"Those of us who do fly across water should know before hand what is the best way. It's a bit late to change your mind when you get close to the water."
That's exactly it though Pulse, I think this question having been raised shows exactly the opposite, that most of us in actual fact have opinions to go by but no definitive answer. I know I for one have thought about it, as I hope most PPL's who have ever crossed water have.
Still not sure I know the best way, whichever looks the "safest" at the time given the conditions etc I guess is the best answer, and if it came to it, I don't think science would come in to play too much anyhow, more a bit of luck perhaps.