Type II B
German submarine U-20, 1. U-Flottille, Kiel, 1940

Type II B
Type B was manufactured in the largest number of all Type II submarines.
Until the second half of 1936, Germaniawerft AG and Deutsche Werke AG in Kiel built 18 Type II B submarines, which were designated U-7 to U-24.
In March 1940, the Flander Werke AG in Lübeck, completed two more units – U-120 and U-121.
Initially, they were supposed to be sold, but in the end the were commissioned in the Kriegsmarine.

(U-7 - F. Krupp Germaniawerft AG, Kiel (werk 541).

Type II B was longer – 42.7 m.
That allowed for installation of an additional fuel tank, which increased its range at 8 knots from 1600 to 3100 NM.
Due to hull modifications crash diving time was reduced to 25 seconds.


General characteristics:

Type:
Coastal submarine

Displacement:
279 t (275 long tons) surfaced
328 t (323 long tons) submerged
414 t (407 long tons) total

Length:
42.70 m (140 ft 1 in) o/a
28.20 m (92 ft 6 in) pressure hull

Beam:
4.081 m (13 ft 4.7 in) o/a
4 m (13 ft 1 in) pressure hull

Height:
8.60 m (28 ft 3 in)
Draught
3.90 m (12 ft 10 in)

Propulsion:
2 × MWM RS 127 S 6-cylinder diesel engines, 700 PS (690 shp; 515 kW)
2 × SSW PG VV 322/36 double-acting electric motors, 360–375 PS (355–370 shp; 265–276 kW)

Speed:
13 knots (24 km/h; 15 mph) surfaced
7 knots (13 km/h; 8.1 mph) submerged

Test depth:
150 m (490 ft)

Complement:
3 officers, 11 non-commissioned officers, 11 enlisted

Sensors and processing systems:
Gruppenhorchgerät

Armament:
3 × 53.3 cm (21 in) torpedo tubes (bow)
5 torpedoes or 1 torpedo and 9 TMB mines
various 2 cm (0.79 in) C/30 anti-aircraft gun