Joop Carp and fellow crew member Bernard Carp were brothers. After his gold medal in 1920 in the 6.5 m class, Joop won another bronze medal in the 6 m class in 1924 together with his boat Willem Six. In 1921, he graduated from Leiden University to become a lawyer. Initially, he worked as vice-president for Fokker aircrafts. After that he founded the trading company Carp & Co. in Amsterdam, exploiting inventions and became friendly with Prince Bernhard of the Netherlands (1911-2004). When his company opened an office in New York, that was where Carp spent most of his time. He was married to the future Olympic rider Johanna Sybille Hall, also born Dutch. They were divorced and Joop Carp later emigrated to South Africa.