ON THE SEMI-COUPLED NATURE OF THE ROLLING MOTION OF A SHIP.

On the basis of an order of magnitude analysis and numerical calculations it is shown that: The influence of roll on the equations of motion of sway and yaw is small and can be neglected for all practical purposes. The rolling motion can be treated separately as a one degree of freedom with the inclusion of the ″linear″ influence of sway and yaw. This development permits the easier treatment of the troublesome roll motion problem as a non-linear system both in regular waves and for non-linear statistics in a random seaway, with or without an anti-rolling device.