From: Dictionary of American Naval Fighting Ships, Vol. III p 508

Jasper

An opaque and impure variety of quartz, usually red in color, used as a gem. PC--486 was named for towns in Alabama, Indiana, and Texas.

The first Jasper (PYc--13), a diesel-powered yacht, was built as Stranger by Lake Union Dry Dock Co., Seattle, Wash., in 1938 ; purchased 1 July 1941 from her owner, Fred E. Lewis ; renamed Jasper; and placed in service at San Diego 8 July 1941.

After the installation of experimental sound and electronic equipment, Jasper was assigned to the 11th Naval District to perform research work at the Naval Sound Laboratory, San Diego. She continued this important scientific work throughout the war taking part in experiments with radio and sound waves in cooperation with the University of California, Division of War Research. Echo-ranging equipment on board Jasper was used in 1946 to discover a deep 300-mile-wide oceanic layer off the coast of California.

The ship was placed out of service 14 August 1947 at San Diego and turned over to the Maritime Commission for disposal in June 1948.