SM UC-90

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O-4 (UC-90) at Yokosuka
History
German Empire
NameUC-90
Ordered12 January 1916[1]
BuilderBlohm & Voss, Hamburg[2]
Yard number324[1]
Launched19 January 1918[1]
Commissioned15 July 1918[1]
FateSurrendered to Japan, 1 December 1918[1]
Japan
NameO-4
Acquired1 December 1918 [1]
In service1920[1]
Out of service1921[1]
FateDismantled, 1921; used as ASW target, 1924 – 26; scrapped[1]
General characteristics
Class and typeGerman Type UC III submarine
Displacement
  • 491 t (483 long tons), surfaced
  • 571 t (562 long tons), submerged
Length
Beam5.54 m (18 ft 2 in) (o/a)
Draft3.77 m (12 ft 4 in)
Propulsion
Speed
  • 11.5 knots (21.3 km/h; 13.2 mph), surfaced
  • 6.6 knots (12.2 km/h; 7.6 mph), submerged
Range
  • 9,850 nautical miles (18,240 km; 11,340 mi) at 7 knots (13 km/h; 8.1 mph), surfaced
  • 40 nmi (74 km; 46 mi) at 4.5 knots (8.3 km/h; 5.2 mph), submerged
Test depth75 m (246 ft)
Complement32
Armament
Notes15-second diving time
Service record
Commanders:
  • Oblt. Justus Oldekop[3]
  • 15 – 16 July 1918
Operations: None
Victories: None

SM UC-90 was a German Type UC III minelaying submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. Completed in mid-1918, she saw no action during the war and was transferred to the Imperial Japanese Navy afterwards. The submarine briefly served in the IJN during 1920–1921 before she was partially dismantled and ultimately scrapped in 1926.

Design[edit]

A German Type UC III submarine, UC-90 had a displacement of 491 tonnes (483 long tons) when at the surface and 571 tonnes (562 long tons) while submerged. She had a length overall of 56.51 m (185 ft 5 in), a beam of 5.54 m (18 ft 2 in), and a draught of 3.77 m (12 ft 4 in). The submarine was powered by two six-cylinder four-stroke diesel engines each producing 300 metric horsepower (220 kW; 300 shp) (a total of 600 metric horsepower (440 kW; 590 shp)), two electric motors producing 770 metric horsepower (570 kW; 760 shp), and two propeller shafts. She had a dive time of 15 seconds and was capable of operating at a depth of 75 metres (246 ft).[4]

The submarine was designed for a maximum surface speed of 11.5 knots (21.3 km/h; 13.2 mph) and a submerged speed of 6.6 knots (12.2 km/h; 7.6 mph). When submerged, she could operate for 40 nautical miles (74 km; 46 mi) at 4.5 knots (8.3 km/h; 5.2 mph); when surfaced, she could travel 9,850 nautical miles (18,240 km; 11,340 mi) at 7 knots (13 km/h; 8.1 mph). UC-90 was fitted with six 100 centimetres (39 in) mine tubes, fourteen UC 200 mines, three 50 centimetres (20 in) torpedo tubes (one on the stern and two on the bow), seven torpedoes, and one 10.5 cm (4.1 in) SK L/45 or 8.8 cm (3.5 in) Uk L/30 deck gun . Her complement was twenty-six crew members.[4]

Construction and career[edit]

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 15 July 1918 as SM UC-90.[Note 1] As with the rest of the completed UC III boats, UC-90 conducted no war patrols and sank no ships. She was surrendered to Japan on 1 December 1918. The U-boat was renamed O-4 for Japanese service from 1920 to 1921. In 1921 O-4 was partially dismantled at the Kure Navy Yard. Between 1924 and 1926, the hulk of O-4 was used as an antisubmarine warfare target before being sold for scrap.[5]

References[edit]

Notes[edit]

  1. ^ "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.

Citations[edit]

  1. ^ a b c d e f g h i Helgason, Guðmundur. "WWI U-boats: UC 90". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 23 February 2009.
  2. ^ Tarrant, p. 174.
  3. ^ Helgason, Guðmundur. "WWI U-boat commanders: Justus Oldekop". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 20 January 2015.
  4. ^ a b Gröner 1991, pp. 34–35.
  5. ^ Gröner 1991, p. 35.

Bibliography[edit]