a method for determining the motion of a target in underwater acoustics by means of an antenna with misaligned sensors provided with a central sensor c 2 p . it consists in estimating the characteristics of velocity and position of the target x , y relatively to the antenna by means of a likelihood maximum estimator taking account of the differences in propagation times measured between the wave fronts transmitted by the target and reaching the sensors . the motion estimator is initialized by means of an initial state vector x determined on the basis of the values of the azimuths of the target perceived from the mid - points of each pair of sensors , during a determined number of measurements staggered in time . the action of the state vector x takes place in taking account of the value of the elevation of the target with respect to the antenna .