U D4 (Navy)
U-D4 was a submarine of the Dutch Navy , whichfell unfinished into German handsduring the German occupation of the Netherlands in World War II and was thencompleted and usedby the German Navy .
Construction and technical data
The submarine O 26 , one of seven boats of the type O 21 O 27 , was on April 20, 1939 in Rotterdam at the Rotterdamsche Droogdok Maatschappij by a Dutch design from 1937 to set keel . The boats were 77.53 m long and 6.5 m wide, had a surface displacement of 949 tons (submerged 1372 t) and were thus somewhat smaller than the boats of the German Type IX . They had eight 53-cm torpedo tubes and could carry 14 torpedoes . Two diesel engines with 2500 HP each and two electric motors with 500 HP each allowed a top speed of 19 knots above and 9 knots under water. Their radius of action was about 7100 nautical miles when crossing the water and cruising at ten knots. The boats were equipped with a snorkel - but it was only used for a better supply of fresh air and not for driving with diesel engines close under the water surface as protection against detection, as was the case with the later German boats. The crew consisted of 4 officers and 41 men.
German spoils of war
When the German Wehrmacht attacked the Netherlands on May 10, 1940, the boat was not quite ready in the shipyard . The shipyard staff tried to sink the boat, which was still lying on the pile, but the surprisingly quick German occupation of the south bank of the Maas on May 14th thwarted this venture. Two sister boats, which are also still under construction, O 25 and O 27 , were also German prey. All three were then completed and put into service by the Navy with the numbers U-D3 (ex O 25 ), U-D4 (ex O 26 ) and U-D5 (ex O 27 ). With these boats, the Kriegsmarine also captured the snorkel ("trimd diesel systeem" or "snort system"), which was already installed in the Dutch navy in the submarines O 19 and O 20 .
Navy
U-D4 has been prepared by the 23 November 1940 stack left and on 28 January 1941, the command of Lieutenant Commander Helmut Brummer-Patzig put into service and the 1st U-boat Flotilla in Kiel allocated. First, test drives were undertaken to try out the snorkel, but these were finally canceled (contrary to the wishes of the German submarine designer Christoph Aschmoneit ) because this technology was not considered to be usable in the harsh North Atlantic . The snorkels were removed from all three boats.
U-D4 then only served as a test and school boat, probably because of its many defects. From May to July 1941 it belonged as a test boat to the 3rd U-Flotilla in Kiel, then until December 1942 as a school boat to the 5th U-Flotilla in Kiel. From January 1943 to November 1944 it was assigned as a school boat to the 27th U-Flotilla in Gotenhafen . In July it was used to test underwater refueling by the supply boat U 490 , a so-called milk cow . It was then converted into a submarine tanker and was used to train submarine crews in underwater refueling. By the end of 1944, around 220 such exercises had been carried out. In November 1944 the boat came to the 24th U-Flotilla in Gotenhafen and in January 1945 to the 18th U-Flotilla in Hela .
It was decommissioned on March 19, 1945 and sunk by its remaining crew on May 3, 1945 in the Kiel Naval Arsenal. The wreck was lifted and scrapped after the war.
Commanders
|