Who created a court for explorers in Portugal?
I'm not sure what you mean by "Court." but the royal personage who created a school of navigation was Prince Henry the Navigator. Henry, the third son of King John, was intensely religious, and was determined to spread Christianity. He also had a keen interest in navigation and exploration, and founded one of the first schools of navigation in the Western world. Much of the learning taught at Henry's school had been known to Islamic navigators for many years, including the use of the Astrolabe to determine distance travelled when out of sight of land, and the lateen sail for sailing when winds were not favorable. Henry sponsored the voyages of Bartolomeo Diaz who reached the southern Cape of Africa before his crew forced him to turn around. His discovery was significant as it was believed that the southern tip of Africa joined the Northern border of Eurasia, making a sea route to Asia impossible. Diaz's voyage proved this was wrong. He was followed by Vasco da Gama, also sponsored by Prince Henry, who reached Calcutta India.