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.

[1][Note 2] After these steps alleviated their most urgent needs,[2] the Austro-Hungarian Navy selected the German Type UB II design for its newest submarines in mid 1915.

[1] Although there is no specific notation of a range for the U-27 class, the German UB II boats, upon which the class was based, had a range of over 6,000 nautical miles at 5 knots (11,000 km at 9.3 km/h) surfaced, and 45 nautical miles (83 km) at 4 knots (7.4 km/h) submerged.

The UB II boats were shorter by about 3 feet (0.91 m) in length, but nearly identical in beam and draft.

[7] With the plans purchased, Austro-Hungarian Navy began the intricate political negotiations to assign the six boats—to be designated U-27 to U-32—between Austrian and Hungarian firms.

[4][Note 4] Of the initial order of six boats, two were allocated to the Austrian firm of Cantiere Navale Triestino (CNT) operating out of the Pola Navy Yard,[Note 5] and the balance to the Hungarian firm of Ganz Danubius in Fiume.

[4] Later in 1916, the seventh boat of the class, U-40, was laid down, after having been presented to the Navy as a gift by the Österreichischen Flottenverein, and an eighth, U-41,[4] as a replacement for U-6,[5] which had been lost in May.

[3] The seventh and eighth boats were constructed by CNT at the Pola Navy Yard.

[3] Shortages of labor and materials plagued subcontractors and, consequently, the delivery dates for the boats were not met.

[1] The U-27 class boats were the last domestically built submarines completed for the Austro-Hungarian Navy.

The boats were towed from Cattaro to Bizerta, but U-29 foundered en route; U-31, U-41, and the others were scrapped within twelve months of their arrival there.

[10] U-27, the lead boat of the class, was built by the Austrian firm of Cantiere Navale Triestino (CNT) at the Pola Navy Yard and launched on 19 October 1916.

[18] The boat, under the command of Linienschiffsleutnant Friedrich Fähndrich, sailed from Cattaro on 31 March 1917 and was never heard from again.

[21] In addition to damaging the British light cruiser Weymouth in October 1918, during the battle of Durazzo.

[10] U-40 was ordered after the funds to purchase the boat were presented by the Österreichischen Flottenverein as a gift to the Austro-Hungarian Navy.

[26] The Italian destroyer Ardea claimed to have sunk U-40 in a depth charge attack on 26 April 1918,[27] but the boat was surrendered to Italy at Venice in 1919 and broken up.

[5] U-41 sank a single French steamer of 4,604 GRT during her short wartime career,[29] and was at Cattaro at war's end.