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67rway

Prop Sing

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67rway

I recently had the misfortune of having to get my Acme prop straightened. Long sad story made short, I have seemingly nicely balanced running gear that's aligned to specs, but each and every time I drop it in forward gear there is an audible singing/ringing sound that I'm told is from the prop, caused by the polishing off of the CNC finish on the dinged blade. The sound is only present for 3-4 seconds, but it is quite annoying. :(

If memory serves this has been mentioned on the old site previously, but I've been unable to find out what folks do about it (short of a new prop).

Does anyone know of any tricks to fix/alter this?

Thanks in advance!

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andyb

Buy a new prop and keep the repaired one as a back-up if it is a big worry.

I too have had similar misfortune, usually combined with non boating people onboard, leaving you to be skipper, ropey, fender and everything in between. I have also picked up slalom/jump course magnets a couple of times and the damage to props is quick and final.

So called expert prop repairers usually get a close result but never like out of the box.

The last repaired prop was 1.5 km/h out on rev based speeds on the slalom course; something that could be worked around by recalibrating Perfect Pass, but when I put a new replacement on, I had to recalibrate it again.

Such is life with soft nibral props I guess.

Edited by andyb

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88Skier

One draw back to CNC props is that they don't repair as well as the regular type does. I'd get a new prop, especially with a new boat.

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MIKEGOUGH1

I damaged a brand new Acme 13 x 12.5, 4 blade after less than a month. What a terrible feeling. I sent it back to Acme with the hopes of like new repairs. Not so, it is close, but I get some top end vibration that I did not get when new and I do not get with my other 4 blade Acme. So now my new Acme is my backup. Expensive back up, but what can you do. There is a place in Pensacola, Fl. that claims they can fix it for me. I'm not sure what they can do that Acme could not, but the say their computerized machine with get it back to factory specs. I think I may spend the $95 and give them a try. I'm so far in the hole with it now, what the heck.

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Skiier64

I had the same singing problem so I called Acme and they told me to file the trailing edge of the blades flat and that would fix it. I took the prop off and used a file to make to trailing edge flat and now I don't hear it any more.

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whiteVLX
I had the same singing problem so I called Acme and they told me to file the trailing edge of the blades flat and that would fix it.  I took the prop off and used a file to make to trailing edge flat and now I don't hear it any more.

Exactly! I have the email from acme somewhere, I'll dig it out and post the instructions. IIRC they told me to place the prop upside down on a bench and file the prop so that the edge was perpendicular to the bench. Don't quote me on that, like I said I'll go find the email.

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whiteVLX

I found it.....I have the contact email and phone if anyone needs I'll PM it to you.

Hi Steve,

Most of the time the cause of that high pitch wine, or what is generally referred to as "sing", is due to the trailing edges of the prop not having square (or, in other words, sharp 90 degree edges). More specifically, if you place the propeller on a table, with the leading edges of the propeller down on the table, and the tips of the prop up (or, in other words, the trailing edges of the prop are up). The upper most edge should be sharp ----

not rounded off. In other words, the edge formed by the trailing edge of the blade and the top surface of the blade (or the pressure surface), should be very square or 90 degrees ---- not rounded off.

This problem can be corrected with a standard metal file run along the trailing edge of each blade.

(Note, to help clarify this explanation, and that which you want to

accomplish: It is acceptable for the leading edge of each blade on a propeller can be a more sharpened knife-like edge, but the trailing edge of each blade should be more like what you have when you cut a rectangle in half, verses "U"-shaped, which is what you do NOT want, and which is most likely what is causing the sing that you have now.)

If you need further explanation, please feel free to call us. And if you feel uncomfortable trying to correct this issue yourself, you are welcome to send the propeller to us, and we will correct the issue.

Sorry for the inconvenience.

Thank You,

Jim Thelen

Sales Engineer

Acme Marine Group

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