A '''Plimsoll marl''' is a series of horizontal lines, corresponding to the seasons of the year and fresh or saltwater, painted on the outside of a ship marking the level which must remain above the surface of the water for the vessel’s stability.<ref>[http://www.marad.dot.gov/publications/glossary/glossary.html U.S. Department of Transportation Maritime Administration]</ref>
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A '''Plimsoll mark''' is a series of horizontal lines, corresponding to the seasons of the year and fresh or saltwater, painted on the outside of a ship marking the level which must remain above the surface of the water for the vessel’s stability.<ref>[http://www.marad.dot.gov/publications/glossary/glossary.html U.S. Department of Transportation Maritime Administration]</ref>