grapnel vs hook and eye

grapnel

noun
  • 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. 

  • A grappling iron. 

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

verb
  • To connect (ships) with a grapnel. 

hook and eye

noun
  • A matched hook and an eye (loop into which the hook can fit), used for fastening. 

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