Stone skipping
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Stone skipping is a pastime which involves throwing a stone with a flattened surface across a lake or other body of water in such a way that it bounces off the surface of the water. The object of the game is to see how many times a stone can be made to bounce before sinking.
The pastime is also called stone skimming, stone skiting, and ducks and drakes in the UK; and stone skiffing in Ireland. The North American Stone Skipping Association (NASSA), formed in 1989 and based in Driftwood, Texas, holds world championships each year; the next is expected to be held at Playa Ros beach in Spain. A similar event takes place every year in Easdale, Scotland.
The world record according to the Guinness Book of Records is 40 skips, set by Kurt Steiner at the Pennsylvania Qualifying Stone Skipping Tournament on September 14, 2002 ([1]).
Research undertaken by a team led by French physicist, Lydéric Bocquet, has discovered that an angle of about 20° between the stone and the water's surface is optimal. Bocquet and his colleagues were surprised to discover that changes in speed and rotation did not change this fact.
Earlier research reported by Bocquet calculated that the world record of 38 rebounds required a speed of 12 m/s (25 mph), with a rotation of 14 revolutions per second.
The rules are:
- The stone's diameter shall not exceed 3in at any point
- The stone must have been formed naturally
- The stone must bounce three times before sinking
- The stone that skims the farthest within the marked lane wins, irrespective of the number of bounces
- Each competitor gets five attempts, with the longest skim counting.
[edit] Further reading
- Spinning Flight : Dynamics of Frisbees, Boomerangs, Samaras and Skipping Stones, Ralph Lorenz, Copernicus New York, September 2006 ISBN 0-38730-779-6
