Ship
Any large floating vessel capable of crossing open waters, as opposed to a boat, which is generally a smaller craft. In earlier times sailing vessels having three or more masts were considered to be ships; in modern times it usually refers to a vessel of more than 500 tons of displacement. Submersible ships are usually referred to as boats no matter their size.

The measurements of ships are given in terms of length, breadth, and depth. The length between perpendiculars is the distance on the summer (maximum) load waterline, from the forward side of the stem at the extreme forward part of the vessel to the after side of the rudderpost at the extreme rear, or to the centre of the rudderstock, if there is no rudderpost. The beam is measured at the widest point from side to side of the ship. The depth is measured at the middle of the length, from the top of the keel to the top of the deck beam at the side of the bulkhead deck. Draft is measured from the keel to the waterline, while freeboard is measured from the waterline to the deck edge.