Here's a puzzling thought: if the boat he is currently floating about in is not the same boat in which he and his father went fishing, so long ago, it is nonetheless an exact copy. Where is his father? He attempts a little trick he had learned to do with dreams. When he was a teen-ager, he had realized, in the middle of a dream, that he could make the dream into whatever he wanted it to be. He was, after all, in control. So, when he dreamt of falling, he could decide to land in safely on his feet. When he dreamt that someone was chasing him, he could have them turn into stone. Or simply stop existing. Now, in order to do this, of course, he realized that he would have to become aware that he was dreaming. This was the key. He would also have to believe that he was dreaming, which was tantamount to not believing in the material reality in which one were, apparently, functioning. He attempts to see his father in the boat.
But this doesn't work. He cannot convince himself that he is dreaming.