I'd thought to build a straight up shanty boat 16' X 8' but in view of cruising grounds on the lower Columbia, Puget Sound, etc. I opted for a more seaworthy hull design which trades off with interior room and headroom.
Still, I've manage 5' headroom, 16" high seating, two 7' bunks, a small galley, head facilities, ground tackle/mooring tackle locker, and room for my roll up Zodiac dinghy.
The interior accommodations would have been larger if my instructions to the hull builder had been followed but I make do now with what I have to work with. On the other hand, the too deep a sweep of the sheer will make it easier for me to board from the docks thereby making lemonade'ish outta lemon sheerline. But that's another story.
Given my druthers as a budding geezer, I'd prefer living on the water any day..or night.
16' X 8'.