Im the gm, and ran it with the idea of 3.5 capsize in mind where a boat would flip over, but stay that way for a while, giving the players plenty of time to find a way to flip it over and/or heal it.
If someone can find where Pazio defined capsizing, I would appreciate it.
Also, just a heads up, but I dont run this encounter as a boat killer...
Ive always allowed players to just heal the boat a bit, do some engineering rp, and flip it back over.
Id 100% like to know the RAW, because the players deserve to know it, but honestly, I like the idea of it being able to be righted with some ingenuity.
Thanks for the responses.