I took my new to me '89 Bayliner Cobra with a 150 Force out on the lake to familized myself with it's operation. Cruised up and down the lake for about 1/2hr, boat handled well and motor purred great. While idling back to the ramp, a buzzer alarm sounded for about 5 seconds then stopped. I'm thinking that this alarm is associated with the motor? What's the alarm for and what do I need to check?