German submarine U-731

History
Nazi Germany
Name	U-731
Ordered	21 November 1940
Builder	Schichau-Werke, Danzig
Yard number	1522
Laid down	1 October 1941
Launched	25 July 1942
Commissioned	3 October 1942
Fate	Sunk on 15 May 1944 near Tangier by British patrol vessels
General characteristics
Class and type	Type VIIC submarine
Displacement	769 t (757 long tons) surfaced; 871 t (857 long tons) submerged;
Length	67.10 m (220 ft 2 in) (o/a); 50.50 m (165 ft 8 in) (pressure hull);
Beam	6.20 m (20 ft 4 in) (o/a); 4.70 m (15 ft 5 in) (pressure hull);
Height	9.60 m (31 ft 6 in)
Draught	4.74 m (15 ft 7 in)
Installed power	2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp) (diesels); 750 PS (550 kW; 740 shp) (electric);
Propulsion	2 shafts; 2 × diesel engines; 2 × electric motors;
Speed	17.7 knots (32.8 km/h; 20.4 mph) surfaced; 7.6 knots (14.1 km/h; 8.7 mph) submerged;
Range	8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced; 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged;
Test depth	230 m (750 ft); Crush depth: 250–295 m (820–968 ft);
Complement	4 officers, 40–56 enlisted
Armament	5 × torpedo tubes (four bow, one stern); 14 × 53.3 cm (21 in) torpedoes or 26 TMA mines; 1 × 8.8 cm (3.46 in) deck gun (220 rounds); 2 × twin 2 cm (0.79 in) C/30 anti-aircraft guns;
Service record
Part of:	8th U-boat Flotilla; 3 October 1942 - 30 April 1943; 1st U-boat Flotilla; 1 May 1943 – 15 May 1944;
Identification codes:	M 50 791
Commanders:	Oblt.z.S. Werner Techand; 3 October 1942 – 30 November 1943; Oblt.z.S. Graf Alexander von Keller; 1 December 1943 – 15 May 1944;
Operations:	4 patrols:; 1st patrol:; 29 April – 12 June 1943; 2nd patrol:; 29 August – 1 November 1943; 3rd patrol:; 19 December 1943 – 18 February 1944; 4th patrol:; 18 April – 15 May 1944;
Victories:	None

German submarine U-731 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 1 October 1941 at the Schichau-Werke yard at Danzig, launched on 25 July 1942, and commissioned on 3 October 1942 under the command of Oberleutnant zur See Werner Techand.

Attached to 8th U-boat Flotilla based at Kiel, U-731 completed her training period on 30 April 1943 and was assigned to front-line service.

Design

German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-731 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged.^[1] She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.74 m (15 ft 7 in). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced, two AEG GU 460/8–27 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 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 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph).^[1] When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-731 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.^[1]

Service history

On the fourth and final war patrol, U-731 was detected on 15 May 1944 by two Catalinas, P-14 and P-1, of VP-63 off Tangiers, when the U-boat tried to force the Strait of Gibraltar. Two British patrol craft, HMS Kilmarnock and HMS Blackfly, received reports of the U-boat and attacked with hedgehogs. U-731 was sunk in position 35°54′N 5°45′W / 35.900°N 5.750°W / 35.900; -5.750; all 54 crew members perished in the attack.^[2]

References

^ ^a ^b ^c ^d Gröner, Jung & Maass 1991, pp. 43–46.
^ Busch & Röll 1999b, p. 236.

Bibliography

Busch, Rainer; Röll, Hans-Joachim (1999a). German U-boat commanders of World War II : a biographical dictionary. Translated by Brooks, Geoffrey. London, Annapolis, Md: Greenhill Books, Naval Institute Press. ISBN 1-55750-186-6.
Busch, Rainer; Röll, Hans-Joachim (1999b). Der U-Boot-Krieg, 1939-1945: Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945] (in German). Vol. IV. Hamburg, Berlin, Bonn: Mittler. ISBN 3-8132-0514-2.
Gröner, Eric; Jung, Dieter; Maass, Martin (1991). German Warships 1815-1945: U-boats and Mine Warfare Vessels. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.

External links

Helgason, Guðmundur. "The Type VIIC boat U-731". German U-boats of WWII - uboat.net. Retrieved 23 July 2015.

[FOOTNOTEGrönerJungMaass199143–46-1] Gröner, Jung & Maass 1991, pp. 43–46.

[FOOTNOTEBuschRöll1999b236-2] Busch & Röll 1999b, p. 236.

[1]

[2]

v t e Type VII submarines
Type VIIA	U-27 U-28 U-29 U-30 U-31 U-32 U-33 U-34 U-35 U-36
Type VIIB	U-45 U-46 U-47 U-48 U-49 U-50 U-51 U-52 U-53 U-54 U-55 U-73 U-74 U-75 U-76 U-83 U-84 U-85 U-86 U-87 U-99 U-100 U-101 U-102
Type VIIC	U-69 U-70 U-71 U-72 U-77 U-78 U-79 U-80 U-81 U-82 U-88 U-89 U-90 U-91 U-92 U-93 U-94 U-95 U-96 U-97 U-98 U-132 U-133 U-134 U-135 U-136 U-201 U-202 U-203 U-204 U-205 U-206 U-207 U-208 U-209 U-210 U-211 U-212 U-221 U-222 U-223 U-224 U-225 U-226 U-227 U-228 U-229 U-230 U-231 U-232 U-235 U-236 U-237 U-238 U-239 U-240 U-241 U-242 U-243 U-244 U-245 U-246 U-247 U-248 U-249 U-250 U-251 U-252 U-253 U-254 U-255 U-256 U-257 U-258 U-259 U-260 U-261 U-262 U-263 U-264 U-265 U-266 U-267 U-268 U-269 U-270 U-271 U-272 U-273 U-274 U-275 U-276 U-277 U-278 U-279 U-280 U-281 U-282 U-283 U-284 U-285 U-286 U-287 U-288 U-289 U-290 U-291 U-301 U-302 U-303 U-304 U-305 U-306 U-307 U-308 U-309 U-310 U-311 U-312 U-313 U-314 U-315 U-316 U-331 U-332 U-333 U-334 U-335 U-336 U-337 U-338 U-339 U-340 U-341 U-342 U-343 U-344 U-345 U-346 U-347 U-348 U-349 U-350 U-351 U-352 U-353 U-354 U-355 U-356 U-357 U-358 U-359 U-360 U-361 U-362 U-363 U-364 U-365 U-366 U-367 U-368 U-369 U-370 U-371 U-372 U-373 U-374 U-375 U-376 U-377 U-378 U-379 U-380 U-381 U-382 U-383 U-384 U-385 U-386 U-387 U-388 U-389 U-390 U-391 U-392 U-393 U-394 U-396 U-397 U-398 U-399 U-400 U-401 U-402 U-403 U-404 U-405 U-406 U-407 U-408 U-409 U-410 U-411 U-412 U-413 U-414 U-415 U-416 U-417 U-418 U-419 U-420 U-421 U-422 U-423 U-424 U-425 U-426 U-427 U-428 U-429 U-430 U-431 U-432 U-433 U-434 U-435 U-436 U-437 U-438 U-439 U-440 U-441 U-442 U-443 U-444 U-445 U-446 U-447 U-448 U-449 U-450 U-451 U-452 U-453 U-454 U-455 U-456 U-457 U-458 U-465 U-466 U-467 U-468 U-469 U-470 U-471 U-472 U-473 U-475 U-476 U-477 U-478 U-479 U-480 U-481 U-482 U-483 U-484 U-485 U-486 U-551 U-552 U-553 U-554 U-555 U-556 U-557 U-558 U-559 U-560 U-561 U-562 U-563 U-564 U-565 U-566 U-567 U-568 U-569 U-570 U-571 U-572 U-573 U-574 U-575 U-576 U-577 U-578 U-579 U-580 U-581 U-582 U-583 U-584 U-585 U-586 U-587 U-588 U-589 U-590 U-591 U-592 U-593 U-594 U-595 U-596 U-597 U-598 U-599 U-600 U-601 U-602 U-603 U-604 U-605 U-606 U-607 U-608 U-609 U-610 U-611 U-612 U-613 U-614 U-615 U-616 U-617 U-618 U-619 U-620 U-621 U-622 U-623 U-624 U-625 U-626 U-627 U-628 U-629 U-630 U-631 U-632 U-633 U-634 U-635 U-636 U-637 U-638 U-639 U-640 U-641 U-642 U-643 U-644 U-645 U-646 U-647 U-648 U-649 U-650 U-651 U-652 U-653 U-654 U-655 U-656 U-657 U-658 U-659 U-660 U-661 U-662 U-663 U-664 U-665 U-666 U-667 U-668 U-669 U-670 U-671 U-672 U-673 U-674 U-675 U-676 U-677 U-678 U-679 U-680 U-681 U-682 U-683 U-701 U-702 U-703 U-704 U-705 U-706 U-707 U-708 U-709 U-710 U-711 U-712 U-713 U-714 U-715 U-716 U-717 U-718 U-719 U-720 U-721 U-722 U-731 U-732 U-733 U-734 U-735 U-736 U-737 U-738 U-739 U-740 U-741 U-742 U-743 U-744 U-745 U-746 U-747 U-748 U-749 U-750 U-751 U-752 U-753 U-754 U-755 U-756 U-757 U-758 U-759 U-760 U-761 U-762 U-763 U-764 U-765 U-766 U-767 U-768 U-771 U-772 U-773 U-774 U-775 U-776 U-777 U-778 U-779 U-821 U-822 U-825 U-826 U-901 U-903 U-904 U-905 U-907 U-921 U-922 U-923 U-924 U-925 U-926 U-927 U-928 U-951 U-952 U-953 U-954 U-955 U-956 U-957 U-958 U-959 U-960 U-961 U-962 U-963 U-964 U-965 U-966 U-967 U-968 U-969 U-970 U-971 U-972 U-973 U-974 U-975 U-976 U-977 U-978 U-979 U-980 U-981 U-982 U-983 U-984 U-985 U-986 U-987 U-988 U-989 U-990 U-991 U-992 U-993 U-994 U-1051 U-1052 U-1053 U-1054 U-1055 U-1056 U-1057 U-1058 U-1101 U-1102 U-1131 U-1132 U-1161 U-1162 U-1191 U-1192 U-1193 U-1194 U-1195 U-1196 U-1197 U-1198 U-1199 U-1200 U-1201 U-1202 U-1203 U-1204 U-1205 U-1206 U-1207 U-1208 U-1209 U-1210
Type VIIC/41	U-292 U-293 U-294 U-295 U-296 U-297 U-298 U-299 U-300 U-317 U-318 U-319 U-320 U-321 U-322 U-323 U-324 U-325 U-326 U-327 U-328 U-691 U-827 U-828 U-929 U-930 U-995 U-997 U-998 U-999 U-1000 U-1001 U-1002 U-1003 U-1004 U-1005 U-1006 U-1007 U-1008 U-1009 U-1010 U-1011 U-1013 U-1014 U-1015 U-1016 U-1017 U-1018 U-1019 U-1020 U-1021 U-1022 U-1023 U-1024 U-1025 U-1063 U-1064 U-1065 U-1103 U-1104 U-1105 U-1106 U-1107 U-1108 U-1109 U-1110 U-1163 U-1164 U-1165 U-1166 U-1167 U-1168 U-1169 U-1170 U-1171 U-1172 U-1271 U-1272 U-1273 U-1274 U-1275 U-1276 U-1277 U-1278 U-1279 U-1301 U-1302 U-1303 U-1304 U-1305 U-1306 U-1307 U-1308
Type VIID	U-213 U-214 U-215 U-216 U-217 U-218
Type VIIF	U-1059 U-1060 U-1061 U-1062
Preceded by: Type II Followed by: Type IX List of U-boats of Germany

v t e Shipwrecks and maritime incidents in May 1944
Shipwrecks	1 May: U-277 2 May: U-674, U-959 3 May: USS Donnell, U-852 4 May: U-371, U-846 5 May: USS Fechteler 6 May: U-66, U-473, U-765 7 May: HMCS Valleyfield 9 May: USS PC-558 10 May: Karukaya, Totila 11 May: USS YF-415 13 May: Ro-501 14 May: America Maru, Inazuma, U-1234 15 May: U-731 16 May: I-176 17 May: U-616 19 May: I-16, U-960, U-1015 21 May: USS LST-353, USS LST-480, U-453 22 May: Asanagi, Hashidate, Ro-106 23 May: Ro-104 24 May: Ro-116, U-675 25 May: U-476, U-990 26 May: Ro-108 27 May: U-292 28 May: UJ 2210 29 May: USS Block Island, U-549 31 May: Ishigaki, Kotaka, Ro-105, U-289 Unknown date: U-240
Other incidents	2 May: USS Parrott 4 May: HMS Elgin 5 May: Hayasui, I-155 12 May: USS Bream, U-1102 15 May: La Sultane 16 May: U-616 21 May: West Loch disaster 24 May: U-476 26 May: Serpa Pinto 27 May: USS Lapon, USS Raton 28 May: USS Permit Unknown date: USS Medusa
1943 1944 1945 April 1944 June 1944

History

Nazi Germany
Name	U-731
Ordered	21 November 1940
Builder	Schichau-Werke, Danzig
Yard number	1522
Laid down	1 October 1941
Launched	25 July 1942
Commissioned	3 October 1942
Fate	Sunk on 15 May 1944 near Tangier by British patrol vessels
General characteristics
Class and type	Type VIIC submarine
Displacement	769 t (757 long tons) surfaced 871 t (857 long tons) submerged
Length	67.10 m (220 ft 2 in) (o/a) 50.50 m (165 ft 8 in) (pressure hull)
Beam	6.20 m (20 ft 4 in) (o/a) 4.70 m (15 ft 5 in) (pressure hull)
Height	9.60 m (31 ft 6 in)
Draught	4.74 m (15 ft 7 in)
Installed power	2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp) (diesels) 750 PS (550 kW; 740 shp) (electric)
Propulsion	2 shafts 2 × diesel engines 2 × electric motors
Speed	17.7 knots (32.8 km/h; 20.4 mph) surfaced 7.6 knots (14.1 km/h; 8.7 mph) submerged
Range	8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	230 m (750 ft) Crush depth: 250–295 m (820–968 ft)
Complement	4 officers, 40–56 enlisted
Armament	5 × torpedo tubes (four bow, one stern) 14 × 53.3 cm (21 in) torpedoes or 26 TMA mines 1 × 8.8 cm (3.46 in) deck gun (220 rounds) 2 × twin 2 cm (0.79 in) C/30 anti-aircraft guns
Service record
Part of:	8th U-boat Flotilla 3 October 1942 - 30 April 1943 1st U-boat Flotilla 1 May 1943 – 15 May 1944
Identification codes:	M 50 791
Commanders:	Oblt.z.S. Werner Techand 3 October 1942 – 30 November 1943 Oblt.z.S. Graf Alexander von Keller 1 December 1943 – 15 May 1944
Operations:	4 patrols: 1st patrol: 29 April – 12 June 1943 2nd patrol: 29 August – 1 November 1943 3rd patrol: 19 December 1943 – 18 February 1944 4th patrol: 18 April – 15 May 1944
Victories:	None