A ship is a large, sea-going watercraft.

A ship usually has sufficient size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb saying (though it does not always apply) goes: “a boat can fit on a ship, but a ship can’t fit on a boat”. Consequently submarines are referred to as “boats”, because early submarines were small enough to be carried aboard a ship in transit to distant waters. Another type of large vessel which is traditionally called a boat is the Great Lakes freighter. Often local law and regulation will define the exact size (or the number of masts) which a boat requires to become a ship (cf. vessel).

During the age of sail, ship signified a ship-rigged vessel, that is, one with three or more masts, usually three, all square-rigged. Such a vessel would normally have one fore and aft sail on her aftermost mast which was usually the mizzen. Almost invariably she would also have a bowsprit but this was not part of the definition.

Nautical means related to sailors, particularly customs and practices at sea. Naval is the adjective pertaining to ships, though in common usage it has come to be more particularly associated with the noun ‘navy‘.