German Type IXD2 submarines were considerably larger than the original
Type IXs.
U-863 had a displacement of when at the surface and while submerged. The U-boat had a total length of , a
pressure hull length of , a
beam of , a height of , and a
draught of . The submarine was powered by two
MAN M 9 V 40/46
supercharged four-stroke, nine-cylinder
diesel engines plus two
MWM RS34.5S six-cylinder four-stroke diesel engines for cruising, producing a total of for use while surfaced, two
Siemens-Schuckert 2 GU 345/34
double-acting electric motors producing a total of for use while submerged. She had two shafts and two
propellers. The boat was capable of operating at depths of up to . The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, the boat could operate for at ; when surfaced, she could travel at .
U-863 was fitted with six
torpedo tubes (four fitted at the bow and two at the stern), 24
torpedoes, one
SK C/32 naval gun, 150 rounds, and a
Flak M42 with 2575 rounds as well as two
C/30 anti-aircraft guns with 8100 rounds. The boat had a
complement of fifty-five. ==Service history==