cockboat vs sculler

cockboat

noun
  • A small rowing boat, especially one pulled behind a larger ship, or used to ferry goods between a ship and the shore. 

sculler

noun
  • A boat rowed by one person with two sculls, or short oars. 

  • One who sculls; an athlete who participates in sculling races. 

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