From the excellent Crumb Trail
Theory is useful but experiments are more satisfying. Many important, age-old mysteries have been solved this way. A recent effort discloses effective methods for stone skimming (or skipping) on water bodies.
Want to skim the perfect stone? A team of French researchers have worked out how, using their very own stone-skipping machine...
To achieve the maximum number of rebounds, the angle between a spinning stone and the water should be about 20 degrees, advises Clanet: "This is the magic angle."
Spin, speed and shape are also important. A stone is more likely to rebound if it is rotating, they found. This is because spin stabilises the object and prevents it from falling into the water.
And there was silly old me thinking that Barnes Wallis had already done these experiments some time ago, as this sketch of his from 1942 shows: