 The Seattle, Washington, firm of W. C. Nickum Sons developed a detailed design and unusual construction procedures for "Explorer" from United States Government designs.The largest ship constructed in the Pacific Northwest since 1924, she was built by Lake Washington Shipyard at Houghton, Washington, as a Coast and Geodetic Survey "ocean survey ship" (OSS).Launched on 14 October 1939, she was delivered to the Coast and Geodetic Survey on 9 March 1940.