Posted by Robert Hill on June 15, 2007 at 17:57:42 from 195.92.168.164 user eclrh.
The Guardian (known as the Manchester Guardian in the days when AR wrote for it) has a weekly column called Notes and Queries, to which readers write in with questions and other readers write in with answers. (The name and concept are stolen from a scholarly magazine published by OUP.)
This Tuesday one of the questions was why a submarine is called a boat and not a ship. Four people wrote in with somewhat different answers. Although the column has its own website (see link below), this particular set of question and answers seems not to be on it, and being lazier than Ed I don't intend to type them in full, but will summarise.
One person (appropriately named Dr Chandler!) said a ship has to have three masts, and 'in the great days of sail a ship was just one of the varieties of vessels that had a particular number of masts and sail arrangement.'
Another writer said a ship is a vessel that can sustain its passengers and crew at sea for seven days without resupply. Anything that can't is a boat. Submarines were not big enough to meet this definition until the end of WWI and so were originally classed as a sub-group of torpedo boats. If subs are still c\lled boats it is a hangover from then.
A third person says something roughly similar to the second. 'You can put a boat on a ship but not a ship on a boat.' First and second world war subs were not truly subs because they travelled on the surface between engagements. Only in the nuclear era did true submarines arise.
The fourth person says: One rows a boat. Every other type of vessel has a specific name, of which there are very many (he lists several, such as coracle, barque, brig, ship etc). A submarine is a submarine, not a boat.