According to the brief history of Australia on the Australian government site, Aussie history
transportation of convicts ended in 1868, and the colony became part of the Commonwealth in 1901.

It seems to me that the aspects of nautical history that interest you all belong to the period 1860-1890. Why not set your story then instead of c. 1900, which is the Edwardian era (think Titanic, not Two Years Before the Mast)?