The area or imaginary surface defined by or within any described lines. In ship-building, the Plan of Elevation, commonly called the SHEER DRAUGHT, is a side-plan of the ship, defined by a surface limited by the head afore, by the stern abaft, the keel below, and the upper side of the vessel above. The Horizontal Plan, commonly called the HALF BREADTH PLAN, comprehends all the lines describing the greatest breadth and length of the ship at different heights or sections. This is named half-breadth plan, because both sides of the ship being exactly alike, only one-half is represented. To the foregoing must be added, the Plan of Projection, commonly called the BODY PLAN, which exhibits the outline of the principal timbers, and the greatest heights and breadths of the same.