Hello Cliff. I've recently flown over water with my P4. I couldn't tell any difference, other than a better radio signal if your on the Bank or shore. The reason I received a better signal for me was due to no obstacle between me and the UAV. Usually I fly from a heavy canopy of Forrest that my Drone pops out of, I'm down on ground level. This is sometimes a signal problem, but over water the signal is nice and strong, low flying not a problem, I usually stay in sport mode until The UAV gets really close to the water than hit P mode for the gain reductions