"Big H" and I have been mounting our transducers on PVC pipes attached to our crates. I became annoyed by sound of water rushing around the pipe (sounds like a running faucet, or worse). I switched to using an aluminum angle bracket (from Home Depot), hammered closed on the wire to the transducer (see pic). It really works great! I screwed the angle bracket to a plastic plug at the end of a narrow black PVC pipe that telescopes inside another foot of pipe that is anchored to the crate using zip ties. We use a large pin through the two pipes to hold the inner pipe in the right position (distance out over the side and angled straight down into the water). I can easily pull the pin and swing the arm up beside the crate when heading through rocky water. I have recently discovered that I can use this system without a crate by wrapping the black tie-down cord around the PVC pipe. Our next step will be to find a way to store the battery in the front hatch, and maybe even mount the transducer up there using the same "down rigger." We mount the fish finder on a Scotty rod holder mounting bracket glued to the boat.
