German submarine U-423

German submarine U-423 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.

She carried out one patrol. She did not sink or damage any ships.

She was sunk by a Norwegian aircraft northwest of the Faroe Islands on 17 June 1944.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-423 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two Siemens-Schuckert GU 343/38–8 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-423 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and two twin 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

Service history
The submarine was laid down on 16 March 1942 at the Danziger Werft (yard) at Danzig (now Gdansk), as yard number 124, launched on 7 November and commissioned on 3 March under the command of Oberleutnant zur See Joachim Methner.

She served with the 8th U-boat Flotilla from 3 March 1943 until her loss.

Patrol and loss
The boat's only patrol commenced with her departure from Kiel on 9 June 1944. On 17 June, she was sunk northeast of the Faroe Islands by depth charges dropped from a Norwegian PBY Catalina flying boat of No. 333 Squadron RAF.

Fifty-three men went down with the U-boat; there were no survivors.