Axis Systems

All curves are internally defined with respect to a right or left handed Cartesian axis system with its origin on the centerline at the intersection of the baseline (Z=0) with the After Perpendicular (AP). The axis system is orientated such that the X-axis is along the longitudinal axis and positive towards the bow. The Y-axis is athwartships and the Z-axis is positive upwards. For working purposes the user can define an axis system with the origin at either the After Perpendicular (AP), the Forward Perpendicular (FP), Midships (MID); or a longitudinal X position, as defined by the user. The X axis can be either positive towards the bow or positive towards the stern. All conversion between the internal axis system and the users working axis system, is handled by the system.

The axis system is in general designed so that the vessel is all in the positive quadrant, that means, no part of the vessel is below the baseline. However, if required, the vessel may descend below the baseline if an alternative baseline is adopted. It remains with the user to select the position of the baseline as required.