(historical) A hooked hand tool for widening the seams of a boat to receive oakum.
2012, J. E. Fender, The Lucifer Cypher
Small fires […] smoldered in half a dozen places, where the few workmen paying oakum into Hampshires hull seams with ravehooks' would periodically repair to warm themselves.
2014, Laura London, The Windflower
But the ship's carpenter had cut his hand open on a ravehook while cleaning out some old caulking on the fo'c'sle, and Cat stayed aloft to attend him.