This past Sunday I found a bunch of corrosion in the connector for my Garmin EchoMap 50 and could not get the unit to power up after cleaning the plug as best I could with with corrosion x and a wire brush. Apparently my leaving the battery switch on overnight with enough residual salt from all the spray I took on Saturday was enough to corrode the positive terminal. I guess the lesson learned is to either wash the boat off with fresh water every night (tough away from home or car wash), leave the connector attached, or flush mount the unit so the connectors are inside the console. AND turn the battery switch off to prevent the salt from forming on the positive terminal. New cable is on the way for $30.