Grain cargo is neither perfectly solid nor liquid. If a hold is not completely full, the surface of the grain can shift and remain inclined toward one side in response to the rolling of the ship, resulting is a somewhat permanent transverse and vertical shift of the center of gravity.
GS is especially equipped to account for the various structural complexities sometimes found in grain holds which obstruct the surface of the grain. Void pockets are modeled as components of the hold. As the cargo shifts within a pocket some of its void may escape to another pocket.
GS calculates volume, volumetric heeling moment, and vertical center of gravity as a function of ullage. It works well for any tank, but is especially applicable to grain holds.
Grain Shift produces screen and printer plots of volume, volumetric heeling
moment, and VCG as a function of ullage.