breakwater vs freeboard

breakwater

noun
  • A low bulkhead across the forecastle deck of a ship which diverts water breaking over the bows into the scuppers. 

  • A wooden or concrete barrier, usually perpendicular to the shore, intended to prevent the movement of sand along a coast. 

  • A construction in or around a harbour designed to break the force of the sea and to provide shelter for vessels lying inside. 

freeboard

noun
  • The vertical distance between the waterline and the uppermost watertight deck of a vessel. 

  • The distance between a water level and the top of something that contains or restrains it (such as a dam). 

  • The distance between the top of sea ice and the water level. 

  • A type of skateboard which simulates the movement of a snowboard when used on a downhill coarse, allowing snowboarding techniques, which has an addition of two centerline casters that extend below the traditional skateboard wheels and bogies. 

How often have the words breakwater and freeboard occurred in a corpus of books? (source: Google Ngram Viewer )