Today, running my crownline br 270 at 4200 rpm, 38MPH, i heard a misc. alarm, which was constant, it was not my depth sounder or garmin. I thought it may be my carbon monoxide detector in my head compartment, but as i slowed down to 8MPH the alarm went off. this is an bowrider and should not of had and carbon build up at that speed in forward cabin. I reviewed my crownline manual ( not much info there) and thought someone could give me some feedback on what other alarm it could be. I appreciate any feed back or thoughts on what i might check. Also noted that oil, temp and voltage gauges read normal. any other thoughts.