Captain vs boater

Captain

noun
  • The title for someone who holds the captain job on a ship or other vessel. 

  • An army officer title in most countries 

boater

noun
  • Someone who travels by boat. 

  • One who works on a boat, especially as captain. 

  • A straw hat, very stiff, with a flat brim and crown. 

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