Wrangel and Wachmeister reserve a sixth torpedo for the turn away

Wrangel and Wachmeister were the only two ships built from a planned class of four, entering service in 1917. Wrangel later served as a target ship before sinking in 1960, while Wachmeister was not broken up until 1951. Two centreline twin launchers and one single tube on each broadside allowed an initial five-torpedo salvo. During the turn away, the remaining offside tube could launch a sixth torpedo behind the first spread, intended to catch a target that had steered between its tracks. The name "spiking the cone" and the account of this tactic depend on one book and an uncertain translation. The tactic suited solo patrols, coastal pairs, convoy protection, and defence of access routes. Conversion to fuel oil in 1927 and the addition of 25 mm Bofors guns and 8 mm machine guns in 1940 kept the ships useful. The single torpedo tubes were removed during rearmament to control weight and displacement.