life raft vs sloop

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. 

sloop

noun
  • A single-masted sailboat with only one headsail. 

  • A sailing warship, smaller than a frigate, with its guns all on one deck. 

  • A sloop-of-war, smaller than a frigate, larger than a corvette. 

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