A Generalized Theory of Green Speeds

Slower greens can challenge players while their putters are still in the bag

I have an admittedly ambitious generalized theory of green speeds that I want to discuss here. I see it as exceedingly difficult to communicate because it relies on multiple variables and is course dependent. I want to propose a theory of green speeds that is designed to maximize the utility of the green in relation to defensive architectural design.

The Basics: Consistent Green Speeds

To start, I'm assuming we all agree that consistency is paramount, so when we are talking about green behavior, we assume it's consistent across an entire course. This should be obvious, so it’s hardly worth discussing.

Penal Design: a Source of Conflict

Of the widely accepted schools of golf design, I sit squarely in the strategic school. Thus, I should address the inherent conflict that exists between the strategic school and penal school. However, I want to give credit where credit is due. From a penal school perspective, I think there will be a much stronger argument for a consistent “faster is better” philosophy.

When looking at a golf course from the penal perspective, we should expect the greens to be mostly flat.¹ When dealing with mostly flat greens, there is some difficulty in making them challenging. An ideal solution to this is increasing green speed. In maximizing green speeds, you maximize the penalty for a player's incorrect speed or line. From this penal perspective, it’s easy to see why you would advocate faster greens. On intentionally flat greens, faster is better.

Strategic Design: Playable Area and Strategic Elements

From a strategic perspective, however, green complexes are as good a tool as any in golf design for offering both optionality and risk-reward strategy. There are plenty of strategic green complexes that have become templates for exactly these reasons, but my focus here is how strategy is affected by green speeds.

This green has a contour designed to exactly replicate a stimpmeter. This demonstrates that with green speeds at eight, both tiers are pinnable, but with green speeds at 12, ending up on the wrong tier means players cannot reach the lower tier without rolling off the green. This overly simplistic example demonstrates the inverse relationship between green speeds and realistically pinnable areas when strategic contours are present.

An important effect that green speeds have on green design is how the green speeds interact with pinnable areas. I’ve heard designers talk about this as a constraint to calculate away, where the contouring depth is adjusted to the green. This works because as the friction goes down, you can effectively create the same motion by reducing the height of contours.² However, when contouring is reduced in height to adjust for the coefficient of friction it has a dramatic impact on approach shots.

Rollout as Strategy

A receptive green and a fallaway greens effects on higher and lower trajectory shots.

While large contours can provide interesting challenges on a green, their real strategic value is in their relation to approach shots. Fallaway greens are a perfect example of this. A standard, back-to-front receptive green will “receive” different types of shots. Fallaway greens, however, will allow high shots to hold, while longer shots that usually have a lower trajectory will run off the back of the green. Using a fallway green, like the one pictured above, allows a course designer to add more interest to reachable par fives by giving players a reason to lay up.

Here, however, we are using contours to reject running approach shots while accepting shots coming in from steeper angles that are able to stop shorter. What happens if we want to do the opposite? How could we design a green that is more receptive to running shots, while being more risky to shots coming in at steeper angles?

MacKenzie’s famous — and lost — 12th green at Sitwell Park Golf Club

One way we can favor lower trajectory shots is with big, steep contours butted up against each other. Alister MacKenzie’s famous 12th green at Sitwell Park is a good example of this.

Running shots are able to hold this green on a variety paths

Here we can see that a running shot, whether it’s just right, too strong, or far too strong, can still hold the green.

High trajectory, high spin shots can only hold the green in a shallow landing zone.

Only a shot that is exactly on target will hold the green here if it’s coming in from a steep angle.

The are in green is the acceptable miss area that can still hold the green.

Here we can see that the range of acceptable error for lower shots is larger than that for higher shots.

The two-dimensional example above, however, is an oversimplification. I don’t want to get too technical, but the main point is that the directional vectors of a ball landing from above, at speed, will impart more velocity on the upper section of downslope than a ball released from a completely stopped position. When the shot has higher spin, this kinetic energy is converted into more velocity, sending the ball downhill. The difference in the velocity of a ball at rest to that of a ball coming in from a high angle can mean the difference between holding the green’s tier or running off.

All this is well and good, but it only provides for a small difference in outcomes. However, when we move the example into three dimensions it becomes much clearer how to illustrate how exceptionally large contours can incentivize different kinds of shots.

Deflection as Defense

In three dimensions, a running shot can change directions on a green so that it can approach a hole from a completely different direction than an aerial approach:

This green can deflect a running shot with the left contour.

On this green, from this angle, we can see a running shot bend up and onto a fallaway green when approaching from the opposite direction.

The green can hold only high loft, high spin shots on the fallaway section from this angle.

Here the same area of the green can be held with a high spin shot from the opposite angle, but there is much, much less room for error. A shot that is too long or too short will be in danger, but the player also needs to worry about whether a shot to the correct distance can even hold the green. The dangers of the high shot are less severe from the opposite angle, but the green is still a fallaway green without the bend in the running approach.

There is a similar result for approaching the center of the green:

The green should allow run up shots to stop short without rolling back down, leaving an uphill putt to a center hole location.

Ideally, the green is not so severe that a shot that runs on won’t roll back off. This allows the player to get close, if imperfect, shots up to the edge of the plateau without too much danger.

However, a high lofted shot that misses right should deflect left and run off.

In contrast, the extra energy from a high-flighted shot should cause a slight miss left to run off the green.

A shot that misses long should spin back and also run off.

Even a shot with a bit of spin that misses long should spin off the green. Again, once the ball gets up to speed here, it should run off the left side, but it should remain stopped if it comes to a stop on this section.

Only a shot that hits the back of this green perfectly should spin toward a center hole location.

Only an extremely well struck and highly spun shot should be able to hold from the same angle as the run up. This approach leaves little room for error, and even then, the player must putt back toward the dangerous slope, whereas the runup should stop and leave an uphill putt.

Here approaching the green from the right is much more dangerous than approaching the green from the left side, but even then, it gives players optionality in approaching on the ground, and that may even provide an advantage.

Slower Greens, More Deflection

The reason why green speeds are the linchpin here is that they control the amount of fall in the fallaway green. If we want to make the approach from the right very dangerous, we need to make it nearly impossible to hold the green, even with a wedge. Looking at the previous green from different approach angles, we see how the risk increases.

This green should demonstrate both optionality and strategic advantage for a left side approach.

The more the shots kick toward the back bunker, the more risk is added to shots from the right side. However, the angle of the green can only be pitched so far until the green becomes unpinnable at high green speeds. This means as green speeds go down, the riskier the shots can be made when approaching from the right side.

Here we can finally see the inverse relationship between green speeds and contours. The faster the green speeds, the smaller the contours must be to make the green playable, so the less deflection we can add to threaten higher lofted shots. The inverse is that the slower the green speed, the larger the contours can be, and the more complex deflections we could impose on higher lofted shots.

This Doesn’t Mean Making Greens as Slow as Possible!

Threatening contours are a tool, just like any other tool in the architect's toolbox. If the architect wants to design strategic contours that reward the ground game while increasing risk for the aerial game, that should be an option, but how often and how much is completely discretionary.³ Every single green will be different, and the vast majority will likely not want to favor one style of play over another.

However, if we want to give architects the tools to reward different shot types and test different skills, we ought to defer to the same architects on what the green speeds should be. As long as green speeds are treated as faster-is-better, we will be tacitly endorsing flatter greens with inherent advantages for the aerial game over a ground game. Once all the greens are set with any intended deflection in mind, it’s worthwhile to then go back and find out the green speed that maximizes playability and fun on all the greens with all the angles in mind.

Here we ought to design the green speeds to suit the greens, not the greens to suit a desired green speed. This is important enough to reiterate. Green speeds are ideal, not because they are fast, but because they maximize the fun and challenges of the greens themselves. Courses with flatter penal greens should be faster, and courses with strategically contoured greens should be slower, but those green speeds need to be consistent from start to finish. Greens interact with approach shots as much as they interact with putts, and when green speeds are viewed as only serving players once they are already on the putting surface, then we’ve already created severe limitations on how the green complexes can influence the game.

1. This may seem counterintuitive to some, but the idea is that shots that are on target should be rewarded under a penal framework, which means that the green should be receptive to shots in general. That means you don’t want to have your shot deflected even if you hit it right to where you want it to go. You penalize people for missing the green, not hitting it.

This point is illustrated by Garrett Morrison on his podcast Designing Golf in “Golf Architecture 101: The Three (or Two?) Schools of Design | Designing Golf,” where he makes a similar argument for fairways and greens.

2. If there is an area for me to be very wrong here it’s this point. While I normally get very nerdy in these essays, getting into the physics of static and kinetic friction is really just beyond the scope of what I can practically add here.

3. I’ve previously discussed the creation of a high shot hazard specifically to address and create risks for specific shot trajectories. I still stand by this idea even if it seems a bit out there.