Built as Perry Cubmarine PC3B in 1963, Tech-diver could operate at a working depth of 600 ft for a maximum dive duration of 6 hours. It was designed to carry a pilot and a non-diving specialist for first-hand inspection and supervision of construction, exploration, and survey operations. It could move forward, backward, hover, execute up and down spirals, and turn on its vertical axis, and it was one of the first submarines with hydraulic manipulating arms. Tech-diver was used in the highly publicized search for a stray H-bomb after two Air Force planes collided off the coast of Palomares, Spain, on 17 Jan 1966, and the bomb was recovered by the U.S. Navy on 7 Apr 1966.