nrg710,
you can draw your desing in Rhinoceros, you must save your desing in *.igs extension (Rhino has the possibility of save your work in many types of extension, is very usefull and esay to mane) . Then, import the file into Hydromax, and open it, review corners, surfaces and touch parts of surfaces. When all is ok, save it in *.msh extension ( hydromax extension is equal to Maxsurf extension).
You can work with the file , modelled easily in rhino, in maxsurf and similar software ( hydromax, hullspeed....).
Now I used this program to modelling and studing diferents hull shape, and efficiency, working with diferent methods to calculate wave resistance and others.