buoy up vs fortify

buoy up

verb
  • To uplift, hearten, inspire, or raise the spirits of. 

  • To keep afloat; to provide with buoyancy. 

fortify

verb
  • To impart strength or vigor to. 

  • To increase the nutritional value of food by adding ingredients. 

  • To increase the defenses of; to strengthen and secure by military works; to render defensible against an attack by hostile forces. 

  • To add spirits to wine to increase the alcohol content. 

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