I had some trouble using a Sidescan Hummingbird Helix 5 SI on my Pescador Pro 120. When a sidescan transducer is mounted in a built-in transducer mount (in hull), the sides don't have a clear line of sight and therefor can't scan left and right. The arm attachments will work, but that's yet another attachment I need to take on and off every time I go. Also it gets clunky when paddling. Instead, I built a transom mount out of a piece of aluminum I bought from Home Depot. Using a step drill bit I drilled countersunk mounting holes, then mounted it to my rudder hardware. Aluminum is very easy to mould, I used a vice clamp to get it into the desired shape. It works great in this spot, no complaints. I do get some feedback when paddling though.