I have a fish finder on the bow of my boat with the transducer mounted on the trolling motor. Nice for staying on top of a crappie brushpile, but pretty useless for finding new areas to fish. I am going to put either an Eagle 480 or a Lowrance x 135 on the dash and wanted to know about mounting the transducer back on the transom area of the boat. It's an aluminum boat and I wanted to see if I should drill into the boat and if so, what do you use to keep the holes from leaking (silicone??)... I believe I've also seen where someone glues a cutting board to the transom area and mounts the hardware on that to keep from drilling into the hull below water level? Any advice or ideas would be appreciated..