And I guess you're stupid for getting lost in a place you've never been to.
Exactly, a bunch of teenagers shouldn't be going out to sea like that- unless of course they had no clue what they were doing. In that case they were ignorant, not stupid.
However, surviving fifty days on the open oceans shows extreme knowledge of survival, but definetely not navigational prowess. In this regard, I conclude that they knew how to sail, and made really bad decisions- hence stupid.
-Penguin