cast anchor vs drop anchor

cast anchor

verb
  • To drop anchor or otherwise moor a ship. 

  • To take up a position. 

drop anchor

verb
  • To release the anchor of a ship or boat, allowing it to fall to the bed of a body of water and thereby securing the vessel in place. 

  • To defecate. 

How often have the words cast anchor and drop anchor occurred in a corpus of books? (source: Google Ngram Viewer )