merchant marine vs seafaring

merchant marine

noun
  • Synonym of merchant navy. The fleet considered as an entire combined force. 

  • A ship dedicated to commercial, rather than military, purposes. 

seafaring

noun
  • The work, or calling of a sailor. 

  • The act, process, or practice of travelling the seas 

adj
  • Living one's life at sea. 

  • Fit to travel on the sea; seagoing. 

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