Probably not; it sounds like you simply have a bad ground or a flakey connection somewhere. To find out for sure, run temporary leads from the battery directly to the radio. I'll bet the screen stops fading, and other boaters can hear you without a problem. If it does and they can, you know your radio is fine and you'll need to chase down the glitch in the wires. Check all connections to make sure they're clean and tight; replace any that show corrosion or weakness.