jackass A kind of heavy rough boat used in NEWFOUNDLAND.  Also, U.S. Navy name for a HAWSE-bag, a canvas bag filled with OAKUM used to plug the HAWSE-HOLES to keep seawater out.

jackass rig Any rig of  a sailing ship that substantially differs from the one normally associated with that type of ship.

– A Sea of Words : A Lexicon and Companion for Patrick O’Brian’s Seafaring Tales by Dean King with John B. Hattendorf and J. Worth Estes.