The three vertical parameters,
· vertical center of gravity, ZG: vertical position where the distributed mass of the vessel is centered
· draft: vertical distance between keel and water line
· deck plane height: vertical distance between keel and deck plane
follows a vertical sign convention where positive values means upwards from the keel level of the vessel, see Figure 1.3.
While the draft plays a crucial role in the computation of the frequency response data of the floating vessel, the deck plane height does not play any role: The deck plane height only determines the displayed deck plane contour on the graphical plots of the vessel (red contour), and is only included as a tool allowing inspection of the planar (XY) extent of the vessel at a particular height above the keel, see Figure 1.6.
Figure 1.3 Vertical sign convention
