Anne
That's a great site that you gave us! Wish my Irish were convicts - I'd have a lot more information about them (sigh!) (Didn't know the Dublin 1911 census had gone online. Trouble is, I have no idea if any of my Huband Smith family were alive and living in Dublin then, so not much use to me!)
In general, if you have convicts who were transported to Australia, there is a large amount of information about them, here and often in their country of origin. The same can't be said for sailors on the ships that brought them here! I can't find any information about the brief naval career of the Joshua Bentley I suspect is my ggggrandfather, so can only claim him provisionally.
MarieC