O21 1940
O27 1945
| Name | No | Builder | Laid down | Launched | Comp | Fate |
| O21 (ex-K XXI) | S801 | De Schelde, Vlissingen | 11/1937 | 21/10/1939 | 5/1940 | stricken 11/1957 |
| O22 (ex-K XXII) | De Schelde, Vlissingen | 11/1937 | 20/1/1940 | 5/1940 | sunk 8?/11/1940 | |
| O23 (ex-K XXIII) | Rotterdamse Droogdok Mij, Rotterdam // Thornycroft, Southampton, UK | 10/1937 | 5/12/1939 | 6/1940 | stricken 12/1948 | |
| O24 (ex-K XXIV) | S804 | Rotterdamse Droogdok Mij, Rotterdam // Thornycroft, Southampton, UK | 11/1937 | 18/3/1940 | 7/1940 | stricken 2/1954 |
| O25 (ex-K XXV) | Wilton-Fijenoord, Schiedam | 4/1939 | 1/5/1940 | 6/1941 // --- | captured incomplete by Germany 5/1940 (UD3) | |
| O26 (ex-K XXVI) | Rotterdamse Droogdok Mij, Rotterdam | 4/1939 | 23/11/1940 | 1/1941 // --- | captured incomplete by Germany 5/1940 (UD4) | |
| O27 (ex-K XXVII) | S807 | Rotterdamse Droogdok Mij, Rotterdam | 8/1939 | 26/9/1941 | 1/1942 // 7/1945 | captured incomplete by Germany 5/1940 (UD5), returned 5/1945, stricken 11/1959 |
|
Displacement standard, t |
902 |
|
Displacement normal, t |
990 / 1205 |
|
Length, m |
77.7 |
|
Breadth, m |
6.80 |
|
Draught, m |
3.95 |
|
No of shafts |
2 |
|
Machinery |
Sulzer 7-cyl diesels / electric motors |
|
Power, h. p. |
5000 / 1000 |
|
Max speed, kts |
19.5 / 9 |
|
Fuel, t |
diesel oil |
|
Endurance, nm(kts) |
10000(12) / 28(8.5) |
|
Armament |
O21-23: 1 x 1 - 88/45 Bofors No.3, 1 x 1 - 40/40 Bofors, 1 x 1 - 12.7/90, 8 - 533 TT (4 bow, 2 stern, 1 x 2, 14) O24: 1 x 1 - 88/45 Bofors No.2, 1 x 1 - 20/70 Oerlikon, 1 x 1 - 12.7/90, 8 - 533 TT (4 bow, 2 stern, 1 x 2, 14) O27 (1945): 1 x 1 - 37/69 Flak M/42, 2 x 2 - 20/65 C/38, 6 - 533 TT (4 bow, 2 stern, 12) |
|
Complement |
39 |
| Diving depth operational, m | 100 |
Ship project history: Ordered as K XXI-XXVII, however "K" letters have been changed on "O" even prior to the beginning of building. Practically repeated O19 class, but without minelaying equipment. Double-hulled, maximal diving depth was 175m. They were equipped by 7cyl Sulzer diesels with snorkel. Thanks to the improved hull form and increase in machinery power max speed has grown. On these submarines they have refused centralized operation by ballast tank valves for diving time reduction.
In May, 1940 yet incomplete O21-24 were formally commissioned and escaped to Britain where have been completed, thus snorkel was removed.
Incomplete O25-27 in May, 1940 were captured by Germans and as UD3-5 were completed for Kriegsmarine under modified project. UD3 and UD4 were stricken and scuttled at Kiel 3/5/1945, subsequently they were salvaged and scrapped. UD5 was returned to the Netherlands in 1945.
Modernizations: 1942, O21, 23: - 1 x 1 - 40/40; + 1 x 1 - 20/70 Oerlikon
early 1950s, all survived: all guns were removed.
Naval service: O22 was lost on a mine in the North Sea in the period 7 till 19/11/1940.
O25
© Ivan Gogin, 2011