Hydrostatics for Jackups - Legwells not considered


Hi have a hull model of a Jackup vessel, and I would like to include the legwell areas in the hydrostatics, but it looks like rhino only considers the shape without them.
Anyone know a solution for this? Or is this a limitation in the hydrostatics tool in Rhino…


Hyrostatics command only works with a single surface or polysurface. The surface/polysurface cannot have any submerged naked edges. Internal volumes are not considered.

Example surface attached.Hydro1.3dm (220.8 KB)

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Thanks for the answer.

So do you mean that that big rectangular hole just in the middle is ignored?

Grasshopper would be a good solution to your problems. You can then reference all the geometry to be included in your calculations and then display the answers or export them to Excel.

You could produce a table of all the required drafts and get the displacements LCB,TCB, VCB, moments etc etc

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No, the big rectangular well in the middle is included.

Attached is a file with two versions of the example; with and without the center well. Run Hydrostatics on each and the results will be different.
Hydro2.3dm (352.3 KB)

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Hi David,

Just tested the models you’ve send me, and if you do the same, you can see that the Water plane area is the same in both models, and it shouldn’t be, as in the second one, the hole area should be subtracted.

Best regards,

The Water Plane Area and Center of Floatation do no take into account the well. Good catch! It looks like they are based on the outside waterline. The other calculated quantities do take the well into account.

I modified the model by moving the well off center to check that the center of buoyancy changes.