gangboard vs trestle

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. 

trestle

noun
  • A trestle bridge. 

  • A folding or fixed set of legs used to support a tabletop or planks. 

  • A framework, using spreading, divergent pairs of legs used to support a bridge. 

  • A horizontal member supported near each end by a pair of divergent legs, such as sawhorses. 

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