U-43-class submarine (Austria-Hungary)

SM U-43 in port, c. 1915–16, while still in the German Imperial Navy (as UB-43)
Class overview
Builders	AG Weser, Bremen[1]
Operators	Austro-Hungarian Navy
Preceded by	U-27-class submarine
Succeeded by	U-48-class submarine
Built	1916
In commission	1917–1918
Completed	2
Lost	0
Scrapped	2
Preserved	0
General characteristics
Type	submarine
Displacement	263 t (290 short tons) surfaced 292 t (322 short tons) submerged[1]
Length	118 ft 5 in (36.09 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, 284 bhp (212 kW) total 2 × electric motor, 280 shp (210 kW) total[1]
Speed	9.2 knots (17.0 km/h) surfaced 5.8 knots (11 km/h) submerged[1]
Complement	22[1]
Armament	2 × 50 cm (19.7 in) bow torpedo tubes; 4 torpedoes 1 × 88 mm/26 (3.5 in) deck gun 1 × 8 mm (0.31 in) machine gun[1]

The U-43 class was a class of two coastal submarines or U-boats operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine) during World War I. The two submarines that comprised the class were Type UB II submarines of the Imperial German Navy, making the two classes identical. From the beginning of World War I, Austria-Hungary had been working to increase the size of its U-boat fleet, so the Imperial German Navy, which was finding it difficult to obtain trained submarine crews, sold two of its UB II boats, UB-43 and UB-47, to its ally in June 1917.

The German Type UB II design incorporated improvements over Type UB I boats, the first coastal submarines of the German Imperial Navy. Among these were twin engines and shafts for more redundancy during operations, a higher top speed, and larger torpedo tubes with double the complement of torpedoes. As a result, the UB II boats were nearly twice as heavy as their predecessor UB I boats.

Both boats of the class were selected for German service in the Mediterranean while under construction. They were shipped via rail to Pola, assembled, launched, and commissioned in the German Imperial Navy, where both enjoyed great success against Allied shipping. In June 1917, the boats were decommissioned, handed over to Austria-Hungary, and then commissioned into the Austro-Hungarian Navy in July. The B in the designation of both boats was dropped, but the submarines retained the same numbers, becoming U-43 and U-47 under the Austro-Hungarian flag. At the end of the war U-43 and U-47 were ceded to Italy and France, respectively, and had been scrapped by 1920.