[WWII] Typ II coastal U-boat (Germany)

[copeab]

Typ II coastal U-boat
Copyright 2011 by Brandon Cope

The Einbaume (dug-out canoes) were the first U-boats built by Germany after WWI and the first batch (six IIA's) were near-copies of the Finnish Vesikko submarine (p.W:MP123), which was tested by the Germans before being sold to Finland. Even as those were under construction an improved version was being designed. The first of the Typ IIB's entered service in 1936, as did all of the Typ IIA's. These boats were inadequate for the demands of WWII, but due to the shortage of larger and newer U-boats in 1939, the Typ II's in service were pressed into combat duties. Some of these boats (six IIBs) were disassembled at their North Sea bases and were transported across continental Europe, to be reassembled and used in the Black Sea (five of the six were scuttled late in the war rather than letting them be captured by the Soviets). Most of the Typ II's were, at one point or another, used for training, which explains why out of a total of 50 boats constructed only eleven were lost in combat (another four were lost in training accidents). Most Typ VII (p.W:IC91) commanders got their start in a Typ II.

Typ IIB's sank or damaged around 115 ships in some 160 combat patrols, although most of these were of smaller ships. The U-10, U-18, U-19, U-20, U-23 and U-24 all went on at least 14 combat patrols each (U-19 and U-24 tied with the most at 20 each). Two boats of this class, the U-120 and U-121, were intended for export when first laid down, but by the time they were completed in 1940 they were required by the Germans; neither saw combat (as well as the U-11 and possibly U-8), both only being used as training boats and scuttled in 1945.

The Typ IIB has a crew of 25. It mounts three 21” torpedo tubes forward. A 20mm AA gun is carried on a pedestal on the fore deck. The engines burn 20.9 gallons of diesel fuel per hour of routine usage. The Typ IIB can travel 1,500 miles at 15 mph surfaced and 40 miles at 5 mph submerged.

Subassemblies: Very Light Corvette chassis with Sub option +7; sealed Medium TD superstructure [Body:T] +3; full-rotation Mini open mount [Sup:T] +1.
Powertrain: 2¥261-kW marine diesel engines with 2¥261-kW water screws and 3,600-gallon standard tanks; 2¥134.5-kW electric motors with 1.05 million-kWs batteries†.
Occupancy: 8 CS Body, 3 CS Sup Cargo: 1,083 Body, 29 Sup

Armor
Body: 4/45
Sup: 4/45
OM: 0/0

Weaponry
3¥533mm Torpedo Tubes [Body: F] (6).
20mm Long Ground AC [OM:F] (2,000).

Equipment
Body: Autopilot; backup driver controls; 500-VSP bilge; 5¥bilge pumps†; 16¥bunks; 50-VSP cargo holds; 25-man environmental control†; 5¥fire extinguishers†; 25-man-days life support†; navigation instruments; precision navigation instruments; 250-man/days of provisions; 1-mile passive sonar. Sup: Navigation instruments; 1¥25’ 15¥ periscope; medium and large radio receivers and transmitters; searchlight. OM: Universal mount.
† Limited access.

Statistics
Size: 134’¥13’¥29’
Payload: 92.5 tons
Lwt: 329 tons
Volume: 3,951
Maint.: 17 hours
Price: $131,000

HT: 12
HP: 27,000 [Body], 360 [Superstructure], 30 [Open Mount]

wSpeed: 15
wAccel: 0.1
wDecel: 0.5(0.6)
wMR: 0.05
wSR: 3
Draft: 13'
Flotation Rating 383 tons.

uSpeed: 8
uAccel: 0.05
uDecel: 0.3(0.4)
uMR: 0.05
uSR: 4
uDraft: 45'
Crush Depth 110 yards.

Design Notes
The 329-ton historical submerged displacement was used for underwater performance calculations. Design wSpeed was 10 mph, uSpeed was 10 mph and design Draft 7 feet; the historical figures were used instead. The historical diving depth was also used. As the chassis used was oversized for the design, most of the empty space should be ignored. One source lists length as 144'.

wSR was lowered as the boat was known to roll excessively on the surface.

For patrols (as opposed to training) up to four 20mm guns were mounted (the extra guns on pedestals on the deck). Up to eight mines could be carried in place of the torpedoes.

Variants
The Typ IIA (1936) displaced 302 tons dived and was 134' long. It had a surface range of only 1,200 miles. Six built.

The Type IIC (1938) was 341 tons dived and 144' long. The longer hull was also used to improve the radio room and add a second periscope, apart from the additional fuel stores. The propellers were shrouded; while this appeared to cause no problems in service, it was not repeated on any other class of U-boats. Surface range was 2,200 miles and surface speed was 14 mph. Elecric motors increased to 306-kW total but submerged speed and range was the same as the IIB. Eight built.

The Typ IID (1940) was basically the same as the IIC, but with self-compensating saddle tanks (beam 16') for greatly improved range (4,025 miles), increasing displacement to 364 tons. As diesel was drawn from the saddle tanks, seawater was let in, maintaining positive buoyancy. With this greatly increased ranged, the IID's patrolled as far as the shores of Western Britain. batteries were also improved, allowing a range of 63 miles at 5 mph. Speed was back up to 15 mph but could only dive to 90 yards. Sixteen built.