Keep an eye on the sailing and more particularly cruising clubs. There will be many boats leaving from North Queensland for the journey across the top to Darwin via the Gulf of Carpentaria. Once in Darwin, you will firstly find the world's finest small city, and you will find there are many boats massing for the various rallies from Darwin through south east Asia. If you're a decent person, you shouldn't have too much difficulty in finding a berth on a sail boat heading north. Make sure you post your desires on club noticeboards, and best of luck.
"if at first you don't succeed....Redefine success"!