I'm talking small boat, where the helmsman is the person in charge. But you have to decide who's making the decisions at 0200 when a blip shows up on the screen. If it's the person down below, fine - go PC. If it's the guy at the helm, he/she needs the radar info available topside.
I'm talking about a 30' boat with a crew of 3 - person off watch is sacked out below, watching dreams. Backup person is huddled under the dodger, hood on foulies turned up, trying to sleep. That leaves #3 to drive, navigate, and watch the radar. Autopilot does most of the driving, but having the radar down below makes no sense in this case.