I got my Phantom Vision 2 for Xmas, and I now have about 15 flights under my belt. 10 of the 15 flights have been over water, but always using GPS mode while I control the Phantom from land. I have had no issues, and the Phantom has worked properly every time. I would like to go out on my boat and fly the Phantom around the boat as the boat moves thru the water like I have seen in some of the videos that are posted, but I would like some advice on the S1 switch position. Under these conditions, I assume GPS mode does nothing for you. Do I need to fly the Phantom in Atti or manual mode? Should I let the Phantom lock on to the GPS satellites and flash green lights before taking off, or does this even matter. Should I practice flying in Atti and manual mode first to get the feel before trying. This maybe a fairly straight forward answer, but I thought I would ask before trying it out. Thanks joejoda