Seriously, this was one of the first episodes. The professor made some type of super glue, but before he was fully able to test it Gilligan used it on the Minnow and it was, as Monty Python might say, an ex-boat.
That's funny, as they used to show the wreck of the Minnow in the Intro of every show. I must have missed that episode you mentioned. Either that, or it was very forgettable.