An item referred to the The Shipbuilder which reported that the German submarine U-21 during the trials a speed of 21 miles achieved. With the dimensions of 65 x 6 metres consisted the armament of 3 torpedo tubes and 2 quick firing guns.(1)
1. Laid down at the Kaiserliche Werft Danzig, Germany in 1910, launched on 8 February 1912, commissioned on 22 October 1913, between 21 September 1915-1 October 1916 serving in the Austro-Hungarian navy as the SM U-36 and accidentally sunk on 22 February 1919. Armed with 4 torpedo tubes and 1-8,8cm gun (in 1916 a second one added) and her speed was 15,4 (surfaced)-9,5 (submerged) knots.