The invention relates to a sensor device for insertion and for measuring tension within a braided, plaited and/or laid line. The sensor device comprises an elongated sensor housing having an outer housing surface and an inner housing surface and at least one pressure sensor arranged inside the elongated sensor housing. The outer housing surface having a substantially elliptic or circular cross sectional area around the longitudinal axis of the sensor housing. Further, the at least one pressure sensor is configured to allow measurement, at least indirectly, of a pressure exerted on the outer housing surface. The invention also relates to a line sensor assembly for mooring of one or more structures, and a method of adjusting the tension in a line sensor assembly and the use of a line sensor assembly.