A coastal submarine or littoral submarine [1] is a small, maneuverable submarine with shallow draft well suited to navigation of coastal channels and harbors. Although size is not precisely defined, coastal submarines are larger than midget submarines, but smaller than sea-going submarines designed for longer patrols on the open ocean. Space limitations aboard coastal submarines restrict fuel availability for distant travel, food availability for extended patrol duration, and number of weapons carried. Within those limitations, however, coastal submarines may be able to reach areas inaccessible to larger submarines, and be more difficult to detect.
The earliest submarines were effectively coastal submarines, but as modern submarine tactics developed during World War I, the advantages of rapid construction and portability encouraged development of UB torpedo launching, and UC minelaying coastal submarines in 1915 to operate in the English Channel. These coastal submarines displaced only 15 to 20 percent the weight of a contemporary conventional U-boat, [2] could be built in one-quarter the time it took to complete a conventional U-boat, and be delivered on railway wagons to operating bases in Belgium. [3] Improved versions of UB and UC coastal submarines were devised. Total production of German coastal submarines during World War I was 136 type UB and 95 type UC. [4]
German submarine construction between the world wars began in 1935 with the building of 24 Type II coastal submarines. These coastal U-boats, with another eight completed prior to hostilities, made North Sea combat patrols during the early months of World War II and then served in the Baltic Sea training crews to operate ocean-going submarines. [5] The 30th U-boat Flotilla of six Type II U-boats was transported overland on the Autobahn and then down the Danube for combat patrols in the Black Sea until September 1944. [6]
Seiner Majestät UB-4 was a German Type UB I submarine (U-boat) in the German Imperial Navy during World War I. She was sunk by a British Q-ship disguised as a fishing smack in August 1915.
The Type UB I submarine was a class of small coastal submarines (U-boats) built in Germany at the beginning of the First World War. Twenty boats were constructed, most of which went into service with the German Imperial Navy Boats of this design were also operated by the Austro-Hungarian Navy and the Bulgarian Navy. In the Austro-Hungarian Navy, it was called the U-10 class.
SM UB-5 was a German Type UB I submarine or U-boat in the Imperial German Navy during World War I. She sank five ships during her career and was broken up in Germany in 1919.
SM UB-46 was a Type UB II submarine or U-boat for the German Imperial Navy during World War I. UB-46 operated in the Mediterranean and the Black Seas, and was sunk by a mine in December 1916.
The Mediterranean U-boat Campaign in the Mediterranean Sea was fought by Austria-Hungary and German Empire against the Allies during World War I. It was characterised by the ability of the Central Powers to raid with near impunity during the first years of the war, causing substantial shipping losses, until the introduction of the convoy system allowed the Allies to drastically cut their losses from 1917 on.
SM UB-42 was a Type UB II submarine or U-boat for the German Imperial Navy during World War I. UB-42 operated in the Mediterranean and the Black Seas during the war. She was broken up at Malta in 1920.
SM UB-14 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was also known by the Austro-Hungarian Navy designation of SM U-26.
SM UB-9 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. UB-9 was ordered in October 1914 and was laid down at the AG Weser shipyard in Bremen in November. UB-9 was a little under 28 metres (92 ft) in length and displaced between 127 and 141 tonnes, depending on whether surfaced or submerged. She carried two torpedoes for her two bow torpedo tubes and was also armed with a deck-mounted machine gun. She was launched and commissioned as SM UB-9 in February 1915.
SM UB-10 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I.
SM UB-11 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. UB-11 was ordered in October 1914 and was laid down at the AG Weser shipyard in Bremen in November. UB-11 was a little under 28 metres (92 ft) in length and displaced between 127 and 141 tonnes, depending on whether surfaced or submerged. She carried two torpedoes for her two bow torpedo tubes and was also armed with a deck-mounted machine gun. She was launched and commissioned as SM UB-11 in March 1915.
SM UB-12 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine disappeared in August 1918.
SM UB-13 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was probably sunk by a British mine net in April 1916.
SM UB-16 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was sunk by a British submarine in May 1918.
SM UB-17 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine disappeared during a patrol in March 1918.
SM UB-2 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. She sank eleven ships during her career and was broken up in Germany in 1920.
SM UB-3 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. She disappeared on her first patrol in May 1915, and was the first of her class to be lost.
SM UB-6 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. The submarine was interned after running aground in neutral Dutch waters, and was scuttled by her crew at Hellevoetsluis.
SM UB-7 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. She disappeared in the Black Sea in September 1916.
SM UB-8 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. She was sold to Bulgaria in 1916 and renamed Podvodnik No. 18, and was the first ever Bulgarian submarine.
The Flanders U-boat flotillas were Imperial German Navy formations set up to prosecute the U-boat campaign against Allied shipping in the Western Approaches during the First World War. Originally operating as a flotilla, it was split in two during the latter part of the war.