Prop noise at high engine RPM?
Posted: Fri Jul 28, 2017 4:18 pm
Our J/109 started making a strange noise at high engine RPMs. The mechanic sea-trialed it today, and came back with a few thoughts, and I am curios experience of others.
He said the engine and sail drive were fine. He though the cavitation / vacuum noise might be coming from the prop. I believe the prop is original to the boat, but I can't be 100% sure. It is a two-blade folding one. I also had the diver last week look at it, and he seemed to think it was fine.
The mechanic thinks either the prop is "wrong" for the boat (too small, pitch too low, not enough cup) or the prop is slipping on the shaft. His reasoning for this diagnosis is that the engine goes to 4200 rpms at full throttle. He thinks it should only go to max 3600 rpms.
Just curious, on your J/109 what is the max rpms of the engine at full throttle? Do you have the original prop?
To be clear, the boat has not done this in the past, and this sound is new, so I doubt the prop is wrong. I have never heard of the prop slipping, but maybe?
He said the engine and sail drive were fine. He though the cavitation / vacuum noise might be coming from the prop. I believe the prop is original to the boat, but I can't be 100% sure. It is a two-blade folding one. I also had the diver last week look at it, and he seemed to think it was fine.
The mechanic thinks either the prop is "wrong" for the boat (too small, pitch too low, not enough cup) or the prop is slipping on the shaft. His reasoning for this diagnosis is that the engine goes to 4200 rpms at full throttle. He thinks it should only go to max 3600 rpms.
Just curious, on your J/109 what is the max rpms of the engine at full throttle? Do you have the original prop?
To be clear, the boat has not done this in the past, and this sound is new, so I doubt the prop is wrong. I have never heard of the prop slipping, but maybe?
