Reddit reviews Vaka: Saga of a Polynesian canoe

I don't own Oliver's book, but he may have been talking about a large proa, not a catamaran. This is a pretty good book about a very large proa, written as a sort of historical novel.

Big proas don't experience the same stresses as big catamarans do, so they can be much wider, and thus quite fast. The boat in Vaka could probably do 20 knots under sail.

>What was the point of these canoes? Why have them instead of fleets of smaller canoes? Wouldn't the loss of one in a cyclone a terrible calamity compared to the loss of two, three, or even four little canoes?

All else being equal, longer boats are faster, roughly in proportion to the square root of the waterline length. A 100' proa would be about twice as fast as a 25' proa. This is an enormous advantage in a sailing conflict, of course.

Vaka goes into quite a bit of the tradeoffs of such a large boat.

The way I'd been told it as a kid growing up, the Tongans were the boatbuilders, with Samoans teaching navigation, and with the help of resources provided by Fijian chiefs (read large trees provided from Fiji's then pristine primary forests). That the halfway point here for this tripartite meeting were the Lauan islands where the people there today continue to reflect their mixed inheritances from culturally (the people can speak both Fijian and Tongan and their house construction mirrors the Samoan styled fale than the bure.
The numbers of 500 and 600 might be an exaggeration by European sailors of the time, Cook observes numbers of 200+, his surprise being more that these larger Vaka were agile and able to match speed with his ship than the passenger numbers.
My laugh about the numbers bit is that for those 600 islanders back in the day, that would probably be the equivalent of maybe 50 regular Samoan bros today 😂 (it's ok I'm Samoan myself).
Tom Davis' book Vaka (https://www.amazon.com/Vaka-Polynesian-Thomas-R-Davis/dp/9820101204) refers to the use of large double hulled boats as being the ferries of the day, transporting people and goods across islands and countries of the day. Their sailing schedules would of course be mapped to a seasonal calendar to when winds changed to prevail in one direction over another.