I have an Islander Bahama 30 with a Volvo Penta MD7 engine. I've noticed that I hear a chirping sound after it is warmed up and I'm in gear at low RMPs, usually when returning from a sail. I don't hear it when running above 1000 RPMs and it only happens at the end of a sail when I'm returning to the slip and things are warmed up. If I put it in neutral, the chirping stops. If I'm in reverse, it stops. Any thoughts?