duckboard vs gangboard

duckboard

noun
  • Wooden, low walkway or short part of a path with one or more planks, logs, or boards laid after each other lengthwise, often two planks wide; also called bog board, bog bridge, or puncheon. 

  • One of a long series of boards laid from side to side as a path across wet or muddy ground; normally used in plural. 

  • A panel of wooden slats typically lain on a concrete floor in a workshop. Compliance of slats arranged in two crossed layers reduces fatigue for a person operating a machine tool or working at a bench. 

gangboard

noun
  • A board or plank used as a temporary footbridge between a ship and a dockside or any gap such as scaffolding. 

  • The boards ending the hammock-nettings at either side of the entrance from the accommodation-ladder to the deck. 

  • A board or plank placed within or without the bulwarks of a vessel's waist for lookouts to walk or stand on. 

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