breakwater vs roadstead

breakwater

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

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

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

roadstead

noun
  • A partly sheltered anchorage; a stretch of water near the shore where vessels may ride at anchor, but with less protection than a harbour. 

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