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 Émile Gagnan Émile Gagnan (November 1900 – 1979) was a French engineer and, in 1943, co-inventor with French Navy diver Jacques-Yves Cousteau of the Aqua-Lung, the diving regulator (a.k.a. demand-valve) used for the first Scuba equipment. The demand-valve, or regulator, was designed for regulating gas in gas-generator engines, but was found to be excellent for regulating air-supply under varied pressure conditions. This allowed people to explore the ocean more easily, even though the original purpose was different. Gagnan was born in the French province of Burgundy in November 1900, and graduated from technical school in the early 1920s. He was