GOLFERS won鈥檛 be able to blame the greens next time they miss a putt. Engineers in the US have designed a device that can test the uniformity of putting greens, ensuring the grass is smooth and even at every hole.
For twenty years, ground staff have been checking greens with a rudimentary device called a Stimpmeter. One end is slowly raised until, at a 20掳 angle, a ball rolls down a ramp and across the green. By measuring the distance it goes, you can compare different greens. If the distance varies by no more than 15 centimetres, the greens on a course are said to be uniform. But the Stimpmeter doesn鈥檛 detect the small variations that can throw putts off course.
So Roch Gaussoin and his colleagues at the University of Nebraska at Lincoln have built a more sophisticated version of the Stimpmeter that measures how a ball鈥檚 speed varies along its path. The ball rolls through a 2-metre-long plastic tunnel on the green (see Diagram) crossed by a series of infrared beams. After the ball breaks the first beam, a computer records the time intervals between each further breakage, giving an accurate picture of changes in the ball鈥檚 deceleration. The results are uploaded to a laptop and analysed, revealing where the greens are slow or rough.
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Early trials of the device showed that mowing increases the variation within each green (Crop Science, vol 39, p 741). Unmowed greens are the most consistent, but the long grass slows the ball too much. Greens mowed twice in the same direction are the most inconsistent. The researchers have yet to test competition greens, which are usually mowed twice in different directions to avoid giving the grass a one-way 鈥済rain鈥�.