Q: Can I use a hull model composed of various PGEN definitions that share surfaces for hydrodynamics?
REV 5.10

A: Absolutely not! You must have a single enclosed surface for hydrodynamics computations. You should use COMPART_SUM panels to make sure your panel areas sum to zero. If you have appendages such as skegs to include for hydrostatics, use "PGEN -DIFTYPE none" to exclude these for hydrodynamics. If you want to include the effects of a moonpool on the motions, you really should use the &SURFACE menu to create a proper 3D Diffraction mesh.