Type II Unterseeboot

Introduction

The Type II Unterseeboot (under sea boat, or U-Boat) was a German U-Boat modeled after the CV-707 Submarine. Too small for sustained operations far from home support, it primarily was used for the training of new German U-Boat commanders.

Background

After World War I, Germany was stripped of her U-Boat fleet by the Treaty of Versailles. In the late 1920’s and 1930’s, the Germans started to rebuild their armed forces. The first Type II U-Boat was laid down on February 11, 1935. Since the world would see this as a step towards major rearmament, Hitler reached an agreement with Britain to build his navy up to 35% of the size of the Royal Navy in surface ships, and equal in submarines. This was agreement was signed on June 18, 1935, and U-1 was commissioned on June 29.

Characteristics

Type II U-Boats were small in size, and earned the nickname of Einbaum (dugout canoe). They could work in shallow water, dive more quickly than contemporary sized ships, and were more difficult to spot due to its low conning tower. However, it had a shallower maximum depth, a short range, cramped conditions, and only five torpedoes.

Type II’s had a single hull, and no watertight compartments. There were three torpedo tubes forward and two torpedoes just aft of the torpedo tubes. There was one 20mm twin-gun mount for anti-aircraft, and no deck gun.

The Type II U-Boat had diesel-electric propulsion. The two diesel engines gave it 700hp for a maximum surface speed of 13 knots. Twelve tons of diesel fuel was carried, which gave it a maximum range of 1600 miles at 8 knots. While submerged, the two electric motors gave 360hp, for a maximum submerged speed of 6.9 knots. The batteries gave 35 miles while submerged, at 4 knots. Later variants had larger electric engines, larger batteries, and/or more diesel fuel.

While maximum depth for submarines varies by each ship (the major factors contributing being quality of construction and degree of damage to the hull), there are design depths. The Type II’s design depth was 490ft. However, on a pre-war dive, U-12’s hull cracked at 340ft – this led to urgent modification to all Type II U-Boats at the time.

Most of the 24-man crew lived around the torpedoes, sharing twelve bunks. Four more bunks were aft of the engine room for the engine room crew.

U-1 - the first Type II U-Boat, and the first U-Boat of Hitlers WWII Navy

Operational History

Most Type II U-Boats only saw combat in the early years of the war. Most of them were then used in training schools. Six Type II’s were stripped down to just the hull, then transported by river and truck to Linz, and finally reassembled for use in the Black Sea against the Soviet Union.

Few Type II U-Boats were lost, mainly because they were training ships, though several were lost to actions. The Type II U-Boat was Germany’s first major step towards re-armament, and gave them experience in construction and operation, laying the foundation for larger U-Boats.

Type IIA

The IIA, the first type of all Type II U-Boats, was a single-hulled, all-welded boat with internal ballast tanks. Its bridge was smaller than other Type II sub-types. It could carry G7a or G7e torpedoes, or TM-type mines.

IIA Specs

Displacement: 254 long tons surfaced; 303 lt submerged; 381 lt total

Length: 134ft 2in overall; 91ft 2in pressure hull

Beam: 13ft 5in o/a; 13ft 1in pressure hull

Height: 28ft 3in

Draught: 12ft 6in

Diesel Engines: 2x MWM RS127S 6-cylinder diesel engines, 700hp

Electric Motors: 2x SSW PGVV322/26 double-acting electric motors, 402hp

Speed: 13 knots surfaced; 6.9 knots submerged

Range: 1300 nautical miles @ 8 knots surfaced; 30 nautical miles @ 4 knots submerged

Test Depth: 490ft

Crew: 22-24

Torpedo Armament: 3x forward torpedo tubes, 5x torpedoes

Guns: 20mm Twin Flak, 850rnds

Type IIB

The Type IIB was a lengthened version of the IIA. Three more compartments were inserted amidships, and more diesel tanks were fitted beneath the control room which increased the range. Diving time also improved to 30 seconds.

IIB Specs

Displacement: 279 lt surfaced; 328 lt submerged; 414 lt total

Length: 140ft 1in o/a; 92ft 6in pressure hull

Beam: 13ft 5in o/a; 13ft 1in pressure hull

Height: 28ft 3in

Draught: 12ft 6in

Diesel Engines: 2x MWM RS127S 6-cylinder diesel engines, 700hp

Electric Motors: 2x SSW PGVV322/26 double-acting electric motors, 402hp

Speed: 13 knots surfaced; 7 knots submerged

Range: 2700 nautical miles @ 8 knots surfaced; 38 nautical miles @ 4 knots submerged

Test Depth: 490ft

Crew: 22-24

Torpedo Armament: 3x forward torpedo tubes, 5x torpedoes

Guns: 20mm Twin Flak, 1000rnds

Type IIC

The Type IIC was lengthened again; another two compartments were inserted amidships for an improved radio room and a second periscope. The diesel tanks beneath the control room were enlarged, increasing the range again.

IIC Specs

Displacement: 291 lt surfaced; 341 lt submerged; 435 lt total

Length: 144ft o/a; 97ft 1in pressure hull

Beam: 13ft 5in o/a; 13ft 1in pressure hull

Height: 27ft 7in

Draught: 12ft 10in

Diesel Engines: 2x MWM RS127S 6-cylinder diesel engines, 700hp

Electric Motors: 2x SSW PGVV322/26 double-acting electric motors, 402hp

Speed: 12 knots surfaced; 7 knots submerged

Range: 3300 nautical miles @ 8 knots surfaced; 36 nautical miles @ 4 knots submerged

Test Depth: 490ft

Crew: 22-24

Torpedo Armament: 3x forward torpedo tubes, 5x torpedoes

Guns: 20mm Twin Flak, 1000rnds

Type IID

The last sub-type was the Type IID. These ships had external saddle tanks for more diesel fuel. As the oil was consumed, sea water would gradually fill the tanks to give compensation for the positive buoyancy. Its range nearly doubled, which enabled it to operate around the British Isles. It also was fitted with Kurt nozzles, which was intended to improve propulsion efficiency.

IID Specs

Displacement: 314 lt surfaced; 364 lt submerged; 460 lt total

Length: 144ft 4in o/a; 97ft 9in pressure hull

Beam: 16ft 1in o/a; 13ft 1in pressure hull

Height: 27ft 7in

Draught: 12ft 10in

Diesel Engines: 2x MWM RS127S 6-cylinder diesel engines, 700hp

Electric Motors: 2x SSW PGVV322/26 double-acting electric motors, 402hp

Speed: 12.7 knots surfaced; 7.4 knots submerged

Range: 4900 nautical miles @ 8 knots surfaced; 49 nautical miles @ 4 knots submerged

Test Depth: 490ft

Crew: 22-24

Torpedo Armament: 3x forward torpedo tubes, 5x torpedoes

Guns: 20mm Twin Flak, 1000rnds

Sources:

www.wikipedia.org

www.ww2ships.com

www.uboataces.com