Maxsurf’s Upright hydrostatic calculations use trapezium integration method on a given number of transverse sections up to the Datum Waterline. The number of sections depends on the precision setting from the Surfaces menu. Medium precision uses 50 sections and highest precision uses 200 sections. Skin thickness is not included in upright hydrostatic calculations. (Use Hydromax for this).

The sections used for calculations are displayed in the view windows while the Calculate Hydrostatics dialog is displayed.

 View a video that shows you how to carry out Upright Hydrostatic calculations, view the Curve of Areas and calculate different Surface Areas.
[Web | Disk]

Ø  Open the MyFirstDesign_TrimmingComplete.msd design that created earlier.

In Profile view you should see something like the image below (Trimming off, Surfaces Locked, Buttocks hidden):

Ø  Check the Frame of Reference:

In the Frame of Reference of this design the Fwd Perpendicular is not set correctly.
Click “Set to DWL” to fix.

Ø  Go Data | Calculate Hydrostatics

The following dialog should appear:

Ø  Click in the Top left corner of the results dialog to select all cells

Ø  Press Ctrl + Shft + C

Ø  Start MS Excel and Paste the results into a worksheet

Let’s now compare these results with when we switch trimming on.

Ø  Set Display | Trimming | Trim Invisible

Zero point locked at Aft Extremity

Ø  Check the Frame of Reference again

Ø  Adjust the Fwd and Aft Perpendicular and Set to DWL.

Notice that the zero point is locked at the Aft Extremity of when this model was first created. It is now time to adjust the zero point to the Aft Perpendicular.

Ø  Set the zero point to the Aft Perpendicular

Ø  Data | Calculate Hydrostatics

Ø  Copy and paste the results into Excel worksheet next to your previous results.

With trimming on the displacement is less than when calculating with trimming off.

After calculating the Hydrostatics, you can also display the Curve of Areas graph:

Ø  Window | Curve of Areas

The vertical line may be moved with the mouse to read off the sectional area at any longitudinal position. By doing this for a number of different drafts a set of Bonjean curve data may be collated. The curve of areas uses 25 sections along the length of the hull by default. You can change this number from the Edit | Preferences menu.

Continue with the section on Calculate Areas.