The ship Pioneer was formerly the U.S.S. Mobjack (AGP 7). The USS Mobjack (AVP-27/AGP-7) was a motor torpedo boat tender in commission in the United States Navy from 1943 to 1946. She saw service in the Pacific theater during the latter portion of World War II.

After the conclusion of her Navy career, the ship served in the United States Coast and Geodetic Survey from 1946 to 1966 as the survey ship USC&GS Pioneer (OSS 31), the third Coast and Geodetic Survey ship of the name. Pioneer departed the U.S. West Coast in April 1947 for her first assignment, which was hydrographic survey work in the Aleutian Islands. She spent the field seasons of 1947, 1948, 1949, and 1950 in the Aleutians, also running sounding lines from points in the Aleutians across the Gulf of Alaska and North Pacific Ocean to points on the U.S. West Coast.

The Pioneer continued offshore hydrographic work in the Pacific Ocean off the U.S. West Coast until 5 March 1957, when she departed San Francisco for the Territory of Hawaii, where she conducted electronic-position-indicator- (EPI-) guided basic survey operations north of the Hawaiian Islands

The Pioneer operated in the Pacific Ocean during her career, making an important discovery of magnetic striping on the ocean floor that made a major contribution to the development of the theory of plate tectonics, and was the first ship in the history of the United States Coast Survey or U.S. Coast and Geodetic Survey to visit the Indian Ocean. The Pioneer was sold for scrap on 4 May 1966 to National Metal and Steel Corporation, Terminal Island, California. [from Wikipedia]