O 21-class submarine
O 21 | |
| Class overview | |
|---|---|
| Name | O 21 class |
| Builders | |
| Operators | |
| Preceded by | O 19 class |
| Succeeded by | Dolfijn class |
| Built | 1937–1942 |
| In commission | 1940–1959 |
| Completed | 7 |
| Lost | 2 |
| Scrapped | 5 |
| General characteristics | |
| Type | Submarine |
| Displacement |
|
| 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 |
|
| Speed |
|
| Range | |
| Complement | 39 |
| Armament |
|
The O 21 class was a class of seven submarines, built for the Royal Netherlands Navy. The boats 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 boats and they entered German service as UD-3, UD-4 and UD-5. The submarines' diving depth was 100 meters (330 ft).
At the start of the Second World War the O 21 class was together with the British U, S and T classes and German Type VII one of the most advanced submarine classes in service.