U-3-class submarine

Both members of the U-3 class, SM U-3 (front) and SM U-4 (right rear), are seen here in this undated photograph.
Class overview
Builders	Friedrich Krupp Germaniawerft, Kiel[1]
Operators	Austro-Hungarian Navy
Preceded by	U-1 class
Succeeded by	U-5 class
Built	1907–09
In commission	1909–1918
Completed	2
Lost	1
Preserved	0
General characteristics
Type	submarine
Displacement	240 t surfaced 300 t submerged[2]
Length	138 ft 9 in (42.29 m)[1]
Beam	14 ft (4.3 m)[1]
Draft	12 ft 6 in (3.81 m)[1]
Propulsion	2 × shafts 2 × kerosene 4-cylinder two-stroke engines,[1][2] 600 bhp (450 kW) total[2] 2 × electric motors,[1] 320 shp (240 kW) total[2]
Speed	12 knots (22 km/h) surfaced 8.5 knots (15.7 km/h) submerged[1]
Range	1,200 nmi (2,200 km) at 12 knots (22 km/h), surfaced[1] 40 nmi (74 km) at 3 knots (5.6 km/h), submerged
Complement	21[1]
Armament	2 × 45 cm (17.7 in) torpedo tubes (both front); 3 torpedoes

The U-3 class was a class of two submarines or U-boats built for and operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine). The U-3-class boats were designed and built by Germaniawerft of Kiel, Germany. The class was a part of the Austro-Hungarian Navy's efforts to competitively evaluate three foreign submarine designs.

The two U-3-class boats, both launched in 1908, were just under 140 feet (43 m) long and were each powered by two kerosene two-stroke engines while surfaced, and two electric motors when submerged. The U-3 class initially had diving problems that were alleviated after several modifications to fins and diving planes. Both boats of the class served in combat during World War I. U-3, the lead boat of the class, was sunk by gunfire in August 1915. U-4 was the longest-serving Austro-Hungarian submarine and sank 14,928 gross register tons (GRT) and 7,345 tons of ships, including the Italian armored cruiser Giuseppe Garibaldi in July 1915. U-4 was handed over to France as a war reparation in 1920 and scrapped.