- Design
- Construction
- References Bibliography
- External links
{{Infobox ship image| Ship image=O 21 haven van Gribalter.jpg | Ship caption= HNLMS O 21
}}{{Infobox ship class overview | Name=O 21 class | Builders=*Rotterdamsche Droogdok Maatschappij (4)- Koninklijke Maatschappij De Schelde (2)
- Wilton-Fijenoord (1)
| NLD}} | O 19|submarine|4}} | Dolfijn|submarine|4}} | Cost= | Built range=1937–1940 | In service range= | In commission range= | Total ships completed=7 | Total ships lost= | Total ships scrapped=
}}{{Infobox ship characteristics | Hide header= | Header caption= | Ship class= | Ship type=Submarine | Ship displacement=*990 tons surfaced | 77.7|m|ftin|0|abbr=on}} | 6.8|m|ftin|0|abbr=on}} | 3.95|m|ftin|0|abbr=on}} | Ship power= | 2500|bhp|0|abbr=on}} each- 2 × {{convert|500|bhp|0|abbr=on}} electric motors
| 19.5|kn|abbr=on|lk=in}} surfaced- {{convert|9|kn|abbr=on}} submerged
| 10000|nmi|abbr=on|lk=in}} at {{convert|12|kn|abbr=on}} surfaced- {{convert|28|nmi|abbr=on|lk=in}} at {{convert|8.5|kn|abbr=on}} submerged
| Ship test depth= | Ship complement=39 | 21|in|mm|abbr=on}} torpedo tubes (4 bow, 2 stern, 2 traversing amidships ) | Ship notes=
}} | 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 UD-3, UD-4 and UD-5. The submarines diving depth was {{convert|100|m}}. DesignOne of the requirements the Royal Netherlands Navy set for the O 21-class was that it had to be able to dive 20 meters deeper than the previous class, which was the O 19-class submarine.[1] ConstructionThe 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 | 2} | 20 November 1937 | 21 October 1939 | 10 May 1940 (uncompleted) | 2 November 1957 | | O 22 | 2} | 20 November 1937 | 20 January 1940 | 10 May 1940 (uncompleted) | 8 November 1940 | | O 23 | 2} | 12 October 1937 | 5 December 1939 | 13 May 1940 (uncompleted) | 1 December 1948 | | O 24 | 2} | 12 November 1937 | 18 March 1940 | 13 May 1940 (uncompleted) | 22 February 1954 | | O 25 | 2}
Commissioned as:
UD-3 | 10 April 1939 | 1 May 1940 | 8 June 1941 | 13 October 1944
3 May 1945 (scuttled) | | O 26 | 2}
Commissioned as:
UD-4 | 20 April 1939 | 23 November 1940 | 28 January 1941 | 3 May 1945 (scuttled) | | O 27 | 2}
Commissioned as:
UD-5 | 3 August 1939 | 1941 | 30 January 1942
13 July 1945 (Dutch navy) | 14 November 1959 | |
References1. ^Gerretse and Wijn, p. 9
Bibliography- {{cite book|last1=Jalhay|first1=P.C.|last2=Wijn|first2=J.J.A.|title=Ik nader ongezien! De onderzeeboten van de Koninklijke Marine|year=1997|publisher=De Bataafsche Leeuw|location=Amsterdam|isbn=9067074624}}
- {{cite book|last1=Gerretse|first1=K.H.L.|first2=J.J.A.|last2=Wijn|title=Drie-cylinders duiken dieper: de onderzeeboten van de dolfijn-klasse van de Koninklijke Marine|year=1993|publisher=Van Soeren|location=Amsterdam|isbn=9068810278}}
External links{{O 21 class submarine}}{{WWIIDutchShips}} 3 : Submarines of the Netherlands|1940s ships|O 21-class submarines |