Nummer: 20317
| Area : | Arctic Ocean |
| Date of attack : | 28.12.1943 |
| Time of attack : | 22:10 |
| Nationality of U-boat : | German |
| U-boat : | U 957 |
| Commander : | Schaar |
| Grid : | AC 5637 |
| presumed target type : | Corvette |
| presumed result : | damaged |
| Used weapon(s) : | Acoustic homing torpedo (gnat) |
| Convoy : | JW.55B |
| Actual tonnage : | ---- -- |
| Actual result : | hit not ascertained |
| Footnote : | U-957 heard one Gnat end-of-run detonation after 11:00 min, and one Gnat detonation after 3:05 min. |
| Convoy : | JW.55B |
| Route of convoy : | Loch Ewe - (Iceland) - Kola Fjord - (Arkhangelsk) |
| Remark to convoy : | Since Dec 1942, former PQ (counter traffic = RA) |