Richard B. Kershner, 68, a retired assistant director of the Johns Hopkins Applied Physics Laboratory who directed work on the world's first satellite system to aid sea navigation, died of respiratory failure Feb. 15 at Holy Cross Hospital. He lived in Silver Spring.

Dr. Kershner joined the laboratory in 1946 and headed missile, booster and launcher research. He became development director of the Terrier missile project, the first surface-to-air missile used by U.S. ships. In 1958, as the first director of the laboratory's space department, Dr. Kershner began developing what became the Navy Transit Satellite Navigation System, which used signals from an orbiting satellite.

Six years later, the system was in operation, guiding Navy ships worldwide with an accuracy of better than one-tenth of a mile. In 1967, the Navy satellite navigation system was released for worldwide commercial use.

Since retiring as the lab's assistant director in 1978, Dr. Kershner has served as its principal adviser for space systems.

He was a three-time recipient of the Navy Distinguished Public Service Award, and had received the Presidential Certificate of Merit for research.

Dr. Kershner was born in Crestline, Ohio, and reared in Baltimore. He earned a doctorate in mathematics at Johns Hopkins University in 1937.

Survivors include his wife, the former M. Amanda Brown of Silver Spring; two sons, Richard B. Jr., of Gainesville, Fla., and James W. of Dennis, Mass., and three grandchildren.