Abstract: A capstan is provided for being secured to a sailing craft in order to tension a line attached to a sail. The capstan includes a fixed base housing a shaft and a gearbox, a barrel around which the line can be wound, the barrel being mounted such that it is capable of rotating in just one direction around the base and connected to the shaft via the gearbox. The rotation of the shaft is accompanied by rotating of the barrel about the base. The capstan includes elements for assessing the tension in the line and for selecting at least one speed when the tension exceeds a predetermined threshold. The gearbox includes an interior annulus, the annulus being mounted such that it can rotate inside the barrel against the effect of elements that apply a friction and/or elastic return force to the annulus so that it can turn in relation to the barrel when the tension is above the threshold.