The coordinate system used by Seakeeper is the same as for Maxsurf. The coordinate system has the origin at the user defined zero point.

Seakeeper User Coordinate System and view Windows are the same as for Maxsurf

When calculating motions at remote locations, the vessel is assumed to rotate about the centre of gravity. Hence the distance of the remote location from the centre of gravity is of interest. Seakeeper calculates this distance internally and all positions are measured in the coordinate system described above.

A vessel has six degrees of freedom, three linear and three angular. These are: surge, sway, heave (linear motions in x, y, z axes respectively) and roll, pitch, yaw (angular motions about the x, y, z axes respectively). For convenience, the degrees of freedom are often given the subscripts 1 to 6; thus heave motion would have a subscript 3 and pitch 5.

Wave direction is measured relative to the vessel track and is given the symbol m. Thus following waves are at m = 0°; starboard beam seas are 90°; head seas 180° and port beam seas 270°.