History of submarines few years before the US, and paralleled subsequent US development in this area. In the 1950s, nuclear power partially replaced diesel-electric propulsion. The sailing of the first nuclear-powered submarine, the USN ""Nautilus"" in 1955 was soon followed by similar British, French and Russian boats. Equipment was also developed to extract oxygen from sea water. These two innovations, together with inertial navigation systems, gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as the crossing of the North Pole beneath the Arctic ice cap by the USS "Nautilus" in 1958. Most of the
Skipjack-class submarine planes were moved to the massive sail to cut down on flow-induced noise near the bow sonar arrays. They were known as sail planes or fairwater planes. The "Skipjack"s were the first class built with sail planes; they were later backfitted on the "Barbel"s. This design feature would be repeated on all U.S. nuclear submarines until the improved , the first of which was launched in 1988. The small "turtleback" behind the sail was the exhaust piping of the auxiliary diesel generator. The "Skipjack"s also introduced the S5W reactor to U.S. nuclear submarines. It was known as ASFR (Advanced Submarine