Sir Charles Parsons, who invented the steam turbine in 1884, couldn't figure out why his revolutionary steam-driven yacht Turbinia could only manage a measly 19 knots when his calculations suggested it should achieve 40 knots – easily making it the fastest ship in the world. Cavitation – the noisy, vibration-inducing 'cold boiling of water' – was robbing its propeller of power. This film explains what causes cavitation and describes how Parsons developed a propeller design that would minimise it and drive his yacht into the record books