Well, I haven't mounted it anywhere yet but I can't believe I am going to have any problems no matter where I put it.
I was in my attached garaged that has a room above it and the house on 2 sides, the other side is fully insulated and drywalled. The front has steel doors that were closed. There are no windows.
It was raining so I didn't pull the boat out and it still had great reception!!
Just need to decide if I want to drill a hole through the dash and leave it there or run the speakers around to the rear nav light and mount it on the gunwale at the back of the boat.
It's too bad the plug doesn't disconnect and you just had to deal with making a hole for the small wire....