be lost at sea

1. Literally, to have disappeared while aboard a boat or ship on the sea. Can you believe that guy survived being lost at sea for a whole week? The doctors say he's in pretty good health too, miraculously. A heavy depression lay upon him for weeks after discovering that his father had been lost at sea. The more time passes, the more it seems like their loved ones are lost at sea.

2. To be puzzled, perplexed, or completely confused (about something). I tried to do well in this class, but I've been lost at sea since we started. I'm lost at sea in this new job of mine. I've never been responsible for these kind of contracts before. Bill is lost at sea because of this calculus problem. Can you help him?