life raft vs rowboat

life raft

noun
  • A usually inflatable raft carried aboard a ship or airplane, used to save lives in case the vessel has to be abandoned in an emergency on the sea. 

rowboat

noun
  • A small open boat propelled by oars (by rowing). 

verb
  • To row a boat of this kind. 

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