Don't try the trial version of Rhinoceros; it will hook you so hard that you won't feel bad about buying the full version.
Seriously, I don't know anything about Intellicad or some of the other choices that have been mentioned. But among the few CAD packages to which I have access, Rhino does curves and surfaces better than any other.
I deal with boatyards all over the world. Most of the ones that use CAD, use AutoCAD, in 2D. But a few of them use Rhinoceros, to model real boats in real
One other thing. I can't quite put my finger on why, but AutoCAD's display presentation is somehow easier to interact with than Rhino's at low resolutions, so once you buy Rhino, you'll be looking for a large, high resolution display, too.