grapnel vs setting pole

grapnel

noun
  • A small anchor, having more than two flukes, used for anchoring a small vessel. 

  • A grappling iron. 

  • A device with a multiple hook at one end and attached to a rope, which is thrown or hooked over a firm mooring to secure an object attached to the other end of the rope. 

verb
  • To connect (ships) with a grapnel. 

setting pole

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

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