paddle wheel vs skeg

paddle wheel

noun
  • A large wheel, fitted with paddles, used to propel a vessel (especially a paddle steamer) 

skeg

noun
  • A fin-like structure to the rear of the keel of a vessel that supports the rudder and protects a propeller. 

  • A surfer; a person who leads a surfing lifestyle. 

  • A look or glance. 

  • A similar construction on a boat that acts as a keel. 

  • A fin that serves to stabilize a surfboard. 

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