Ah right, I wouldn't argue with any of that, but I would reckon that an 8 foot dinghy is about the minimum for an adult to sail comfortably, still I suppose it depends on the size of the adult?
If you aren't a big lumbering oaf like me, you might get away with a 7' pram? I think there is a kit for a 7 foot ply clinker stem dinghy, but it's a bit wee!