“Whiny” Prop Shaft

[Boppy]

Aside from my recent tale of woe about the missing rudder, when I had work done on the prop and rudder stock in 2019 (after I finally found “that rock” after 40+ years on the same lake) I started noticing a “whine” or harmonic ringing from the prop shaft at around 1400-1600 rpm in forward. Thinking it might be the result of work done on the prop and shaft after it was removed, trued and replaced. Any ideas?

[captainmaniac]

If shaft was not truly straightened, that could be an issue.

Engine / shaft / stuffing box / strut alignment... if your collision pushed any of that out of alignment, could also result in that. Had an issue for a couple years where one shaft seemed to have a harmonic drone when rotating at a certain speed, but not others.... eventually found stuffing box nut was cross-threaded, meaning it was not fully aligned with the shaft and was at a (very slight) angle compared with it... causing enough extra friction to cause the drone sound. Once nut was undone and properly reset, no more issues.

So again , alignment of stuff post collision could be worth looking in to.

[prowlersfish]

I agree with captainmaniac. Also, check for a bent strut. could the whine becoming from the trans or engine? One other thing Did you use prop speed on the prop? I have heard cases of it causing a whine.

[Boppy]

Thanks for your advice. I’ll get things looked at either before haul out this year or after haul out next year. Methinks it’s a strut issue but I’ll check the stuffing box nut. Right now, with no rudder, the boat’s not going anywhere….or maybe just in circles in reverse (prop walk to port). FUN TIMES!!