 "Ferrel" was modified from the basic design for an offshore oil rig supply boat and was equipped specifically for oceanographic studies of coastal and inshore waters.She had a large open fantail for the handling of equipment, a crane aft, a trawl winch, an oceanographic winch located amidships, and an A-frame.The Coast and Geodetic Survey intended "Ferrel" to replace the survey ship USC&GS "Marmer" and conduct current surveys in various harbors and waterways along the United States East Coast and United States Gulf Coast.