Definition of "marlinspike"

[…] the afterguard, of whom they have but a sorry opinion, chiefly landsmen, never going aloft except to reef or furl the mainsail and in no wise competent to handle a marlinspike or turn in a dead-eye, say.

1924, Herman Melville, chapter 12, in Billy Budd‎, London: Constable & Co.

There was / that interval of moonless calm filled only / with the water's and the rigging's usual sounds, / then sudden movement, blows and snarling cries / and they had fallen on us with machete / and marlinspike.

1962, Robert Hayden, “Middle Passage”, in David Lehman, editor, The Oxford Book of American Poetry, Oxford University Press, published 2006, page 585