aft vs lifeboat

aft

noun
  • The stern portion of a vessel. 

adv
  • At, near, or towards the stern of a vessel (with the frame of reference within the vessel). 

adj
  • located at the back of a boat, ship, or airplane 

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 

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