Permissible Grain Moments Dialog

In previous versions of Calc, Permissible Grain calculations were part of the Deterministic Stability module. These have now been separated out into a dedicated calculation module, Permissible Grain Moments, which is included by default in the Grain Calibrations folder.The moments can be calculated and plotted using displacement as the independent variable, as an alternative to draft.

Permissible Grain Moments dialog

The independent variable for the tables and graphs (X-value) can be either Draft or Displacement. This is selected using the Appropriate Radio button. The values in the Associated dialog box will change to suit.

Selecting the Add button will bring up a dialog box for adding a range of drafts or displacement. Clicking the Delete button will remove the highlighted drafts or displacements.

The range of VCG’s (vertical centres of gravity) can be edited in a similar way using the associated Add and Delete buttons.

The Assumed VCGf (fluid centre of gravity) is used for calculating the stability righting lever curves and hence the critical KG for grain. The value of this is not normally critical, but should be close to the working VCG of the vessel for accurate results.

Normally, the Trim and Heel angle are set to zero for permissible grain moment calculations.