I have a Hunter 430, 1996 well maintained in very good condition. Took boat out today, sail with perco switch on "1" selected after turning engine off). Put it back on "all" before starting the engine. (Have a separate perko switch that was on "on" for the starter battery.) Boat wouldn't start. Soon after, alarm on nav station goes on (louuud alarm). Engine finally started running, seemed ok, no fire or anything visible, temp on engine ok, batteries reading 14 volts, pressure normal. I thought it could be one of the instruments so I turned all instruments off. Everything on nav station was off and the alarm continued. After a few minutes of running the engine it went off. What in the world was that!!! I don't even know where to start to look. Any help greatly appreciated. (We have a second bilge with alarm but the bilge was dry. Is there an alarm for anything behind the nav station? Thanks for your input.