lifeboat vs wherry

lifeboat

noun
  • A boat especially designed for saving the lives of shipwrecked people or people in distress at sea (either launched from the shore with a crew, or else carried on board a larger ship). 

  • An emergency vehicle carried aboard a spaceship. 

verb
  • To rescue; to carry to safety 

wherry

noun
  • A light ship used to navigate inland waterways. 

  • A flat-bottomed vessel once employed by British merchants, notably in East Anglia, sometimes converted into pleasure boats. 

  • A liquor made from the pulp of crab apples after the verjuice is extracted. 

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