf courses have them too. They don't grade greens with hand shovels. 20' sections of lots of greens have fairly planar slopes.

He mapped greens down to the millimeter, too, for the computer models that were used to plot the AimPoint line on TV, for which he won his Emmy.

43 minutes ago, natureboy said:

Also did he also look at the grain effect on putts 5' or less?

Why?

The last 5' of a 20' putt acts pretty much exactly the same (unless you're a bad putter who launches the ball into the air too much, in which case, you'd get less break on a 5' putt compared to the last 5' of a 20' putt, since the ball's in the air for some of the putt).

43 minutes ago, natureboy said:

If so was there a relationship of deviation per foot of putt due to the grain? There's kind of an implication in the 2" over 20' metric that shorter putts will have a proportional change in break due to grain.

That's not accurate, nor do I think that's been implied. Even a basic understanding of the amounts of break a putt has speaks to that.

Over a 2% side slope a 10' putt breaks 11" and from 20' breaks 25". From 5' it's 5". It's not proportional due to time.

That also doesn't mean a 20' putt over a uniform slope that breaks 25" total will have broken 14" in the first half of the putt, but it does mean that the instantaneous direction of travel at the 10' mark will be at a point 11" away from the center of the cup.

43 minutes ago, natureboy said:

It might be related to distance traveled across the grain at a certain speed. If he ran those tests too, I'd like to read it.

He hasn't shared it publicly.

43 minutes ago, natureboy said:

My expectation is that cross-grain deviation from expected path on a non-grainy green of equal slope would be close to equal on shortish putts as I'd expect the ball to be more susceptible to the cross-grain effects when it's moving slower when it's at the end of a long putt or having being struck softer from a closer initial distance.

Your expectation is wrong, and I already responded to that. The ball doesn't know what it was doing a second ago; only what it's doing right then. The last 5' of a 20' putt are the same as the last 5' of a 5' putt (assuming they're on the same line with the same velocity at the 5' mark).

43 minutes ago, natureboy said:

In the scenario I gave, I was not implying that the grain would only affect the second portion. I was saying the two sections of grain would result in a perceptible change in the curvature of the putt as it traveled to the hole. More curve as the ball is falling downhill with the grain and less curve as it falls against the grain.

No perceptible change is likely, and I didn't assume that you thought it would only affect the second half. I assumed you knew it would affect both halves.

24 minutes ago, natureboy said:

From the perspective of the putter or an observer would the putt appear to move/break even though it is just falling downhill at a different speed, because it has deviated from where your gravity intuition expects it to end up based on the initial curve when it's falling downhill with the grain?

I don't know. People can talk themselves into believing they see all kinds of things. Doesn't mean they did. Or can. I don't really care what people's perceptions are in this; only what really happens.

24 minutes ago, natureboy said:

I wonder if an optical illusion like this (similar to the 'rising fastball' effect) may explain some of those stories where someone swears their putt 'broke uphill'. If you had a seriously imbalanced ball I suppose the torque might create a similar effect, but is that a more common / expected scenario than patches of opposing grain on areas of the same or very similar slope?

People think putts break uphill because their eyes fool them all the time.

This is entirely uninteresting, and I've said about all I can say, or believe is fruitful or beneficial to say. Golfers should not be worrying about these kinds of things. While I enjoy a theoretical discussion now and then, they're about far more important things than this.

[natureboy]

19 minutes ago, iacas said:

Seeing as how we're talking about 2" over 20', I don't think "curve pretty significantly" is accurate.

The curve would be a tiny bit steeper and then shallow out a little bit. That's how it would look. You probably wouldn't even be able to detect it, because the curve naturally sharpens as the ball slows down.

And the effects of grain are still small and take place over time. I doubt it would appear to be a "sudden" movement at all. It's not like the path of the ball would have a "corner" or "kink" in it.

Odd use of the word "significant." The significance was how small it was.

Well I found it interesting. Thanks for participating. I definitely learned about something that I only had a vague notion of before.

The 'significant' was a reference to the fact that the grain had a measurable non-zero effect. 2" in 20' was across a slope with one grain direction (aligned ~ with slope), yes? In that scenario I would agree there would be gradual effects.

If there was a section of constant slope where the grain switched 180* (my scenario) I think the change in the ball's rate of fall downhill would be noticeable because of a deviation from the expected path or destination. The change in friction would be just over instantaneous as the ball crossed the boundary between the differently oriented grains.

Edited January 10, 2017 by natureboy

[iacas]

2 minutes ago, natureboy said:

If there was a section of constant slope where the grain switched 180* (my scenario) I think the change in the ball's rate of fall downhill would be noticeable because of a deviation from the expected path or destination. The change in friction would be just over instantaneous as the ball crossed the boundary between the differently oriented grains.

Again, it likely wouldn't be noticeable because, as I said, the change wouldn't be instantaneous. And the effect would be to shallow out a line (a tiny bit) that's becoming gradually sharper.

For all you know that ball hit a little spike mark or something.

[natureboy]

28 minutes ago, iacas said:

Over a 2% side slope a 10' putt breaks 11" and from 20' breaks 25". From 5' it's 5". It's not proportional due to time.

I understand it isn't but 8%, 9%, 10% of break to total distance is a pretty small difference for how people tend to perceive things. Which is often non-linear at large scale vs. smaller scale.

6 minutes ago, iacas said:

Again, it likely wouldn't be noticeable because, as I said, the change wouldn't be instantaneous.

If there's a sharp boundary, how does the change in friction not affect the rate of change immediately?

Edited January 10, 2017 by natureboy

[iacas]

22 minutes ago, natureboy said:

I understand it isn't but 8%, 9%, 10% of break to total distance is a pretty small difference for how people tend to perceive things. Which is often non-linear at large scale vs. smaller scale.

I think you're just totally guessing here.

And again, I'm not interested at all in perceptions of this kind of stuff. I'm barely even interested, knowing what actually happens, in what actually happens here… because it's so small and insignificant, and even then, only on very very grainy greens.

22 minutes ago, natureboy said:

If there's a sharp boundary, how does the change in friction not affect the rate of change immediately?

It's not a like a plate hitting a wall, or a parachute opening. Again, there's no "corner" or "kink". The shallowing and sharpening effects cancel each other out slightly, and you don't really notice anything.

The ball has momentum and speed and - just like a ball breaking down the slope does so gradually at first and then increasingly more so over time - the tiny force applied takes time to see even the tiny effects.

Seriously, if it affects the last 10' of break about an inch, and let's imagine (though it doesn't happen this way) that this change in direction was immediate. So, 1" over 10', or an angle of… let's see, tan(x) = 1/120, x = 0.47745°.

Whether or not a human can see a change of direction of < 1/2° on a ball curving and bouncing and rolling along a putting green from 10' away is of even absolutely no interest to me at all. I only bothered to pause Sherlock to type that out to you to demonstrate how ridiculous this entire conversation has gotten.

Particularly since, you know, that change in direction does not happen immediately, but over the entire ten feet remaining, and as with most forces, it accelerates. Almost no change at first, then a little bit, and a little more, and then a bit more…

Kevin, you seem to have learned nothing from your time away.

[Buckeyebowman]

On 1/9/2017 at 9:03 AM, saevel25 said:

In the midwest there is little to no grain on the greens. I've played in Florida and the grain pretty much follows the slope of the green. 

For me, I think of grain more in terms of influencing speed. Putts with the grain are faster, and will break more. 

I have to agree with this. I really don't notice grain much around here except on a couple of courses. We played a course last year where we confronted the classic "TV" grain situation. My buddy had hit through the green and was on a slight upslope behind it. From that vantage point the green looked "shiny" almost metallic in appearance! From below, the green appeared to be a deep, dark green!

My buddy knew his shot was going to be slick, but when the ball first hit the ground, I thought he'd made a masterful shot! But, it wound up 25-30' below the hole! I'd find it hard to believe that putting across grain like that, that once the ball "takes the break" and begins to turn downhill, that it won't just "dive" and that you need to make allowances.

[boogielicious]

I've played grainy Florida greens and it really didn't affect my reads at all. I just needed to get speed correct. I putted about the same there as I do in New England.

[natureboy]

On 1/10/2017 at 0:07 AM, iacas said:

Again, it likely wouldn't be noticeable because, as I said, the change wouldn't be instantaneous. And the effect would be to shallow out a line (a tiny bit) that's becoming gradually sharper.

For all you know that ball hit a little spike mark or something.

I totally buy the spike mark idea.

Quite often conventional wisdom makes an association based on lots of accumulated experiences that has some merit, but ascribes the wrong root cause as explanation.

On grasses and/or locations that tend to exhibit a stronger grain habit on greens you're likely to get more long grass stems growing sideways that effectively avoid the mower blades, but get scuffed up by later foot traffic.

So golfers with experience of grainy greens might ascribe observed deviations to shifting grain direction in the grass variety rather than an unusual frequency of ornery long stems that get lifted / bent up such that they influence the ball.

I still think there's a chance built-in expectations of a putt's motion may also be at play. As you say the expectation is that the putt will curve more as it slows due to the extra time gravity has to apply torque. An experienced putter will form an expectation of what that putt will do based on how hard they hit it vs. their intent and the way the ball behaves relative to their initial read in the first part of the putt.

Say when first struck it seems initially 'right' for a slick sidehiller falling with the slope and grain. It starts curving quite a bit with an expectation that it will curve even more as it slows. Then if the putt trajectory flattens even just a bit across an opposite (uphill) grain change, the ball doesn't end up where their internal model (based on experience) anticipate it 'should be'. So the brain may ascribe illusory motion to it.

Spoiler

 

Quote

For years batters swore that some pitchers could throw a rising fastball. The laws of physics say this is impossible. Instead, it's an illusion caused when the pitcher throws a faster pitch than the batter has seen. In bottom figure b, the batter watches the ball for the first part of its flight and calculates its drop. Then he looks down at the bat and the ball appears to have jumped because it's higher than where his mental model predicted it would be, based on earlier, slower pitches as shown in the top illustration. (Graphic by Alison Habel)

Quote

 

The purpose of changing pitch speeds is not to fool the when computer, but rather to fool the speed estimator and consequently the where computer. 

https://pdfs.semanticscholar.org/2e1a/f7d17ba803ae9842688be3bdbadae8b662f5.pdf

 

It's a small actual deviation, but a large perceived deviation by highly experienced and skilled athletes

 

On 1/9/2017 at 11:43 PM, iacas said:

That's primarily what he tested: the many planar sections of greens at Kapalua (IIRC). And most other golf courses have them too. They don't grade greens with hand shovels. 20' sections of lots of greens have fairly planar slopes.

He mapped greens down to the millimeter, too, for the computer models that were used to plot the AimPoint line on TV, for which he won his Emmy.

I wasn't wondering if he examined planar slopes. I was wondering if he specifically looked at sections of green where the grain direction was contrary to the average expectation of going with that planar slope...'grain breaks' rather than slope breaks if you will.

The 2" over 20' might have only measured the effect of grain that is going with the slope as is 'typical'. He may not have been looking for sections of grain that did not go with the slope to see if there was any different impact. He may have looked and wasn't able to find any. But that was what I was referring to. Not whether he measured level sections of green.

On 1/11/2017 at 7:01 AM, boogielicious said:

I've played grainy Florida greens and it really didn't affect my reads at all. I just needed to get speed correct. I putted about the same there as I do in New England.

I haven't played many 'grainy' greens myself...there's one green on a severe side slope that is also severely shaded and has pretty strong grain going up and down a ridge in the green. But it's with the slope.

I've also experienced pretty noticeable deflections from when the Poa is seeding. But even that unevenness was oriented pretty vertically IIRC.

Edited January 14, 2017 by natureboy

[David in FL]

9 minutes ago, Hardspoon said:

I love when announcers treat grain on putting greens like it's some sort of magical force. 

"It will run out on the hill after the hole, since the grain changes there."

...or because it's downhill, dummy.

No argument that grain generally tends to go with the slope, but like the slope it can change throughout the line of putt.  Some of the Bermuda strains are very grainy and definitely contribute to both the speed and break....  

[iacas]

9 minutes ago, David in FL said:

No argument that grain generally tends to go with the slope, but like the slope it can change throughout the line of putt.  Some of the Bermuda strains are very grainy and definitely contribute to both the speed and break....  

Not really. As has been discussed many times here.

[David in FL]

4 minutes ago, iacas said:

Not really. As has been discussed many times here.

I know.

But you're wrong on that.  It's less these days with some of the newer strains, but grain can definitely be a consideration with some.  Stop by next time you're down here and I'll show you some...  

[iacas]

4 minutes ago, David in FL said:

But you're wrong on that.

Nope.

Grain barely affects break.

[David in FL]

Just now, iacas said:

Nope.

Yep.

 

[iacas]

Just now, David in FL said:

Yep.

Uhhh, no.

I've done the tests myself. Mark Sweeney has done the tests. You've been proven wrong.

[saevel25]

10 minutes ago, David in FL said:

But you're wrong on that.  It's less these days with some of the newer strains, but grain can definitely be a consideration with some.  Stop by next time you're down here and I'll show you some...  

I've played in Orlando many times over the past 10 years. The grain only influences the speed of the putt. 

[David in FL]

4 minutes ago, iacas said:

Uhhh, no.

I've done the tests myself. Mark Sweeney has done the tests. You've been proven wrong.

I've played thousands of rounds on Bermuda greens...and have proven that I'm right.   

 But as I said, next time you're down here, I'll take you to a couple of courses where you'll struggle if you don't consider the grain in addition to the slope.  Admittedly, there aren't as many as there used to be.

If you'd care to share the actual testing protocols and results though, including the specific strains tested, I'd love to see it though...

 

14 minutes ago, saevel25 said:

I've played in Orlando many times over the past 10 years. The grain only influences the speed of the putt. 

Mostly speed, true.  But certainly something to consider.  

Again, it's somewhat strain dependent.  Most of the courses you've played are likely using some of the newer strains that have less grain...