I have an 89 Ranger bass boat that I've upgraded to a newer depth finder and put the sensor in the same location as the previous owner had it, on the back of the boat on the drivers side, pretty much how the manual showed it. I notice that I get a decent sized rooster tail on that side of the boat that I'm confident is from the sensor. Is this normal? Should I have went with the in hull reciever instead? I also notice that at speeds higher than 30MPH it doesn't even pick up any type of fish, not sure it that is also normal.