U-Boat Type XXI

The U-boat Type XXI was a German submarine in service with the Kriegsmarine in 1945, at the end of World War II. It was an advanced electro-diesel U-boat, whose main characteristic was stealth; effectively, it was extremely silent, compared to Allied submarines of the time. The reason for this lay on its powerful and well-made electric motor: a Siemens-Schuckertwerke GU 365/30, which had an output of 1,840 Kw. But it ran smoothly and silently. Hence, the name "electroboat". It also had a new hull design.

Below, three Type XXIs; U-2502, U-2514, and U-2518. Photo taken after the war in 1946.

The first Type XXI was launched as U-2501 on May 12, 1944, under the command of Otto Hübschen. After a series of trials, which went on for almost a year, the first operational U-boat Type XXI was the U-2511, which entered service with the Kriegsmarine in early March 1945. By then Germany was losing the war as the Red Army was already at the gates of Berlin. Under the command of Korvkpt Adalbert Schnee, the U-2511 sailed from Kiel to Norway on March 18, 1945, two months before the end of the war.

The U-2511 suffered a series of light damage sustained during very deep diving tests. This kept it in the yard for reparation for a short time. Meanwhile, six other Type XXI U-boats were already in service. The U-2511 was back at sea when the order to stop hostilities came. However, this did not prevent Schnee from launching a mock attack against a heavily defended British cruiser. The German boat broke through the British escort screen and the commander continued until the target was in the sights, then Schnee aborted the attack and ordered the submarine into deeper depths, without being detected by the powerful British sonars. Thus, he proved that the new U-boat lived up to expectations.

Technical Characteristics

The pressure hull of the Type XXI U-boat consisted of 8 prefabricated sections, with three sections built exclusively by the assembly shipyards at Blohm & Voss, in Hamburg, and AG Weser, in Bremen. The other sections were made at secondary construction yards. It had a double hull; the outer hull and the pressure hull. Aside from its extremely efficient electric motor, the Type XXI was equipped with two MA, four-stroke, 6-cylinder, diesel engines, which provided power for surface cruising and snorkel operations.

This new German U-boat established a radical change in submarine warfare. It was no longer necessary to use the tale-tell periscope to detect and attack the enemy. Thus, optical means was ruled out. A high technological device for orientation and detection had been developed. It was called the "balcony hearing device". It picked up the propeller sounds of an enemy convoy or fleet at much greater distance than had previously been the case using the old optical observation of the periscope. The device sent out impulses which was reflected by the underwater surfaces of the enemy surface ships. The impulses bounced back to the submarine, indicating the direction and distance.

Specifications

Type: electro-diesel submarine

Length:  76.70 m (outer hull); 60.50 m (pressure hull)

Beam: 6.60 m (outer hull); 5.30 m (pressure hull)

Draft: 6.86 m

Displacement: 1,819 tons (submerged); 1,621 tons (surfaced)

Powerplant: two SSW electric motor-generators, GU-365/30, delivering 2,500 HP at 520 rpm, for submerged navigation. Two MAN 6-cylinder, four-stroke diesel engines, putting out 2,000 HP for surface cruising.

Maximum Speed: 17.2 knots (underwater); 15.6 knots (surface).

Range: 5,100 nautical miles at 15.6 knots; 11,150 nautical miles at 12 knots.

Maximum Depth: 300 meters

Armament: six 533-mm torpedo tubes, with 20 torpedoes.

Below, the aft portion of the German submarine showing the two propellers and the rudder, in the dry dock.

One of the 8 sections that made up the U-boat. This one held the two diesel engines. You can notice that one is already inside.