|Name||No||Builder||Yard No||Laid down||Launched||Comp||Fate|
|Undine||C48||Vickers-Armstrong, Barrow||2/1937||5.10.1937||8/1938||sunk 7.1.1940|
|Unity||C66||Vickers-Armstrong, Barrow||2/1937||16.2.1938||12.1938||collision 29.4.1940|
|Ursula||C65 - N65, 2.1949- S...||Vickers-Armstrong, Barrow||2.1937||16.2.1938||12.1938||to Soviet Union 5.1944 - 2.1949 (В-4) (V-4), BU 5.1950|
|Max speed, kts, kn||
11.25 / 10
|Displacement standard, t||
|Displacement normal, t||
630 / 730
|No of shafts||
2 Paxman-Ricardo diesel-generators, 2 electric motors
|Power, h. p.||
615 / 825
diesel oil 38
3 x 1 - 12.7/62, 6 - 533 TT (4 bow, 2 ext bow, 10)
Ursula: 1 x 1 - 76/45 20cwt QF Mk II, 3 x 1 - 12.7/62, 6 - 533 TT (4 bow, 2 ext bow, 8)
|Electronic equipment||type 129 sonar|
|Diving depth operational, m||60|
These submarines were originally designed as unarmed targets for ASW training. Already after design approval it was decided to arm them with torpedoes. Fore end was redesigned for placing 4 TTs in the pressure hull and two more out of it, in a special fin. Single-hulled. Feature of this class that only electric motors were coupled with shafts and diesels used only in a role of generators. There were first British pure diesel-electric submarines.
New boats received a designation as "U" class, have appeared very successful, and better than boats of other classes suited for actions in Mediterranean and Northern Seas, however originally a class have limited to three units of the 1936 Programme.
about 1942 - 1943, Ursula: can carry 6 M2 mines instead of torpedoes, + type 286W or type 291W radar
2/1949, Ursula: 1 x 1 - 76/45 CP Mk V, 6 - 533 TT, type 286W or type 291W radar, type 129 sonar
Undine was sunk 7.1.1940 in North Sea by DCs of German minesweepers М1201, М1204 and М1207. Unity was lost 29.4.1940 in collision with s/s Atle Jarl in the North Sea.