Same here (GT51M-TH ) - mounted on the keel on my 330 Express, right between the generator and AC thru hulls. I also have a big Airmar B175HW which I use 98% of the time as it has much better resolution. Most of my fishing is quite deep and not on structure, so I haven't found the sidevu or clearvu all that useful, but I also don't tend to watch them much so I who knows what I'm missing!