German submarine U-23 was a Type IIB U-boat of Nazi Germany's Kriegsmarine, built in Germaniawerft, Kiel. She was laid down on 11 April 1936 and commissioned on 24 September.
German Type IIB submarines were enlarged versions of the original Type IIs. U-23 had a displacement of 279t when at the surface and 328t while submerged. Officially, the standard tonnage was 2500NaN0, however. The U-boat had a total length of 42.7m (140.1feet), a pressure hull length of 28.2m (92.5feet), a beam of 4.08m (13.39feet), a height of 8.6m (28.2feet), and a draught of 3.9m (12.8feet). The submarine was powered by two MWM RS 127 S four-stroke, six-cylinder diesel engines of 700PS for cruising, two Siemens-Schuckert PG VV 322/36 double-acting electric motors producing a total of 460PS for use while submerged. She had two shafts and two 0.85abbr=onNaNabbr=on propellers. The boat was capable of operating at depths of up to 80-.
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for 35- at ; when surfaced, she could travel at . U-23 was fitted with three 53.30NaN0 torpedo tubes at the bow, five torpedoes or up to twelve Type A torpedo mines, and a 2cm (01inches) anti-aircraft gun. The boat had a complement of twentyfive.
At 04:45 on 4 October 1939, U-23 scored one of the Kriegsmarines early successes of the war when she torpedoed and sank with gunfire, the merchant ship Glen Farg about 60nmi south-southwest of Sumburgh Head (southern Shetland). One person died, while 16 survivors were picked up by and landed at Kirkwall the next day.
In 16 patrols U-23 sank seven ships for a total of including two warships, as well as damaging a warship and an auxiliary warship.
Over the course of her service with the Kriegsmarine, U-23 had ten commanding officers, the most famous of whom was Kapitänleutnant Otto Kretschmer, who went on to become the top scoring U-boat ace. After service in the Atlantic with the 1st U-boat Flotilla, U-23 served as a training boat with the 21st U-boat Flotilla from July 1940 until September 1942. U-23 was then transported in sections along the Danube to the Romanian port of Galați. She was then re-assembled by the Romanians at the Galați shipyard and sent to the Black Sea port of Constanţa, Romania, with the 30th U-boat Flotilla until September 1944.[1]
U-23 was scuttled by her crew on 10 September 1944, off the coast of Turkey in the Black Sea at position 41.1833°N 30°W to prevent her capture by the advancing Soviets.
On 3 February 2008, The Daily Telegraph newspaper reported that U-23 had been discovered by Selçuk Kolay, a Turkish marine engineer, in 160feet of water, three miles from the town of Ağva.[2] [3]
| - | Date | Name | Nationality | Tonnage[4] | Fate[5] |
|---|---|---|---|---|---|
| 4 October 1939 | Glen Farg |  | 876 | Sunk | |
| 8 December 1939 | Scotia |  | 2,400 | Sunk | |
| 11 January 1940 | Fredville |  | 1,150 | Sunk | |
| 12 January 1940 | Danmark | | 10,517 | Total loss | |
| 23 January 1940 | Varild | | 1,085 | Sunk | |
| 18 February 1940 | 1,375 | Sunk | |||
| 19 February 1940 | | 5,225 | Sunk | ||
| 22 February 1940 | Loch Maddy | | 4,996 | Total loss | |
| 24 August 1943 | Shkval | 35 | Sunk | ||
| 15 October 1943 | TSC-486 Sovetskja Rossiya | 1,005 | Damaged | ||
| 23 October 1943 | Tanais | 372 | Sunk | ||
| 5 April 1944 | SKA-099 | 56 | Damaged | ||
| 29 May 1944 | Smelyj | 71 | Sunk | ||
| 1 September 1944 | Oituz |  | 2,686 | Sunk |