U-27-class submarine (Austria-Hungary)

The lead boat of the U-27 class of submarines, SM U-27, is seen here at her launch on 19 October 1916.
Class overview
Builders	Cantiere Navale Triestino, Pola (4)[1] Ganz Danubius, Fiume (4)[1]
Operators	Austro-Hungarian Navy
Preceded by	U-20 class
Succeeded by	U-43 class
Built	1916–1917
In commission	1917–1918
Completed	8
Lost	2
Preserved	0
General characteristics
Type	submarine
Displacement	264 t (291 short tons) surfaced 301 t (332 short tons) submerged[1]
Length	121 ft 1 in (36.91 m)[1]
Beam	14 ft 4 in (4.37 m)[1]
Draft	12 ft 2 in (3.71 m)[1]
Propulsion	2 × shaft 2 × diesel engine, 270 bhp (200 kW) total 2 × electric motor, 280 shp (210 kW) total[1]
Speed	9 knots (17 km/h) surfaced 7.5 knots (14 km/h) submerged[1]
Complement	23–24[1]
Armament	2 × 45 cm (17.7 in) bow torpedo tubes; 4 torpedoes 1 × 75 mm/26 (3.0 in) deck gun 1 × 8 mm (.323 cal) machine gun[1]

The U-27 class was a class of eight submarines or U-boats built for and operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine) during World War I. The class was based upon the German Type UB II design of the German Imperial Navy and was constructed under license in Austria-Hungary.

After the Austro-Hungarian Navy had filled its most urgent needs for submarines after the outbreak of World War I, they selected the German Type UB II design for its next group of submarines in mid 1915. Orders for the first six boats were placed in October 1915 with the Austrian firm of Cantiere Navale Triestino and the Hungarian firm of Ganz Danubius. Two more boats were ordered in 1916, bringing the class total to eight.

The boats were just over 121 feet (37 m) long and were armed with two bow torpedo tubes, a deck gun, and a machine gun. For propulsion they were equipped with twin diesel engines for surface running and twin electric motors for subsurface movement. Although the class was based on the German design, the Austro-Hungarian U-boats were heavier and slightly faster underwater, but less heavily armed than their German counterparts

All eight boats were commissioned into the Austro-Hungarian Navy between 1917 and 1918 and saw active service during the war. SM U-27 and SM U-28 were the most successful in terms of ships sunk and gross register tonnage sunk, respectively. Two boats sank only one ship each, and a third, SM U-30, sank no ships. U-30 was also the only boat of the class to be lost during the war. The remaining seven were ceded to France and Italy as war reparations and six were scrapped by 1920; the seventh sank while being towed to Bizerta for scrapping.