The son of a former Torquay police inspector, John Maynard attended Torquay Grammar School before joining the Royal Air Force (RAF) as a cadet. After cadet training, Maynard was granted a commission as a flying officer and eventually became a squadron leader. With living by the sea, Maynard became a keen sailor and in 1968 won the British Finn Championship. A couple of months later he went to Mexico to compete in the Olympics and finished 22nd overall in the Finn class. He was in fifth place after the opening race. In the 1970s Maynard became a Royal Yacht Association coach and put together a training programme for Olympic hopefuls. He also continued sailing in Masters events beyond the age of 55.