Hi insane. here are some answers i found for you. No size in meters etc as apparently that doesn't work for this.
A ship can carry a boat but a boat can't carry a ship. Another one is down to functionality. A boats functionality happens on deck but a ship inside it.
This I found as well.
- Among sailing vessels, the distinction between ships and boats is that a ship is a square-rigged craft with at least three masts, and a boat isn't. With regard to motorized craft, a ship is a large vessel intended for oceangoing or at least deep-water transport, and a boat is anything else.
Hope this helps.
Thanks for your answer!
But hypothetically speaking (or theoretically speaking, I'm not sure which one applies here better) if I could downsize a ship, a proper big ocean going ship, on which length would it stop being a ship and turn in to a boat? Like in the movie Downsizing. The downsized people were still people, even if they were very little people. And no, I haven't seen the movie. Just the trailer. Very intriguing.
If you make it small enough to fit onto another ship then yes it's a boat.