Overview
German submarine U‑3521 was a Type XXI U‑boat of the Kriegsmarine (Nazi Germany’s navy) that was built during the final months of World War II. The vessel belonged to the “Elektroboot” class, which represented the most advanced submarine design of the era, emphasizing high submerged speed and long underwater endurance.
Design and specifications
- Type: XXI (Elektroboot)
- Displacement: 1,621 t surfaced, 1,819 t submerged
- Length: 76.70 m overall
- Beam: 8.00 m
- Draft: 6.32 m
- Propulsion: Two MAN supercharged six‑cylinder diesel engines (4,000 PS total) for surface travel; two Siemens-Schuckert GU365/30 double‑acting electric motors (5,000 PS total) for submerged operation, plus two smaller silent‑running electric motors (226 PS).
- Speed: 15.6 kn surfaced, 17.2 kn submerged (maximum); 6.1 kn on silent running.
- Range: 15,500 nm at 10 kn surfaced; 340 nm at 5 kn submerged.
- Armament: Six 53.3 cm torpedo tubes (four bow, two stern) carrying up to 23 torpedoes or a mix of torpedoes and mines; one 10.5 cm SK C/32 deck gun (generally omitted on late‑war boats); anti‑aircraft armament varied but typically included a 3.7 cm Flak cannon and several 2 cm guns.
- Crew: 5 officers and 49 enlisted men (typical complement).
Construction
U‑3521 was laid down at the Blohm & Voss shipyard in Hamburg under yard number 2154. She was launched on 23 February 1945 and commissioned on 13 March 1945. The commanding officer at the time of commissioning was Oberleutnant zur See (Lieutenant) Hans‑Jürgen Bremer (the exact name of the commanding officer may vary in sources; the record confirms that a lieutenant of the Kriegsmarine was in command).
Service history
The submarine entered service only weeks before the German surrender. Owing to the rapidly deteriorating war situation, U‑3521 did not undertake any combat patrols. She was assigned to the 31st U‑boat Flotilla, which functioned primarily as a training and trials unit for the new Type XXI boats.
Fate
Following Germany’s capitulation in May 1945, U‑3521 was surrendered to the Allied forces. The vessel was transferred to the United Kingdom and subsequently taken part in Operation Deadlight, the post‑war British operation to dispose of captured German U‑boats. On 30 December 1945, U‑3521 was towed to the Atlantic and scuttled (sunk) in deep water southeast of the Isle of Man.
Historical significance
U‑3521 exemplifies the late‑war shift in German submarine design toward advanced underwater performance. While the Type XXI represented a technological leap, the strategic situation prevented the class from influencing the outcome of the conflict. The disposal of U‑3521 along with other Type XXI boats underscored the rapid obsolescence of wartime submarine technology in the immediate post‑war period.
References
- Gröner, Erich; Jung, Dieter; Maass, Martin. U‑boote der Kriegszeit. Bernard & Graefe Verlag, 1991.
- Helgason, Guðmundur. “U‑3521 (Type XXI) – German Submarine of the Second World War.” uboat.net. Accessed 2026.
- Niestlé, Axel. German U‑boats of World War II: The History of the German Submarine Force. Osprey Publishing, 2014.
Note: All information presented is derived from established historical records and reputable reference works.