Zenith Chronometer de bord 5011 K marine Chronomete 5011 K Heirloom of my grandfather (1933 - 2016) Captain international shipping. I saw there in the cabinet behind glass. Since I can remember. He had this in possession and it came from his last ship. Here an unusual and rare, Marine chronometer 5011K by Zenith: Chronomètre de Bord The name of the Swiss manufacturer as always been associated with precision. The cal. 5011 was Zenith’s last observatory chronometer movement Under direction of designer J.-P. Gerber, the 5011 K was developed in the late '50s and debuted in 1960. It was produced for three purpose with its special large diameter: as a chronometer for competition , a chronometer for sea and air navigation and to fit high-end pocket watch. In 1967, the caliber established a record for accuracy for a mechanical watch. Zenith winding stem mount system. Charles Fleck, one of the most famous chronometer adjusters at Zenith from 1925 to 1956, is the inventor of the dual index regulator, in the end of the 1940. The system was later patented under patent no. 292133 in August 1951. The system allows to secured the accuracy by a bigger friction with the balance bridge. The movement wins the Neuchatel Observatory contest of 1967. the movement is no more used since 2007, but remains one of the pride of the Swiss brand. According to scholars, 5’400 movements were produced between 1960 and 2002, including 2,300 shipped to Ulysse Nardin for their marine chronometers.