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The following manual provides Orca3D hydrostatic and stability results for several primitive shapes with varying mesh densities and drafts.  The values are compared to known, analytic calculations to verify the accuracy of Orca3D’s calculations.  The shapes used are a cube, a sphere, a horizontally oriented cylinder, a cone, and a vertically orientated cylinder.

 

The cube’s simple shape and flat surfaces allows Orca3D to accurately calculate hydrostatic and stability properties at lower mesh densities

 

Hydrostatic and stability calculations using the sphere, vertical cylinder, cone, and horizontal cylinder are accurate within 1% error for mesh densities between 0.5 and 1.0.  There is a noticeable accuracy improvement for the sphere calculations between mesh densities of 0.6 and 0.7, whereas noticeable differences in accuracy for the vertical cylinder, cone, and horizontal cylinder occur between mesh densities of 0.7 and 0.8.  These accuracy differences are documented in the tables below and in graphical form in the mesh density accuracies section.

 

These same primitive shapes were also tested for free float conditions.  Each shape was given three input weights and the results were compared to analytic calculations.

 

Righting arm curves were verified for the sphere and the horizontal cylinder.  As expected, the righting arm remained zero when the VCG of each object was at its centroid and followed a sine curve when it was placed elsewhere.