grapnel vs grappling iron

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. 

grappling iron

noun
  • A metal hook, attached to the end of a line, used to hold two ships together. 

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