Prop shaft runout

[rmjohns]

I've been looking through here on how to determine if there is too much runout out in the propshaft. I've seen reference to removing the shaft from the boat, which I think in my case is going to mean cutting the shaft at the coupling which somewhat removes the concern on runout.

With the boat on the hard with an inexpensive runout gauge, I can measure about .008 just mounting the gauge against the middle of the shaft where it exits the boat and rotating the shaft by hand. Not sure how valid a measurement that is though.

Prop shaft runout

It did have a little shake, but I can't tell if that's normal diesel shake or shaft wobble.
Running Diesel

Thought I'd query the collective.

Rob.

[Ron Hill]

Rob : Was your "dial Indicator" measuring the shaft - half way between the transmission coupling and the front of the strut?  Also the hull is somewhat warped on jackstands - that's why you don't tune the rigging or have a final engine alignment on the hard!  If it was, I wouldn't think that .009 " is much "out of round", but I have no way of confirming my guess!!

A thought

[Kyle Ewing]

Rob, How is the shake when you run up in idle vs. in gear? Things change when you put the boat in the water so plan to get close on the hard.

[rmjohns]

Thanks guys..  I do feel like I noticed a vibration of the type where it wasn't really noticeable at 1000 RPM, but I would notice it as 1200 and then it would smooth out at 1500. It wasn't so much that when asked my wife said she noticed it, so it wasn't like the boat was shaking apart.  I did find a notch in one of the leading edges of the propeller blades (It's a 2 blade now) and I already have a 3 blade Campbell sailor to install, so maybe I'll leave it for a season and see how it feels with the new prop.

Rob

[Ron Hill]

Rob : It would seem to me that the "out of round" should be worse the higher the RPM !!

If the vibration gets worse at a higher RPM but then smooths out at even a higher RPM, I believe that you are dealing with engine vibration rather than shaft vibs!!  My guess

A thought