On the way back from the seal hunt ambush, everyone is stuffed full of unfortunate seal hunters. Some are just stuffed more pleasantly than others.
Unlike Selene, Ronas can't just willy-nilly digest things like boats, and though he'll eventually regurgitate the boat minus its passengers, there's plenty of assorted junk on board that will have to leave his body the hard way.
The lesson to be learnt is don't swallow a boat unless you don't mind passing things like oars and life rings. 83