A method for calculating a tension (T) in a towed antenna. The method includes towing the antenna in water, wherein the antenna includes plural particle motion sensors distributed along the antenna; measuring with the plural particle motion sensors vibrations that propagate along the antenna; calculating a value of a phase velocity (vp) of the vibrations that propagate along the antenna based on (1) an offset between two particle motion sensors and (2) a time delay of the vibrations that propagate from one of the two particle motion sensors to another one of the two particle motion sensors; selecting a relation that links the phase velocity (vp) to the tension (T); and using the value of the phase velocity and the relation to determine the tension (T) at various locations of the plural particle motion sensors along the antenna.