The Collaborative International Dictionary of English v.0.48:

Ravehook \Rave"hook\ (r[=a]v"h[oo^]k), n. (Shipbuilding)
   A tool, hooked at the end, for enlarging or clearing seams
   for the reception of oakum.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ravehook
    n 1: a hooked hand tool used to prepare the seams of a boat for
         oakum