SM ''UC-91'' was a German Type UC III

minelaying A minelayer is any warship, submarine or military aircraft deploying explosive mines. Since World War I the term "minelayer" refers specifically to a naval ship used for deploying naval mines. "Mine planting" was the term for installing contro ...

submarine or

U-boat U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare ro ...

in the

German Imperial Navy The Imperial German Navy or the Imperial Navy () was the navy of the German Empire, which existed between 1871 and 1919. It grew out of the small Prussian Navy (from 1867 the North German Federal Navy), which was mainly for coast defence. Wilhel ...

(german: Kaiserliche Marine) during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

Design

German Type UC III submarine Type UC III minelaying submarines were used by the Imperial German Navy () during World War I. They displaced at the surface and submerged, carried guns, 7 torpedoes and up to 14 mines. The ships were double-hulled with improved range and sea- ...

, ''UC-91'' had a displacement of when at the surface and while submerged. She had a length overall of , a beam of , and a draught of . The submarine was powered by two six-cylinder four-stroke diesel engines each producing (a total of ), two electric motors producing , and two

propeller shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power and torque and rotation, usually used to connect ...

s. She had a dive time of 15 seconds and was capable of operating at a depth of . The submarine was designed for a maximum surface speed of and a submerged speed of . When submerged, she could operate for at ; when surfaced, she could travel at . ''UC-91'' was fitted with six mine tubes, fourteen UC 200 mines, three

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s (one on the stern and two on the bow), seven

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...

es, and one SK L/45 or Uk L/30

deck gun A deck gun is a type of naval artillery mounted on the deck of a submarine. Most submarine deck guns were open, with or without a shield; however, a few larger submarines placed these guns in a turret. The main deck gun was a dual-purpose ...

. Her

complement A complement is something that completes something else. Complement may refer specifically to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-clas ...

was twenty-six crew members.

Construction and career

The U-boat was ordered on 12 January 1916 and was launched on 19 January 1918. She was commissioned into the German Imperial Navy on 31 July 1918 as SM ''UC-91''."SM" stands for "Seiner Majestät" ( en, His Majesty's) and combined with the ''U'' for ''Unterseeboot'' would be translated as ''His Majesty's Submarine''. As with the rest of the completed UC III boats, ''UC-91'' conducted no war patrols and sank no ships. She sank after a collision with the steamer ''Alexandra Woermann'' on 5 September 1918 in the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and ...

. The salvage vessel raised the wreck the following day and was repaired. She was en route to surrender on 10 February 1919 when she foundered in the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

.Gröner, p. 62

References

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Bibliography

* * * * {{DEFAULTSORT:Uc091 Ships built in Hamburg German Type UC III submarines U-boats commissioned in 1918 Maritime incidents in 1918 U-boats sunk in 1918 U-boats sunk in 1919 Maritime incidents in 1919 World War I submarines of Germany World War I shipwrecks in the Baltic Sea World War I shipwrecks in the North Sea World War I minelayers of Germany 1918 ships