The x-stern was first tried in practice in the early 1960s on the USS "Albacore", an experimental submarine of the US Navy. While the arrangement was found to be advantageous, it was nevertheless not used on the US production submarines that followed due to the fact that it requires the use of a computer to manipulate the control surfaces to the desired effect. Instead, the first to use an x-stern operatively was the Swedish Navy with its "Sjöormen" class, the lead submarine of which was launched already in 1967, before the "Albacore" had even finished her test runs. Since it turned out to work very well in practice, all subsequent classes of Swedish submarines ("Näcken", "Västergötland", "Gotland", and "Blekinge" class) have or will come with an x-rudder.