History
Nazi Germany
Name	U-1233
Ordered	14 October 1941
Builder	Deutsche Werft AG, Hamburg
Yard number	396
Laid down	29 April 1943
Launched	23 December 1943
Commissioned	22 March 1944
Fate	Surrendered on 5 May 1945 Sunk on 29 December 1945 in position 55°51′N 8°54′W / 55.850°N 8.900°W / 55.850; -8.900 during Operation Deadlight
General characteristics
Class and type	Type IXC/40 submarine
Displacement	1,144 t (1,126 long tons) surfaced 1,257 t (1,237 long tons) submerged
Length	76.76 m (251 ft 10 in) o/a 58.75 m (192 ft 9 in) pressure hull
Beam	6.86 m (22 ft 6 in) o/a 4.44 m (14 ft 7 in) pressure hull
Height	9.60 m (31 ft 6 in)
Draught	4.67 m (15 ft 4 in)
Installed power	4,400 PS (3,200 kW; 4,300 bhp) (diesels) 1,000 PS (740 kW; 990 shp) (electric)
Propulsion	2 shafts 2 × diesel engines 2 × electric motors
Speed	18.3 knots (33.9 km/h; 21.1 mph) surfaced 7.3 knots (13.5 km/h; 8.4 mph) submerged
Range	13,850 nmi (25,650 km; 15,940 mi) at 10 knots (19 km/h; 12 mph) surfaced 63 nmi (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	230 m (750 ft)
Complement	4 officers, 44 enlisted
Armament	6 × torpedo tubes (4 bow, 2 stern) 22 × 53.3 cm (21 in) torpedoes 1 × 10.5 cm (4.1 in) SK C/32 deck gun (180 rounds) 1 × 3.7 cm (1.5 in) Flak M42 AA gun 2 x twin 2 cm (0.79 in) C/30 AA guns
Service record
Part of:	31st U-boat Flotilla 22 March – 31 October 1944 33rd U-boat Flotilla 1 November 1944 – 5 May 1945
Identification codes:	M 49 604
Commanders:	K.Kapt. Hans-Joachim Kuhn 22 March 1944 – 14 April 1945 Oblt.z.S. Heinrich Niemeyer 15 April – 5 May 1945
Operations:	1 patrol: a. 24 December 1944 – 28 March 1945 b. 31 March – 3 April 1945
Victories:	None

German submarine U-1233 was a Type IXC/40 U-boat built for Nazi Germany's Kriegsmarine during World War II.

Design

German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-1233 had a displacement of 1,144 tonnes (1,126 long tons) when at the surface and 1,257 tonnes (1,237 long tons) while submerged.^[1] The U-boat had a total length of 76.76 m (251 ft 10 in), a pressure hull length of 58.75 m (192 ft 9 in), a beam of 6.86 m (22 ft 6 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.67 m (15 ft 4 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.92 m (6 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).^[1]

The submarine had a maximum surface speed of 18.3 knots (33.9 km/h; 21.1 mph) and a maximum submerged speed of 7.3 knots (13.5 km/h; 8.4 mph).^[1] When submerged, the boat could operate for 63 nautical miles (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 13,850 nautical miles (25,650 km; 15,940 mi) at 10 knots (19 km/h; 12 mph). U-1233 was fitted with six 53.3 cm (21 in) torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm (4.13 in) SK C/32 naval gun, 180 rounds, and a 3.7 cm (1.5 in) Flak M42 as well as two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of forty-eight.^[1]

Service history

U-1233 was ordered on 14 October 1941 from Deutsche Werft AG in Hamburg-Finkenwerder under the yard number 396. Her keel was laid down on 29 April 1943 and was launched on 23 December 1943. About three months later she was commissioned into service under the command of Korvettenkapitän Hans-Joachim Kuhn (Crew 31) in the 31st U-boat Flotilla on 22 March 1944.

After completing training and work-up for deployment U-1233 was transferred to the 33rd U-boat Flotilla for front-line service on 1 November 1944. The U-boat left Horten Naval Base on 11 December 1944 for the first and only war patrol. After returning to Kiel, Kuhn was relieved as commander by Oberleutnant zur See Heinrich Niemeyer (Crew X/39) on 15 April 1945. In May 1945 U-1233 transferred to Fredericia in order to surrender to Allied forces. En route U-1233 and two accompanying U-boats - U-155 and U-680 - were attacked by Allied aircraft. In the course of the attack one P-51 Mustang of No. 126 Squadron RAF was shot down.

In June 1945 the surrendered U-boats were transferred to Wilhelmshaven under British guard from where they sailed for Loch Ryan, a collecting point for Operation Deadlight. On 28 December 1945 U-1233 was towed to sea by HMS Freedom. When the cable slipped the U-boat was sunk by artillery fire from HMS Onslaught on 29 December 1945 in position 54°51′N 8°54′W / 54.850°N 8.900°W / 54.850; -8.900