I've been researching Polynesian navigation recently so can clarify in summary (from memory!) with hopefully relative accuracy.

Most of our knowledge regarding pre-modern navigation in the Pacific comes from very few locations with traditions that were still survived relatively intact in the late 20th century, at the time westerners (mostly Aussies/Kiwis) took an interest. That lead to a sort of not-very-accurate lets-port-it-to-Hawaii US-funded rah-rah, but the fact is that all different island groups had their own navigation traditions. The one we know most about is from Poluwat, in the Gilbert Islands, which are part of Micronesia, east of the Philippines and some distance north of Papua New Guinea.

There the layout of the islands was mostly east-west, though some voyaging did occur north/south (eg. raiding of northeast PNG) the celestial knowledge used and preserved was heavily weighted for east-west navigation within this part of the ocean. People respected the season and did not depart without the blessing of elders - those experienced in the patterns of weather, who could best judge seasonal dangers.

A great resource for learning more about the early Pacific cultures is the Journal of the Polynesian Society, whose issues are almost all online and searchable courtesy of Auckland University @ http://jps.auckland.ac.nz/

It is incorrect to generalize about boat designs, since they were very different in different areas. For example nearby in far eastern PNG there were huge crab-claw sails (the most efficient form of sail in the world, according to the only(?) published serious physics expert that appears to have done wind tunnel tests and devoted his career to such investigations, Mr. Marchaj) on the craft known as Lakatoi. There is a fair list of pre-modern Austronesian lineage craft @ https://en.wikipedia.org/wiki/List_of_multihulls#Pre-modern_...

Most of the pre-modern navigation information we have relates directly to https://en.wikipedia.org/wiki/Wa_%28watercraft%29 - a recently front-page featured article mostly written by me from scratch.

There were however two main waves of peopling in this region, the first with the Aboriginal Australians some 60,000-40,000 years ago (recently affirmed by more genetic studies: nearly the whole world received peoples at this stage) and a later re-hash with a new genetic population perhaps 10-15,000 years ago. Following that, a sort of hybrid neo-culture called Lapita took pottery, obsidian and other technology and pushed the peopling out to further islands, ultimately resulting in the Polynesian world, which is very young (many islands peopled less than 1000 years ago). Survivors of the very first wave are known under various names across Asia but are typically darker/more negroid looking and there are pockets in northern Malaysia, lots of islands, coastal Vietnam, eastern India and Burma, southwest China, etc. Some became sea-dwelling peoples ("sea gypsies") in the Philippines and southern Burma, so their connection with voyaging cannot be denied.

The key innovation was the invention of the multihull, which is undoubtedly Austronesian (a branch of the earlier migration, who moved to Taiwan, then came south down through the Philippines, spreading west as far as Madagascar again, and east as far as South America according to recently published genetic evidence, see https://en.wikipedia.org/wiki/Pre-Columbian_trans-oceanic_co...). Various studies place the biggest variety (3-hull trimaran type, 2-hull type, sail types) and temporal location of the initial development circa the Philippines, though there has been some suggestion that coastal Vietnam (probably around the northern portion, near Haiphong on the Red River delta and Halong Bay) may be the true home. In any case, we have solid documentation of multihull voyaging in stone images on Sumatran temples by ca. 1000 years ago.

One of the best places in the world to see some of these original full scale watercraft preserved is the ethnological museum in Berlin... don't miss it if you visit.

Amazing world out here :)