Prop Shaft Squeal

With my head in the lazarette I can hear a squeal from the prop shaft. It only happens at low RPMs. The cutlass bearing is at least seven years old. Need to give it a good going over when we haul.

 The shaft RPM was 717.7 (as measured with the optical tachometer) x 2.57 reduction = 1844 RPM. About what the helm's electronic tach reads.

 An IR thermometer on the header tank reads a 180F while the helm's engine temperature reads 190F—about 10F high. I still suspect a bad ground in the helm. Need to run a larger gauge wire.