On 6 May 1920 asked the Chief of the Dutch Naval Staff at The Hague, Netherlands the liaison officers at London, England and Berlin, Germany to supply all available and/or necessary information dealing with minelayer-submarines. The reason for this request was a possible project for such submarines to be used in Dutch territorial waters or in the Dutch East Indies. In the Dutch naval shipbuilding program for 1925 was such a submarine for the Dutch East Indies planned. The Naval Law was however refused by the Parliament. The first minelayer-submarine in the Royal Netherlands Navy was the former German UC 8 of 1915. Interned during the First World War and later bought by the Dutch cabinet and taken into the service as Hr. Ms. M 1. Despite the intention was the first newly built minelayer submarine not earlier realized as in 1936. The O 19 (first to be named K XIX) was laid down on 15 June 1936. The Kon. Mij. De Schelde at Vlissingen, Netherlands designed in 1929-1934 a minelayer submarine but which was never built.
The Dutch liaison officer at Berlin supplied details about the German submarines adding some general information. He wrote that before the First World War Germany did not possessed any minelayer submarine. In the German navy was none place for such a submarine, only for submarines which could cooperate with the Hochseeflotte (the major surface warships). There were still no ideas in merchant trade war using mines in 1911. The mines were stored in six (later types seemed to have 5 according to the liaison officer) chutes and in fact always lying in the water. The disadvantage was that the mines on top sometimes stuck partly above the water out causing a possible corrosion of important components. To prevent this corrosion were the mines to be laid within 5-6 days after leaving the base. When the chutes were filled with the mines, were these to be tightened to prevent a gliding downwards. This sliding was a potential danger when transferring the mines while it was possible that a mine came below the submarine. As a result was already one submarine destroyed. It was also believed that C type submarines at sea also were destroyed by their own mines. Later were the boats fitted out with an additional safety to prevent damage by an own mine losing it anchor. The liaison officer remarked that the chute-system had the advantage of being very simple.
Displacement 168 (surfaced)-225 (submerged) tons. Speed 6,3 (surfaced)-5,6 (submerged) miles. Able to take 12 type UC120-150 mines with her. The armament consisted of 1 machinegun for which 1.600 cartridges were available. Fitted out with 1-90 hp diesel machinery for surface drive and 1-75 electric machinery for submerged drive. The crew numbered 1 officer and 13 petty officers and sailors.
Source
Archive Dutch Naval Staff 1886-1942 (National Archive, The Hague, Netherlands) inventory 132a.
Note
The magazine Schiffbau dated 23 April 1919 supplied for this type the following details. Displacement 168 (surfaced)-183 (submerged) tons, dimensions 34,0 (overall) x 3,13 (over thrushes)x 3,0 metres. Horsepower 1x90hp (surfaced)-1x175 hp (submerged). Maximum speed 6,2 (surfaced)-5,2 (submerged) knots. Oil bunker capacity maximum 3 ton. Range 800 nautical miles with a speed of 5 knots surfaced and submerged 50 nautical miles with a speed of 4 knots. The website https://en.wikipedia.org/wiki/German_Type_UC_I_submarine. Building at the shipyard of AG Weser, Bremen, Germany with yard number 225 ordered on 23 November 1914, laid down on 26 January 1915, launched on 11 April 1915, commissioned on 23 April 1915 and sunk on the North Sea after striking a mine on 26 June 1918.
