Like many members of the royal family, Mountbatten was an aficionado of polo. He received U.S. patent 1,993,334 in 1931 for a polo stick.[116] Mountbatten introduced the sport to the Royal Navy in the 1920s, and wrote a book on the subject.[3] He also served as Commodore of Emsworth Sailing Club in Hampshire from 1931.[117] He was a long-serving Patron of the Society for Nautical Research (1951–1979).[118]