The ship was purchased for war use by the Navy on December 15, 1941 and being commissioned as the USS Chalcedony designated PYC-16 on weather duty for the Hawaiian Sea Frontier.
George Allan Hancock had inherited Rancho La Brea and made his fortune in oil but had developed a scientific interest as a result of excavations at the La Brea Tar Pits on the ranch and, after exploring the pools on the ranch with his first boat, going to sea and eventually earning his master's papers.
[5] A Hancock owned and captained vessel following Velero II, Oaxaca, had carried twelve passengers including two representatives of the California Academy of Sciences on a voyage as far as the Galápagos Islands in 1927.
[17] An example of the work is found in the description of documentation of the early voyage extending from Mexico to the Galápagos during which collection was made at twenty-three stations.
[19] On December 15, 1941 Velero III was acquired by the Maritime Commission from the University of Southern California and turned over to the Navy which had the vessel converted to wartime use at San Diego Marine Construction Company before commissioning February 27, 1942 as USS Chalcedony designated PYC-16 with Lieutenant (junior grade) Erwin E. Smith, USNR commanding.
[20][3] Chalcedony served at San Diego with the 11th Naval District until sailing for Hawaii on April 21, 1942 for weather station duty with the Hawaiian Sea Frontier.
[3] On April 11, 1948 Velero IV was launched at National Iron Works, San Diego with dignitaries of the University of Southern California, the Foundation, Navy and science participating.