Solo diving II. In the late 1940s, after the invention of the Aqua-lung by Cousteau and Gagnan, the first retail underwater breathing apparatus for sport was commercially marketed. As the sport expanded through the 1950s, several sporting organisations – notably the Young Men's Christian Association (YMCA) – began scuba training programmes for swimming enthusiasts, thus began the codification of what was believed to be proper practices for the expanding amateur sport of scuba diving. The buddy system was thought to be a useful corollary to the "never swim alone" edicts of the YMCA swimming and lifesaving programmes. Cousteau independently implemented a buddy
Émile Gagnan employed as an engineer specializing in high-pressure pneumatic design by the large gas-supply firm Air Liquide. The first production 'Scaphandre Autonome' - or 'Aqualung' was released in France in 1946 under the identification code "CG45" ("C" for Cousteau, "G" for Gagnan and "45" for 1945, year of the patent). A year later, in 1947, Émile Gagnan and his family emigrated to Montreal, Quebec, Canada and he transferred to the employ of Canadian Liquid Air Ltd. There he set up a lab and proceeded to engineer, design, prototype and patent a very large number of SCUBA and undersea technology firsts, including