life raft vs pinnace

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. 

pinnace

noun
  • A light boat, traditionally propelled by sails, but sometimes a rowboat. Pinnaces are usually messenger boats, carrying messages among the larger ships of a fleet. 

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