The eggbeater kick propels swimmers in an upward direction. This was replaced in 1951 with the Sikorsky HO4S helicopter (the "Eggbeater"). "Eggbeater" turbines, or Darrieus turbines, were named after the French inventor, Georges Darrieus. The eggbeater kick is a highly refined and efficient method of treading water. Goalkeepers must be able to perform the eggbeater kick to a high standard. The intermeshing rotors quickly earned it the nickname "eggbeater". An average eggbeater height is usually around collarbone level. The eggbeater kick is used in several different types of swimming activities. Eggbeater kick can be used to move through the water if the body is angled. In April 1993, Kline quit the band to work on his own musical project, Eggbeater. The "eggbeater kick" is another important skill of synchronised swimming.