Based on an original so-called block sketch dated May 1917 handed over by the commissary of police at Vlissingen to the Dutch naval staff
Submarines of this type served in the German (UB-1 class), Austro-Hungarian (U-10 class) and Bulgarian navies. Preceded by the UA and succeeded by the UB II class (SM UB-18-47). Building ordered on 15 October 1914, laid down by Germaniawerft, Kiel, Germany with yard number 246 on 4 December 1914, disassembled sent and send by rail to Pola [nowadays Pula, Croatia] for delivery to the Austro-Hungarian navy, however refused, reassembled and launched in April 1915, commissioned in the German navy on 23 April 1915, sold to Bulgaria on 25 May 1915, renamed Podvodnik No. 18, involved in actions against the Russian armed forces, handed over to France on 23 February 1919 and broken up at Bizerte, Tunisia in August 1921.
General technical class characteristics. Displacement 127 (surfaced)-142 (submerged) tons and as dimensions 23,62 (pressure hull)-27,88/28,10 (over all) x 3,15 x 7,30 (depth) x 3,03 (draught) metres or 77.6-91.6/92.2 x 10.4 x 23.11 x 9.11 feet.. The machinery consisted of 1 diesel engine and 1 electric motor driving one screw allowing a speed of 6,47 (surfaced)-5.5 (submerged) knots and a surfaced range of 1.860 nautical miles with a speed of 5 knots and submerged 45 nautical miles with 4,5 knots. Test depth 50 metres/160 feet and able to dive within 33 seconds. Their crew numbered 14 men. The armament consisted of 2-45cm/17.7” torpedo tubes in the bow for which 2 torpedoes were carried and 1-0,8cm/0.31” machinegun.