U class SS 
United Kingdom: 7 (49 bygget)
| Begun | Launch | Completed | Notes | ||
| N87 Una | Chatham Dockyard | -5-40 | 9-7-40 | 27-9-41 | BU 4-49 |
| Upshot (V-klassen) | |||||
| N82 Umpire | Chatham DYd | -1-40 | 30-12-40 | -7-41 | warloss; collision 19-7-41 |
| N93 Unbeaten | Vickers-Armstrong | -11-39 | 9-7-40 | -11-40 | warloss; sunk 11-11-42 |
| P34/N55 Undaunted | Vickers-Armstrong | -8-40 | 20-8-40 | -12-40 | sunk 13-5-41 Mediterranean |
| Undine | Vickers-Armstrong | -12-39 | 1-10-40 | -2-41 | warloss; sunk 20-7-41 |
| N56 Union | warloss | ||||
| P36/N95 Unique | Vickers-Armstrong | -10-39 | 6-6-40 | -9-40 | warloss; sunk 23-10-42 Biscay |
| N66 Unity | sænket 29/4/40 ud for Norge | ||||
| P37/N99 Upholder | Vickers-Armstrong | -10-39 | 8-7-40 | -10-40 | warloss; sunk 14-4-42 |
| P38/N89 Upright | Vickers-Armstrong | -11-39 | 21-4-40 | -9-40 | BU 12-45 |
| P59/N97 Urchin (P97) | Vickers-Armstrong | -12-39 | 30-9-40 | -1-41 | >Polen 1-41 |
| P40/N17 Urge | Vickers-Armstrong, Barrow | -10-39 | 19-8-40 | -12-40 | warloss; sunk 28-4-42 |
| P41/N65 Usk | Vickers-Armstrong, Barrow | -11-39 | 7-6-40 | -10-40 | warloss; sunk 28-4-41 |
| P42/N19 Utmost | Vickers-Armstrong, Barrow | -11-39 | 20-4-40 | -8-40 | warloss; sunk 24-11-42 |
| Vandal (se herunder) | warloss | ||||
| P 32 | Vickers-Armstrong, Barrow | 30-4-40 | 15-12-40 | 3-5-41 | ramte mine i Middelhavet 18-8-41 |
| P33 | Vickers-Armstrong, Barrow | 18-6-40 | 28-1-41 | 30-5-41 | warloss |
| 1941P34 Ultimatum | Vickers-Armstrong, Barrow | 19-6-40 | 11-2-41 | 29-7-41 | - |
| P35 Umbra | Vickers-Armstrong, Barrow | 19-7-40 | 15-3-41 | 2-9-41 | ophugget 1946 |
| P37 Unbending | Vickers-Armstrong, Barrow | 30-8-40 | 12-5-41 | 5-11-41 | ophugget 1950 |
| 1941 Programme (12) | |||||
| P42 Unbroken | Vickers-Armstrong, Barrow | 30-12-40 | 4-11-41 | 29-1-42 | >Sovjetunionen 6/1944; ophugget 5/1950 |
| P56 Usurper | Vickers-Armstrong, Barrow | 18-9-41 | 24-9-42 | 2-2-43 | warloss; sunk Mediterranean |
| P57 Universal | Vickers-Armstrong, Newcastle | 5-9-41 | 10-11-42 | 8-3-43 | ophugget 6/1946 |
| P58 Untamed | Vickers-Armstrong, Newcastle | 9-10-41 | 8-12-42 | 14-4-43 | sank 30/5/1943; bjærget |
| P59 Untiring | Vickers-Armstrong, Newcastle | 23-12-41 | 20-1-43 | 9-6-43 | >Grækenland 7/1945 (Xifias II (Y-10)) |
| P61 Varangian (Group III) | Vickers-Armstrong, Tyne | 23-12-41 | 4-4-43 | 10-7-43 | ophugget 6/1949 |
| P62 Uther | Vickers-Armstrong, Newcastle | 31-1-42 | 6-4-43 | 15-8-43 | ophugget 4/1950 |
| P63 Unswerving | Vickers-Armstrong, Newcastle | 17-2-42 | 19-7-43 | 3-10-43 | ophugget 7/1949 |
| P64 Vandal | Vickers-Armstrong, Barrow | 17-3-42 | 23-11-42 | 20-2-43 | sænket 24-2-43 (37 K) |
| P65 Upstart | Vickers-Armstrong, Barrow | 17-3-42 | 24-11-42 | 3-4-43 | >Greece (Amphitriti) 1945 |
| Varne>Ula (Group III) | Vickers-Armstrong, Barrow | 29-4-42 | 22-1-43 | 3-4-43 | >Norway as S300 Ula 4/1943; ophugget 1965 |
| P67 Vox>Curie | Vickers-Armstrong, Barrow | 29-4-42 | 23-1-43 | 2-5-43 | >France as Curie 2-5-43, retur 7/1946 |
| P51 Unseen | Vickers-Armstrong | 30-7-41 | 16-4-42 | 2-7-42 | ophugget 9/49 |
| N59 Ursula | Vickers-Armstrong | til USSR 6/44 | |||
| Ullswater?? | - | - | - | - | - |
Notes: A simple type, useful for A/S training and capable of being produced rapidly in large numbers. Several have been transferred to Allied Navies. Most of main ballast tank capacity in inside pressure hull. propulsion differs from other types, there being no direct Diesel drive.
Frankrig: 2 (Curie+)