As a step towards improved prediction and reduction of the magnetic signature from ships, this report studies roll-induced eddy currents. A simple model is developed, in which the current density is proportional to frequency, conductivity and object size (viewed perpendicularly from the magnetic field), but saturates when the object size reaches the skin depth, which is the characteristic current density decay length. The model is successfully used to estimate magnetic fields from different objects. The report also studies ferromagnetic effects on the roll-induced currents. A condition is derived for when a source model needs to account for the ferromagnetic signature. Furthermore, the report presents an expression which approximates the ratio between the roll-induced magnetic signature and the induced ferromagnetic signature for a given object. In order to measure and construct a source model of the roll-induced signature from an object as a function of roll frequency, course and magnetic inclination, measurements with a vertical and port-starboard oscillating magnetic field are sufficient. Measurements in the stern-bow direction are needed to account for the effect of pitch and yaw as well. If the movement has several frequency components, these will couple, implying that the total signature cannot be determined by superposition of single frequency models.