The Frame of Reference dialog is used to specify the positions of the key locations used in ship design. These positions are:
The DWL is used for all calculations in the Calculations window, calculation of the Sectional Area Curve in the Curve of Areas window and calculation of surface areas.
The Frame of Reference dialog has functions to automatically locate the Baseline at the lowest point of the hull (the Find Base button) and to set the Fore and Aft Perpendiculars to the extreme ends of the DWL (the Set to DWL button).
In all cases where the Forward or Aft Perpendicular is updated, the Amidships position is calculated to be at the midway position between the perpendiculars.
Note:
All values are entered relative to the Zero Point. However, it may be that the zero point is set to the position of one of the elements in the Frame of Reference. In this case, the Zero Point is not updated until you click OK in the Frame of Reference dialog. See Setting the Zero Point on page 16 for more information.
Watch a short video
that shows you how to setup the Frame of Reference and the Zero Point and
define the Grid.
To set the Frame of Reference
Ø Press the Find Base button in the bottom left
This will find the lowest point of your surface model.
Ø Enter the DWL height relative to the current zero point:
For example: when your baseline is at -0.85 m and your draft is 0.5 m then you should enter -0.35 m.
Ø Press the Set to DWL button to set the Fwd and Aft perpendiculars to the DWL.
You can then manually update the Aft perpendicular to eg the rudder stock location if needed.
Ø Click OK
Please note that your Frame of Reference position values are dependent on the location of the zero point and changes when Setting the Zero Point will affect the Frame of Reference.