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Beta Marine Repower Solutions -> Beta Marine Engines -> Whine from new Beta 38 in certain RPM range
Post Info TOPIC: Whine from new Beta 38 in certain RPM range
Blue Moon


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Whine from new Beta 38 in certain RPM range
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Out running my new Beta 38 for the first time this past weekend, I noticed a higher-pitched whine that came up at about 2400 RPM and continued though about 3300 RPM. Below or above that RPM range, this particular whine diminished amidst all of the other engine and boat sounds. I have the TMC60A down-angle transmission, and I guess the whine could be coming either from that or the engine. Of course my old engine and transmission were very different, but I never before had such a whine in a particular RPM range.

Any similar experience or suggestions for diagnosing?

 



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Stanley


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Hi, this sounds like a singing propeller. The best solution is to ask the prop shop to an anti squeal edge on the trailing edge of the propeller blades.
Here is a link to one discussion on the subject www.cruisersforum.com/forums/f114/singing-prop-what-to-do-15445.html
If you do a search on the web, you will find many such discussions and some papers written on the same subject.

Stanley

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Blue Moon


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Thanks for the reference. Sounds like a variety of somewhat conflicting theories but most seem to ID the whine or tone as happening in a narrow RPM range, which makes sense for resonance phenomena. But my whine happens over a relatively broad RPM range and the frequency of the whine seemed to change significantly in amplitude but not in frequency as the engine RPM was adjusted, making me think it might be something other than a simple resonance or harmonic from the prop. I will contact the prop shop and get some feedback there, and will also make some acoustic spectrum measurements to pin down the frequency of the whine and try to relate that to the prop rotation speed (engine RPM/2.45 for me, right?).

May I'll also follow the advice of one writer in the forum link reference you provided, waiting for the prop to grub up just a bit!



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Sabre362


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We have a new Beta 30 that has the same issue. I thought it was because the installer had not used the flexible coupling, so I had our yard add it this season. Same problem. The whine starts from around 2200 rpm on up to our normal cruising speed of 2800 rpm and beyond. I am going to put an audio spectrum analyzer on it to get the frequency. The problem only occurs in gear, so it has to be somewhere in the drive train, shaft or propeller.

I also read the link to the singing prop...very interesting, but I don't think that is the problem.

 

 

 



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JilliQ


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I have Beta 30s in my catamaran and have the whine 2400 & up.
Had props "ground", no help, different props no help. Anyone get
a resolution? I'd really like to get rid of the whine.

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David Hough
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