I just got a humminbird 596cHD DI and the transducer that came with it is for transom mount. Humminbird said that they would exchange it for a shoot thru hull transducer. This was what I had when I bought the boat back in 1995. I am kind of Leary about drilling holes in my boat, so I am thinking about the shoot through hull one. My question is, is there any difference in performance between the two, one being in the water and the other through the hull. This is a nice unit and I do want to get everything it offers, and yes I have joined the 21st century when it comes to electronics.Thumbs Up