HNLMS O 12

HNLMS O 12 was the lead ship of her class of submarines built for the Royal Netherlands Navy during the 1930s for European service. Completed in 1931, the boat was being overhauled when Germany invaded the Netherlands in 1940 during the Second World War. She was scuttled by the Dutch to prevent her capture, but the boat was salvaged by Nazi Germany's Kriegsmarine and taken into service as UD-2 in 1943. After serving as a training boat, she was scuttled again by the Germans in May 1945.

O 12 after being launched
History
Netherlands
Name	O 12
Builder	Koninklijke Maatschappij De Schelde, Vlissingen
Laid down	20 October 1928
Launched	8 November 1930
Commissioned	20 July 1931
Fate	Scuttled on 14 May 1940, Marine salvage
Nazi Germany
Name	UD-2
Commissioned	30 January 1943
Decommissioned	6 July 1944
Fate	Scuttled on 3 May 1945
General characteristics
Class & type	O 12-class submarine
Displacement	548 long tons (557 t) (surfaced) 715 long tons (726 t) (submerged)
Length	198 ft 3 in (60.4 m)
Beam	18 ft 6 in (5.6 m)
Draft	11 ft 9 in (3.6 m)}
Propulsion	2 × 900 bhp (671 kW) diesel engines 2 × 300 bhp (224 kW) electric motors
Speed	15 knots (28 km/h; 17 mph) (surfaced) 8 kn (15 km/h; 9.2 mph) (submerged)
Range	3,500 nmi (6,500 km; 4,000 mi) at 10 knots (19 km/h; 12 mph) (surfaced) 12 nmi (22 km; 14 mi) at 8 kn (15 km/h; 9.2 mph) (submerged)
Test depth	280 ft (85 m)
Complement	31
Armament	4 × 21 in (533 mm) bow torpedo tubes 1 × 17.7 in (450 mm) stern torpedo tubes 2 × single 40 mm (1.6 in) AA guns

Design and description

The O 12-class submarines were designed to patrol home waters and were the first Dutch boats to have an uniform armament of 21-inch (530 mm) torpedoes. The boats had a length of 193 feet 3 inches (58.9 m) overall, a beam of 18 feet 6 inches (5.6 m) and a draft of 11 feet 9 inches (3.6 m).^[1] They displaced 548 long tons (557 t) on the surface and 715 long tons (726 t) submerged. The submarines had a crew of 31 officers and enlisted men.^[2]

For surface running, the boats were powered by two 900-brake-horsepower (671 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 300-horsepower (224 kW) electric motor. They could reach 15 knots (28 km/h; 17 mph) on the surface and 8 knots (15 km/h; 9.2 mph) underwater.^[1] On the surface, the boats had a range of 3,500 nautical miles (6,500 km; 4,000 mi) at 13 knots (24 km/h; 15 mph) and 12 nmi (22 km; 14 mi) at 8 knots (15 km/h; 9.2 mph) submerged.^[2] The submarines had a diving depth of 280 feet (85 m).^[3]

The O 12 class was armed with five 21-inch torpedo tubes. Four of these were in the bow and one in the stern. They were also armed with two 40-millimeter (1.6 in) Bofors AA guns;^[2] these were on single watertight mounts that retracted into the conning tower when submerged.^[1]

Construction and career

O 12 was ordered on 4 October 1927 and laid down on 28 October 1928 at the shipyard of Koninklijke Maatschappij De Schelde in Vlissingen.^[4] The boat was launched on 8 November 1930 and commissioned on 20 July 1931.^[2]

When Germany invaded the Netherlands on 10 May 1940, O 12 was being overhauled at Willemsoord, Den Helder, and had to be scuttled to prevent her capture intact on 14 May. The Germans refloated the submarine and sent her to the Wilton-Fijenoord shipyard in Rotterdam to be repaired. On 30 January 1943, she was taken into service by the Kriegsmarine as UD-2.^[4] After serving as a training boat, she was taken out of service on 6 July 1944 and moved to Kiel, where she was scuttled in the harbor in May 1945.^[2] Afterwards, UD-2 was raised and demolished.^[5]