Bob, you don't need water in the tray. there's not another bassboat out there with an epoxied transducer in their bilge that keeps water in the bilge just for the transducer.
Now I'm sure the Elites that fished st Claire recently may agree that a bit of water in the bilge is nothing compared to the waves washing over some of their boats during that tourny!!! I thought Chris Lane was going to swamp his Legend with all the water he took over the back of the boat.