What qualifies as a "boat" or an "automobile"?

Are all crafts that travel on water considered "boats," even barges, yachts, canoes, rafts, etc?

Are all motor vehicles considered "automobiles," even trucks, semis, and motorcycles?

Solution 1:

No in both cases. A "boat" is something small in size compared to a barge, ship, freighter and implies an appropriate form of propulsion. Certainly not steam, as with a large vessel, and probably not with a pole (or high hopes), as with a raft. Informally, I hear some people use boat to mean any sort of vessel. I usually wonder if the speaker doesn't know the difference or perhaps is making a small joke.

An automobile is personal, passenger-oriented transportation, also something small relative to other types. The term doesn't include busses, trucks, or motorized bicycles. "Vehicle" is the all-encompassing term.

Solution 2:

Depends who you are asking - to a sailor there are a huge range of distinctions, especially when it comes to sailing (wind powered).

In the navy everything is a ship except submarines which are boats.

Solution 3:

In general, a boat is defined as a vessel which can be carried by a ship - So boat covers everything from small dinghys through some yachts - but this can be quite subjective. An oil tanker could never be considered a boat and a dinghy could never be considered a ship - In between is a somewhat grey area.

There are also special considerations eg hovercraft - which use the same navigation lights as an aircraft and are neither ships nor boats.