German submarine fleet consisted of several types according to the Dutch magazine Marineblad dated 1937 no. 2

An item referred to the magazine Le Yacht dated 23 January 1937 reported that the German submarine fleet consisted of several types. The U 1 -24 were 250 ton submarines with an armament of 3 torpedo tubes and 1 machinegun and a crew numbering 25 men. The U 25-26 were 712 ton submarines with 6 torpedo tubes and 1-10,5cm gun and a crew numbering 40 men. The U27-36 were 500 ton submarines with an armament of 5 torpedo tubes and 1-8,5cm gun and a crew numbering 35 men.