Phil Christieso
Junior Member
- Joined
- Jun 1, 2016
- Messages
- 83
- Reaction score
- 4
- Location
- Nelson NZ
None of the above. The rumble comes from the stern bearing and is a totally different sound to the prop noise. The rumble stops because the alternator load on the pulley acts as a third bearing, maybe inducing some side load, dampening the bearing noise from the cutlass. The prop noise is reduced because this stops the prop attaining the higher rpm which causes the prop noise. That's how simple it is.