\Wa"ter line`\
1. (Shipbuilding) Any one of certain lines of a vessel,
   model, or plan, parallel with the surface of the water at
   various heights from the keel.
Note: In a half-breadth plan, the water lines are outward
      curves showing the horizontal form of the ship at their
      several heights; in a sheer plan, they are projected as
      straight horizontal lines.
2. (Naut.) Any one of several lines marked upon the outside
   of a vessel, corresponding with the surface of the water
   when she is afloat on an even keel. The lowest line
   indicates the vessel's proper submergence when not loaded,
   and is called the {light water line}; the highest, called
   the {load water line}, indicates her proper submergence
   when loaded.
{Water-line model} (Shipbuilding), a model of a vessel formed
   of boards which are shaped according to the water lines as
   shown in the plans and laid upon each other to form a
   solid model.