I feel that there is a major factor that nobody takes into account when modern people set out to replicate possible ancient voyages ("Erectus Ahoy," SN: 10/18/03, p. 248: Erectus Ahoy). It is that they're attempting to get from point A to point B, which they know exists, but ancient seafarers weren't. Setting off from Timor on a 600-mile voyage without knowing whether there is any land out there seems like a terrific leap of faith. Even sailors in the Middle Ages were scared that they were going to sail off the edge of the world. Surely, Homo erectus would be.
Researcher Robert G. Bednarik says that from Bali to Timor, Stone Age seafarers could see across each sea barrier to the next island's shore by climbing volcanic outcrops. He suggests that these experienced mariners also recognized indirect evidence of Australia, such as bushfire smoke