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
Sail (submarine) as an observation platform. It also provides an entrance and exit point on the submarine that has enough freeboard to prevent the submarine being swamped. Underwater the sail acts as a vertical stabilizer. In some submarines, the sail also supports diving planes, which are control surfaces used for underwater stability and steering. Sail (submarine) In naval parlance, the sail (American usage) or fin (European/Commonwealth usage) of a submarine is the tower-like structure found on the dorsal (topside) surface of submarines. Submarine sails once housed the conning tower (command and communications data center), the periscope(s), radar and communications masts (antenna), though