water line

• water-line
• waterline

water line (plural water lines)

1. (shipbuilding) the outline of a horizontal section of a vessel, as when floating in the water.^[1]
2. (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. 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.
3. (nautical) 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.
   • 1627, John Smith, chapter 9, in A Sea Grammar‎, London: John Haviland, page 45:

     The water line is to that Bend or place she should swim in when she is loaded.

   • 1851 November 14, Herman Melville, “Chapter 9”, in Moby-Dick; or, The Whale, 1st American edition, New York, N.Y.: Harper & Brothers; London: Richard Bentley, →OCLC:

     […] Jonah throws himself into his berth, and finds the little state-room ceiling almost resting on his forehead. The air is close, and Jonah gasps. Then, in that contracted hole, sunk, too, beneath the ship’s water-line, Jonah feels the heralding presentiment of that stifling hour, when the whale shall hold him in the smallest of his bowels’ wards.

   • 1932, Neville Shute, chapter 15, in Lonely Road‎, London: Heinemann:

     None of us were more than shaken by the blast; we pulled ourselves together, and I laid and fired again. And that went better, for I holed her on the water line and that shell burst inside.

4. The line corresponding to the surface of the water touching any submerged object or body.
   • 1897, Frank R. Stockton, “The Widow’s Cruise”, in A Story-teller’s Pack‎, New York: Scribner, pages 94–95:

     Not far away, off our weather bow, there was a little iceberg which had such a queerness about it that the captain and three men went in a boat to look at it. The ice was mighty clear ice, and you could see almost through it, and right inside of it, not more than three feet above the water-line, and about two feet, or maybe twenty inches, inside the ice, was a whopping big shark, about fourteen feet long,—a regular man-eater,—frozen in there hard and fast.

   • 1913, Enos A. Mills, “The Primitive House”, in In Beaver World‎, Boston: Houghton Mifflin:

     The Lily Lake beaver house, in which the old beaver spent the drouthy winter, was a large roughly rounded affair that measured twenty-two feet in diameter. It rose only four feet above the normal water-line.

5. The level at which water meets land along the shore of a body of water.
   • 1895, Rudyard Kipling, “The Undertakers”, in The Second Jungle Book‎, London: Macmillan, page 87:

     Little creeks ran into [the river] in the wet season, but now their dry mouths hung clear above water-line.

   • 1932, E. C. Brill, chapter 4, in The Secret Cache‎, New York: Cupples & Leon, page 30:

     The shore along which they rowed was, at first, wooded to the water line.

   • 1960, Andre Norton, chapter 10, in Storm over Warlock‎, New York: Ace Books, page 106:

     […] both animals remained upslope, showing no inclination to descend to the water line.