grappling hook vs setting pole

grappling hook

noun
  • A type of hook attached to a line and designed to be thrown at a target (e.g. rigging of an enemy ship) for the purpose of catching hold of it. 

setting pole

noun
  • A pole, often iron-pointed, used for pushing boats along in shallow water. 

How often have the words grappling hook and setting pole occurred in a corpus of books? (source: Google Ngram Viewer )