German submarine U-1021

German submarine U-1021 was a Type VIIC/41 U-boat of Nazi Germany's Kriegsmarine during World War II.

Laid down on 6 May 1943 at the Blohm & Voss yard in Hamburg, the submarine was launched on 13 April 1944, and commissioned on 25 May 1944, under the command of Oberleutnant zur See William Holpert.

Design
German Type VIIC/41 submarines were preceded by the heavier Type VIIC submarines. U-1021 had a displacement of 759 t when at the surface and 860 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 Brown, Boveri & Cie GG UB 720/8 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-1021 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), one 3.7 cm Flak M42 and two 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

Passive sonar
U-1021 was one of only ten Type VIIC's to be fitted with a Balkongerät (literally 'Balcony apparatus or equipment'). The Balkongerät was used on U-boats (GS U-682, GS U-788, GS U-799, GS U-997, GS U-1105, GS U-1172, GS U-1306, GS U-1307 and GS U-1308). The Balkongerät was standard on the Type XXI and the Type XXIII. Nonetheless, it was also fitted to several Type IXs and one Type X. The Balkongerät was an improved version of Gruppenhorchgerät (GHG) (group listening device) with double the hydrophones.

Service history
U-1021 served with 31st U-boat Flotilla, a training unit, and later with 11th U-boat Flotilla from 1 December 1944 until its disappearance in March 1945.

Patrol and loss
U-1021 sailed from Bergen on 20 February 1945 and headed for the waters around Land's End.

U-1021 was presumed to have been sunk on 30 March 1945 in The Minch in the Hebrides, by depth charges from the British frigates HMS Rupert (K561) and HMS Conn (K509).

Discovery
However, the wreck of U-1021 was identified by nautical archaeologist Innes McCartney and historian Axel Niestle in December 2006, 7 nmi off Newquay, Cornwall, at position 50.555°N, -5.19333°W, close to two other U-boats, GS U-325 and GS U-400. Further research by Innes McCartney led to the conclusion that all three submarines were sunk in the Bristol Channel by a deep-trap minefield. Minefield "HW A3", which was fatal to U-1021, was laid by HMS Apollo (M01) on 3 December 1944.

The attack of 30 March 1945 previously assumed to have sunk U-1021 is now believed to have sunk GS U-965.