I have a conceptual problem here, maybe you can help me. Suppose the distance was 1,000 meters. Your calculations are correct, of course - after 3 1/3 hours ship 1 is at 666 2/3 meters, while ship 2 is at 333 1/3 meters. But after 5 hours ship 2 is at the bottom, while ship 1 is half way to the bottom. There can't be two different solutions, so what is wrong with my logic?