Type U 5 was a class of four gasoline-powered U-boats built between 1908 and 1911 which served in the Imperial German Navy during World War I. The class was the earliest U-boat type to see active service during the war. All four of the boats were lost within 14 months of war breaking out.
Type U 5s had an overall length of The boats' beam was , the draught was . The boats displaced when surfaced and when submerged.
Type U 5s were fitted with two Körting 6-cylinder and two 8-cylinder two-stroke paraffin engines with a total of for use on the surface and two SSW double-acting electric motors with a total of for underwater use. These engines powered two shafts, which gave the boats a top surface speed of , and when submerged. Cruising range was at on the surface and at submerged. Constructional diving depth was .
The U-boats were armed with four torpedo tubes, two fitted in the bow and two in the stern, and carried six torpedoes. The boats' complement was 4 officers and 24 enlisted men.
Type U 5 U-boats were the first U-boats to be equipped with a radiotelegraphy station. This station had a range of between U-boats and double that distance towards shore stations. Two aerial masts were installed on the deck, which could be lowered from inside the boat. A crude underwater telegraph consisting of a bell with a clapper activated by compressed air, was also introduced with the Type U 5s, but this system was not deemed satisfactory.
All four boats of the class were built at Germaniawerft in Kiel starting in 1908. They were commissioned between July 1910 and June 1911.