Hello slate people
Do you remember those excursions to the river, when you learned how to skim a stone on the water? Those were the good old days. More recently, I bet most of us have taught our children and/or grandchildren the perfect technique for stone skimming. According to the scientific paper “Skimming and skipping stones”, by Steve Humble, and published in 2002, for a long and pleasant shoot, we need a flat stone, about the size of the palm and between 10 to 15 g. The Guinness Records for skipping a stone is currently set on 88 times, while for skimming distance is 121 m. Much more than the 6 to 12 times I achieve (and less than 10 m).
There is a lot of physics involved in stone skimming. Mark Rober, in his Youtube video “Rock Skip Robot- The Science of Perfect Rock Skipping”, which I recommend, there are four key points for a perfect shoot: 1) 20° angle for the bounce take-off of the rock, 2) 20° angle of incidence of the stone on the water surface, 3) Good spin of the stone, and 4) a flat stone with a smooth bottom. This last point finally leads me to my favorite topic, slates. Indeed, those slates that you can find in the river or the sea, with their edges smoothen by the water, are perfect for practicing skimming. In fact, the astonishing slate islands, in Scotland, hold the celebration of the Stone Skimming World Championships. This event, first celebrated in 1983, attracts people from all over the world, gathering more than 300 participants. For this year, the competition will be held on Sunday 25th September on the little island of Easdale. Easdale is one of these places that will move anyone with slate on his/her veins. Once one of the main production areas for roofing slate in Britain, its mining history came abruptly to its end in 1850, when a hurricane hit this part of the coast, flooding the mines that at that time had reached up to 90 m below the sea level. Today, Easdale has become a quiet and nice spot, holding a small community of less than 60 people. The landscape is formed by slate, and the former mines, now pools of marine water, are a perfect place for freediving.
So remember, in case you are nearby by the end of September, take the 5 minute ferry trip to Easdale and enjoy the Stone Skimming World Championships. The registration fee is only 5 pounds.