Remember that the boat (called the Ra) was sailing to a place it knew existed. The boat was not chartering through unknown territories and sailing away from its homeland (a very unegyptian thing to do). Australia is a pretty long way away from Egypt, further than Iberia and America, and that took until 1492! IF there was a storm and it POSSIBLY was powerful enough to drive them all the way to Australia and they HAPPENED to have about nine times the amount of provisions they would need, as well as MIRACULOUS amounts of rain then it isn't IMPOSSIBLE. I will admit that it MAY have happened, but I really do doubt it.