In July 1944, ships of the Baltic Fleet sank the German medium submarine VIIC series "U 250" in the northeastern part of the Gulf of Finland. In this regard, the People's Commissar of the Navy, Admiral of the Fleet N.G. Kuznetsov decided: "According to the type of the German submarine "U 250" in 1945, design a medium-displacement submarine and submit it to me for consideration. Henceforth, until the development of the specified project, the work in the TsKB-18 NKSP on project 608 should be stopped." After familiarizing himself with materials on captured submarines (VIIC, XXI, XXIII series, etc.) in early January 1946, the Commander-in-Chief of the Navy, on the proposal of the Main Directorate of Shipbuilding of the Navy, approved the TTZ for the medium submarine of project 613.