O 21-class submarine

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O 21 haven van Gribalter.jpg
HNLMS O 21
Class overview
Name: O 21
Builders: R.D.M, Rotterdam (4)
Koninklijke Maatschappij De Schelde, Flushing (2)
Fijenoord, Rotterdam (1)
Operators:  Royal Netherlands Navy
 Kriegsmarine
Preceded by: O 19 class
Built: 1937–1940
Completed: 7
General characteristics
Type: Submarine
Displacement: 990 tons surfaced
1205 tons submerged
Length: 77.7 m (254 ft 11 in)
Beam: 6.8 m (22 ft 4 in)
Draught: 3.95 m (13 ft 0 in)
Propulsion: 2 × 2,500 bhp (1,864 kW) diesel engines
2 × 500 bhp (373 kW) electric motors
Speed: 19.5 kn (36.1 km/h; 22.4 mph) surfaced
9 kn (17 km/h; 10 mph) submerged
Range: 10,000 nmi (19,000 km; 12,000 mi) at 12 kn (22 km/h; 14 mph) on the surface
28 nmi (52 km; 32 mi) at 8.5 kn (15.7 km/h; 9.8 mph) submerged
Complement: 39
Armament: 4 × 21 inch bow torpedo tubes
2 × 21 inch stern torpedo tubes
2 x 21 inch (1x2) external-traversing amidships

The O 21 class was a class of seven submarines, built for the Royal Netherlands Navy. The ships were still incomplete at the start of the German invasion of the Netherlands O 21, O 22, O 23 and O 24 were hastily launched and escaped to the United Kingdom. O 25, O 26 and O 27 were not able to escape and were captured by the German forces. The Kriegsmarine ordered the completion of the ships and they entered German service as U-D3, U-D4 and U-D5. The submarines diving depth was 100 meters.

Construction[edit]

The ships were built by three different shipyards. O 21 and O 22 were built by the Koninklijke Maatschappij. O 23, O 24, O 26 and O 27 by R.D.M, Rotterdam and O 25 also in Rotterdam at Fijenoord shipyard.

Name Laid down Launched Commissioned Decommissioned
O 21 20 November 1937 21 October 1939 10 May 1940 (uncompleted) 2 November 1957
O 22 20 November 1937 20 January 1940 10 May 1940 (uncompleted) 8 November 1940
O 23 12 October 1937 5 December 1939 13 May 1940 (uncompleted) 1 December 1948
O 24 12 November 1937 18 March 1940 13 May 1940 (uncompleted) 22 February 1954
O 25
Commissioned as:
U-D3
10 April 1939 1 May 1940 8 June 1941 13 October 1944
3 May 1945 (scuttled)
O 26
Commissioned as:
U-D4
20 April 1939 23 November 1940 28 January 1941 3 May 1945 (scuttled)
O 27
Commissioned as:
U-D5
3 August 1939 1941 30 January 1942
13 July 1945 (Dutch navy)
14 November 1959

External links[edit]