Kriegsmarine U- Boat Type VIIB
Type VIIA, designed in 1933-1934, were the first of a new generation of German attack U-boats. Soon it was discovered that the only real drawback of the VIIA was the small fuel storage for the role intended. That was improved in the VIIB which had additional 33 tons of fuel in external saddle tanks which gave them additional range of about 2,500n/miles at 10 knots. They were also considerably more powerful and slightly faster, had two rudders instead of the one found on the VIIA-this gave them even more agility.
Type VIIB had the same armament as the VIIA, the only major armament difference was that 3 additional torpedoes could be stored for a total of 14, and torpedo tube No.5, at the stern, was put under the waterline.
The next development of this type was the mass production of Type VIIC with several improvements.
Specifications, Type VIIB:
Displacement (srf/sub tons): 753/857
Dimensions (L*B*D meter): 66.50*6.20*4.74
Propulsion: diesel-electric 2*1,600hp supercharged MAN,6 cylinder, M6V 40/46 diesels , 2*325hp AEG GU 460/8-276 electric motors, 2*62 AFA type 27 MAK 800 or type 33 MAL 800W or 800E battery cells, 2 shaft
Speed (srf/sub knots): 17.9/8
Range (srf/sub n/miles@knots): 8,700@10/90@4
Diving depth (meter): 100 (crush depth 200)
Complement: 4 officers and up to 42 enlisted
Torpedo: 4*21"(533 mm) bow torpedo tubes, 1*21" stern torpedo tubes, total of 14 torpedoes
Mines: 26*TMA or 39 TMB in lieu of torpedoes
Armament: 88/L45mm main deck gun, 1*20/C30mm AA gun. Later in the war, AA armament was improved by adding a single 37mm and changing the single 20mm mount to two single mount 20mm guns. Late in the war, snorkels were added and the deck gun was removed.
A total of 24 boats were built in this class;
U-45-55, 11 hulls by Germaniawerft, Kiel 1936 to 1939
U-73-76, 4 hulls by Bremer Volkan, Bremen 1938 to 1940
U-83-87, 5 hulls by Flender Werke, Lübeck 1938 to 1941
U-99-102, 4 hulls by Germaniawerft, Kiel 1937 to 1940
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