Abstract: A stem duct of a ship used to achieve the reduction of the ship's propulsion wave height and the improvement in the laminarity of the flow around the ship's bow, so that the ship is able to move with an increased speed and/or with reduced fuel consumption. The duct is mounted on each side of the bow frontal surface and has an airfoil section fitted, arranged in the direction of the flow, with its leading edge at the duct inlet and its trailing edge at the duct outlet. Following mounting of the duct, a passage is created for the flow, between the duct's interior surface, consisting of the convex airfoil surface, and the ship's bow surface. The flow passing through the passage acquires an increased speed and a reduced pressure, thereby leading to an improved slip of the ship.