SM U-66

History
German Empire
Name:	U-66
Ordered:	2 February 1913
Builder:	Germaniawerft, Kiel
Yard number:	203
Laid down:	1 November 1913, as U-7 (Austria-Hungary)
Launched:	22 April 1915
Commissioned:	23 July 1915
Fate:	3 September 1917 - Lost on or after 3 September 1917, possibly in the Dogger Bank area to a mine. 40 dead (all hands lost)
General characteristics
Type:	German Type U 66 submarine
Displacement:	791 t (779 long tons) surfaced 933 t (918 long tons) submerged
Length:	69.50 m (228 ft) (o/a) 54.66 m (179 ft 4 in) (pressure hull)
Beam:	6.30 m (20 ft 8 in) (o/a) 4.15 m (13 ft 7 in) (pressure hull)
Height:	7.95 m (26 ft 1 in)
Draft:	3.79 m (12 ft 5 in)
Propulsion:	1 × shaft 2 × Germania 6-cylinder four-stroke diesel engines, 2,269 shp (1,692 kW) total 2 × SSW electric motors, 1,223 shp (912 kW) total
Speed:	16.8 knots (31.1 km/h; 19.3 mph) surfaced 10.3 knots (19.1 km/h; 11.9 mph) submerged
Range:	7,370 nmi (13,650 km; 8,480 mi) at 8 knots (15 km/h; 9.2 mph) surfaced 115 nmi (213 km; 132 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth:	50 m (160 ft)
Complement:	4 officers, 32 enlisted men
Armament:	5 × 45 cm (17.7 in) torpedo tubes (four bow, one stern) 12 torpedoes 1 × 8.8 cm (3.5 in) SK L/30 deck gun, later replaced by 10.5 cm (4.1 in) SK L/45 deck gun
Service record
Part of:	Baltic Flotilla (October 1915 – January 1916) 4th Flotilla (January 1916 – September 1917)
Commanders:	Kptlt. Thorwald von Bothmer 23 July 1915 – 16 June 1917 Kptlt. Gerhard Muhle 17 June – 3 September 1917
Operations:	7 patrols
Victories:	24 merchant ships (68,962 GRT) sunk 1 merchant ship (3,157 GRT) damaged 1 merchant ship (1,005 GRT) taken as prize

SM U-66 was the lead ship of the Type U-66 submarines or U-boats for the Imperial German Navy (German: Kaiserliche Marine) during World War I. The submarine had been laid down in Kiel in November 1913 as U-7, the lead ship of the U-7 class for the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine). They became convinced after the outbreak of war in August 1914 that none of these submarines could be delivered to the Adriatic via Gibraltar, and sold the entire class, including U-7, to the German Imperial Navy in November 1914.

Under German control, the class became known as the U-66 type and the boats were renumbered; U-7 became U-66, and all were redesigned and reconstructed to German specifications. U-66 was launched in April 1915 and commissioned in July. As completed, she displaced 791 tonnes (779 long tons) when surfaced and 933 tonnes (918 long tons) submerged. The boat was 69.50 metres (228 ft) long and was armed with five torpedo tubes and a deck gun.

As a part of the Baltic and 4th Flotillas, U-66 sank 24 ships with a combined gross register tonnage of 69,967 in six war patrols. The U-boat also torpedoed and damaged the British cruiser Falmouth in August 1916. U-66 left Emden on her seventh patrol on 2 September 1917 for operations in the North Channel. The following day the U-boat reported her position in the North Sea but neither she nor any of her 40-man crew were ever heard from again. A postwar German study offered no explanation for U-66's loss, although British records suggest that she may have struck a mine in the Dogger Bank area.

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