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Much like the location of a property has a major impact on its value, the location where green speed is measured has a significant effect on the measurement’s accuracy and value to the superintendent. After all, if a green speed measurement is not a reasonable representation of the entire putting green, decisions based off it may not produce the desired outcomes. This article is dedicated to understanding what makes a good Stimpmeter® measurement area and how a turf manager may go about selecting one.

Measuring green speed with a Stimpmeter is a simple process. You roll three golf balls in one direction on a level area, measure the average of the three rolls with a tape measure, repeat the process in the opposite direction, and then average the averages from both groups to arrive at one green speed measurement. The process is essentially the same with the GS3™ Ball, except you use one GS3 and roll it three times in each direction. The DEACON® management system does the math for you and the roll test also provides smoothness and trueness readings along with speed.

Whether you are using golf balls and a tape measure or the GS3, getting accurate readings is predicated on finding a good location for the Stimpmeter test, which can be difficult depending on the design of the greens and their speed. Let’s define a few terms and lay out a procedure that will have you selecting good locations in no time.

Flat Versus Level

Do you know the difference between a flat area and a level one? Both of these terms are important when looking for a quality Stimpmeter location. Flat refers to a surface that is level and smooth, without any curves, bumps or irregularities. A flat surface is a true plane. For example, the edge of a Stimpmeter is flat regardless of its orientation. A surface that is level is perpendicular to gravity – i.e., you could put a bubble level on it and the bubbles would be in the center. A surface can be flat but not level, or level and not flat; they are related but independent properties.

When considering where to measure green speed, a surface that is flat and level is the ideal scenario because ball roll distance would be essentially the same in each direction. Unfortunately, most putting greens do not have totally flat and level surfaces because greens typically have some amount of tilt and contour. An area that is flat but not level describes a tilted plane. Green speed can be measured accurately on a tilted plane without using a formula to correct for the impact of slope so long as the distance between averages in each direction does not exceed 18 inches. Surfaces that are level but not flat have bumps even though they are essentially perpendicular to gravity. This scenario presents unique challenges when measuring green speed. If a ball is released from the Stimpmeter into an upslope or downslope, it will change the initial velocity of the roll and impact the distance. Similarly, slope can change at the end of the roll which will impact how quickly the ball stops. Unfortunately, most locations on a putting green are neither flat nor level. So, what is one to do? How can a good Stimpmeter spot be identified?

Finding a Good Spot on an Imperfect Surface

The following are practical steps to help identify a zone to measure green speed that provides an accurate reflection of current putting green conditions. Once you find a good location, mark it with dots using a permanent marker or spray paint so that you can consistently take measurements in the same place over time. This is standard practice when we take green speed measurements during USGA championships and is something I recommend to all superintendents for taking comparable readings over time.

“Once you find a good location, mark it with dots using a permanent marker or spray paint so that you can consistently take measurements in the same place over time.”

First, find an area that looks flat and level. Roll a ball across the area to make sure there is minimal break right or left. Look to see how the slope changes. Is some of the area slightly uphill and some slightly downhill or does the slope move in a consistent direction? An area that tilts in one general direction (flat but not necessarily level) is preferable so long as the gradient is not too steep. If you want to be sure, use a 36-inch digital level at multiple points across the area to assess how the slope changes. Ideally, try to find an area with uphill or downhill slopes less than 0.5%.

Once you have a potential area, perform a normal Stimpmeter test with three balls rolled in each direction. If the difference in distance between the two sets of rolls is less than 18 inches, the location has good potential and the green speed measurement is not being unduly influenced by slope. Make temporary marks at the two ends of your measurement area or place a tee in the ground at each location. For most courses, a 12-foot-long rolling area will be fine. If you have green speeds that seasonally reach or exceed 12 feet, see if your location can be stretched to 13 or 14 feet.

If you cannot find any areas that are long enough, use the 2x notch on the back of the Stimpmeter for a shorter roll. We use the 2x notch regularly at USGA championships because it is difficult to find a long enough area when putting greens are at championship speed. To use the 2x notch properly, just follow the standard Stimpmeter test procedure and double the average distance.

Once you have a potentially good location, fine tune it. Try to find a roll direction that minimizes horizontal break. In our experiences, an area with a slope moving in one direction is preferred. Try to avoid using a crowned area where balls are being released into an upslope that immediately reduces the initial velocity of the ball. This can result in a green speed reading that is slower than what it would be on a flatter area. Ideally, you also avoid valleys where the ball is released on a downslope in both directions. These areas are tricky because initial velocity is higher at both ends and this may distort the speed depending on the remainder of the terrain across which the ball is rolling.

Once the location and roll direction are established, permanently mark the area identified by placing dots at both ends of the desired path. It is preferred to start your measurements in the direction where ball roll is farthest to ensure that the balls stay within the marks. At USGA championships, we draw an arrow to identify where the first set of rolls should be initiated.

Final Thoughts

Prime real estate holds its value over time and so does a good Stimpmeter location. Imagine the value in having excellent green speed data not only on a given day but over many months and seasons. The more reliably your green speed measurements match actual conditions, the more useful this information will be for planning and course setup. Take your time scouting for good locations, and once you find them stick with them.