that the submarines must be transportable by rail, which imposed a maximum diameter of . The rushed planning effort—which had been assigned the name "Project 34"—resulted in the Type UB I design, created specifically for operation from Flanders. The boats were to be about long and to displace about with two bow torpedo tubes. Boats of the Type UB I design were built by two manufacturers, Germaniawerft of Kiel and AG Weser of Bremen, which led to some variations in boats from the two shipyards. The eight Germaniawerft-built boats were slightly longer at length overall, while the twelve Weser-built boats came in shorter than their counterparts. All were abeam and had a draft of . The boats all displaced while surfaced, but differed slightly in displacement submerged. The slightly longer Germaniawerft boats displaced while submerged, as they weighed more than the Weser boats. The drivetrain of the boats consisted of a single propeller shaft driven by a Daimler (Germaniawerft) or Körting (Weser) diesel engine on the surface, or a Siemens-Schuckert electric motor for underwater travel. The Weser boats were capable of nearly on the surface and a little more than submerged. The Germaniawerft boats were about slower than their Bremen-made counterparts. The boats were equipped with two bow torpedo tubes and carried two torpedoes. They were also armed with a single machine gun affixed to the deck. None of the Type UB I boats had a deck gun. Construction The German Imperial Navy ordered its first fifteen Type UB I boats on 15 October 1914. Eight boats—numbered UB-1 to UB-8—were ordered from Germaniawerft of Kiel, and seven boats—numbered UB-9 to U-15—from AG Weser of Bremen. After two of the class, UB-1 and UB-15, were sold in February 1915 to ally Austria-Hungary (becoming U-10 and U-11 in the Austro-Hungarian Navy), the German Imperial Navy ordered UB-16 and UB-17 from Weser. A further three for Austria-Hungary —U-15, U-16, and U-17—had been ordered from Weser by April, bringing the total number constructed to 20. UB-1 and UB-2 were laid down on 1 November 1914 at the Germaniawerft yard at Kiel. UB-1 was launched on 22 January 1915, just 75 working days later. UB-2s launch followed on 13 February. Among the Weser boats, UB-9 was laid down first, on 6 November 1914, and launched on 6 February 1915, a week ahead of UB-2. These first three boats launched underwent trials in home waters, but