Buddy diving just before and after the Second World War. After the invention of the "aqualung" by Cousteau and Gagnan, the first commercially underwater breathing apparatus became available for sale for sporting purposes in the late 1940s. As the new sport of scuba diving rapidly expanded through the 1950s, several sporting organisations—notably the YMCA—began programmes to train swimming enthusiasts in this new aquatic pastime, and began to codify what they believed were proper practises for this expanding sport. The YMCA considered the buddy system a useful corollary to the "never swim alone" rule of their swimming and lifesaving programmes. Cousteau himself independently
Ted Eldred was protected by US patent and international patents, so Eldred set about designing the Porpoise CA (a prototype), the world's first single hose regulator. Eldred referred to the French model as the Gagnan Aqua Lung, as designer Émile Gagnan was the Frenchman who actually designed the device for Jacques-Yves Cousteau. This new design was superior to the Aqua Lung, and did not violate any of the existing patents. Eldred's regulator was never patented as his business was too small for the expense. The first production model was designated the CA-1. (C A for compressed Air, 1 for single cylinder) He