Propellor Ring

[Ray & Sandy Erps]

I haven't seen this symptom listed here yet.  We just replaced the cutlass bearing and had the propellor tuned up (balanced and pitch corrected so they're all the same).  The propellor makes a ringing noise above 2200 rpm now.  At first I thought maybe it was the cutlass bearing squealing a bit, but it's a ringing noise, not a squealing noise.  I recollect being on a power boat several years ago that had new propellors put on and it made similar ringing noise.  I figure it will go away as soon as it grows a baracle on one blade but in the meantime, it kind of bugs me.  I teased the wife and told her I was going to jump in with a hammer and put a ding in one blade to see if that makes the noise go away.

Anyone know what that's all about.

[Ron Hill]

Erps : You need to inspect the prop blades.  I've heard the prop noise can be attributed to a "sharp" leading edge .  Take a file and "square" off the edges of the blades and see if that doesn't help.  

[Craig Illman]

I'll bet a dip in Swinomish channel in your Speedo to do that filing will be quite refreshing!! or is your boat up in Anacortes?

- Craig Illman

[Roc]

I had the same ringing on my prop years back, and was told it was because the blades were 'too sharp'.

I recently had my prop reconditioned by Black Dog propeller.  I asked them about the ringing to see if they would need to do anything different to alleviate it.  They told be it's because the blades were out of balance.

Now, the ringing on my prop happened AFTER it was reconditioned the first time (this is going back years ago), and I just let it go, since it goes away after some slime accumulates on the prop.  Being out of balance as the cause didn't make sense to me.....but.....I did learn from Black Dog that you are NOT supposed to block the prop when reinstalling it.  You will throw the blades off, after you just had it reconditioned!!

So, this past spring, when I installed my prop, I did not block it and just took Ron's suggestion in holding it with my hand to get the nut tight.

The ringing is now gone.

[Ray & Sandy Erps]

Craig,

I keep her in Shelter Bay off Swinomish Channel.  I think Swinomish is Salish  jargon for "current going the wrong way".

I have to work the next two weekends, so I think I'll wait and see if the props sliming up takes care of it.  Otherwise, I'll take the wet suit along next time we're out and try squaring off the blade edges.   That will be a little more subtle then my original hammer idea.

[Jeff McKinney]

I believe the problem is a variant of cavitation induced by the "too sharp" blades as previously noted. The air bubbles form around the blades (much as when going from idle to full speed too quickly) and the blades start vibrating inside the air pocket that forms around them.

I don't have anything to offer that hasn't been said to solve this. Good luck.