jetty vs roadstead

jetty

noun
  • A wharf or dock extending from the shore. 

  • A part of a building that jets or projects beyond the rest, and overhangs the wall below. 

  • A structure of wood or stone extended into the sea to influence the current or tide, or to protect a harbor or beach. 

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 jetty and roadstead occurred in a corpus of books? (source: Google Ngram Viewer )