Shaft Vibration. Could the propeller cause this?

[joyfull]

New Beta 43hp installation on a 43ft sailing boat. There is visible shaft movement at the through hull fitting with vibration.

I am concerned is is improper alignment of the engine and coupling with the shaft.

The installer says the alignment is good and thinks it is the Autostream (expensive Australian prop) feathering propeller that is causing the shaft movement.

My question is it possible if the blades are not correctly adjusted and balanced (they can be adjusted to different engine torque etc) that the propeller could cause the shaft to wobble?

 

[Refueler]

Anything that shaft is connected to if not set correctly can lead to shaft movement / vibration.

My 4-99 drove me nuts and I huckered down into the shaft bilge - sure it was stern seal / cutlass ....

Finally had boat lifted and it was engine mounts shot .... new mounts and she was sweet as a baby.

I note you say new installation - has the movement been there since first run ? Think a serious check of alignment of mounts / engine / shaft and set of prop ...
Prop could cause it IF blades not identical in set. But to 'wobble' ? That implies serious movement ....

Its not something to skimp on I'm afraid.

 

[Graham376]

If the shaft runs out (prescribes a small arc) at the stern gland when running at tick over, it's most likely out of alignment or bent. If you have R & D coupling, easy enough to check the alignment with a feeler gauge - RandD_Shaft.pdf (randdmarine.com)

 

[Supertramp]

If the shaft runs out (prescribes a small arc) at the stern gland when running at tick over, it's most likely out of alignment or bent. If you have R & D coupling, easy enough to check the alignment with a feeler gauge - RandD_Shaft.pdf (randdmarine.com)[/URL

I had some similar problems after getting a survey on my recent purchase. Surveyor noted cutless wear and play and advised checking alignment. The end result was to realign the engine with new beds, add a new flexible coupling after the gearbox and of course new cutless bearing. The installation was 12 years old but low use and had retained the original 30 Yr old flexible coupling which was knackered and was the root cause. So check anything that was "reused" in the interest of economy.

 

[Slowboat35]

I have a similar problem with a new Beta 35 installation using a Featherstream. General vibration (we've already changed the geabox under warranty) and high noise levels. Can't seem to get to the bottom of it.
Incedentally I was advised to retain the probably 30 old flexible coupling (as an economy measure) which is a big aluminium hemispherical thing the size of half a melon... I wonder if that's it. I had been wondering if the Featherstream was being affected by turbulence from the keel aperture (long keeler) but perhaps there's one more thing to eliminate before ditching it and returning to a fixed blade prop.

Here it is on the old Yanmar. What is it? Anyone know it's reputation or details? What does the team think?

 

[Supertramp]

I have a similar problem with a new Beta 35 installation using a Featherstream. General vibration (we've already changed the geabox under warranty) and high noise levels. Can't seem to get to the bottom of it.
Incedentally I was advised to retain the probably 30 old flexible coupling (as an economy measure) which is a big aluminium hemispherical thing the size of half a melon... I wonder if that's it. I had been wondering if the Featherstream was being affected by turbulence from the keel aperture (long keeler) but perhaps there's one more thing to eliminate before ditching it and returning to a fixed blade prop.

Here it is on the old Yanmar. What is it? Anyone know it's reputation or details? What does the team think?

Beyond my expertise, but look for any play in the "melon" where the shaft exits. I had a choice of fixed 3 blade or Brunton folding prop and chose fixed partly because simple appeals and I am not looking for extra speed (long keeler). End result is smooth and quiet and hopefully remains so for many years. If I develop a problem I would look for slight play either end of the propshaft allowing oscillation and vibration to develop.

 

[Neeves]

And a dirty prop will cause vibration. How long has the yacht been sitting idle.

Jonathan

 

[Slowboat35]

Brand new prop. Polished shiny clean.

 

[Bilgediver]

New Beta 43hp installation on a 43ft sailing boat. There is visible shaft movement at the through hull fitting with vibration.

I am concerned is is improper alignment of the engine and coupling with the shaft.

The installer says the alignment is good and thinks it is the Autostream (expensive Australian prop) feathering propeller that is causing the shaft movement.

My question is it possible if the blades are not correctly adjusted and balanced (they can be adjusted to different engine torque etc) that the propeller could cause the shaft to wobble?

Is the shaft to gearbox coupling a flex type or ridged? If it is ridgid then like a pal of mine you might have an unusual problem which luckily we discovered at installation during the completion of a sailaway Hunter 32.

What we discovered and heaven knows how the manufacture achieved it was that a shaft coupling had been supplied with the face of the flange not at 90 deg to the shaft axis. Fortunately when checking alignment and my pal confirming all was fine I suggested he turn the shaft 180 degrees and check again. The alignment was way off. We were both surprised. A replacement appeared PDQ from the vendor who did not believe us.

To check yours just slacken off and remove the bolts from the shaft coupling and check the flange with a feeler to conform it is face to face. Turn the shaft 180 degrees and check again. If the reading changes then the flange face is not true and when bolted up, the end of the shaft will try to waggle around.

Highly unlikely it is this but worth checking.

 

[gordmac]

Was the alignment done ashore? Depending on how the boat was supported and the hull stiffness the alignment could be out due to the boat changing shape.
How old is the cutless bearing?