I"m talking about a program like Professional Home Design.. but for boats... where yes designing the structure is part of it but the biggest part is just doing the interior decorating... so that you can play with different colors and spaces and walk through it in first person 3d to see how the space feels...
more of a boat decorating software than a design software... to tell if there's room for a wrap around sitting area or a reorganized kitchen... the "girly" (no offense ladies) stuff not the hull design...
For us, nothing beats the tactile. After gutting our first sloop including all bulkheads, we spent a month fitting her out with cardboard cabinetry. From fridges, bulkhead, bunks, stove, sink, shower, heads and engine compartment we built it all in cardboard. Having a full size mockup we could walk around our little yacht and get an exact sense of how we could maximise available space and what worked and what didn't. Sure it was initially time consuming but we were then able to use the cardboard as templates for the actual build. Everything went together perfectly.
As far as decor, we take wide angle internal pics and run them through photoshop where with a few simple layer masks you can view every colour and finish under the sun before you so much as open a paint tin.