The displacement dialog is used to specify the range of displacements to be used for the KN, Limiting KG and Floodable Length calculations.

The VCG may also be specified, in this case it is measured from the vertical zero datum.

For KN analysis, the VCG will only have an effect if the analysis is free-to-trim. It will be used to determine the LCG if an initial trim value is specified. It will also be used to improve the accuracy of the KN results.

For Floodable Length calculations, which are always calculated free-to-trim, the VCG will be used to calculate the LCG if an initial trim value is specified. Also, because the analysis is very sensitive to trim, the VCG is needed to provide an accurate balance of the trimming moment. (As the trim angle increases the longitudinal movement of the centre of gravity due to its vertical position becomes more important.)

In the case of the Limiting KG analysis, the actual VCG is used and the VCG input field will state “not applicable”.