page_title: History of submarines
section_title: Interwar
hierarchical_section_title: History of submarines / Interwar
caption_attribution_description: 日本語: 英国潜水艦M2号と艦載飛行機 English: HMS M2 and her Sea Plane.
context_page_description: Beginning in ancient times, mankind sought to operate under the water. From simple submersibles to nuclear-powered underwater behemoths, humans have searched for a means to remain safely underwater to gain the advantage in warfare, resulting in the development of the submarine.
context_section_description: Diesel submarines needed air to run their engines, and so carried very large batteries for submerged travel. These limited the speed and range of the submarines while submerged.
  An early submarine snorkel was designed by James Richardson, an assistant manager at Scotts Shipbuilding and Engineering Company, Greenock, Scotland, as early as 1916. The snorkel allowed the submarine to avoid detection for long periods by travelling under the water using non-electric powered propulsion. Although the company received a British Patent for the design, no further use was made of it—the British Admiralty did not accept it for use in Royal Navy submarines.
  The first German U-boat to be fitted with a snorkel was U-58, which experimented with the equipment in the Baltic Sea during the summer of 1943.  The technology was based on pre-war Dutch experiments with a device named a snuiver (sniffer).  As early as 1938, a simple pipe system was installed on the submarines O-19 and O-20 that enabled them to travel at periscope depth operating on its diesels with almost unlimited underwater range while charging the propulsion batteries. U-boats began to use it operationally in early 1944.  By June 1944, about half of the boats stationed in the French bases were fitted with snorkels.
  Various new submarine designs were developed during the interwar years.  Among the most notable were submarine aircraft carriers, equipped with a waterproof hangar and steam catapult to launch and recover one or more small seaplanes.  The submarine and its plane could then act as a reconnaissance unit ahead of the fleet, an essential role at a time when radar was not available.  The first example was the British HMS M2, followed by the French Surcouf, and numerous aircraft-carrying submarines in the Imperial Japanese Navy.
  Early submarine designs put the diesel engine and the electric motor on the same shaft, which also drove a propeller with clutches between each of them. This allowed the engine to drive the electric motor as a generator to recharge the batteries and also propel the submarine as required. The clutch between the motor and the engine would be disengaged when the boat dived so that the motor could be used to turn the propeller.  The motor could have more than one armature on the shaft — these would be electrically coupled in series for slow speed and parallel for high speed (known as "group down" and "group up" respectively).
  In the 1930s, the principle was modified for some submarine designs, particularly those of the U.S. Navy and the British U-class.  The engine was no longer attached to the motor/propeller drive shaft, but drove a separate generator, which would drive the motors on the surface and/or recharge the batteries. This diesel-electric propulsion allowed much more flexibility.  For example, the submarine could travel slowly whilst the engines were running at full power to recharge the batteries as quickly as possible, reducing time on the surface, or use of its snorkel.  Also, it was now possible to insulate the noisy diesel engines from the pressure hull making the submarine quieter.
  An early form of anaerobic propulsion had already been employed by the Ictineo II in 1864.  The engine used a chemical mix containing a peroxide compound, which generated heat for steam propulsion while at the same time solved the problem of oxygen renovation in an hermetic container for breathing purposes.  This system wasn't employed again until 1940 when the German Navy tested a system employing the same principles, the Walter turbine, on the experimental V-80 submarine and later on the naval U-791 submarine.
  At the end of the Second World War, the British and Russians experimented with hydrogen peroxide/kerosene (paraffin) engines, which could be used both above and below the surface.  The results were not encouraging enough for this technique to be adopted at the time, although the Russians deployed a class of submarines with this engine type code named Quebec by NATO.  They were considered a failure. Today, several navies, notably Sweden, use air-indep
caption: HMS M2 launches a specially designed Parnall Peto seaplane. It sank accidentally in 1932.
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