On Stranger Tides was the first book I read by my friend Tim Powers. I did it to familiarize myself with his work before going to a workshop where he taught in 1989. It's a good book.
I'm delighted to hear from him that the title of the new Pirates Of The Caribbean: On Stranger Tides film is no coincidence: it is indeed based on his book. Word is that the fee they paid can support him him for 3-4 years. And like often happens, I can't imagine that very much of the book has made it into the film, Tim's books are simply too... thoughtful, very little of them fit for today's Action-Is-King Hollywood world. So from one viewpoint, Tim gets the best of both worlds, he got the money, and they don't ruin his book because they are making another film basically.
Of course the eternal mystery is: what are they thinking? Why does Hollywood pay writers very, very handsomely to buy rights to books, and then change the story beyond recognition? It's like buying a house because you really like it, and then tearing down most of the walls and changing the layout totally.
Tim himself tells me:
"It differs entirely from the book except in having Blackbeard and the Fountain of Youth in it. Not the way I pictured the F of Y, either!"