What is Frequency of clip?
Even if the so-called current economic “recovery” continues, superintendents will continue to operate with less money and resources while dealing with increasing pressure from management and golfers on course conditions.
Always looking for new or enhanced ways to save time, money and increase turf health, many superintendents are taking a renewed interest in frequency of clip (FOC). Updated reel technology from equipment manufacturers has breathed new life into the discussion by allowing superintendents to control and adjust frequency of clip like never before. Across the country, more superintendents are adding FOC to their toolbox of settings to help them better manage turfgrass.
But what exactly is frequency of clip? If you ask 10 superintendents, you’re likely to get 10 different answers. Frequency of clip is simply another measurement superintendents can use, much like height-of-cut or Stimpmeter readings. Frequency of clip measures the distance between mower shear points (or clips) in the grass and is affected by three separate inputs: number of reel blades, reel speed and mower speed.
“Frequency of clip is one of those things that, as superintendents, we probably don’t utilize to its full capacity,” said Scott Newman, GCSAA superintendent at Spring Creek Ranch in Tennessee. “For us, FOC is part of the daily conversations we have about mowing heights and groomers. We adjust it before the member-guest to get green speeds up without rolling. But what I would say to other guys is ‘Why not try it?’ It only takes five seconds to change.”
How is FOC calculated?
The actual FOC calculation can be derived using the formula in figure 1. For a real-life example, an operator walk mowing at 3.8 mph with a 15-blade reel turning at 2,200 RPM would be cutting with an FOC of .122.
It is important to note that increasing (or tightening) your FOC actually equates to a lower FOC value and decreasing FOC results in a higher value. So when a superintendent says he’s “increasing/tightening his clip rate,” he’s actually adjusting the FOC on the mower to a lower setting.
What Frequency of clip means in the grass
As the mower travels forward, the bedknife pushes against the grass in front of it. At the same time, the reel blade is gathering grass as it moves toward the bedknife. The opposing forces gather the grass together at the shear point. After the grass is cut, the grass springs back into place – this cutting action produces very small peaks and valleys in the grass. Although indistinguishable by the human eye, these high and low points have a profound effect on ball roll.
Frequency of clip and height-of-cut
On fairways and other higher cut areas, some turf professionals suggest that your FOC should be within 10 percent (higher or lower) than your height of cut. At these higher heights-of-cut, when the FOC is greater than 10 percent of the height-of-cut, short, choppy wave patterns may appear, known as marcelling. Keeping FOC approximately equal to or less than the height-of-cut eliminates marcelling and improves ball roll.
On greens and lower heights-of-cut, the relationship between FOC and height-of-cut is not as intrinsically related. Superintendents and technicians should experiment with different settings to see what works best.
Practical application
Traditionally, a superintendent wanting to increase ball speed would likely lower the height-of-cut, double cut or use a greens roller. Not only do these practices cause extra stress on the grass and sacrifice turf health, they also require the use of more labor, water and chemicals.
A superintendent preparing for a member-guest tournament can tighten his FOC to increase ball roll significantly without lowering the height-of-cut.
“For an upcoming tournament, I wanted to increase our green speeds by three to four inches, but I wasn’t keen on lowering the height-of-cut and we didn’t have the time to double cut,” said Mike Rienzi, GCSAA superintendent at Kiva Dunes in Gulf Shores, Ala. “My technician suggested we tighten up the FOC on our walkers. I watched him do it, which took all of five seconds. We went and Stimped the greens after mowing and we actually increased green speed by more than four inches. I was floored at how easy and effective FOC adjustment can be.”
In day-to-day conditions, superintendents can adjust FOC to maintain current ball speed and actually raise the height-of-cut. Trevor Broersma, GCSAA superintendent at Washington National Golf Club outside of Seattle, started experimenting with FOC adjustments earlier this year.
“By playing around with the frequency of clip on our walking greens mowers, we were able to raise our height-of-cut from .115 to .130 and still maintain an 11-foot roll on our greens,” said Broersma. “We also found that with the higher clip rate, we don’t have to mow every day. We are now rolling every other day which is giving us the most consistent speeds we’ve ever had, it’s amazing.”
Getting started
Although FOC is a very precise formula, it is not always an exact science on the turf. Superintendents new to FOC will work with their technicians to experiment with different settings, usually moving up or down 10-20 percent at a time. To monitor changes, superintendents may use a prism to evaluate stragglers and record Stimpmeter readings after FOC changes. Some superintendents will actually weigh clippings to compare grass volumes at different FOCs.
After experimenting, superintendents will arrive at an ideal series of FOC settings for day-to-day play, post-topdressing or aerifying, tournaments or severe weather conditions. Some mowers allow up to six FOC presets that can be programmed into the mower’s control box.
Making mower adjustments
Traditionally, the only way to change frequency of clip was to change reel blade count and alter mow speed.
To help superintendents increase FOC quickly and easily, equipment manufacturers have recently added blades to standard reels. In addition to changing blade count and mow speed, all mowers offer some level of FOC control, most using gears and pulleys.
For an informational video on frequency of clip, visit www.youtube.com/jacobsenturf.