Hey, w2f4- I have twin counter-rotating outboards, and my transducer was factory mounted at Boston Whaler. It is a transom mount navman that goes with my unit. It's funny how you mention problems near the RR bridge, because I always lose signal there. I don't get snow or interference, I actually get large gaps in any bottom readings whatsoever. The GPS part works great, although my first 6000i had to be replaced under warranty as the GPS would lose signal. In the ocean, more than 10-15 mph and I start getting crappy bottom readings.I hear of guys on their way to a spot and they pass some fish, so they stop there. Unless I was going like 5-10mph, I could never do that. Also, my pixels will get real large like cubes at times. Very frustrating. I have already changed the transducer, brain, and the cables. It may be the actul unit which would suck as I will be without it for a few months while Northstar fixes it.