Slippery Slopes

My favorite golf quote comes from golf architect Harry Colt, “In no case should a green be contoured so that a ball runs away from the putter like a swine possessed by the devil.” As greens get faster, satanic swine are an increasing problem.

Many clubs try to resurface greens by using the no-till or minimal disturbance methods in place of full mix replacement. In so doing, it’s possible to alter grades slightly by a trimming 1-2 inches off ridges and adding similar amounts of mix to swale bottoms, while still remaining within typical mix depth standards of 10 to 14 inches. Altering total grades by 4 inches over 50 feet reduces a 4 percent grade to 3.33 percent, which may be acceptable slopes for your green speed. If not, a full mix and tile renovation may be required.

According to my survey of superintendents, today’s typical green speeds are 9.5 to 10.5 on average courses (with seasonal or special tournament speeds of 10 to 12) but even greens built in the 1960s to 1980s (due for remodels now) can be problematic. Some courses keep greens at tournament speeds of 12 to 14 and have even more slippery slopes.

It’s generally agreed a “fair” putting surface allows golfers to get even downhill approach putts within three feet of the hole and keeps break for short second putts “within the hole” to reward good shots. More importantly, flat areas around the hole location reduce time consuming green reads and three putts, thus keeping challenge reasonable for everyday play and reducing slow play.

The general industry recommendation is to keep cupping areas between 2 to 3 percent. However, two other sources suggest slopes might be slightly steeper:

1. A chart produced by Jerry Lemons, ASGCA, regarding “Putting Green Speeds, Slopes, and ‘Non-Conforming’ Hole Locations” published in the July 2008 USGA Greens Section Journal.
2. Dual reading method.

Based on empirical research, Lemons provides maximum, marginal and critical slope recommendations. He notes hole locations in marginal slope areas can’t have any changes of grade right around the cup to be fair. He correlates decreasing slope to increased Stimpmeter readings, as shown in CHART A.

In the dual reading method, hole locations are placed only where digital level readings of both downhill and cross slope have a combined total slope of <5.5 percent (sometimes reduced to a combined limit of <5 percent on the front half of greens to reduce ball mark damage and make front cup locations less treacherous).

For comparisons, we must convert these combined readings to one actual downhill slope as used in the other guidelines. The Pythagoras theory indicates that the maximum downhill slope from a combined reading of 5.5 percent would be 2.82 to 3.88 percent. The maximum slope occurs when both downhill and cross slopes are 2.75 percent, whereas 1.75 percent and 3.5 percent yields “only” 3.17 percent actual slope.

Those slopes closely mirror Lemons’ range of 2.9 percent for “recommended” and 3.85 percent for highest “marginal slope” at green speeds of 14. But Lemons’ chart suggests higher slopes can exist where green speeds are more typical, if they can be counted on to remain so, and still be puttable.

At any course where I am renovating greens, I start by having golfers identify their toughest hole locations. At one club with daily Stimpmeter readings of 13, every hole location mentioned as “borderline unfair” had a combined reading of 5.6 percent or greater, mirroring championship standards. However, conditions and golfer preference at your course will vary and may be set by management at public courses without golfer input.

Then, we must consider your course’s presentation philosophy and anticipate future conditions, including:

• Will your course follow the long-term trend towards ever faster greens via improved agronomy?
• Will your maximum speed be a result of annual seasonal conditions or periodic annual events?
• Will the role of your course change, for example, from private to public, or ultra-private “player’s” club to family club?
• Is your course a probable tournament site?
• Above and beyond specific hole location complaints, do your everyday golfers:
  • Like the challenge of your greens as is?
  • Or do they favor more (or less) challenge?
• Will your new grass type and/or construction method increase green speed?
• Does slow play affect the enjoyment of your course?

With a consensus on how these questions affect green slope, you probably should allow for construction error, because grade changes of just an inch can put you over your desired maximum slope. Further, contractors from company to company (and even from crew to crew within one good company) vary in their precision.

My takeaway of suitable green slopes? Every course is unique but they need to get their greens right when undergoing renovation. And getting green slopes right involves considering both the big picture and the littlest of details.