While preparing the design of the Saukko, the Germans also prepared a design for a seagoing submarine for the Finnish Navy. Three submarines were built to this design, and like the Saukko, they were fitted for mine-laying, the mines being supplied by the Germans. Being designed for use against Russian bases (never very far from the Finnish bases), radius of action was not of prime importance to this design, and only 20 tons of fuel oil were carried (as opposed to the 67 tons carried by the German Type VIIa based on this design.